具有几个光振荡周期的飞秒激光脉冲

从麦克斯韦方程组出发 ,推导出了具有几个光振荡周期的飞秒激光脉冲在非线性光纤中传输的方程和非线性光纤的折射率。给出了描述具有几个光振荡周期的飞秒激光脉冲在非线性光纤中传输方程的解。研究了在非线性光纤中自相位调制导致具有几个光振荡周期的飞秒激光脉冲频谱展宽 (脉宽压缩 )的详细物理过程。研究了非线性光纤中飞秒光孤子产生的条件     

Auto-correlation Properties of Scattering Light in Ultrasound-modulated Random Media

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｅｘｔｒａｃｔｉｎｇｕｓｅｆｕｌｉｎｆｏｒｍａｔｉｏｎａｂｏｕｔｔｈｅｄｙｎａｍｉｃａｌｓｃａｔｔｅｒｅｒｓｆｒｏｍｔｈｅｔｅｍｐｏｒａｌｆｌｕｃｔｕａｔｉｏｎｓｏｆｓｃａｔｔｅｒｉｎｇｌｉｇｈｔｆｉｅｌｄｈａｓｂｅｅｎｓｔｕｄｉｅｄｆｏｒｍａｎｙｙｅａｒｓ.Ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｄｉｆｆｕｓｉｎｇ ｗａｖｅｓｐｅｃｔｒｏｓｃｏｐｙ[1～ 3 ] (ＤＷＳ)ｈａｓｅｘｔｅｎｄｅｄｔｈｅｔｒａｄｉｔｉｏｎａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｓｉｎｇｌｅ ｓｃａｔｔｅｒｉｎ…     

Fiber Ring Laser In-cavity Phase Modulation

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｏｐｔｉｃａｌｃｏｍｍｕｎｉｃａｔｉｏｎ ,ｏｐｔｉｃａｌｓｅｎｓｉｎｇｓｙｓｔｅｍ ,ａｎｄｈｉｇｈｒｅｓｏｌｕｔｉｏｎｓｐｅｃｔｒｏｓｃｏｐｅ ,ｌａｓｅｒｓｏｕｒｃｅｓｗｉｔｈｎａｒｒｏｗｌｉｎｅｗｉｄｔｈａｒｅａｌｗａｙｓｎｅｃｅｓｓａｒｙ .Ｆｉｂｅｒｒｉｎｇｌａｓｅｒｓａｎｄａｃｔｉｖｅｆｉｂｅｒｒｉｎｇｒｅｓｏｎａｔｏｒｆｉｌｔｅｒｓｍａｙｂｅａｐｐｌｉｅｄｔｏｐｒｏｄｕｃｅｎａｒｒｏｗｌｉｎｅｗｉｄｔｈｌａｓｅｒｓ .Ｂｅｃａｕｓｅｔｈｅｃｈａｒａｃｔｅ…     

Strong optical feedback in birefringent dual frequency laser

Strong optical feedback in a birefringent dual frequency He--Ne laser with a high reflectivity feedback mirror has been investigated for the first time. The output characteristics of two orthogonally polarized modes are demonstrated in two different optical feedback cases: one is for both modes being fed back and the other is for only one of the modes being fed back. Strong mode competition can be observed between the two modes with strong optical feedback. And when one mode's intensity is near its maximum, the other mode is nearly extinguished. When both modes are fed back into the laser cavity, the mode competition is stronger than when only one mode is fed back. The difference in initial intensity between the two orthogonally polarized modes plays an important role in the mode competition, which has been experimentally and theoretically demonstrated.     

Carrier shock and frequency conversion of a few—cycle pulse laser propagating in a non—resonant two—level atom medium

We have studied the spectral behaviour of few-cycle soliton pulses in a non-resonant two-level atom medium by solving the full Maxwell－Bloch equations. It is demonstrated further that the carrier effects play an important role in the propagation of the few-cycle pulse laser. When the frequency detuning is not very large, both the population distribution and the refractive index of the medium follow the oscillatory carrier field instantaneously; in this case, carrier-wave compression or carrier shock occurs, and a supercontinuum broader than that in the resonant medium may be generated. When the frequency detuning is large, the carrier shock is weak and the spectrum is not continuous, only showing an odd harmonic radiation.     

Effects of walk-off on cross-phase modulation induced modulation instability in an optical fibre with high-order dispersion

This paper investigates the effects of walk-off among optical pulses on cross-phase modulation induced modulation instability in the normal dispersion region of an optical fibre with high-order dispersion. The results indicate that, in the case of high-order dispersion, the walk-off effect takes on new characteristics and will influence considerably the shape, position and especially the number of the spectral regions of the gain spectra of modulation instability. Not only the group-velocity mismatch, but also the difference of the third-order dispersion of two optical waves will alter the gain spectra of modulation instability but in different ways. Depending on the values of the walk-off parameters, the number of the spectral regions may increase from two to at most four, and the spectral shape and position may change too.     

Optimization of Output Properties for Bias Signal-Modulated in a Single-Mode Laser

Defining the quantity K as the signal-to-noise ratio （SNR） and the normalized intensity fluctuation C（O） of a single-mode laser for bias signal modulation driven by color noises with colored correlation, the whole output properties of the laser system is described by K. It is found that there is a maximum in the curves of K versus D, Q, and io. The optimization parameters are gained.     

Experimental and theoretical studies of a high repetition rate fiber laser, mode-locked by external optical modulation

An experimental and theoretical study of a high repetition rate laser source operating on a novel mode-locking technique is presented. This technique relies on the fast saturation and recovery of a semiconductor optical amplifier induced by an external optical pulse and has been used to obtain 4.3 ps pulses at 20 GHz. A complete mathematical model of the fiber ring laser is presented describing the mode-locking process in the laser oscillator and providing solutions for the steady-state mode-locked pulse profile. The critical parameters of the system are defined and analyzed and their impact on the formation of the mode-locked pulses is examined. The comparison between the theoretical results and the experimental data reveals very good agreement and has allowed the optimization of the performance of the system in terms of its critical parameters.     

双闭环光纤陀螺控制回路研究

本文讨论了采用数学据齿波和方波调制方案的闭光纤陀螺系统的实现。在此基础上,进一步研究了针对消除由于斜坡复位幅度２π不精确给系统带来的误差而设计的第二闭环回路（幅值回路）。结果表明：第二闭环回路的加入能很好地在短时间内消除由复位幅度２π不精确带给系统的偏差。     

基于软件编码的FLEX高速寻呼测试仪的研制

基于FLEX和POCSAG寻呼协议,采用单片机AT89C55为控制核心,以MCS-5l汇编语言实现软件编码,研制了一套兼容POCSAG协议的FLEx高速寻呼测试仪．本文详细讨论了实现FLEx高速寻呼协议的软件编码技术．在对数据块进行交织时,提出了一种简化的软件编码措施,将多相复用模式的交织数据块简化为单相模式进行处理,从而减小了编码难度．