We demonstrated the high sensitivity and mechanical strength temperature and strain sensor based on liquid-infiltrated Fabry-Perot interferometer (FPI). The sensor is fabricated by splicing a short section of single-mode fiber (SMF) between two sections of SMF with a large intentional lateral offset forming open-cavity. For its high thermo-optic coefficient (TOC), isopropanol leads to a huge wavelength variation of the reflection spectrum while external temperature changes. The sensor was used to monitor the change of temperature and obtained a sensitivity of up to -655.0pm/°C in the range of 20 to 45 °C. In addition, the sensor presents a high sensitivity to a strain of 20.8pm/με. The sensor is expected to be used in high-sensitivity temperature and strain monitoring environments.
In this paper, we proposed and demonstrated a parallel optical fiber Fabry–Perot interferometer (FPI) for temperature and strain sensor based on an optimized 3×2 steps fabrication process, aiming to improve the quality of the sensitivity by use of the Vernier effect. The sensor consists of two FPIs with different propagation mediums in parallel connection, which is formed by pairs of built-in plate reflectors, another is fabricated by splicing a three-hole fiber (THF) supported by a suspension core, the higher thermal-optical coefficient can improve the temperature sensitivity. In temperature and strain sensing, two different combinations of FPIS are used as sensing units and matching reference units respectively. The amplification is matched to the wavelength range of the light source by accurately controlling the cavity length between the two FPIs. The temperature and strain sensitivities achieved in the experiment are 182.15 pm/°C and 201.47 pm/µε, respectively. The separate settings of temperature and strain sensing amplification increase the flexibility applications of dual-parameter amplification sensors.
A hybrid structure sensor is proposed for curvature and strain measurement. The sensor is fabricated by cascading the Michelson interferometer (MI) based on the up-taper and the Fabry-Perot interferometer (FPI) based on the air cavity. The MI is sensitive to curvature, and the FPI is sensitive to strain. Therefore, the cascade of sensing structures can realize the simultaneous measurement of curvature and strain. The curvature and strain sensitivity of the sensing structure are 2.59 nm/m-1 and 1.63 pm/με, respectively. The cascade of the FPI and the MI enables the end face of the MI to be effectively encapsulated, avoiding the crosstalk of external factors. The hybrid structure sensor has the advantages of simple structure, low cost, and easy preparation. The structure has the potential to be applied to structural health detection and biomedicine.
We experimentally demonstrated a scheme for the magnetic field measurement based on an in-line Michelson interferometer (MI) and magnetic fluid (MF). The tip packaged technology of a Michelson interferometer is proposed. The sensor is composed of microspherical structure, single-mode fiber (SMF), hollow-core fiber (HCF), quartz tube, and MF. Since the refractive index of the MF will be changed with the intensity of the magnetic field, the effective refractive index (ERI) of the cladding can be changed, which leads to correlative moves of the reflection spectrum. The magnetic field sensitivity of -118.7 pm/mT is obtained in the magnetic range from 1.36 to 11.8mT. We present a sensing structure, compared with other sensors, that has the advantages of simple, compact, and easy integration. The proposed sensor is expected to offer significant potential for detecting weak magnetic fields.
A refractive index (RI) sensor based on three microspheres array (TMSA) Michelson interferometer (MI) is proposed and experimentally demonstrated. The sensor was composed of a TMSA which introduces higher-order cladding mode and a section of silica fiber which is used to transmit light. Due to the flatness and cleanliness requirements of Michelson’s Fresnel reflector, a special packaging method by microtubule was used to protect the end face. The coupling efficiency between the core and the cladding of MI is proved by the coupled mode theory. The results show that the greater the effective refractive index difference (ERID) between different modes, the greater the coupling coefficient can be obtained, and the TMSA achieves the improvement in the ERID between modes. The interference arm of the sensor is 2.7cm, and the size of the microsphere is less than 230 μm. It is discussed in further detail that the order of the excited cladding mode is closely related to the sensitivity of the RI sensing. The experimental results show that the sensitivity of the RI is -56.121nm/RIU. The characteristics of TMSA make it suitable for operation in a variable environment without cross-sensitivity, which may open up new avenues for local temperature sensing.
