密集波分复用激光光源的声光偏频无调制频率锁定

利用声光调制器(AOM)的偏频特性,以CH4分子吸收线R9支一条强吸收线(λ=1.6378μm)作为参考频率,实现了对外腔式半导体激光器的无调制频率锁定。实验中在100 s内典型的频率起伏小于5.6 MHz,较激光器自由运转时的频率起伏34 MHz有了显著的改善,而误差信号的阿仑(Allan)方差平方根(即稳定度)在平均积分时间为16 s时达到最小值5.75×10-10。该方法实现了基于气体分子吸收线的半导体激光器无调制锁频,并且CH4分子在1.6~1.7μm处有丰富的振转光谱,满足光纤通信中对激光器输出波长的要求,可应用于光纤通信中激光光源的频率锁定。     

偏频锁定法稳定塞曼氦氖激光频率

研制成一种互锁的无调制的塞曼He-Ne激光稳频器。稳频中心调谐在左右旋光差频曲线的最大斜率点上,以获得有较大的激光输出功率,环路能给出快速锁定,秒级频率稳定度优于2×10~(-10)。     

注入锁定半导体激光器调制特性研究

通过速率方程建立外光注入半导体激光器的理论模型,在注入锁定条件下对其进行稳态及小信号分析,研究了注入光对调制特性的影响.结果表明,强光注入在一定程度上增大了谐振频率和调制带宽,但是抑制了响应增益,通过增大偏置电流加以补偿,才能获得理想的响应增益和带宽;并且外光注入大大降低了低频调制时的频率啁啾.     

激光脉冲偏频锁定技术的发展

综述了偏频锁定技术的意义、应用及其在国内外的发展状况,并详细介绍了各种脉冲外差频率鉴频方法和它们的优缺点。     

CO_2相干激光的偏频锁定

在CO_2相干激光探测系统中,信号光和本振光的频率稳定度,直接影响着激光的相干性,从而影响了探测系统的精度和成象的分辨率。将欲发射的CO_2激光偏频锁定到本振CO_2激光的频率上,由于偏频锁定的频率跟踪精度很高,从而可以使发射的CO_2激     

基于铯原子D2线光抽运光谱的半导体激光器偏频锁定

通过探测在连续调谐抽运光作用下的气室对频率确定的探测光的吸收,可获得光抽运光谱,探测光和抽运光同时耦合不同的超精细跃迁时可形成光抽运光谱的峰值,此时两个光场有确定的稳定性依赖于原子能级的频率差。利用光抽运光谱并结合锁频环路,完成了参考频率为原子超精细分裂的连续半导体激光器间的偏频锁定。通过选择不同的超精细能级,两个激光器输出激光的频率偏移可以锁定在数百兆赫兹的激发态超精细能级间隔或约9 GHz的基态能级间隔附近。     

CO_2脉冲激光偏频锁定系统

综述了目前脉冲激光偏频锁定的发展状况 ,总结了各种脉冲激光偏频锁定的方法 ,并提出了宽带全数字鉴频方法 ,带宽达到 2～ 10 0MHz,以及以鉴频器为基础的简单偏频锁定系统设计。介绍了电光外调制CO2 脉冲激光与连续CO2 激光之间的偏频锁定实验 ,光脉冲重复频率为 10kHz ,脉宽为 5 μs。实验频率锁定结果良好 ,频率稳定度为 1 2 7× 10 -7(阿仑方差 )。     

可调谐外差式激光偏频锁定

本文提出一种可调谐外差式激光偏频锁定方法,讨论了这种技术在频域内测量激光器瞬稳以及不同频谱振荡的激光器之间进行锁定的可能应用。给出了两台选支CO_2激光器上锁定实验的结果。考虑了本振频率不稳定性对锁定精度的影响。     

注入锁定半导体激光器的相位调制特性研究

本文研究了在考虑载流子变化引起折射率变化的情况下,注入锁定半导体激光器(LD)的相位调制(PM);并提出了在PM时,对伪强度调制(SIM)的抑制.     

注入锁定对半导体激光器调制特性的影响

本文给出了注入锁定半导体激光器动态频率漂移的解析表达式。分析表明:对不同类型的激光器,注入锁定对动态频率漂移的影响是不同的,注入较大的光功率有利于抑制激光器的动态频率的漂移。     

Multiwavelength sources using laser diodes frequency-locked toatomic resonances

It is shown that low-cost compact disk AlGaAs laser diodes make it possible to realize manifold optical sources with precise and stable wavelengths when locked to rubidium vapor resonances. Many optical frequency references can be obtained with the use of absorption cells containing a foreign gas or by placing cells in static magnetic fields. The same approach can be used with other wavelengths required by optical fiber communications     

Direct frequency demodulation with frequency-locked Gunn oscillators

The use of a frequency-locked Gunn oscillator as a frequency demodulator is described. A detection sensitivity of ?40 to ?30 dBm is obtainable with detected signals in the millivolt range.     

