电控宽带连续调谐外腔半导体激光器

介绍了一种电控调谐的外腔半导体激光器，并对其连续调谐特性进行了理论和实验分析。压电陶瓷（ＰＺＴ）（双晶片）的电扫描角度可达１°，采用适当的外腔结构，靠ＰＺＴ可同时改变外腔腔长和光栅衍射角，实现输出波长的调谐。该器件调谐范围最大可达１５ｎｍ，连续调谐范围（无跳模）为５０ＧＨｚ     

可调谐单模激光器的制作

对于大容量的波分复用（ＷＤＭ）光通信系统,精确控制波长及波长间隔是系统应用的关键．而对于信道间隔为 ０．８ ｎｍ的 ＷＤＭ系统,要求波长与 ＩＴＵ的标准价差小于±０．０１ ｎｍ．因此,波长可精确调谐的单模激光器成为必需．本文介绍了我们制作的两种波长可调谐的单模激光器：可调谐ＤＦＢ激光器和可调谐ＤＢＲ激光器．其中,可调谐ＤＦＢ激光器采用的是热调谐方式,即改变ＤＦＢ激光器的工作温度,实现了波长向长波方向连续移动 ２．２ ｎｍ;可调谐 ＤＢＲ激光器采用的是注入电流的方式,实现了 ６．５ ｎｍ的准连续调谐． 可调…     

高性能InAs/GaAs量子点外腔激光器

为了获得高性能的量子点外腔激光器(ECL),利用InAs/GaAs量子点Fabry-Perot(FP)腔激光器研制了光栅外腔可调谐ECL。对InAs/GaAs量子点ECL进行了一系列的性能测试,主要包括单模稳定性测试、单模调谐范围测试、阈值电流密度测试、无跳模连续调谐测试和输出功率测试。在室温条件下获得了24.6nm的连续调谐范围,覆盖波长从999.2nm到1 023.8nm,并且实现了波长无跳模连续调谐。在调谐范围内最低阈值电流密度为1 525A/cm2,而且在中心波长处获得的单模输出功率为15mW,单模边模抑制比(SMSR)高达35dB。研究结果表明,通过构建光栅外腔可以实现高性能的InAs/GaAs量子点ECL。     

光纤布拉格光栅半导体激光器的稳定性

介绍了由光纤布拉格光栅（FBGs）组成的光纤激光干涉仪中半导体激光二极管波长稳定和调谐改进的方法,发展了基于分层介质（LDM）和传输矩阵结合法进行高精度计算任意光纤光栅（切趾、啁啾等）的模拟方法。在模拟和商业可得到的光纤光栅测量基础上,设计了1种特殊的100mm长切趾型光纤布拉格光栅。我们期望FBG在改进760nm波长半导体激光器的线宽和无跳模调谐范围的应用中能提高基于这些二极管的光纤激光干涉计的分辨率。建立了基于垂直腔面发射激光器（VCSEL）的绝对光纤激光干涉仪,使用FBG进行稳定波长和控制调谐范围,并对其装置进行了介绍。     

扫描激光波长计

本文报道一台适用于连续可调谐激光器自动扫描控制的激光波长计．它由两组游标标准具ＶＥＴ（ＶｅｒｎｉｅｒＥｔａｌｏｎ）和一旋光单色仪ＯＡＭ（ＯｐｔｉｃａｌＡｃｔｉｖｉｔｙＭｏｎｏｃｈｒｏｍａｔｏｒ）组成，波长测量重复精度优于±５０ＭＨｚ，测量波段为０．４～１．２μｍ。文中给出了在０．９３μｍ附近实验结果。     

大范围连续调谐的InAs/InP(100)外腔量子点激光器

实现了一种工作在连续波(CW)模式下InAs/InP(100)外腔量子点激 光器(EC-QDL)。激光器采用小型化的Littrow 外腔结构,中心波长为1.6μm且输出光方向固定。在室温条件下, 对InAs/InP(100)量子点外腔激光器进行 了一系列性能测试。实验结果表明,器件的单模大范围波长调谐达56.5nm,覆盖波长从1566.9623.4 nm,获得30 GHz的无跳模连续调谐范围,在中心波长1.6μm附近单 模输出功率达8mW,并 在无跳模连续调谐范围内获得了30dB以上的边模抑制比(SMSR)。     

光纤光栅调谐全光纤激光器

本文提出了一种利用光纤光栅作为调谐装置的可调谐全光纤激光器。实验结果表明：该调谐装置操作简便,性能稳定。激光器输出波长连续可调,输出波长复现性误差小于０．００８ｎｍ,输出功率大于１ｍＷ,激光谱线宽小于０．０１ｎｍ,波长调谐范围大于６．４ｎｍ。     

