Linewidth predictions for Raman fibre lasers

The linewidth of cascaded Raman fibre lasers is investigated theoretically as a function of the laser parameters. The increase with pump power is compared to experimental results. The effect of two design parameters is described: cavity length and output-reflector properties.     

一种基于MEMS技术的可调谐光滤波器

文章介绍了一种基于微电子机械系统(MEMS)技术的可调谐光滤波器(TOF),分析了其基本原理和光学结构,给出了合理的设计方案及所进行的实验验证.实验结果表明,该滤波器性能优良,20 dB带宽<0.65 nm,3 dB带宽<0.24 nm,整个光路的插损控制在2 dB以内.根据该方案设计的滤波器具有体积小、成本低和波长调...     

Linewidth enhancement factor for quantum-well lasers

The linewidth enhancement factor ? is calculated for an idealised GaInAs quantum-well laser. Values between 1 and 2 are found for a range of possible lasing energies. Somewhat larger values are expected for GaInAs quantum wells with InP barriers. It is concluded that dramatic reductions in ? are not to be expected for quantum wells.     

MEMS可调谐平顶窄带光学滤波器

设计了一种基于MEMS技术的可调谐光学滤波器,它通过光栅将输入的宽带光信号色散展开,以一个MEMS扭镜选择将对应滤波器通带的光信号反射至输出端,从而实现光学滤波和波长调谐功能。滤波器的输入端采用单模光纤,输出端采用多模或者少模光纤,可以实现窄带且平顶的通带特性。经过参数优化,仿真分析得结果显示,采用多模/少摸光纤输出的两种滤波器,其0.5 dB和25 dB带宽分别为0.95 nm/0.29 nm和1.39 nm/0.69 nm,分别满足100 GHz和50 GHz信道间隔的DWDM系统要求。由于输出端采用多模或者少摸光纤,从该滤波器输出的光信号不能继续在单模光纤中传输,只能由光探测器接收,因此该滤波器一般应用于全光网络节点中的下载端口。     

MEMS型可调外腔激光器的研究

文章提出了一种以MEMS TOF(微电子机械系统可调光滤波器)和标准具作为波长选择元件,LC(液晶)作为相位补偿元件,平面反射镜提供光反馈的可调外腔半导体激光器结构。实际研制了该结构的激光器样品,实验测得该激光器的输出功率>10dBm,边模抑制比>50dB,可调谐范围达到7nm,线宽约为200kHz。     

Linewidth enhancement in quantum-well lasers

We have developed explicit approximations for the Hnewidth enhancement factor in quantum-well lasers. These simple expressions represent a quick and easy means of calculating the linewidth enhancement factor under a variety of operating conditions, and help us to understand the physics influencing this important parameter.     

两路光纤激光器外腔式互注入锁相实验研究

提出了一种获得相干合成激光输出的新方法。利用45°半透半反分束镜和角锥反射器,通过对两路独立振荡光纤激光器(FL)成功实现外腔式能量相互注入锁相输出,在远场观察到清晰稳定的干涉条纹(可见度约0.5),获得了功率约400mW的相干合成激光输出,功率合成效率接近80%。整个互注入锁相系统中的元件均采用高功率器件,因此本方法可以在更高功率条件下运行。     

Linewidth enhancement in distributed-feedback semiconductor lasers

It is demonstrated that the linewidth enhancement in distributed-feedback (DFB) laser diodes can differ significantly from (1+ alpha /sup 2/), where alpha is Henry's linewidth enhancement factor. The influence of the relevant laser parameters, the detuning of the gain peak wavelength, a pi /2 phase shift and a reflecting end facet on the linewidth enhancement is discussed with respect to an improved DFB laser design.<>     

Linewidth of 1.3?m cleaved-coupled-cavity lasers

The linewidth and side-mode suppression ratio of three variable-gap C3 lasers were measured as a function of output power and drive currents. With feedback carefully eliminated, the narrowest linewidth obtained was 8 MHz at an output power of 13.6 mW. There was little correlation between line-width and suppression ratio.     

