First, the effect of detuning on squeezing of coherent light is studied by Jaynes-Cummings model in a large N (initial mean photon number) limit. Analytical formulae for quadrature variances are obtained both in one-photon and two-photon transition cases. These formulae show that the effect is quite different in these two cases. In addition, explicit expressions for the k-th minimum of the suppressed variance are given when k is fairly large, which obviously shows it tends to zero according to 1/k². Second, squeezing of coherent light field in a cavity by repeated interaction with atoms is studied. Numerical calculation shows the variance (delta) can be reduced by this process to a certain extent for suitably chosen interaction time t. But the squeezing becomes worse if the number of times K is too large. In the two-photon transition case, with a favorably chosen value of t, analytical formulae for (delta) (N, K) are obtained in large N approximation. These formulae show definitely that the least variance (delta) goes down when K increases up to quite a large value, and the achievable minimum value of (delta) ² is in the order of 1/N^1/2. Besides, the light field so obtained is nearly in a pure state with a minimum uncertainty product (delta) ₁(delta) ₂ equals 1/4.

Purcell's formula for the cavity enhancement of QED rates in terms of the density of states can be generalized to each position inside a cavity, and this local density of states can be explicitly evaluated for simple geometries such as a droplet. The density of states satisfies certain sum rules, which imply that when averaged over frequency and position, there can be no significant change of transition rates compared to the case of an extended medium.

In this lecture I consider the question of characterization of nonclassical light in terms of measurable quantities. I show that there are many situations where the usual methods based on the Q and S parameters fail and which call for new measures of the nonclassical light. I also present newer methods of producing nonclassical states of quantum systems.

The atomic response to resonant light irradiation near vapor-dielectric interfaces is monitored via high-resolution reflection spectroscopy. One demonstrates that this Doppler-free spectroscopic technique yields a novel probe of atomic dynamics and QED atom-surface long- range interaction. It provides for the first time a spectral evidence of van der Waals attraction, and the method is intrinsically applicable to the observation of surface interaction exerted on excited atoms. Effects related with atomic excitation level, nature of the dielectrics, and atomic collisions are discussed.

Active control devices have long been proven effective in reducing the fluctuations of various physical parameters, both in electronics or in optics. In particular, systems controlling the intensity fluctuations of a laser beam by opto-electronic feedback are now widely used to reduce laser intensity noise. Such systems, make use of a beamsplitter (B), deviating part of the incoming beam onto a photodetector (PD). The resulting photocurrent, suitably amplified and filtered, is then fed into an intensity modulator (IM) which corrects the intensity fluctuations of the output beam. The correction can be applied either before the beamsplitter or after it.

Using the linearized Langevin equations and spectral matrix, we calculated the squeezing spectra of the coupled mode in the output field for the process of parametric down-conversion with frequency degenerate but polarizations non-degenerate. The squeezing as a function of the driving field is obtained. We compare our results with that of the semiclassic and indicate that it is possible to generate a two-mode squeezed state with large amplitudes. The quantum correlation between the signal and the idler modes is also discussed.

The process of the spontaneous emission (SpE) from an active microscopic cavity (microcavity) is shown with emphasis on mirror separation of the order of the optical wavelength. The relevant effects of SpE enhancement and inhibition, non-exponential decay, and emission anisotropy are outlined for a cavity terminated by mirrors bearing either metal -- or semiconductor -- multilayered coatings. Finally, an experiment regarding the possibility of detecting the field distribution within the cavity of the emission wavelength is shown.

We investigate bistability and squeezing of driven two-photon (TP) optical systems such as TP optical bistability (OB) and TP laser with injected signal (LIS), affected by the additional intracavity TP absorption effect.

The aim of this paper is to try to find out the possibility of reducing the photon number noise in an optically pumped three-level atomic system. Consider a three-level atomic system. The atomic transition between level 1 and level 3 is forbidden. Each atom is incoherently excited to upper level 3 from level 1, transits to level 1 through intermediate level 2, and emits photons at frequency (omega) ₁ and (omega) ₂. We place the atoms with the above feature into an oscillator and may obtain two coherent light beams, whose frequency are (omega) ₁ and (omega) ₂, respectively. There may be some correlation between these two light beams. We make one beam to control the pump source by a feedback loop and expect to reduce the noise of photon number of the other beam.