外腔半导体激光器动态模稳定性的研究

为了研究调谐过程中外腔半导体激光器的模稳定性,采用多光束干涉理论推导Littrow结构外腔半导体激光器的腔增益,并模拟其模结构。分析了光栅面和转臂不在同一平面的情形下,在光栅转动调谐时,通过匹配光栅的反馈波长变化率与外腔波长变化率,推导出最佳的初始外腔长度,并研究了动态模稳定（无跳模调谐）的范围;采用严格的耦合理论和光线变换矩阵分析了准直（耦合）透镜的位置对系统后向耦合效率的影响。结果表明,系统后向耦合效率最大可达99%,极大地压窄了中心波长为780nm半导体激光器的线宽,外腔半导体激光器的理论线宽为未加外腔时的0.96%,动态模稳定范围可达6.8nm。     

可调谐激光光源

AgilentTechnologies公司推出一种 81 60 0B型高性能可调谐激光光源 ,其光谱范围可覆盖整个密集波分复用 (DWDM )传输谱带。该激光光源的波长范围为 1 40 0～ 1 640nm ,最大调谐速度为80nm/s ,内置实时波长测量仪器。此外 ,该公司还生产Panda型保偏光纤输出装置。 81 60 0B型光源能以连续无跳模形式扫过全波长范围。其大功率接口可提供 + 8.0dBm的增益 ,而其低SSE端口可提供 + 3.5dBm的增益 ,可完成DWDM元件的多站测量。 (No .1 9)可调谐激光光源…     

量子阱混杂单片集成宽可调谐激光器与半导体光放大器(英文)

采用量子阱方法集成半导体光放大器的取样光栅可调谐激光器,这在国内尚属首次．该器件波长调谐范围可达33nm,在放大器注入50mA电流时,输出光功率可达10mW,同时边模抑制比可达35dB以上．     

DBR单纵模光纤激光器波长温度调谐

报道了采用DBR方式,利用8 mm的高浓度掺Yb3+单模光纤,实现了波长为1 064 nm的单纵模调谐激光稳定输出的实验结果。该DBR谐振腔有效腔长为16 mm,输出最大功率为7.4 mW,通过半导体制冷器温控改变谐振腔的温度,实现了0.824 nm的单纵模无跳模调谐。采用光纤外差法,并利用低损耗环形器和光纤反射镜倍增延迟线长度提升测量精度的方式,测量得到激光最大线宽为4.4 kHz。单纵模激光的弛豫震荡峰位于900 kHz处,其相对强度噪声为-110 dB/Hz,当频率大于1.5 MHz时相对强度噪声为-145 dB/Hz。     

Wavelength tuning of a semiconductor laser using nematic liquidcrystals

The authors report a single frequency, extended cavity laser diode operating at 1500 nm wavelength and using an intracavity liquid cell wavelength filter to tune the wavelength over 6 nm by mode hopping. Continuous tuning over the free spectra range of the cavity is also demonstrated     

Detecting mode hopping in semiconductor lasers by monitoringintensity noise

Mode-hopping semiconductor lasers exhibit intensity fluctuations which are correlated to the level of mode-hopping activity. It is shown that these fluctuations occur at a level that is easily measured and that mode hopping can be detected with a p-i-n photodiode and an AC voltmeter having microvolt sensitivity. A plot of intensity fluctuations versus laser case temperature and injection current displays periodicities in the conditions under which mode hopping occurs. These regularities are explained in terms of the peak gain wavelength passing the longitudinal mode wavelength as temperature changes. The occurrence of mode hopping is determined by junction temperature (which determines the relationship of the gain peak with longitudinal mode structure) and injection current (which determines mode-hopping frequency). The junction temperature is itself a function of case temperature and injection current. The stability map shows that precise control of the operating parameters is not sufficient to avoid mode hopping. It is necessary to have these parameters set properly     

Sensitivity of grating-coupled surface emitters to length-inducedphase variations

The longitudinal mode structure of a two-gain section, three-grating surface emitting laser is studied as a function of length-induced phase variations. It is found that several mode hops occur in the course of changing the length of one of the gain sections by one grating period. Although the number of mode hops can be reduced by optimizing the design, stable, single-mode laser operation appears to require control of the optical length of each gain and grating section to better than one wavelength     

Observation of acetylene molecular absorption line with tunable, single-frequency, and mode-hop-free erbium-doped fiber ring laser

We succeeded in observing one of the absorption lines of acetylene [P(16)] using an erbium-doped fiber-ring laser, which is the first such observation using a fiber-ring laser. The observed linewidth of the P(16) linear absorption was approximately 450 MHz. Mode competition and mode hopping were suppressed by using an ultra narrow-band fiber Bragg grating and a Fabry-Perot filter in the ring laser, respectively. Wavelength fine-tuning was carried out by changing the cavity length of the fiber-ring laser; the fine-tuning range was about 850 MHz (0.01 nm). Furthermore, wavelength tuning was achieved by controlling the temperature of the fiber Bragg grating, and the coarse timing range was about 0.2 mn.     