Linewidth and alpha-factor of detuned-loaded DBR lasers

The authors report measurements of the α-factor and linewidth of DBR (distributed Bragg reflector) lasers fabricated with weak grating constants. Such devices exhibit detuned-loading effects, and the measured values depend strongly on the tuning current of the Bragg section. α-factor behavior is found to agree with earlier theoretical predictions. Linewidth behavior is shown to be dominated by carrier shot noise in the tuning section. A theoretical analysis of the DBR laser is outlined including detuned loading and carrier shot noise effect     

Linewidth of monolithic external cavity DFB lasers

An expression for the linewidth of DFB lasers with lossy external cavities is derived. The influence of facet reflectivity and high feedback levels is discussed     

微电机械系统使光通讯用可调谐激光器成为可能

动态重组的下一代光纤通讯系统要求配置能将信号传输到任意波分复用通道，并能在通道中实现转换的波长可调谐激光器。目前世界各国科学家积极投入此项研究工作，正在考虑各种方案以实现工作稳定、高效率和廉价的可调谐激光器，其中就包括采用悬臂式微电子机     

Linewidth and feedback sensitivity of semiconductor diode lasers

It is shown that the feedback sensitivity of a diode laser is closely related to the free-running laser linewidth and that several formally different expressions in the literature for the linewidth with and without the explicit use of K factors are indeed essentially equivalent     

Low-loss and compact V-band MEMS-based analog tunable bandpass filters

This paper presents compact V-band MEMS-based analog tunable bandpass filters with improved tuning ranges and low losses. For compact size and wide tuning range, the two-pole filters are designed using the lumped-elements topology with metal-air-metal (MAM) bridge-type capacitors as tuning elements. Capacitive inter-resonator coupling has been employed to minimize the radiation loss, which is the main loss contributor at high frequencies. Two filters have been demonstrated at 50 and 65 GHz. The 65-GHz analog tunable filter showed a frequency tuning bandwidth of 10% (6.5 GHz) with low and flat insertion losses of 3.3 /spl plusmn/ 0.2 dB over the entire tuning range.     

Single-frequency tunable semiconductor lasers

Work on single-frequency tunable-wavelength semiconductor lasers with an external cavity based on fiber Bragg gratings formed in a single-mode optical fiber is reported. Methods for discrete and continuous tuning of the emission wavelength are considered. The described lasers emit dynamically stable radiation with a narrow linewidth (10 kHz) in the wavelength range of 635–1650 nm.     

Mid-infrared tunable quantum cascade lasers for gas-sensingapplications

The quantum cascade (QC) laser does not involve the material bandgap for the generation of light. Therefore, InP- and GaAs-based III-V semiconductor materials can now be used for the generation of long-wavelength, mid-infrared light. These materials are also straightforward to process and pattern. This is essential for the more sophisticated device geometries such as distributed feedback (DFB) lasers. DFB lasers provide a very elegant and reliable method to achieve a well-defined single-wavelength emission (called single-mode operation) as opposed to the usually multiple-mode emission of free-running Fabry-Perot resonators. QC-DFB lasers were first demonstrated in 1996. They have evolved very rapidly and have already shown great promise in many different gas-sensing applications     

Linewidth enhancement factor in strained quantum well lasers

The linewidth enhancement factor α of strained quantum-well lasers is analyzed by the k-p perturbation method using the effective-mass approximation. It is found that the α factor in a strained In_0.80Ga_0.20As/InP quantum-well (QW) laser with 1.9% biaxial compression is less than 1.5. For a strained QW laser with p-type modulation doping (MD) of 5×10 ¹⁸ cm^-3, the α factor is as small as 0.8. It is also demonstrated that the spectral linewidth and wavelength chirping in the strained MD QW laser are significantly less than those in conventional bulk and QW lasers     

可调谐激光器波长控制

文章介绍了可调谐激光器的波长调节及稳定控制的设计方法,并通过试验验证了其可行性.该设计由温度控制、偏置电流控制及锁波电路3部分组成,温度控制粗调波长,偏置电流控制微调波长,而锁波电路主要是针对外界温度发生变化时提供反馈.它适用于温度控制型分布反馈式 (DFB)可调谐激光器的外围电路设计.