We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To r...We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To realize a stable output of 780 nm semiconductor laser, an FTMTS optical heterodyne frequency stabilization system is constructed. Before entering into the frequency stabilization system, the probe laser passes through an acousto-optical modulator （AOM） twice in advance to achieve tunable frequency while keeping the light path stable. According to the experimental results, the frequency changes from 120 MHz to 190 MHz after the double-pass AOM, and the intensity of laser entering into the system is greatly changed, but there is almost no change in the error signal of the FTMTS spectrum. Using this signal to lock the laser frequency, we can ensure that the frequency of the laser changes with the amount of AOM shift. Therefore, the magneto-optical trap （MOT）-molasses process can be implemented smoothly.展开更多
The method for measuring the strain of an object using an optical fiber and a frequency modulation(FM) coupled cavity semiconductor laser is proposed.This method uses the coherent FM heterodyne principle of the Michel...The method for measuring the strain of an object using an optical fiber and a frequency modulation(FM) coupled cavity semiconductor laser is proposed.This method uses the coherent FM heterodyne principle of the Michelson interferometer and can avoid the π/2 nonreciprocal phase bias and phase shifting problem existing in general fiber optic interferential sensors, the maximum detection range is limited by the coherent length of the semiconductor laser and its relative factor.展开更多
<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat ...<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat frequency signal is obtained by self-heterodyne detection. The frequency changes are converted to the envelope of beat frequency signal after amplitude-frequency response. The active frequency sweep linearization is realized by feeding envelope deviations back to the drive currents of the lasers by a feedback loop. A simulation model is built to verify this scheme by Simulink. This scheme does not need high-performance, expensive lasers, complex linearization or tedious post-processing processes, which are of great significance for related applications. </div>展开更多
We demonstrate a 1550-nm narrow-linewidth fiber ring laser with stable single polarization by using single-mode Er-doped fiber as active fiber and saturable absorber. A polarization-maintaining circulator is used to a...We demonstrate a 1550-nm narrow-linewidth fiber ring laser with stable single polarization by using single-mode Er-doped fiber as active fiber and saturable absorber. A polarization-maintaining circulator is used to acquire single-polarization laser light with the degree of polarization of 99.8%--99.9%. The linewidth measured using a delayed self-heterodyne method is less than 0.5 kHz. Frequency of the fiber laser can be modulated by driving the waveguide phase modulator with proper voltage. A Mach-Zehnder interferometer with the optical path difference between two arms of about 36 km is used to study the long-distance coherent detection of the fiber laser for frequency-modulated continuous-wave application.展开更多
The modulation response characteristics of a Fabry-Perot semiconductor laser(slave FP-LD) subjected to light injection from another Fabry-Perot semiconductor laser(master FP-LD) have been investigated theoretically.Th...The modulation response characteristics of a Fabry-Perot semiconductor laser(slave FP-LD) subjected to light injection from another Fabry-Perot semiconductor laser(master FP-LD) have been investigated theoretically.The results show that the modulation response performances of the slave FP-LD depend on the light injection strength,the central mode frequency detuning Δf and the mode spacing difference Δλ between the slave FP-LD and the master FP-LD.With the increase of the light injection strength from the master FP-LD,the 3 dB modulation bandwidth of the slave FP-LD will be enhanced;however,if the injection strength is increased to certain degree,the front side of the relaxation oscillation peak will be reduced to below 3 dB,which results in the rapid decrease of the 3 dB modulation bandwidth.With the increase of Δf,for a relatively small injection strength level,the 3 dB modulation bandwidth will behave a monotonous enlargement until the slave FP-LD operates in a period-one state(P1).For a relatively strong optical injection level,the slave FP-LD has a broad injection-locked frequency detuning area.Within the injection-locked area,with the increase of frequency detuning Δf,the 3dB modulation bandwidth increases at first and then decreases after experiencing a maximum value.For given light injection strength and frequency detuning,the 3 dB modulation bandwidth of the slave FP-LD has two maximums and behaves a symmetrical distribution with the change of Δλ.By choosing reasonable parameters,the 3 dB modulation bandwidth can be significantly improved.For the parameter values selected in this paper,the 3 dB modulation bandwidth can increase 5.5 times compared with the case of free running.展开更多
基金Project supported by the National Key Scientific Instrument and Equipment Development Project,China(Grant No.2014YQ35046103)
文摘We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To realize a stable output of 780 nm semiconductor laser, an FTMTS optical heterodyne frequency stabilization system is constructed. Before entering into the frequency stabilization system, the probe laser passes through an acousto-optical modulator （AOM） twice in advance to achieve tunable frequency while keeping the light path stable. According to the experimental results, the frequency changes from 120 MHz to 190 MHz after the double-pass AOM, and the intensity of laser entering into the system is greatly changed, but there is almost no change in the error signal of the FTMTS spectrum. Using this signal to lock the laser frequency, we can ensure that the frequency of the laser changes with the amount of AOM shift. Therefore, the magneto-optical trap （MOT）-molasses process can be implemented smoothly.
