Single-polarization wavelength-tunable fiber laser with anonreciprocal cavity

Unidirectional, continuously tunable, and polarized oscillation in an erbium doped fiber ring laser is demonstrated without an isolator. Nonreciprocal oscillation is realized with one polarization splitter and two polarization controllers. Fine tuning is realized with fiber birefringence. The laser spectrum is continuously tunable from 1530 to 1560 nm with line widths less than 0.2 nm; the degree of polarization at the output is 92%     

低阈值短腔随机分布反馈光纤激光器

设计了一种低阈值短腔随机分布反馈光纤激光器,采用1455 nm的激光二极管泵浦一段色散补偿光纤,采用正向反馈和反向反馈两种结构分别将一阶随机激光阈值降至760 mW和520 mW,且反向反馈结构的二阶阈值与一阶阈值相同,分析了色散补偿光纤长度对阈值的影响,实验证明优化色散补偿光纤长度是降低一阶与二阶随机激光阈值的有效方法。     

Single-polarization operation of fiber distributed feedback (DFB)lasers by injection locking

This paper investigated injection locking characteristics of a fiber distributed feedback (DFB) laser operating in dual polarizations, and found that it could operate in a single polarization by injection locking. The locking bandwidth was less than 10 MHz, much narrower than DFB laser diodes as a consequence of longer cavity length and resulting longer photon lifetime. As a more practical method to realize single-polarization operation of the fiber DFB laser, we proposed self-injection locking with a polarization-selective optical feedback composed of a mirror and a polarizer, and demonstrated a stable single-polarization operation     

Dual-wavelength erbium-doped fiber laser with asymmetric fiber Bragg grating Fabry-Perot cavity

A novel dual-wavelength fiber laser with asymmetric fiber Bragg grating（FBG） Fabry-Perot（FP） cavity is proposed and experimentally demonstrated. A couple of uniform FBGs are used as the cavity mirrors, and the third FBG is used as intracavity wavelength selector by changing its operation temperature. Experimental results show that by adjusting the operation temperature of the intracavity wavelength selector, a tunable dual-wavelength laser emission can be achieved. The results demonstrate the new concept of dual-wavelength lasing with asymmetric FBG FP resonator and its technical feasibility.     

Fabry-Perot semiconductor laser injection locking

Injection locking of a semiconductor laser is studied using a Fabry-Perot (FP) model. For low injection powers the FP model gives the same results as the rate equation model. At higher injection powers, the FP laser has an unlimited injection locking bandwidth; however, regions of the bandwidth are dynamically unstable. The influence of the linewidth enhancement factor on injection locking and its stability are also studied using the FP model. Finite values of the linewidth enhancement factor lead to increased locking bandwidth, asymmetry in the locking range and a saddle-node bifurcation in the injection locked solutions, of which only lower carrier density arm has linearly stable solutions.     

High efficient and narrow linewidth fiber laser based on fiber grating Fabry-Perot cavity

A high Er3+-doped narrow linewidth fiber laser based on fiber Bragg grating Fabry-Perot cavity was demonstrated. The spatial hole burning effect was restrained by a fiber Faraday rotator. Two short fiber Bragg grating Fabry-Perot cavities as narrow bandwidth filters discriminated and selected laser longitudinal modes efficiently. A stable single-frequency 1534.83 nm laser was acquired. Pumped by two 976 nm laser diodes and two-ended output, the fiber laser exhibited a 12 mW threshold. Total 39.5 mW output power and one end 22 mW output power were obtained at the maximum 145 mW pump power. Optical-optical efficiency was 27% and slope efficiency was 29.7%. The output power seemed to be saturated when pump power increased. The 3 dB linewidth of the laser was less than 7.5 kHz, measured by the delayed self-heterodyne method with 15 km monomode fiber. The high power narrow linewidth fiber laser can be used in high resolution fiber sensor systems.     

激光锁定Fabry-Perot干涉仪精密测量电容

为了实现pF量级小电容的精密测量,建立了基于激光锁定Fabry-Perot干涉仪的精密电容测量系统。对该系统所采用的计算电容原理、激光锁定干涉仪方法及其整数级次确定方法进行了研究。首先,根据Lampard和Thompson电学基本原理介绍了Fabry-Perot干涉仪的结构与工作方式,采用一种锁定干涉仪测量位移的方法。其次,介绍了Fabry-Perot干涉仪的光路设计,详细分析了干涉仪锁定控制系统的工作状态以及锁定状态下干涉仪腔长的抖动情况。通过分析利用电容值确定干涉仪整数级次变化的可行性,提出了基于1 pF标准电容器确定Fabry-Perot干涉仪整数级次的实验过程。最后,介绍了Fabry-Perot锁定干涉仪的台阶式位移过程以及利用该套系统测量电容的重复性。实验结果表明:Fabry-Perot干涉仪在锁定状态下,腔长抖动峰峰值为0.4 nm,测量1 pF标准电容器重复性达到5.010-9。     

Characteristics of AlGaAs Fabry-Perot cavity type laser amplifiers

Signal gain, saturation power, and noise bandwidth, which are important parameters determining preamplifier and linear repeater system performance [1], were measured for an AlGaAs Fabry-Perot cavity type laser amplifier. The unsaturated signal gain increases with the pumping level and a maximum signal gain as high as 27 dB is obtained near oscillation threshold. The saturation output power, at which the signal gain is decreased from the unsaturated value by 3 dB, is -6 to -8 dBm. The beat noise powers between signal and spontaneous emission components were measured. The error rate characteristics of an AlGaAs laser preamplifier and Si photodiode scheme were studied at a data rate of 100 Mbits/s. The experimental results on noise powers and error rate performance are in reasonable agreement with the theoretical analysis given in an accompanying paper [1].     