If the idler photon flux is continuously measured in a photon-counting detector and the photocurrent fluctuations are fed back to control the pump intensity, the output signal state will be an amplitude-squeezed state (near-number state) at low frequencies and high feedback loop gain. Electromagnetic field in number-phase minimum-uncertainty states (amplitude- squeezed states), and its limit (photon-number states) have potential applications in optical communication, precision measurement, and atomic spectroscopy, and gravitational wave detection. These states have been the focus of considerable attention.

We investigate the quantum fluctuations of the fields produced in sum- and difference- frequency generation from light initially in the squeezed state. Under certain conditions the output may also be squeezed.

Abstract not available.

In this paper we present a squeezing operator for a pulsed squeezed light and give the concise expressions and the features of the intensity and noise as a function of time and frequency for the pulsed squeezing field. The generation for pulsed squeezed state light (PSSL) has been studied. In this paper we present a ket for PSSL and give the concise expressions of the intensity and the noise as functions of time and frequency and discuss their frequency features. We also propose a scheme in which the pulse train and the frequency spectrum of the noise can be simultaneously determined.

The mathematical structure of orthonormalization eigenstates of a^k and their quantum statistical characters are studied.

The exact solution to a quantum forced anharmonic oscillator is derived. The equation of motion is solved by using the integral operators and iteration method. As a result, the time development of the displacement and momentum operators of the forced anharmonic oscillator is obtained. These operators are presented as a Laplace and a subsequent inverse Laplace transform of suitable functionals.

We present analytical expression for the s-parametrized quasiprobability distribution W((alpha) , (epsilon) , s) for the negative binomial states. As special cases, for s equals -1, 0, and 1, W((alpha) , (epsilon) , s) reduces to the Q-distribution, the Wigner distribution, and the Glauber-Sudarshan P-function, respectively.

We present herein a phenomenological approach to the critical phenomena in the dissipative systems, including the optical bistable system, the laser, etc., which satisfies the principle of detailed balance. The substantial discussion is started from the standpoint that there are two kinds of critical points: stable and unstable, associated with the continuous and discontinuous transitions, respectively. In several senses this work would be a development of Landau's second order phase transition theory in equilibrium thermodynamics.

The effect of dissipation of dense plasmas on spontaneous radiation of ionized atom is investigated by Langevin equations and Weisskopf-Wigner approximation. Analytical expression for emission rate is obtained, the Einstein formula is corrected by a new added term caused by thermal photons, and the Einstein A coefficient is also modified due to damping of the light. The lifetime of the excited ion is modified correspondingly.

The present paper establishes the photonic superguiding theory in polar crystals with a high nonlinearity. In the quantum theory it is shown that photons can feel an attractive effective interaction by exchanging of virtual phonons. Such an interaction leads to the superguiding state, in which photons with opposite wave vectors and spins are bound into pairs. The photon pairs travel without scattering attenuations. In the classical theory we prove that the crystals exhibiting the photonic superguiding state are the self-defocusing media in which temporal bright solitons can propagate. The optical solitons do not suffer from dispersion. If the photons propagating in a waveguide enter the superguiding state, the waveguide exhibits both an ultralow energy loss and a high transmission rate.

Nondegenerate parametric down-conversion in OPO with two KTP crystals was experimentally researched. The two-mode squeezed state light was observed when three longitudinal modes were resonated simultaneously.

According to the higher-order squeezing defined by Zhang et al., the properties of higher- order squeezing of the orthonormalized eigenstates of the higher powers a^k (k>= 3) of the annihilation operator a are studied. Our results show that all of them are minimum uncertainty states of the operators Z₁(N) and Z₂(N) (N equals mk, m equals 1, 2, ...) for even and odd k, and all of them have the Nth-order squeezing [N equals (m + 1/2)k, m equals 0, 1, 2, ...] for even k.

We study some properties of the states a^+mS(r)0> and a^mS(r)0> (S(r) equals e^{-$ (a(superscript 2}-a⁺²)) which are engendered by the excitations and de-excitations on a squeezed vacuum state, respectively. Using the mathematical induction method, we easily show that such states are normalized as two different forms of Legendre polynomials of squeezing parameter r. The Wigner functions of these states are also derived and analyzed.

In this paper, we calculate the photon statistics of resonance fluorescence of a two-level atom driven by a laser field. The results show that the photon statistics tend to Poissonian if we consider the photon statistics starting from the ground state of the atom. We propose a possible method to test the photon statistics of resonance fluorescence.