A 1.5- mu m laser package frequency-locked with a novel miniature discharge lamp

The authors report a packaged distributed feedback (DFB) laser frequency-locked to the Kr 1s/sub 2/-2p/sub 8/ transition at 1.54782 mu m using a novel miniature discharge lamp. This transition is not only close to the wavelength where typical single-mode optical fibers show minimum attenuation but also gives a large optogalvanic signal. This lamp generates more than an order of magnitude larger optogalvanic signal for the same input power than conventional indicator lamps of comparable size. The frequency stability of the laser package is better than 2 MHz, and the fiber-to-laser coupling loss (<2 dB) is very stable against temperature fluctuations and mechanical vibrations.<>     

Frequency stabilization of laser diode using a frequency-locked ring resonator to acetylene gas absorption lines

The frequency stabilization of a 1.5 mu m distributed-feedback (DFB) laser diode using a planar lightwave circuit (PLC) ring resonator whose resonant frequency is locked to /sup 12/C/sub 2/H/sub 2/ and /sup 13/C/sub 2/H/sub 2/ gas absorption lines is described. The resonant frequency of PLC ring resonator was stabilized within a 5 MHz peak-to-peak fluctuation. With this ring resonator the outer frequency fluctuation of the DFB laser diode was stabilized within 10 MHz at every resonant frequency at 5 GHz intervals. The stability demonstrated is as good as the method using molecular absorption lines as a reference. The stabilized frequency can be selected at any point on the optical resonant peaks of the optical resonator.<>     

Adaptive cancellation of crosspolarisation: experiments with unmodulated signals

An experiment on the adaptive cancellation of crosspolarisation is reported. The measurements were performed on a 2.2 km long horizontal link at 12 GHz using linear polarisations. The cancellation system proved to be very efficient even for the most severe meterological events.     

Optical sweeper with double-heterodyne frequency-locked loop

An optical sweeper is constructed with a 1.5 mu m distributed Bragg reflector (DBR) laser for quick frequency-response measurement of high-speed optical receivers. The laser is successfully controlled over a 16 GHz tuning-range by using a double-heterodyne frequency-locked loop. S/N-improved measurement is also demonstrated at sweep speeds as fast as 1 GHz/s.<>     

一种功率稳定的氦-氖激光器

本文介绍了一种改进后的新型氦-氖激光器，其时间功率稳定性提高到3％，方位功率稳定性提高到6％。它具有制造方便、输出功率可调等优点。文中从力学原理出发，讨论了改进前后两种结构的静力学性质。     

DFB激光器的高稳定宽带锁频方案设计和实现

提出了一种可用于两台半导体分布反馈(DFB)激光器的高稳定宽带锁频方案,高稳定光频锁定范围可覆盖50MHz至11GHz.通过测量和计算得出两台DFB激光器的光频差与目标频率之间的误差,然后基于比例-积分-微分(PID)控制算法反馈控制其中一台DFB激光器的温度和电流,分别粗调和微调其输出光频率,最终实现两台激光器的光频差锁定.实验结果表明,在连续工作2小时内宽带锁频稳定度的均方根误差优于5MHz,接近理论极限.     

A 50 MHz phase- and frequency-locked loop

A monolithic phase/frequency-locked loop has been developed for operation at up to 50 MHz. The loop combines wide capture range and narrow bandwidth, making it ideal for timing recovery in digital transmission systems. The 24-pin device features an electronically-tuned voltage-controlled LC oscillator and includes the input differentiation and full-wave rectification circuitry required for clock recovery from unipolar nonreturn-to-zero (NRZ) data.     

Start-oscillation conditions in modulated and unmodulated O-type oscillators

The starting conditions for the O-type backward-wave oscillator are computed for large values of C, QC and d, using both digital and analog methods. A general method of solving complex polynomials called the "downhill" method is applied both to the secular equation and then to the RF voltage equation to obtain starting conditions. The analog computer is used to solve simultaneously, by trial and error method, the linear circuit and ballistic differential equations. The analog method is applied to the modulated BWO in order to determine the effects of modulations on the starting conditions. Extensive calculations of BWO starting conditions have been made for a wide range of C, QC and d.