We propose to introduce a phase shift in each ring of the multi-stage interleavers based on add-drop resonator Mach–Zehnder interferometer to quantitatively measure the wavelength offset of each interleaver, thus a demultiplexer with uniformly segmented multi-channel output can be obtained. It is found that the additional phase of a certain interleaver is equal to the offset value of this stage plus the accumulated offset value of all previous stages. Following this rule, the quantitative cascade rule can be summarized, and theoretically an infinite-channel demultiplexer will be obtained. Combining fine-tuning and thermal tuning machining method, this cascade rule can guide the fabrication of stable and tunable demultiplexers in the integrated silicon photonics technology. Our method will provide a potential application for the fabrication of dense wavelength-division multiplexing systems with ultra-large capacity.
A vector curvature sensor based on a single fiber Bragg grating (FBG) is proposed and experimentally demonstrated. The sensor is easily fabricated by encapsulating an FBG on a thin steel plate with ultraviolet glue. When the FBG deviates from the neutral plane, its effective refractive index and grating constant are changed by bending, therefore, the sensor can realize curvature measurement. Due to the opposite stress direction on the two sides of the neutral plane during bending, the sensor can realize vector measurement of curvature. The curvature sensitivity of the sensor in convex and concave bending is 558.42 pm/m-1 and -818.09 pm/m-1, respectively. This sensor has the advantage of simple structure, low cost, and easy industrial production. It has potential applications in engineering health monitoring and deformation measurement.
A highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler (OMC) is proposed and investigated. Isopropanol is a kind of material with high thermo-optic coefficient. By encapsulating the OMC into isopropanol environment, the OMC can be turned to a highly sensitive temperature sensor. Using this approach, we experimentally demonstrate a temperature sensor. By optimizing the waist diameter of the OMC, an ultrahigh temperature sensitivity of -5.89 nm/° has been achieved at the waist diameter of 2.2 μm in the range of 30-40°.
A simple composite cavity fiber tip (CCFT) Fabry-Perot interferometer (FPI) is proposed and experimentally demonstrated. The composite cavity is composed of an air cavity and a silica cavity. The air cavity is an elliptical air hole embedded in the SMF. The silica cavity is a short section of SMF cascaded to the air cavity. The CCFT FPIs were applied for temperature sensing. To take advantage of the FP’s resonant property, a laser whose wavelength is tuned to the steep slope of one of the FP resonances is used to interrogate the CCFT FPI system. With a laser interrogation, a small wavelength shift caused by a small temperature change will then be translated into a large change in output power, which can be easily detected. Therefore, the temperature sensitivity can be enhanced significantly, and the CCFT FPI can routinely resolve much smaller temperature changes.
A miniature fiber-optic sensor fabricated by fuse splicing a section of hollow silica tube between two sections of single-mode fiber is proposed and experimentally demonstrated for simultaneous measurement of the liquid refractive index (RI) and temperature. The sensitivities of RI and temperature are measured by linear fitting, respectively, and corresponding detecting resolutions are obtained by the sensitivity matrix. The different response sensitivities of two dips to RI and temperature manifest that the structure proposed can be used for simultaneous measurement. The experimental evidence indicates that the miniature fiber sensor with advantages of easy fabrication, ultracompactness, and robustness is insensitive to axial strain.
We studied a miniature optical fiber sensor based on in-line Fabry-Perot interferometer for strain measurement. The sensor was fabricated by splicing a section of hollow core tube (HCT) between two single mode fibers. The reflective spectrum of the interferometer exhibits a number of resonance wavelength dips owing to destructive interference of two reflective lights. The experiment results demonstrate that, as the strain increased, the resonance wavelength exhibits a redshift behavior. The maximal strain sensitivity obtained by linear fitting is 4.55pm/με. The device proposed has high potential in construction engineering, industry production, and high speed rail due to its merits of electromagnetic immunity, miniature structure and ease of fabrication.
We provide a novel arithmetic for the calculation of the transmission equation in a structure based on the add-drop resonator. Moreover this method can be applied on all the structures containing add-drop resonators or analogous configurations to simplify the calculation and the light path analysis. The characteristics of the transmission spectra in add-drop interferometer with two different kinds of curves are analyzed. We find out the reason for the different transmission spectra and draw an analogy with the under coupling, over coupling, and critical coupling. These results will provide some useful information and a new track to analyze the structures in this field.
