光纤光栅外腔半导体激光器频率调谐技术研究

在分析了光纤光栅外腔半导体激光器(FBG-ECL)基本特性的基础上,调研了适用于该类型激光器的频率调谐方法,包括温度调谐法和应力调谐法,选取轴向应力调谐法改变光纤光栅的布拉格中心波长,进而实现频率调谐。利用压电陶瓷(PZT)来对光纤光栅施加轴向应力,通过调整PZT驱动电压值的大小来控制光纤光栅布拉格中心波长的变化量。实验结果表明,对于波长1550 nm的光纤光栅激光器,当PZT的驱动电压增加到126 V时,可实现 0.8 nm,即100 GHz的调谐范围以及每周期2 ms的调谐速度。     

Narrow-stripe distributed reflector lasers with first-order vertical grating and distributed Bragg reflectors

Narrow-stripe 1.55-/spl mu/m wavelength distributed reflector lasers consisting of both distributed Bragg reflectors and vertical grating of the first Bragg order were fabricated. A low threshold current I/sub th/ of 2.8 mA, a differential quantum efficiency /spl eta//sub d/ of 28% from the front facet, and a submode suppression ratio of 44 dB were obtained for structures with a stripe width of 1.3 /spl mu/m and a cavity length of 150 /spl mu/m.     

光纤光栅外腔半导体激光器理论模型分析与选取

为了讨论三腔镜近似或耦合腔近似两种等效腔模型对计算光纤光栅外腔半导体激光器等效反射率等参量的近似程度,挑选出最优的理论模型,采用数值计算的方法进行模拟仿真,得到了两种模型在采用切趾光纤Bragg光栅和非切趾光纤Bragg光栅情况下的阈值增益等特性曲线。结果表明,在采用切趾光纤Bragg光栅,特别是切趾深度较大的情况下,采用三腔镜近似模型更加符合实际情况。此研究结果对分析和设计单纵模光纤光栅外腔半导体激光器具有一定的参考价值。     

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.     

1.52μm,60kHz线宽光纤布拉格反射镜外腔半导体激光器

本文报道1.52μm光纤布拉格反射镜外腔窄线宽半导体激光器的制作和实验结果,已实现光谱线宽60kHz,边模抑制比优于30dB,输出功率>-5dBm,频率稳定度为50MHz。     

Microchip vertical external cavity surface emitting lasers

Monolithic vertical external cavity surface emitting lasers of cavity mode volume <1 mm/sup 3/ have been fabricated in the 850 and 980 nm wavelength range. Pump-limited output power >350 mW in a TEM/sub 00/ mode was obtained at 850 nm. Output power >2.5 W was obtained at 980 nm.     

Parametric optimization of the Bragg reflectors in a laser with the vertical cavity and nonlinear frequency conversion

The structure of the Bragg reflectors in a vertical-cavity laser in which three-wave nonlinear mixing is used to generate the emission in the mid-infrared spectral region is optimized. It is shown that the reflection band of the Bragg reflectors can be broadened appreciably in comparison with conventional quarter-wavelength reflectors formed of the same pair of materials. Using this approach, it becomes possible to produce a laser with nonlinear frequency conversion based on the lattice-related nonlinearity in a GaAs/AlGaAs system; this laser emits in the region of <10 μm. The output characteristics of such a laser with the emission wavelength of about 9.7 μm are analyzed numerically.     

Multiwavelength picosecond pulses generated from a self-seededFabry-Perot laser diode with a fiber external cavity using fiber Bragggratings

A novel scheme for generating multiwavelength short pulses using fiber Bragg gratings (FBGs) was demonstrated. In this scheme the external cavity length for all wavelengths selected by the gratings is intrinsically identical and the FBGs can be cascaded into the external cavity. Simultaneous generation of 1-GHz dual-wavelength short pulses with a wavelength separation of 1.6 or 18 nm was demonstrated. A sidemode suppression ratio (SMSR) better than 30 or 25 dB was achieved at both wavelengths in the former and latter cases respectively. Three-wavelength 1-GHz ps pulses with a SMSR better than 25 dB at all three wavelengths were also successfully generated     

外腔长度变化对光纤光栅外腔LD激射波长的影响

密集波分复用(DWDM)光纤通信系统对光源的波长稳定性有很高的要求。主要就可供DWDM系统选用的光源之一光纤光栅外腔半导体激光器(FGESL)的波长稳定性进行讨论。通过计及半导体激光器(LD)、外腔及光纤光栅(FG)三者的共同作用,根据光纤光栅外腔半导体激光器的相位条件确定FGESL的激光纵模分布后,理论上研究了FGESL的激射波长随FG外腔长度的变化。结果表明,外腔较短时,外腔长度的微小变化可以导致FGESL的激射波长产生显著的变化;外腔较长(大于10 cm)时,外腔长度的变化对FGESL的激射波长基本没有影响。     

Dynamic regimes of the dual-wavelength vertical external cavity surface-emitting laser

The stability of the stationary state and periodic oscillations of the radiation intensity of the dual-wavelength vertical external cavity surface-emitting laser is analyzed. It is demonstrated that the stationary state is always stable for the laser with independent active areas that contain quantum dots of different depths. A map of dynamic regimes with the values of parameters that correspond to the cw lasing, periodic oscillations of intensity, and complicated dynamics (quasi-periodic or chaotic regimes) is constructed for the laser with coupled active areas. The dynamics of the laser radiation in the quasi-periodic regime is numerically simulated. It is demonstrated that relatively slow variations in the amplitude with characteristic times of several or several tens of microseconds are typical of the short laser pulses that are formed at time intervals of tens of picoseconds. The period of the pulse train is approximately equal to the round-trip time of the external laser cavity.     

