An optical parameter oscillator base on KTP nonlinear optical crystals and a frequency doubling Nd:YAG lase was built. The wavelength of the signal light could be tuned from 750-800nm. At the wavelength of 780.2nm it could provide 62mJ each pulse with duration of 14 ns and spectrum (FWHM) about 0.4nm, and at the wavelength of 755nm the energy of each pulse was 10mJ with duration of 8ns. When the signal passed through a 10cm long Rb cell with Ar buffer gas at the temperature of 120°C and the wavelength was tuned from 779nm to 781nm, it could be observed that the fluorescence in the cell changed from dim to clear at first and then declined. Fluorescence could also be observed when the signal wavelength was 755nm and the cell was heated to 180℃. Which indicated that this OPO can provides over 1MW peak power for the research of rubidium lasers and rubidium-rare gas excimer lasers.
In this paper, a simple one dimensional heated flow analysis model and 3-D finite volume method (FVM) is set to
discuss the real gas dynamic effect in FDPAL. We found that huge amount of waste heat deposited in extreme compact
volume size will notably affect active medium’s local velocity, temperature and the density distribution along flow
direction, and would accordingly affect pump beam’s absorption and change optimized lasing conditions, hence, a
comprehensive model incorporate gas dynamic effect should be built for DPAL’s next stage development. We further
proposed that expanding fluid channel may be a choice to increase optical thickness along pumping direction and
alleviate this effect.
Excimer Pumped Alkali Laser (XPAL) is a hopeful choice to solve Diode Pumped Alkali Laser (DPAL)’s
disadvantages. Theoretical and experimental investigations of Rb-Ar XPAL were carried out in this paper. Time
dependent rate equation model illustrated that extreme pump strength was needed to exceed threshold and to assure
efficient cw running. 780nm lasing of four level Rb-Ar excimer was realized with a surrogate 15 ns pulsed optical
parametric oscillator (OPO). Possible resonator configuration may increase pumping strength was proposed.
HF chemical laser with MOPA configuration is a good solution to achieve high output power with high reliability.
Kinetic models for HF amplifier are important for prediction and optimization of the performance of MOPA chemical
lasers. In this paper, a simplified model for HF chemical laser amplifier is presented. The main processes which are
included in the model are: (a) chemical pumping of HF (v=2) and HF (v=1), (b) stimulated transitions and spontaneous
emission. (c) relaxation of vibration excited HF molecule by H2,N2 and HF. Some assumptions are taken in this model:
(a) the density of H2, N2, HF, translational temperature and velocity of gas mixture are averaged across the laser cross
section, (b) only two vibration-rotational transitions (2P6, 1P7) occurs in the amplifier, (c) gas temperature does not
change during the lasing process in the amplifier. Based on these assumptions, a set of three-level rate equations is
formulated and then solved by an iterative technique. Comparison is made with recent experimentally obtained data from
a low power discharge-driven CW HF laser with MOPA configuration. It is shown that experimental results are
consistent with the calculation from the simplified model.
The gain media of the quantum dot lasers consist of InAs QDs in an InGaAsP matrix on an InP substrate. The
quantum dot lasers have different free spacing ranges (FSRs) corresponding to Fabry-Pérot (F-P) cavity lengths. A
silicon ring resonator and a QD laser have been combined to form comb laser. The output characteristics of the
combined comb laser were investigated. The measured FSR was about 2.8nm and the extinction ratio was about
10(dB) when the FSR of the QD laser was about 0.4nm and the FSR of the ring resonator was about 0.47nm. The
experimental results show that the ring resonator had a strong control on the FSR and extinction ratio of the comb
The phase information of the thin heated air cylinder transection was acquired with a self-collimated interferometer
and line CCD camera at the frame rate of 27kHz , based on the presumption of axial symmetry ,using addition algebraic
reconstruction algorithm , 2-dimension index-of-refraction distribution of the heated air in the transection was acquired
,and the 2-dimension temperature distribution was calculated, the temperature shift was observed, the central
temperature of the air cylinder changed between 330K and 430K. The results show the method could be used to the
measurement of near axial symmetry aero-optical medium.
Coherent combination of fiber lasers through mutual injection locking is demonstrated experimentally in this paper. By
moving the mutual injection couplers from the output port to the high reflection feedback port of the lasers, a modified
combining configuration is constructed with obviously enhanced slope efficiency as compared with the conventional
one. The laser efficiency increases from 29.7% to 37.8% by this modification. The corresponding maximum output
power enhancement of the combined laser is 26.6%. This modification increases not only the individual child laser
powers but also the combining efficiency. The physical connotation of the modification on the improvement of the laser
performance has been discussed.
Laboratory turbulence generator has been established by heaters and fans. Turbulence of different strength is able to be simulated by changing the temperature. Plane Shack-Hartmann wave-front sensor is used to measure turbulence. The measurement indicates that turbulence has properties of locally homogeneity and isotropy approximately. One-dimensional Shack-Hartmann wave-front sensor with high temporal sampling frequency and spatial resolution is designed, which is made up of 28×1 cylindrical microlens array and linear CCD with frame frequency from 100Hz to 3000Hz. Wave-front after propagating through the laboratory generated turbulence is measured by the wave-front sensor. From displacement of the intensity centroid, the components of angle-of-arrival fluctuation in different positions along linear CCD direction are acquired. One-dimensional correlation function of angle-of-arrival is estimated. Under the hypothesis of locally homogeneous and isotropic random field, it is convenient to derive one-dimensional correlation function of angle-of-arrival by method of spectrum analysis of random processes with stationary increment. The result of experiment indicates that one-dimensional correlation function of angle-of-arrival confirms to the theoretical derivation approximately.
Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.
By means of Hartmann Sensor at the rate of 419 Hz, a series of dynamic degraded wave front of collimated laser transport perpendicularly across a heated air flow was measured. The airflow was generated using a vertical-placed nozzle. An integral result of the airflow density distribution was educed. Both span-wise direction and stream-wise direction structure convection were observed. Some pilot study of flow field visualization was made.
The optically active, turbulent flow field was investigated to simulate a low speed two-dimensional heated jet. Dynamic spatio-temporal index-of-refraction distribution and velocity profile of the turbulent flow field were obtained by applying computational fluid dynamic methods, the corresponding optical path difference numerical results were educed by optical computational methods. Some relationships between the flow large-scale structure and corresponding optical path differences are inferred.
The concept of the free-vortex aerodynamic windows (FADW) is one of the best effective methods taking the place of the conventional beam output crystal windows of high power laser. An experimental model of the supersonic free-vortex aerodynamic window has been designed and made in our latest study. This paper studies the aero-optical phenomena of the FADWs supersonic jet to realize the laser optical quality degradation caused by the free- vortex jet, and to find out the relation of output laser beam quality through the FADW to the structure of the FADWs shearing interferometry. At last the structure of FADWs jet has been studied by means of shearography.