We investigate the phase and group delay in eye-like ring resonator with the effect of different coupling coefficients and attenuation factors. The eye-like structure is composed of two bus waveguides coupling with the outer ring and the two rings coupling together which have the same perimeters. The eye-like ring resonator has two outputs which have different transmission characteristics. In this paper, we measure the group delay of the two outputs through changing the coupling coefficients and the attenuation factors of the inner and the outer ring. The result shows that the two outputs have reverse group delay (superluminal and slow light) which will have potential use in slow light fiber, optical buffers and optical switches.
We theoretically demonstrate the transmittion spectra and dispersion characteristics based on the electromagnetically induced transparency like effect in the nested fiber double-ring resonator with the transfer matrix theory; the system which are connected by three directional couplers consists of two inner rings, one outer ring and one straight waveguide. The simulation results show that the tunable group delay can be realized by changing the coupling coefficients. In the NDRR coupled Mach-Zehnder interferometer system, we obtained fast light and slow light simultaneously. By adjusting appropriate parameters, we can archive flat band group delay curve that has a profound application in optical interferometer, optical buffer, optical filter, optical modulator, dynamic or static optical sensing field.
KEYWORDS: Nanocrystals, Upconversion, Luminescence, Temperature sensors, Optical properties, Ytterbium, Thulium, Holmium, Temperature metrology, Far infrared
In the present paper, we first demonstrate NaLuF4: Yb3+: Tm3+/Ho3+ rare earth nanocrystals in microstructure hollow fiber. An analysis of the intense blue upconversion emission at 450 and 475 nm in Tm3+/Yb3+ codoped NaLuF4 under excitation power 0.65W available from solid laser emitting at 980nm, has been undertaken. Fluorescence intensity ratio (FIR) variation of temperature-sensitive blue upconversion emission at 450and 475 nm in this material was recorded in the temperature range from 300 to 345 K. The maximum sensitivity derived from the FIR technique of the blue upconversion emission is approximately 0.005 K−1. The results imply that Tm3+/Yb3+ codoped NaLuF4 is a potential candidate for the optical temperature sensor.
We compare the temperature sensitivity between the nested fiber ring resonator (NFRR) and the nested fiber ring resonator coupled Mach-Zehnder interferometer (NFRRCMZI). Theoretical results indicate that the temperature sensitivity of the NFRR is almost twelve times higher than that of NFRRCMZI with same parameters, hence complex MZI system can be removed and the whole sensing system will be more compatible without sacrificing the sensitivity. Taking feedback waveguide part as the sensing element in NFRR structure, the limitation of optical quality factor on sensitivity will be broken and arbitrary sensitivity can be acquired by easily setting different feedback waveguide length.
We theoretically investigate the series-coupled fiber double-ring resonator is not exactly the same perimeter, that is, when the double-ring resonator cannot be completely in resonance state, the output characteristics and dispersion characteristics of spectrum and its manifestations. In this paper, we introduce light exhibits different spectral output characteristics through double-ring resonator, when the two rings’ length ratios are δ=1,1.1,1.5, 2. Among them, δ=2 is particularly representative. When the second resonator has the same parameters, the group refractive index of the double-ring resonator whose length ratio is 2 higher than the single ring resonator two or three orders, these results indicate that we could improve the sensitivity of the double-ring resonator because sensitivity is directly related to the group refractive.
Indium doped zinc oxide (IZO) thin films were grown on sapphire substrate by radio frequency (RF/DC) magnetron sputtering technique. The structural characterization and surface morphology of IZO thin films were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The XRD results show that the samples exhibit polycrystalline characteristics and still retained wurtzite structure. The surface morphology of the samples reveals the average crystallite sizes are increased as indium content. In addition, the linear optical properties of IZO thin films were studied by UV-VIS spectrometer with wavelength range 200-900 nm. The high transmittances and the band gap values were observed in both thin films. Moreover, the nonlinear optical absorption and refraction of IZO thin films were investigated using nanosecond Z-scan technique. These samples show self-focusing optical nonlinearity and good two-photon nonlinear optical absorption behaviors. Therefore, these studies make the IZO thin films as the applications in nonlinear optical devices.
