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题名	光纤光栅外腔半导体激光器的纵模特性
作者	罗颖
学位类别	硕士
答辩日期	1999
授予单位	中国科学院上海光学精密机械研究所
导师	方祖捷
关键词	光纤光栅 外腔 半导体 纵模特性
中文摘要	光纤光栅自问世以来，由于其良好的选频特性，稳定的性能以及丰富的功能，而成为一种得到广泛应用的新型光纤器件。由光纤光栅构成的光纤光栅外腔半导体激光器，则具有优良的单纵模运转特性，而且波长可控性和重复性好，温度稳定性好，对半导体激光器的要求低，高速调制时没有明显的啁啾，从而有望成为未来的高速大容量通信系统中的光源。本文主要概括总结了本研究小组在光纤光栅外腔半导体激光器的理论研究、关键工艺以及特性测量研究三方面的结果。在理论研究方面，根据实际情况，采用了一个考虑到耦合损耗的外腔激光器模型，利用速率方程对光纤光栅外腔半导体激光器的工作特性进行了模拟计算，获得了纵模特性与器件结构参数和工作条件的关系。在光纤光栅峰值反射率的选择问题上，得出反射率一般在3-6dB为最好。光栅主峰线宽一般要求小于纵模间隔，以提高边模抑制比。光纤光栅的反射峰位置与半导体激光器的增益谱的峰值位置的应尽量吻合，以避免发生当两峰之差超过一定距离时，激光器会在LD增益峰附近发生激射的情况。光纤光栅的长度也是一个关键问题，因外腔的引入降低了类共振频率，影响了最高调制频率，所以应在工艺允许的条件下，尽可能地缩短外腔的长度。在工艺方面，基本上解决了半导体激光器腔面的增透以及它与光纤的耦合两项关键的技术。改装了原有的电子束镀膜机，在真究系统中增加了L-I测试装置，使管芯增透后的剩余反射率做到10~(-3)以下。分析了光纤头形状对耦合效率的影响，采用腐蚀工艺加电火花处理，形成球端圆锥形光纤头，使耦合效率基本达到30%以上。用普通商用F-P激光器管芯，其前腔面用介质膜增透，剩余反射率控制在10~(-3)以下，光纤光栅峰值反射率约为3-6dB，光纤耦合端头部加工成球锥形。增透管芯与光纤光栅耦合后，实现了光纤光栅外腔激光器的激射。其典型阈值电流约为20mA，输出功率大于1mW。对所研制的外腔激光器进行了测量。在直流工作状态下，获得了边模抑制比大于40dB，线宽约为0.1nm的单纵模工作的实验结果。采用140Mb/s伪随机码和300-1000MHz 标准信号调制光纤光栅外腔激光器，测量了器件的动态光谱。获得了边模抑制比大于30dB的单频激光输出。动态线宽不大于0.1nm。特性测量表明，理论模拟与实验结果基本一致。
英文摘要	Fiber Bragg gratings has become a widely-used new fiber device since its discovery, because of its good characteristics of optical spectrum, stability and abundant functions. External-cavity semiconductor laser incorporated with fiber Bragg gratings also has good single-mode operating characteristics, wavelength controllability, temperature stability. It can use ordinary F-PLD chip as its internal active region, which lowers the cost of the device; and when modulated at high speed, it does not suffer from wavelength chirping. So the FBG-ECL is hopefully becoming the light source for future high-speed and high capacity communication systems. In this thesis, some main results in the research of FBG-ECL are presented including theoretical simulations, key technologies of device fabrication and measurements of device characteristics. In theoretical respect, taking coupling loss into consideration according to practical situations, a model of external-cavity is formed. Static and dynamic operation characteristics of the device are simulated by using the rate equations. Relations between its longitudinal mode characteristics and parameters and operating conditions of the device are derived. As to the peak reflectivity of FBG, a reflectivity of 3 to 6dB will meet the requirement. The linewidth of FBG is required to be narrower than longitudinal mode interval to improve side mode suppression ratio. The peak of the LD chip gain spectrum should be as near as possible to the peak of the FBG spectrum lest the FBG-ECL lase at the F-P modes near the gain peak of LD chip. The length of FBG external cavity is another key problem, for the existence of external cavity decreases the relaxation resonance frequency, and it tends to degrade laser diode modulation speed. So the length of external cavity should be as short as the technology permits. In technological respect, problems existing in the two key techniques: AR coating of LD facet and coupling between fiber and LD chip, have been solved primarily. By adding a L-I testing device in the vacuum system, residual reflectivity of Ar coating can be controlled to be less than 10~(-3). Influences of the contour of fiber tip on coupling coefficient are analyzed. Using etching technology and electrical spark machining, a conical tip is formed on the fiber, which makes the coupling coefficient larger than 30%. By coupling a commercial F-P LD chip, whose intracavity facet is AR coated with a single quarter wavelength ZrO_2, with an FBG fabricated in the lab, whose peak reflectivity is about 3-6dB, the lasing of FBG-ECL is realized. Typical threshold current is about 20mA, and output power is over 1mW. Single mode operation with side mode suppression ratio more than 40dB, spectral linewidth nearly 0.1nm is achieved under static condition. Using 140Mb/s pseudo-random code and 300 to 1000MHz standard signal as the modulation signal, output spectra are also measured, single frequency output with side mode suppression ratio over 30dB, dynamic linewidth below 0.1nm is obtained. The measurements of device characteristics show that experimental results are mostly coincident with theoretical simulations.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16461]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	罗颖. 光纤光栅外腔半导体激光器的纵模特性[D]. 中国科学院上海光学精密机械研究所. 1999.

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