Proposals on detecting atomic stabilization have been suggested through possible generation of strong even-ordered harmonics or through blue shifted ATI peaks. The strength of observable signals has been the center issue of discussions. In this paper we remark on an alternative way in which stabilization process may be effectively detected. We show that in bichromatic fields the degree of ionization can be modulated by as much as 20% by changing the relative phase. In an experiment, by recording this phase modulation, one can calibrate and determine the degree of stabilization. In microwave ionization experiments reported, bichromatic field intensity has already been used as a sensitive probe in studying the so called quantum localization border.

The resonant radiation pressure effect induced by `white' laser radiation is discussed. Experimental results on atomic beam deceleration and vapor compression induced by the resonance radiation pressure effect are reported. The `white' laser radiation has been simulated by a multimode long cavity dye laser.

In this paper we first discuss the limitations of the frequency accuracy and stability in current standards. We then list some effects of quantum optics which allow us to overcome the difficulties limiting the performance of standards both in the microwave and the optical region. Finally, the optically pumped cesium beam frequency standard built up at our laboratory is described to show how the principles work in this special case.

We discuss recent experiments investigating the effects produced by laser irradiation of cantilevers utilized as force sensors in atomic force microscopy (AFM). Thermal and pressure effects are observed for cantilevers freely moving in air. Mechanical fluctuations of the cantilevers due to thermal noise of the environment have also been measured.

This paper reports the observation of stable trapping of a transparent microparticle. The trap is a light induced hybrid one which consists of both light pressure force and fluid force. A theoretical analysis and experimental results are given. The possible applications are also discussed.

Here we report some initial results in the study of optical pumping and laser cooling of metastable Mg atomic beam. Eighty-five percent of optical pumping efficiency and laser cooling effect have been observed. We have successfully used frequency doubled diode laser in the experiments as a velocity analysis light source because diode laser is important for making a practical magnesium frequency standard.

We used a dielectric microsphere model which is based on geometrical optics to describe the generation of trapping force by a single laser beam. Our results show that the microsphere can be trapped in some cases. For a typical microsphere, which has a 10 microns diameter, the trapping point is about 2 microns below the focusing point of the laser, and the trapping range is about 4 microns. The transverse trapping range is about 16 microns. And we find, that if we use suitable TEM mode of the laser beam, we can raise the trapping force for several times. This model can also be extended to biological cells.

Experimental observation of laser cooling and collimation of moving atoms in an absorption cell by light pressure force of an intense standing light wave field is reported. The hyper-fine structure of atomic sodium has been observed due to the cooled and collimated atoms and the mechanism of laser cooling and collimation of atoms is discussed.

The dynamical behavior of an intracavity modulation (IM) laser system with a feedback device is discussed in this paper. Some of the modulating methods, i.e., intracavity acousto-optic modulation (IAOM), intracavity electro-optic modulation (IEOM), and intracavity magneto- optic modulation (IMOM), etc., are introduced. The chaotic behavior of these laser systems with a feedback device is analyzed.

The ordered structures of two-species ions stored in a Paul trap are simulated. It is shown that the homo-charged two-species ion clusters display separating and mixing structures for different mass ratio, and the hetero-charged ion clusters consisting of four to seven ions are stable.

We introduce a new technique of micro-chopper by use of atomic force lever to study flying micro particles. Our preliminary results demonstrate that the device response to the air molecular beam intensity is 10⁸/second.

We present a review of various schemes in which the quenching of spontaneous emission takes place in correlated emission laser (CEL). In particular we discuss Hanle laser, quantum beat laser, and a two-photon CEL. We also discuss noise-free amplification in a two-photon CEL.

Using a one-dimensional piecewise function mapping, we have developed a method for controlling chaos in an optical bistable system theoretically and numerically. This method could be applied to other nonlinear dynamical systems.

Tunable UV coherent radiation in the wavelength region 319.2 nm to approximately 354.2 nm has been generated by unequal-frequency hybrid resonance of Na₂-Na system and followed four-wave mixing. The wave-mixing processes and experimental results are discussed.

Abstract not available.

By hybrid and two-photon pumping covering a wide wavelength region of 685.0 - 718.0 nm in a K₂-K system, yellow stimulated defuse-band radiation corresponding to the transition 2 ³$PRD_g yields a ³(summation)_u⁺ of molecular potassium was generated. The excitation and collision energy-transfer mechanisms are discussed.