We theoretically analyze the electromagnetically induced transparency (EIT)-like spectrum in the Eye-like resonator configuration. The EIT-like spectrum results from the interference between the inner ring and the outer ring. In this paper, we obtain a tunable group delay and bandwidth of the transparency window through changing the coupling coefficients and the attenuation factors of the inner and the outer ring. The tunable group delay and the bandwidth will have potential application in optical switching or tunable delay lines and tunable bandwidth filter.
We theoretically investigate a basic structure that the series-coupled double ring resonator coupled two straight waveguide. We calculate the transmission function and phase shift through transfer matrix theory .The system consists of two rings, three straight waveguide and four couplers which the drop port and the though port are coupled to a bus waveguide .We obtain a tunable flat delay line which mitigates the deleterious effects of group delay dispersion in this structure through adjusting 4 coupling coefficient of the couplers, the attenuation factor of ring waveguide and the perimeter of 2 rings. The ability to realize the phenomenon is important for applications such as optical switching, and tunable bandwidth filter applications.
We theoretically investigate an all-fiber interleaver consisting of a two-stage cascaded Mach-Zehnder interferometer (MZI). The simulation results of the all-fiber interleaver presented symmetrical and asymmetrical output spectra and a uniform flat-top spectral response by changing the coupling coefficient of the couplers. In addition, the interleaver proposed can realize arbitrary passband width ratio between the two output ports by adjusting the coupling coefficient of the couplers involved. A near box-shaped spectral response can be generated through setting suitable parameters, at the same time, the passband and stopband of optical interleaver are improved significantly. This interleaver proposed should be useful to realize the deployment of flat-top all-fiber asymmetric interleaver in dense wavelength division multiplexing (DWDM) networks of high spectral efficiency.
The filtering characteristic of double-waveguide parallel-coupled microring resonators is theoretically investigated in this paper. Transfer matrix of the structure consisting of arbitrary number of rings is deduced. Number of very narrow symmetrical transparent channels within each stop-band can increase to any integer by extending rings of the structure, and any one or more channels can be continuously tuned and switched on/off selectively by adjusting the additional phase shift between adjacent rings. The structure is compact, reliable, flexible and tunable, and has potential vital applications for optical switches in dense wave division multiplexing (DWDM) systems.
We theoretically and experimentally study an add-drop ring resonator to achieve tunable Fano resonance. In this system, the Fano resonance results from the interference of two beams from add and through port. The line shapes of the Fano resonances are tunable through controlling the phase bias of the two beams from add and through port. At the same time, add-drop ring resonator structure enabling the truly on/off switching mechanism is realized when the phase bias is 0 or π. The experimental results well agree with the theoretical calculation.
The interaction between plasmonic resonances, sharp modes, and light in nanoscale plasmonic systems often leads to Fano interference effects. This occurs because the plasmonic excitations are usually spectrally broad and the characteristic narrow asymmetric Fano line-shape results upon interaction with spectrally sharper modes. We investigate a plasmonic waveguide system using the finite-difference time-domain (FDTD) method, which consists of a metal-insulator-metal waveguide coupled with a rectangle and a ring cavity. Numerical simulations results show that the sharp and asymmetric Fano-line shapes can be created in the waveguide. Fano resonance strongly depends on the structural parameters. This has important applications in highly sensitive and multiparameter sensing in the complicated environments.
We theoretically investigate the series-coupled double micro-ring resonator as tunable optical delay line.
Tunable optical delay line can be achieved by tunable self-coupling coefficient and attenuation factor of
micro-ring waveguide. Through choosing suitable parameters of structure, the series-coupled double
micro-ring resonator can obtain flat delay line that mitigates the deleterious effects of group delay
dispersion.
KEYWORDS: Resonators, Mach-Zehnder interferometers, Sensors, Temperature metrology, Sensing systems, Temperature sensors, Signal to noise ratio, Phase shifts, Transparency
We theoretically investigate the properties of the series-coupled fiber double-ring resonator in a Mach–Zehnder interferometer as highly sensitive temperature sensor. By comparison of phase difference between two arms, we acquired suitable phase difference of 0.5π between two arms in a Mach–Zehnder interferometer for sharpest asymmetric line shape around the resonance wavelength. We also analyze the effect of parameters on the sensitivity and the detection limit by measuring the intensity change at a fixed wavelength. For the 30dB signal-to-noise ratio system, the sensitivity and the detection limit can achieve 720.8/°C and 4.16×10−6 °C, respectively. These results indicate that this structure is suitable for highly sensitive, compact and stable sensors.