基于F-P的光纤气体检测系统

简单介绍了利用F-P的可调谐性提出的一种新型的基于1550nm宽带光源的光纤气体检测系统的工作原理、实验装置软硬件设计以及利用该实验装置进行实验数据处理的思想--FFT一次谐波算法和计算光谱面积的算法.利用一次谐波的方法进行了实验,得出实验结果和结论.     

用可调谐法布里-珀罗腔测量光纤光栅波长

提出了一种利用压电陶瓷构成的可调谐法布里 -珀罗腔测量光纤光栅反射波长的方案 ,该方案可以直接将波长转换为电信号。阐述了该方案的基本原理 ,并讨论了在设计法布里 -珀罗腔时应考虑的几个问题。     

Passive FM locking and pulse generation from 980-nmstrained-quantum-well Fabry-Perot lasers

Multiple-order passive frequency modulation (FM) locking in 980-nm lasers has been measured using autocorrelation and optical spectra. Optical fiber dispersion provided a simple means of converting the coherent FM output to an amplitude modulation (AM) pulse train at multiples of the laser round-trip frequency. We have produced such pulses at frequencies of up to 233 GHz from a single source with no external modulation. Extension of this technique should be possible with 1550-nm lasers     

Gold nanoparticles film for Q-switched pulse generation in thulium doped fiber laser cavity

Passively Q-switched thulium doped fiber laser (TDFL) has been successfully demonstrated using gold nanoparticles (GNPs), which were embedded into polyvinyl alcohol as saturable absorber (SA). The stable self-starting Q-switched laser was generated to operate at 1 891 nm when a tiny piece of the prepared film was slot in between two fiber ferrules and incorporated into the laser cavity. The repetition rate can be adjusted from 48.54 kHz to 49.64 kHz while the pulse width decreased from 3.52 μs to 2.38 μs with the increase of 1 550 nm pump power from 840 mW to 930 mW. The corresponding pump power output power linearly increased from 3.62 mW to 6.3 mW with a slope efficiency of 2.53%. The maximum peak power and pulse energy were recorded at about 39 mW and 0.12 µJ, respectively at pump power of 930 mW. The Q-switching operation was caused by the surface plasmon resonance absorption of GNPs.     

Distributed feedback fiber Raman laser

We analyze the properties of a distributed feedback fiber laser based on Raman amplification. Such a laser is quite practical and has a number of novel properties. We model numerically the laser dynamics, analyze in detail the role of the nonlinear refractive index of the fiber and argue on the optimal design parameters     

High-power supercontinuum generation in a nested linear cavity involving a CW Raman fiber laser

We construct a novel nested linear cavity configuration to generate supercontinuum (SC) under continuous-wave pump. With this structure, stimulated Raman scattering and four-wave mixing can affect the whole region of the SC spectrum while the pump line is removed outside of the continuum, and a symmetrical spectrum can be obtained. The properties of the structure are demonstrated by using 3.5-km single-mode fiber, and an SC centered at 1315 nm with the bandwith of 102 nm and the output power of 1.3 W is achieved. By tuning the feedback fiber Bragg grating, we can easily adjust the spectral shape of SC to fit different requirement.     

Transmission line description of optical feedback and injection locking for Fabry-Perot and DFB lasers

A general theory of semiconductor lasers is presented in which the static and dynamic properties are expressed in terms of the effective left and right reflectivities at a given reference plane in the laser. The theory applies to Fabry-Perot and DFB solitary lasers and to laser configurations with strong optical feedback or strong light injection.     

Injection locking of an additive-pulse mode-locked fiber laser

Injection locking is utilized to synchronize an additive-pulse mode-locked fiber laser to an external pulsed 76.0-MHz laser source. The spectral and temporal performance of the additive-pulse mode-locked fiber laser and the required conditioning are discussed. A low-jitter temporal synchronization is achieved     

基于波长锁定泵浦单振荡级千瓦光纤激光器

采用976 nm锁波长激光二极管（LD）双向泵浦掺Yb全光纤激光器,单谐振腔输出1.2 kW近单模激光,总光光转换效率为70.8%,光束质量Mx21.03,My21.55,实验验证在千瓦功率量级内,正、反泵浦相互影响不明显。光纤激光器从阈值电流到最大电流范围内,输出功率随泵浦功率曲线基本线性,在1 kW功率下做8小时稳定性测试,稳定度在2%以下。激光器可在宽温度范围内工作,温度循环试验表明,输出功率随温度变化具有较好的一致性。     

Chaos in wavelength of tunable semiconductor laser diode with time-delayed Fabry-Perot feedback

With time-delayed Fabry-Perot feedback, chaos in the wavelength of a tunable semiconductor laser diode has been successfully demonstrated. The nonlinear feedback function can be easily tuned by varying the optical path difference of a Fabry-Perot cavity. Experimental results are compared with theoretical simulation and good agreement is obtained.     

Experiments on modulation properties and optical feedback characteristics of laser diodes stabilized by an external cavity or injection locking

In the wavelength range near 1.3-μm, single-mode operation of laser diodes is achieved by means of an external cavity and injection locking. The influence of digital modulation and optical feedback from a directly taper-coupled fiber is investigated. Lasers stabilized by injection locking showed excellent side-mode suppression at CW-operation but strong side modes when the laser was modulated. The frequency of the main mode is neither affected by modulation nor by optical feedback from the fiber. On the contrary the laser stabilized by an external cavity exhibited good side-mode suppression even when it was modulated. However, the frequency stability of the main mode was influenced severely by optical feedback and modulation. A transmission experiment over 21 km at a bit rate of 2.24 Gbit/s showed that this simple stabilization method is sufficient for applications in optical wide-band IM-PCM transmission systems.