Suppressing mode hopping in semiconductor lasers by orthogonal-polarization optical feedback

Mode hopping is characterized by a stochastic exchange of power between two longitudinal modes of a laser, inducing a high-level intensity noise in the laser's output. This investigation proposes an orthogonal-polarization optical feedback (OPF) method to suppress mode hopping in semiconductor lasers. Experimental results indicated that, under some operating conditions, mode hopping could be completely suppressed by an OPF of around -29.3 dB in feedback ratio while the laser was conducted into a single-mode state. Moreover, the mode-hopping region was significantly reduced, enabling the laser's wavelength to be tuned continuously over a wider range. These results can be used to greatly improve the performance of semiconductor lasers.     

Mode stabilization method for superstructure-grating DBR lasers

A wavelength stabilization method for widely tunable superstructure-grating (SSG) distributed Bragg reflector (DBR) laser is described. The output characteristics under tuning are studied theoretically and experimentally. It is found that peak reflectivity states, in which the lasing mode is just aligned with the reflection peaks of both DBR's, are obtained at saddle points in the output characteristics while changing the two SSG-DBR currents. Based on these results, a method for the Bragg frequency control of the two SSG-DBRs is proposed. The feedback control circuit keeps the lasing mode at a peak reflectivity state, and it suppresses mode hopping. Additionally, the oscillation mode is locked to arbitrary reference wavelengths of an optical filter. Stabilization at 200 GHz (1.6 nm)-spaced 16 wavelengths was achieved within the wide tuning range of the SSG-DBR laser. Control was maintained under a laser temperature variation of ±5°C as a result of the Bragg frequency control of the two DBR's     

Synchronized chaotic mode hopping in DBR lasers with delayedopto-electric feedback

We propose and demonstrate a scheme for generating synchronized chaotic mode hopping in two wavelength-tunable lasers. Chaotic mode hopping resulting in large hops in wavelength is induced by delayed feedback of an electrical signal proportional to the intensity of the laser output which passes through an optical filter. Mode hopping among up to 11 modes was experimentally observed and optical signals in each wavelength band show a different on-off modulation time series. Analysis of the time series indicates high dimensionality. By using a unidirectional coupling method that injects part of the output of one laser into another, we can synchronize the chaotic mode hopping of two separate lasers and obtain synchronized chaotic on-off modulation patterns in multiple corresponding wavelength bands. The robustness of the synchronization with respect to the parameter mismatch and the effects of the coupling strength are investigated. The chaotic mode hopping dynamics and synchronization are well described with a numerical model that includes the characteristics of the laser tuning and the filter transmission. A multiplexed data transmission scheme using chaotic carriers is proposed and experiments demonstrate that multiple messages can be simultaneously recovered when chaos synchronization is achieved     

用于应力传感的双芯光纤马赫-曾德尔干涉仪

将一根单模双芯光纤(TCF)熔接在两根单模光纤(SMF)间,实验制得双芯光纤马赫-曾德尔干涉仪(MZI)型梳状滤波器。用干涉原理分析了器件的传输谱相邻峰值的波长间隔与波长、TCF长度和两纤芯间有效折射率差的关系。结果表明,在滤波器梳状传输谱中的某中心波长处,相邻峰值的波长间隔与该中心波长的平方成正比,与TCF长度和两纤芯间有效折射率差的乘积成反比。实验检测了所制器件的应力特性,结果表明在轴向微应力的作用下,器件的传输谱向短波长方向移动,且微应力敏感度为-0.64 pm/με。     

140-nm Quasi-Continuous Fast Sweep Using SSG-DBR Lasers

We demonstrate a single-mode and fast wavelength swept light source by employing superstructure-grating distributed Bragg reflector (SSG-DBR) lasers for use in optical frequency-domain reflectometry optical coherence tomography. A noteworthy feature is that our laser employs a thermal drift compensator (TDC). By utilizing the TDC, we achieved a fast wavelength sweep without any unexpected mode hopping. We newly designed and fabricated SSG-DBR lasers covering the following four wavelength bands: 1496-1529, 1529-1564, 1564-1601, and 1601-1639 nm. We achieved a stable operation for the whole wavelength range. A wide wavelength tuning of 143 nm was achieved within 1.4 ms. A single-mode, wide, and fast wavelength sweep was demonstrated.