The interaction between plasmonic resonances, sharp modes, and light in nanoscale plasmonic
systems often leads to Fano interference effects. This occurs because the plasmonic excitations are
usually spectrally broad and the characteristic narrow asymmetric Fano line-shape results upon
interaction with spectrally sharper modes. We investigate a plasmonic waveguide system using the
finite-difference time-domain method, which consists of a metal-insulator-metal waveguide coupled
with a circle and a disk cavity. Numerical simulations results show that the sharp and asymmetric
Fano-line shapes can be created in the waveguide. Fano resonance strongly depends on the structural
parameters. This has important applications in highly sensitive and multiparameter sensing in the
complicated environments.
We investigate the light propagation characteristics that depend on strong dispersion response in two-ring resonant structure. Strong dispersion response brings obvious effective phase shift change in resonant arm of Mach-Zehnder interferometer. We propose that two-ring coupled Mach-Zehnder interferometer exhibits sharp asymmetric Fano line shape. It mainly decided by the combined action of a π/2 phase bias in reference arm and effective phase shift in resonant arm. It can greatly enhance the sensitivity of sensor. It allows for measuring effective refractive index change down to 10-9 refractive index units.
We propose the modulation period and amplitude of the typical square wave phase bias modulation (SWPBM) applicable to a resonator-based interferometric fiber-optic gyroscope (R-IFOG) and theoretically study the performance of the R-IFOG under SWPBM. Under SWPBM of the proposed modulation period and amplitude, the R-IFOG possesses a performance distinct from that under the hypothetical time-independent phase bias. Also, the sensitivity of the R-IFOG with SWPBM to a slow rotation rate is boosted in comparison to that without phase bias, and the rotation direction can be indicated. Furthermore, the ultrahigh sensitivity can be attained by an R-IFOG of an extremely short fiber length when the R-IFOG with SWPBM consists of a high finesse resonator. Therefore, the SWPBM of the proposed modulation period and amplitude enables highly sensitive and compact integrated closed-loop R-IFOGs.
We report the experimental observation of dispersion transition from abnormal dispersion (fast light) to normal dispersion (slow light) in a side-coupled ring resonator. We reveal that the transition from fast light to slow light can occur, when the tuned loss of the resonator results in the experience from the undercoupled regime to the overcoupled regime. Also, we experimentally fabricate the fiber side-coupled ring resonator, and measure the group delay of the resonator by coupling the resonator to a fiber Mach-Zehnder interferometer (MZI). The measured experimental results demonstrate the dispersion transition, and are in good agreement with the corresponding theoretical results. The sidecoupled resonator with the tunable dispersion (group delay) can exploited for optical storage devices, slow light Fourier transform (FT) interferometric spectrometers, white light cavities (WLCs), optical switches, optical routers, and optical sensors.
The slow light technology prompts the realization of the all-optical storage, by which one can store the information of different wavelengths at their corresponding locations. The induction of plasmon induced transparency (PIT) provides a reliable and easy implement way to achieve slow light transmission and optical storage on the nanometer scale. Meanwhile, the linewidth and position of the PIT can be adjusted by changing the parameters of materials and structures, rather than just depend on the atom level itself in Electromagnetically induced transparency (EIT). More importantly, it can also be integrated with semiconductor devices on the chip, which is an exciting expectation for optoelectronic integration. PIT technology can pave a new way to optical information processing.
We demonstrate the electromagnetically induced transparency like spectrum in the nested fiber ring resonator with the transfer matrix theory; the system consists of two rings and two waveguides which are connected by four couplers. The simulation results show that the tunable group delay can be realized by changing the coupling coefficients. At transmission window, the transmittance can achieve approximately 97.2% with the 0.05ns group delay. Through tuning the coupling coefficients, the group delay can vary from 0.05ns to -21.23ns and the bandwidth of the transparency window can vary from 37MHz to 15MHz.The ability for realizing such transparency resonance and for controlling the group delay or the bandwidth of such resonance is important for applications such as optical switching, as well as tunable bandwidth filter applications.