Linewidth and FM characteristics of a distributed feedback laser monolithically integrated with a tunable external cavity

A narrow linewidth has been obtained in a new 1.5 ?m distributed feedback laser integrated monolithically with a tunable external cavity. The linewidth of 18 MHz has been achieved by tuning the current in the external cavity, and the FM response was flat from 100 kHz to 500 MHz.     

Characteristics of distributed Bragg reflector active optical filters

The transfer function characteristics of distributed-Bragg-reflector (DBR)-based active optical filters are described. Small and large signal characteristics are presented, and a variety of nonlinear effects obtained in the large signal regime such as gain saturation, frequency pulling, and wavelength domain bistability are demonstrated. While these nonlinear effects may be detrimental to conventional filter applications, they may possibly be explored for new approaches in wavelength domain logic, switching, and routing. The filter can also be used in a reversed configuration. Compared to the characteristics described, the small signal transmission transfer function remains unchanged but the input power at which the nonlinear effects take place is increased by 20-30 dB. This is due to the much reduced reflected power inside the filter cavity. At the same time, however, the noise power added to the amplified signal is also significantly increased.<>     

Characteristics of a semiconductor laser coupled with a fiber Bragg grating with arbitrary amount of feedback

Stationary characteristics (such as laser frequency at threshold, light-intensity curve, etc.) and relative intensity noise of laser diodes coupled with an external Bragg reflector are studied for arbitrary amount of optical feedback. We put the stress on the interplay between external and internal cavities when the feedback strength is increased. For strong feedback, new stationary solutions that do not exist in the case of conventional feedback appear, while the ellipse, which usually contains the modes and so-called antimodes, collapse in the plane frequency-gain. Finally, analytical expressions are compared with numerical results obtained through a new approach that uses Green functions.     

电泵浦垂直外腔面发射激光器振荡特性的理论分析及实验研究

对具有InGaAs/GaAsP量子阱周期增益结构有源区的980 nm电泵浦垂直外腔面发射激光器(EP-VECSEL)的振荡特性进行了理论分析及实验研究.模拟并分析了耦合腔条件下EP-VECSEL的振荡特性与其分布布拉格反射镜(DBR)及外腔镜反射率之间的关系,并根据理论分析结果对器件结构进行了优化设计.在实验上制备出具有不同外腔镜反射率的EP-VECSEL器件,并对其连续波(CW)振荡特性进行了研究.实验结果表明,有源区直径为300 μm的EP-VECSEL器件在外腔镜反射率为90 %时阈值电流为1.2 A,注入电流为4 A时连续激光输出功率为270 mW; 在外腔镜反射率为95%时阈值电流为0.9 A,4 A下输出激光功率为150 mW.实验结果与理论分析结论符合较好,说明本文采用的理论分析方法能有效模拟及优化EP-VECSEL器件的振荡特性.     

分布式光纤光栅传感系统的波长检测技术

波长检测技术是当前光纤光栅传感领域的重点和难点之一,光纤光栅传感系统的一个显著优点是易构成分布式传感网络系统,实现多点、多区域同时检测.文章以几个典型的解调系统为例,重点分析了分布式光纤光栅传感系统中信号解调的工作原理、特点和性能.     

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。     

Pulse retiming based on XPM using parabolic pulses formed in a fiber Bragg grating

We experimentally demonstrate a novel all-optical all-fiberized pulse retiming scheme incorporating parabolic pulses generated in a linear fashion through pulse shaping in a superstructured fiber Bragg grating. The scheme relies on chirping the signal to be retimed using cross-phase modulation with the broader parabolic clock pulses, and subsequently retiming it through linear propagation in a dispersive medium. We demonstrate the cancellation of up to 4-ps root-mean-square timing jitter for /spl sim/2-ps data.     

分布式FBG的粮仓温度监测系统实验研究

提出了一种新型的粮仓温度监测系统,即利用分布式光纤布喇格光栅传感系统从整体上实现对温度的实时监测.在实验基础上,利用origin软件作出了温度与中心波长的关系图,同时与作为标准的K型热电偶测量数据进行对比,偏差曲线显示光纤布喇格光栅测得温度与标准温度接近,偏差在±0.45℃的范围内,表明本监测系统的测量准确度较高,可以满足粮仓温度监测的要求.     

光纤光栅外腔半导体激光器波长调谐方法研究

可调谐光纤光栅外腔半导体激光器（FBG-ECL）激射波长由光纤光栅布喇格波长决定,调谐光纤光栅布喇格波长可以改变激光器的激射波长.重点介绍采用轴向应力、径向应力和温度对光纤光栅布喇格波长的调谐.布喇格中心波长的偏移与轴向应力、径向应力和温度等变化量均呈极好的线性比例关系,且在较大的测量范围内一直保持线性关系.详细说明了光纤光栅外腔半导体激光器采用这三种方法调谐时的特点、适用范围,并对它们的性能进行了比较,给出在不同条件下适合的调谐方法.     

嵌埋材料对分布式布拉格反射镜腔共振模式的影响

低维材料嵌入微腔已经广泛应用于纳米激光器和探测器等。为了实现增益材料和光学微腔之间的有效耦合,需要深入研究嵌埋材料对腔共振模式的影响。本文主要讨论了嵌埋材料的厚度、位置、腔层厚度以及分布式布拉格反射镜的对数对腔供着模式的影响。结果表明,腔共振模式随嵌埋材料位置的不同呈现周期性变化并且在λ/2光程周期内存在最大峰位移。最大峰位移随腔层厚度增加而减小,但与嵌埋材料的厚度成正比。分布式布拉格反射镜的对数不影响腔共振模式。这些结果为光学器件的设计和实验现象的分析提供了指导,并且可以应用于不同波长分布式布拉格反射腔结构。