The carrier lifetime, mobility, and drift velocity are the important parameters of photoconductors. Normally, several independent tests such as conductivity, Hall effect, and decay of photoconductivity, etc., are used to measure these parameters separately. Pc decay sometimes becomes size limited, however, quite a lot of device configurations have small dimensions. Particularly, at low temperature pc decay may be nonexponential, that leads to some errors in the measurement. We applied the photo-mixing technique to measure the transport parameters. When a multimode laser beam is incident upon the photoconductor sample, the carrier generation rate of the sample will contain frequency components made up of the sum, difference, harmonics, and dc components of the incident frequencies as a bias is applied to the sample. We have generalized the theory of photo-mixing for the case of an unmode-locked multimode laser light incident upon a semiconductor. The results yield the photocurrent as a sum of a dc and an ac part.

An optical fiber laser with ring structure has been built. The fiber ring laser consists of an erbium doped fiber which is spliced into the two selective ports of a conventional fused fiber coupler. Argon laser at (lambda) equals 514.5 nm was used as the pump source. Pulses of 1 mW peak power and 80 microsecond(s) duration were observed at a wavelength of 1535 nm.

Abstract not available.

An Nd³⁺-doped single-mode fiber laser pumped by Ar⁺ laser is reported. By using the interface, it was made simple and had a low threshold of 1.02 mW.

Spectrally and temporally resolved measurements of stimulated Raman scattering (SRS) from flowing ethanol droplets are presented. The equal frequency spacings of the SRS peaks are an order of magnitude smaller than the spacings for morphology-dependent resonances (MDRs) of a perfect sphere. The observed temporal oscillations of the SRS from two segments of the droplet rim are 180 degree(s) out-of-phase and dependent on the azimuthal mode number, m, of the MDR. The observed frequency splitting and precession of the MDR about the symmetry axis of an oblate droplet is consistent with perturbation predictions of the frequency splitting of a (2n + 1)-degenerate MDR of a perfect sphere.

Abstract not available.

Bistability and bifurcation of the transmitted light from a Fabry-Perot cavity containing carbon disulphide liquid have been studied experimentally. With polarized molecules instead of Eichler et al.'s, electron-hole pairs, the experimental results have been simulated successfully, also the possibility of observing chaos in experiment and pulse compression by an FP resonator is discussed.

Some results of probing to the common properties, including bistability, transient behavior, and instability of the excitonic optical nonlinear dynamic systems, such as interaction of light field with carrier in semiconductor, or anharmonic vibration of lattice in ionic crystal, are presented. Since the excitonic optical bistability (EOB) was found, it has garnered much attention for its advantage in properties and application prospects. Some models have been proposed for different kinds of OB. However, so far as we know, there has been relatively less concern given to the common dynamic characteristics of these systems, which are significant for applications. On the other hand, the instability of the EOB device certainly has the same importance, the study for which is not ample yet. In this paper we study the increasing absorptive OB, the behaviors of responding to inject signal, also the self-pulsing and chaotic phenomena in the excitonic OB systems.

The photon distribution probability and the mean photon number in a high Q cavity are calculated based on the Jaynes-Cummings model for double m-photon lasers. The results show that the collapse and revival of the mean photon number are affected by the atomic coherences.

Formally defining the `linear laser gain' G((tau) ) as <(tau) > equals 1/2<(tau) G((tau) )>, we show that laser operation of squeezed light is possible in double effective two-photon correlated-spontaneous-emission lasers.

Squeezing of one mode field interacting with a three-level cascade atom are studied by the Schrodinger equation, using the Jaynes-Cummings (J-C) model depending or not depending on the coupling of field strength. Deepest squeezing of field, 0.138 or 0.133 and some interesting consequences are obtained in the multiphoton process.

In this paper k-order squeezing in kth-harmonic generation is studied. The k-order squeezing of a fundamental can exist if the kth-harmonic is originally in a coherent state including in the vacuum. It is also shown that the normal squeezing of the kth-harmonic depends on the k- order squeezing of the fundamental.

The variational method is used to study the combined effects of self-focusing, self-phase modulation, and diffraction in both homogeneous and inhomogeneous material. Similarities and differences with respect to the results derived from the aberrationless paraxial approximation are pointed out.

In consideration of the interaction of both the driving field and the atom's radiation field itself, the resonance spectrum irradiated by a two-level system in a cavity is calculated. The spectrum thus obtained shows some new features in comparison with that of a two-level system in free space. The five-peak structure in the resonance fluorescence spectrum is shown for the first time, and very narrow central peak width for a good cavity also is observed.

A pulse compression system was constructed by means of Brillouin and Raman stimulated backward scattering. It was used to convert pump pulses of 5 ns duration at 1064 nm into ultraviolet pulse of 10 to approximately 20 ps at 315 nm.