文摘The method for measuring the strain of an object using an optical fiber and a frequency modulation(FM) coupled cavity semiconductor laser is proposed.This method uses the coherent FM heterodyne principle of the Michelson interferometer and can avoid the π/2 nonreciprocal phase bias and phase shifting problem existing in general fiber optic interferential sensors, the maximum detection range is limited by the coherent length of the semiconductor laser and its relative factor.
文摘<div style="text-align:justify;"> A scheme of frequency sweep linearization of semiconductor lasers using a feed-back loop based on amplitude-frequency response is demonstrated in this paper. The beat frequency signal is obtained by self-heterodyne detection. The frequency changes are converted to the envelope of beat frequency signal after amplitude-frequency response. The active frequency sweep linearization is realized by feeding envelope deviations back to the drive currents of the lasers by a feedback loop. A simulation model is built to verify this scheme by Simulink. This scheme does not need high-performance, expensive lasers, complex linearization or tedious post-processing processes, which are of great significance for related applications. </div>
文摘We demonstrate a 1550-nm narrow-linewidth fiber ring laser with stable single polarization by using single-mode Er-doped fiber as active fiber and saturable absorber. A polarization-maintaining circulator is used to acquire single-polarization laser light with the degree of polarization of 99.8%--99.9%. The linewidth measured using a delayed self-heterodyne method is less than 0.5 kHz. Frequency of the fiber laser can be modulated by driving the waveguide phase modulator with proper voltage. A Mach-Zehnder interferometer with the optical path difference between two arms of about 36 km is used to study the long-distance coherent detection of the fiber laser for frequency-modulated continuous-wave application.
基金Supported by the Open Fund of the State Key Laboratory of Millimeter Waves of China (Grant No.K200805)Natural Science Foundation of Chongqing City of China (Grant No.CSTC-2007BB2333)
文摘The modulation response characteristics of a Fabry-Perot semiconductor laser(slave FP-LD) subjected to light injection from another Fabry-Perot semiconductor laser(master FP-LD) have been investigated theoretically.The results show that the modulation response performances of the slave FP-LD depend on the light injection strength,the central mode frequency detuning Δf and the mode spacing difference Δλ between the slave FP-LD and the master FP-LD.With the increase of the light injection strength from the master FP-LD,the 3 dB modulation bandwidth of the slave FP-LD will be enhanced;however,if the injection strength is increased to certain degree,the front side of the relaxation oscillation peak will be reduced to below 3 dB,which results in the rapid decrease of the 3 dB modulation bandwidth.With the increase of Δf,for a relatively small injection strength level,the 3 dB modulation bandwidth will behave a monotonous enlargement until the slave FP-LD operates in a period-one state(P1).For a relatively strong optical injection level,the slave FP-LD has a broad injection-locked frequency detuning area.Within the injection-locked area,with the increase of frequency detuning Δf,the 3dB modulation bandwidth increases at first and then decreases after experiencing a maximum value.For given light injection strength and frequency detuning,the 3 dB modulation bandwidth of the slave FP-LD has two maximums and behaves a symmetrical distribution with the change of Δλ.By choosing reasonable parameters,the 3 dB modulation bandwidth can be significantly improved.For the parameter values selected in this paper,the 3 dB modulation bandwidth can increase 5.5 times compared with the case of free running.