We theoretically investigate the properties of the eye-like ring resonator (ERR) configuration as a highly sensitive temperature sensor. We theoretically calculate the temperature sensitivity and the temperature detection precision of the configuration as a temperature sensor. The temperature sensitivity and the temperature detection precision of our configuration can achieve 837.91/ °C and 0.015°C respectively. Furthermore, we optimize the parameters of the proposed ERR configuration to enhance the temperature sensitivity and the temperature detection precision. This proposed structure enables highly sensitive, compact and stable temperature sensors.
We experimentally demonstrate that the spectral resolution of Fourier transform interferometer could be greatly
enhanced by utilizing the dispersive property of semiconductor GaAs in the near infrared region and it is inversely
proportional to the maximum group delay time that can be achieved in the system. The spectral resolution could be
increased 6 times approximately by using GaAs contrast with conventional FT interferometer under the same conditions.
We demonstrate a Mach-Zehnder(M-Z) interferometer coupled with a nested fiber ring resonator. The
numerical results shows that the sensitivity of the M-Z interferometer is enhanced by its strong
dispersive response at resonance. Large enhancement factor will be get nearing critical coupling.
Based on the solution of the density matrix of motion equations we gave a theoretical simulation and experimental measurement of reduction of light propagation for a doped Er+ fiber by population oscillation. The effects of the concentration of doped Er ion density and fiber length were given in the paper. The measured data was agree with theoretical simulation well. Maximum delay is 10.75ms. The delay is tunable by changing modulation frequency and laser input power. The result showed the delay based on slow light in fiber can be proposed a novel optical delay line.
Defects in thin film are the most important factors resulting in laser-induced damage of far-infrared laser thin film components, and always a major concern. The defect is a primary problem for infrared thin film of 3.8um in some optical systems. In this paper, single layer of ZnS YbF3 and multilayer coating is produced by thermal evaporation, and species, properties and derivation of defects in these thin films are introduced firstly, Then, the influence of material and evaporation rate on the surface defect density of laser thin film is analyzed. Finally, this paper put forward the appropriate deposition rates of thin film. The result shows that the nodule and concave hole defects are the mainly in the infrared thin film of 3.8um, and YbF3 has a great effect on the defect density in thin film. Also, the deposition rate of YbF3 has a large effect on the number and area of particles deposited on the substrate, as the evaporation rate increases, the number of particles increases markedly. It is possible that the spitting change of fused deposition material increases when the rate increases, since the centre temperature of fused deposition material increases. The defect density from 7.3X10-3 reduces to 6.8X10-4 through reducing the rate. Finally, the authors found it was appropriate when deposition rates were 4Å/s for ZnS and 2Å/s for YbF3, respectively.
In this paper, the fundamental principle of optical limiting by using nonlinear grating is theoretically described and
experimentally observed. And a device which has a nonlinear liquid solution filled between a surface-relief diffraction
grating and a polymer plate was designed to fulfill the purpose of optical limiting. By measuring the dependence of
output energy on input energy, we got the transmittance of the device. Based on theory and experiment, we analyzed the
limiting character of the device sandwich-liked.
We used a chemical method to synthesize three kinds of PbS nano-particles. There were different spatial forms in the nano-particles. The part of them were nano-ribbons with different length in shape, other parts were in nano-particles. We measured the nonlinear optical performance of suspension of three kinds of PbS nanoparticles, including nano-ribbons, nano-particles, in ethanol by nonlinear transmission and Z-scan technique with a doubled frequency Nd:YAG laser at 532nm. It was found that the PbS nanoparticles with various spatial structures exhibit good optical limiting performances. The maximum nonlinear refractive index is about 6.96x10-4cm2/GW, nonlinear absorption coefficient is about 6.98cm./GW.
KEYWORDS: Chemical species, Optical filters, Laser optics, Polarization, Potassium, Laser applications, Polarizability, Tunable lasers, Absorption, Signal to noise ratio
In this paper, the semi-classical theory was utilized to theoretically analyze K-532nm Laser-induced dispersion optical filter (LIDOF), and theoretical model was given. By solving the density matrix equations, the system induced polarizability was gained, and eventually the transmission spectra were gained by theoretical calculation.