Saturating absorption and optical bistability (OB) with ns switching time in Langmuir-Blodgett (LB) films of phthalocyanines derivatives on reflection have been studied at room temperature (RT) in the near ultraviolet region for the first time. The saturating intensity (I_s) and switching intensity for the OB at 337.1 nm are about 1 MW/cm² and 5 MW/cm², respectively. The experimental results show that the major nonlinear and positive feedback mechanisms for the OB are the change of refractive index caused by the saturating absorption and the simple F-P cavity due to the natural faces of the sample, respectively.

In this paper, the general ring cavity model of passive and active optical systems is presented. In the mean field and the Gaussian one transverse mode approximations, the steady state and stability properties of the systems are analyzed for mixed absorptive and dispersive cases. It is found that when the transmissivity ratio M (equals T₁/T₂) varies, the bistable loop changes its size and even the systematic behavior varies from the bistability mode into the amplification mode, and the instability domain on the steady state curve varies obviously. The mode-pulling formula and bistable threshold with varying values of M are also discussed.

We consider N three-level atoms in a single ported-optical ring cavity interacting through two- photon transitions with a cavity mode. The cavity is driven by an external coherent field, with detuning from the interferometer and the atomic transition. Damping of the atoms and the cavity is included.

Abstract not available.

Ambipolar diffusion coefficient of CdS:Cu has been obtained by time-delayed four-wave mixing with incoherent light. The result, Da equals 0.3 cm²s^-1, coincides with other reports.

The effect of saturation and multiplicative noise in a single-mode laser containing both additive and multiplicative white noise are investigated. Compared with the experimental measurement, good agreement is obtained in the threshold regime.

In this paper, we use two-photon absorption (TPA) of GaAs, realize the temporal shaping of single longitudinal mode Q-switched pulses. The experimental results agree with the numerical solutions well.

The theory of high resolution spatial spectroscopy is developed in this paper, and the results of real-time measurement for velocity distribution of Na sodium atoms and its hyperfine structure by this new spectroscopy method is reported.

In this paper, we put forward the photon cross section model based on our preceding work on effective spontaneous emission cross sections, and give a qualitative and clear explanation of the quenching of spontaneous emission coefficients in plasmas and in laser cavity.

The optical parametric process with ultrashort pulse is investigated theoretically and experimentally. Reliable numerical method is used. The comparison between the theory and the experiments shows the directing bearing of our work.

We present herein an approach to the interaction of coherent light with the anharmonic lattice vibration of ionic crystal and give a mechanism for increasing absorption optical bistability.

Lines at 354.5 nm (6s5f³F₃⁰ - 6s5d³D₂), 394.4 nm (6s8d³D₂ - 6s6P³P₁⁶), 410.0 nm (6s8d³D₃ - 6s6P³P₂⁰) and 973.5 nm (5d7p¹P₁⁰ - 6s7s¹S₀) in barium vapor have been observed and identified as cascade stimulated collision-induced fluorescence originated from some end states of stimulated Raman scattering.

A novel Raman scattering formalism is derived from the quantum collision theory. The formalism is naturally inclusive of the self-energies of quasi-particles and may be applied to calculate the line-shape and line-width of Raman spectrum.

The modulation instability in monomode optical fibers with fifth-order nonlinearity, fiber loss, higher-order dispersion, and the temporal variation of third-order nonlinearity is studied. Yielding conditions and maximal modulational growth rate are discussed in detail. The results obtained show that the modulation instability can be produced in the range of not only anomalous dispersion but also normal dispersion.

This paper reports the photoresponse of photolithographic YBaCuO superconducting film at liquid nitrogen (LN) temperature range under the irradiation of He-Ne laser and optically pumped far infrared laser. The relationship of laser photoresponse of YBaCuO film to chopping frequency is studied theoretically and experimentally in detail.

The production of Raman wave pumped by elementary soliton propagating in optical fibers is studied analytically and numerically. The approximated analytical results show that cross- phase modulation results in the added periodical amplification of the Raman wave, and the maximum amplification distance exists due to the soliton pump fiber loss. The numerical results demonstrate that the smaller the pulse walk-off, the more effect the energy transfer from soliton to Raman wave.

Laser absorption in inertial confinement fusion plasma has been theoretically studied with assumed high powered lasers using Maxwell's equations for inverse bremsstrahlung absorption process with two sets of density profiles, namely linear and exponential. It is found that the shorter wavelength with small pulse time and high irradiance of laser is required to interact with low atomic number target in inertial confinement fusion scheme.

Two-photon excitation of metastable 2S hydrogen atoms, on an atomic beam, toward (high n) Rydberg states permits metrology on Rydberg Constant at the 10^-10 level. Direct frequency comparisons of lasers are in progress toward the 10^-11 level.

A very weak perturbation around the 6s²52d ²D_3/2 high Rydberg series of Lu has been studied. An intensity distribution of the optical spectrum around the perturber exhibits well developed Fano profile with significant decrease of radiative life time by the perturbation. Microwave two-photon transitions among the 6s²nd ²D_3/2 series are measured to determine the accurate energy level structure of the perturbed series. Analysis of the microwave spectrum as well as the intensity profile and its delay-time dependence has led to the determination of accurate spectroscopic parameters.

The paper summarizes the authors' major results achieved recently with their collaborators on the study of molecular Rydberg states and nonlinear spectral effects. The results include the findings of diversified nonlinear spectral effects, the recognition of new spectral regulations and their identification methods for molecular two-photon excitation spectra simplified by the mechanism of near-resonant enhancement, and proposals and demonstrations of manifold mechanisms for generating stimulated and coherent radiation from infrared to ultraviolet wavelength regions out of simple molecules or via them.

A study of the tuning characteristics of two commercial visible diode lasers with a grating external cavity is presented. The grating and external cavity length were synchronously tuned by a low voltage actuator.

We investigated mixing and alternating techniques of fabrication, effects of subphase addition, and determination of chromophore orientation for potential applications of Langmuir-Blodgett (LB) films to organic optical nonlinear devices of new generation.

We report the first observation of the geometric phase of a quantum system driven by laser fields. The observable geometric phase effects in optical FM spectroscopy, here distinguished from various known lineshape changes due to spectroscopic or technical causes, are characterized by the following aspects: (1) Dramatic lineshape variation of the optical heterodyne signal due to a monotonic signal phase change with increasing probe power; (2) The lineshape changes are associated with a nearly pure phase-change effect; and (3) The phase-change rate with probe power depends on rf sideband frequency, and less strongly on the rf modulation index.

Laser spectroscopy is widely applied to many fields now. One of its applications is in the field of evaporation dynamics where in both vapor expansion cooling and internal electronic temperature it is still open to further investigation. Dr. Knight, Dr. Solarz, and Dr. Beekmann once made some remarks on these two topics, so far however, no systematic experimental method has been developed to verify the predictions of theoretical work and to obtain most of the physical parameters. The present authors believe that by using the technique of laser induced fluorescence to measure the velocity distribution of the atomic beam at different powers of electron beam we can do it to a great extent.

Two new results are revealed. First, in the strong-field region of cavity-mode the two-atom emission spectrum shows four peaks for N > 1 (vs. three for N equals 1). The distance between the two inner peaks is twice as large as the corresponding one in the one-atom spectrum due to atomic cooperation. Second, the inclusion of atomic dipole-dipole interaction makes the emission spectrum asymmetric; this effect is most obvious in the vacuum field.

Optical heterodyne spectroscopy is one of the ultrasensitive and high resolution laser spectroscopies. During past years, it has extended from saturation absorption to two-photon transitions in a three level quantum system of atoms and ions. The particularly interesting case is the modulation transfer spectroscopy, where the optical heterodyne detection is performed via nearly degenerate four-wave mixing (NDFWM) in the nonlinear medium. In this report, the modulation transfer spectroscopy is used to observe the optical heterodyne saturation absorption and two-photon transition spectra simultaneously in Na₂ without Doppler background. The line shapes of optical heterodyne signal are discussed in detail.

The technique of laser magnetic resonance was used to investigate the ³(rho) ₁- ³(rho) ₀ transition within the 6s6p ³(Rho) excited states of atomic mercury. The isotope shifts of Hg in the ³(rho) ₁-³(rho) ₀ transition were directly determined. The results are: (Delta) (nu) _IS^198,200 equals -26.2 +/- 3.0 MHz, (Delta) (nu) _IS^198,202 equals -55.8 +/- 3.0 MHz, (Delta) (nu) _IS^198,204 equals -82.6 +/- 3.0 MHz. Their results are more accurate than those of previous studies.

The present authors have observed and analyzed the power broadening and central frequency shift of uranium transition, and so far the latter has never been reported.

A beam machine with a VUV/XUV monochromator scanned by a stepping motor controlled by a micro-computer has been built during the last 3 years in our lab. The experiment of the spectroscopy radiated from the beam has been started. The spectra of Ar_n around 105 - 126 nm and He_n around 584 - 601 nm have been found. An improving of the experiment is on going. The second purpose of our experiment is to look for more cluster spectra and to explore the possibility of their lasing, and the third purpose is exploring a method of observing cluster by measuring its radiated spectra.