We have observed slow light propagation with a group velocity as slow as 27.52±0.05m/s in a ruby crystal at room temperature. The Gaussian-like pulse signal, which was gained by modulating beam at 514.5nm, was injected into a ruby crystal. The spectral hole effect, attributed to high laser power density, leads to the induced refractive index steep rising. According as this rising, the group velocity of pulse propagation in the ruby becomes very slowly. The experiment result shows that the velocity of pulse propagation depends on the modulation frequency, laser power, the position of crystal and the profile of signal waveform. At the same condition the Gaussian-like pulse obtains much slower velocity than sinusoidal signal.
A theoretical model for the Laser induced dispersion optical filter (LIDOF) is presented. The filter has a higher transmission and a narrower line width than excited-state Faraday anomalous dispersion optical-filter (ESFADOF). The theoretical treatment is valid for different atoms LIDOF systems.
In this paper we investigated potassium Faraday filter at 770 nm theoretically and experimentally. With a potassium cell of 0.01 m in length in an axial magnetic field of 0.0815T, line-center operation has been achieved. The calculated peak transmission has reached 93% with a FWHM bandwidth of only 1.6 GHz, the measured FWHM bandwidth of the filter is 2.2 GHz, which is in detail agreement with the theoretical result.
KEYWORDS: Potassium, Optical filters, Magnetism, Chemical species, Absorption, Telecommunications, Digital signal processing, Signal processing, Bismuth, Free space
In this paper we investigated potassium Faraday filter at 766 nm theoretically and experimentally. With a potassium cell of 0.01m in length in an axial magnetic field of 0.0815T, the line-center operation has been achieved. The calculated peak transmission has reached 83 percent with a FWHM bandwidth of only 1.5GHz, the measured FWHM bandwidth of the filter is 1.6GHz, which is in good agreement with the theoretical result.
In this paper, the theoretical model and experimental demonstration of Cs 852nm FADOF in weak and strong magnetic field are discussed. Whenthe FADOF system working under the weak field, the theoretical and experimental results are agreement with the previous repot. In the case of strong field, when performing condition is B equals 0.0883T, T equals 351K, the line-center operation is observed. The comparison between the theory and the experiment gives reasonably expected results.
An ultranarrow bandwidth sodium Faraday anomalous dispersion optical filter is studied theoretically and experimentally for the 3P3/2 $IMP 3S1/2 transition including hyperfine Zeeman effects. With a Na cell of 3cm in length in an axial magnetic field of 316 Gauss, the peak transmission has reached about 38 percent with a FWHM bandwidth of only 1.5GHz. Theoretical and experimental results are in good agreement for the transition.
A near infrared potassium Faraday anomalous dispersion optical filter was theoretically studied for the transition, including hyperfine ef fects. In the paper the Zeeman splittings of potassium were calculate d for the given transition, that is, diagonalizing the disturbed matri x, and finding out the Zeeman sublevels position and transition freque ncies. Next we obtain an expression for the bulk polarizability tensor . Finally we acquire the transition coefficient relating to the polari zability tensor. The effect of temperature and magnetic field on prope rties of Faraday optical filter were investigated. The optimum filter operating condition was also obtained. The single peak bandwidth of th e optical filter is about 0.86GHz, equivalent noise band width is 2.4G Hz. The transmission is approximately 94.1 percent under the optimum c ondit ion.
In this paper, the experiment results of Cs 455 nm Faraday Anomalous Dispersion Optical Filter transmission were given. The observation was discussed and analyzed.
With several different glasses for nonlinear optical materials we first observed the far field multiple-ring fringes in them using a cw Ar+ laser as a light source at 514.5 nm and 488.0 nm, respectively. The central brightness of multiple-ring fringes could be controlled through changing incident power or the sample position near the focus. This phenomenon is considered as a result of spatial self-phase modulation caused from self-focusing. The thresholds of fringes and the thresholds of laser damage in three kinds of glasses are different from one another. Moreover, the far-field fringes of reflecting light were watched carefully. The light power limiter of optical density D equals log 1/T(lambda ) equals (infinity) can be constructed with the phenomenon.
In this paper, the filtering characteristics of Cs atomic filter were theoretically and experimentally investigated, especially the influence upon the Cs atomic filter's properties with Ar buffer gas.
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