In the study of dynamic light scattering (DLS), the autocorrelation function of the scattered light is one of the most important problems. Through the relationship between autocorrelation function and autocorrelation function of scattered light intensity, using the technology of photon correlation spectroscopy (PCS), we can measure the physical and the chemical properties of the illuminating system. In the illuminated system, the Brownian movement of the scattering particle is a result of dynamic light scattering. In this paper, calculations are presented of the autocorrelation of scattered field by a monodispersion system of spherical particle in colloid following statistical properties of Brownian movement and theory of classical electromagnetic field. The approximation of results which we get was the same single exponential functions in general use, and the results applied to the situation for the Brownian particles in an electric field. The spectral density difference between the two situations is discussed and it is suggested that this result may be employed in the experiments of the quantitative analysis of mixtures of charged macromolecules in colloid.

'3p-3s transition of high charge ionized Be -like- Ne -like ions may form short the wavelength laser'. The energy level can be seen as in Fig. 1. The energy levels and spectra of high charge ionized Ne-like and F-like ions have been researched systematically thory and experiment25. But the researches for N-like ions which may be the same candidates for lasing action are nearly still within the limits of 2s, 2p and 3d configurations". According to MCDF code, we calculated recently the energy levels of 3s, 3p configurations and transition wavelengths of 3p—3s configuration for N-like ions of 15 Z 30. In this pater, using again the above-methioed method, we calculated the same question for heavier F-like of 31 Z34.

The hot-band oscillation of CO₂ laser with saturable absorber shows new features in passive Q-switching instability. A proposed model is applicable to the nonlinear dynamic process including vibration-to-vibration energy transfer which influence the passive Q- switching instability. The vibrational rate constant is determined for the first time from the analysis of the passive Q-switching instability.

The schemes of laser without inversion depend on the mechanisms involved in the generation of coherence. Three-level schemes between discrete states in the (Lambda) -configuration, and the role played by the coherent population trapping phenomenon, are discussed.

A new two-photon interference method to measure coherence time and pulse width of ultrashort pulses is proposed. Experiments are performed on cw-modelocked dye-laser pulses.

In this paper the first observation of up-conversion luminescence phenomenon of ErP₅O₁₄ and HoP₅O₁₄ noncrystalline is reported. It is found that the up-conversion mechanism for ErP₅O₁₄ noncrystalline is sequential two-photon absorption by a single Er³⁺ ion, however, for HoP₅O₁₄ noncrystalline its up-conversion mechanism is energy transfer between Ho³⁺ ions.

Since Zel' dovich discovered the phase conjugate character or stimulated Brillouin scattering (SBS), there has been considerable interest in using phase conjugation to improve the beam quality of high power laser. In this paper we report our investigation of the Nd:YAG laser oscillator with a SBS cell filled with high pressure gas SF₆ as the SBS nonlinear medium. The SBS cell acts at the same time as the phase conjugating mirror and as the Q-switch because of its intensity dependent reflectivity. As a result laser pulses with the energy of 100 mJ and the duration of 10 - 25 ns per pulse have been obtained. The beam profile is nearly TEM₀₀-mode.

In this paper, we report observation of average control of laser beam self-focusing in submillimeter liquid fiber, and the largest spectral broadening of the pump laser line originated mainly from the central self-trapped filament. The intensity-dependent frequency shift was revealed by the time-resolved study, and a laser-induced molecular structural change was proposed. Altering the experimental arrangements we can choose one or two of the different nonlinear processes to dominate in our fiber setup.

The research of excimer laser has long been a very important aspect of laser science. During the search for a new type of excimer laser medium, we first suggest a NaS system of I-VI column element combination. Because of the low excitation threshold of Na and the energy storage capability of S, the excimer laser system of this combination is expected to have high energy storage and high efficiency tunable characteristics. For experimentally investigating the NaS excimer laser system, we first calculated its potential curves theoretically using the Ab Initio method, and analyzed the results. Some theoretical parameters such as balanced inter- nuclear distance R_e, potential well depth D_e, vibrational frequency spectra (omega) _e, transition wavelength (lambda) _j, etc., were obtained.

A new cw self-frequency-doubling laser operating on high-gain polarization of Nd:MgO:LiNbO₃ has been demonstrated in a nearly concentric resonator. A maximum second-harmonic output of 4.6 mW and a conversion efficiency up to 11.7% per watt were achieved.

Recently, there has been great interest in the two-step excitation for the generation of coherent XUV radiation with low pump threshold. The two-step excitation process is as follows: the energy is first stored in a metastable level, and subsequently converted into coherent XUV radiation by stimulated resonant anti-Stokes Raman scattering (SRASRS). The He/K mixture two-step pumping system was first proposed by V.O. Panpanyan et al., in 1983. The main kinetic process is that the He^*(2³ S) state is produced in a discharge. It makes use of strong collisional energy transfer from He^* (2³S) to populate potassium high lying quartet metastables K (3p⁵3d4s⁴P_5/2). By using 1.209 micrometers and 498 nm laser as the second step excitation, from the quartet state and through SRASRS the 64.3 nm and 59.8 nm coherent XUV radiation is obtained. This paper discusses several physical problems of the system.

We report experimental results of radiation amplification without population inversion in sodium according to a four-level model.

Based on the different changes of the velocity distributions of the ground and excited levels due to the level dependence of collision cross sections in a flowing system, a new mechanism for the light amplification without population inversion is presented.

Pulsation behaviors of optically pumped HCOOH 433 micrometers , CH₃I 447 micrometers , and CH₂CF₂890 micrometers sub-millimeter laser were experimentally studied. Pulsation frequency varies continuously with tilting the output cavity mirror or changing the gas pressure. Two-frequency pulsation was observed and it developed easily into chaos by condition changing such as cavity tilting. Laser chaos was not sensitive to condition changing and was able to persist for quite a long time.

We have performed an investigation of the optical feedback on laser diodes from an external mirror. We have examined at different values of the laser current the switching time distribution between different states and the power spectrum of the laser diode light intensity.

Abstract not available.

Cavities containing nonlinear x⁽³) media, either purely parametric or made of two-level atoms, can be efficient squeezing devices. We derive criteria in order to assess their potentialities, and we discuss the perspectives opened by motionless atoms.

We present experiments on optical elements for metastable helium atoms. Lenses and beam splitters have been demonstrated both by diffraction from freestanding microstructures in gold foils and by passage through a standing light wave with a large period. The optical properties and the quality of the different elements are compared and discussed.

The potential depth of a magneto-optical trap for neutral lithium atoms has been measured to be 0.38 K with a new method in which the escape velocity of laser heated atoms is measured by observing the Doppler shift of the fluorescence. The decay rate constant for the trapped atoms due to ultra-cold collision has been determined to be 1.0 X 10^-11 cm³/s, showing no discrepancy with the existing theory based on the fine structure changing collisions.

Young's double slit interferometry, electric focusing, and two dimensional trapping of a laser- cooled neon atomic beam in the 1s₃ metastable state are demonstrated.

The work on the one-atom maser is reviewed. The superconducting maser cavity made of niobium and cooled to 0.5 K to exclude thermal photons has a quality factor of 3 X 10¹⁰. Velocity-selected Rydberg atoms pump the maser. The field inside the cavity is investigated by probing the atoms leaving the cavity. The dynamics of the Rabi nutation were investigated. Furthermore, the statistics of the photons in the cavity were determined to be sub-Poissonian corresponding to photon-number fluctuations of 70% below the vacuum-state limit. The one-atom maser is the only maser system which leads to nonclassical radiation even when pumping processes with Poissonian statistics are used. Some applications of the one- atom maser to study the quantum measurement process also are discussed.

We investigate the quantum statistics of the fields produced when squeezed light is used as input in certain three-wave and four-wave interactions such as second harmonic generation and degenerate four-wave mixing.

Ultralow temperatures produced with polarization-gradient cooling now allow atoms to be trapped in shallow optical potential wells. We present evidence for the quantized motion of atoms in a 1-D optical molasses with the observation of spontaneous Raman transitions between vibrational levels in these wells, observed in fluorescence. In addition, we discuss the features of a far off resonance trap (FORT) -- a single focus dipole force trap so far off resonance to be an essentially ground-state trap.

Several cavity quantum electrodynamic phenomena have been observed in liquid microdroplets. These include cavity-induced spectral changes, emission lifetime modification, and enhanced lasing and Raman gains.

We present new experimental schemes for studying radiatively coupled atomic multilevel systems. These methods are aimed at creating order within the sublevel multiplets of complex multilevel systems and at extracting precise and detailed information about the order present in those systems. Time-resolved experiments provide not only static, but also dynamic information about these systems. Due to their high sensitivity and spatial selectivity, they may also be applied for magnetic resonance spectroscopy.