摘要
有源光纤环形腔,由于在腔中含有增益介质,所以其工作特性具有多态性。在阈值以下即环形腔本身不产生激光时,可作为扫描式光谱分析仪、滤波器和延时线等等;在阈值以上时,则能成为环形腔激光器和环形腔光纤陀螺等。根据不同的需要,可在腔中放入相应的增益介质,其中由掺铒光纤+泵浦组成的有源光纤环形腔掺铒光纤环形腔最受人们的重视。
本文将在掺铒光纤环形腔的基础上展开对掺铒光纤激光器的理论和试验研究,所作的具体工作如下:
(1)采用二能级结构模型对掺铒光纤激光器进行设计。对其增益、输出功率特性进行了理论分析,推导出了计算增益、最佳光纤长度、光纤掺铒浓度、最佳输出耦合比、重叠积分因子等重要参量的公式。并分析了影响激光器输出的各种因素:腔长、输出耦合比、谐振腔损耗。利用现有设备,测量了掺铒光纤的自发辐射谱,研制出了掺铒光纤环腔激光器,得到了线宽O.93nm、输出功率-1dBm的激光输出。
(2)对注入锁定技术进行了理论研究,给出了光纤环形腔注入锁定的带宽公式。并进行了光纤环形腔激光器注入锁定的试验研究,得到了输出光功率约为2dBm,线宽约为0.64nm的注入锁定激光输出,并对试验现象进行了分析。
(3)深入分析了单/双道Mach-Zehnder(M-Z)光纤干涉滤波器的滤波特性和复合腔选模的工作原理。并利用M-Z光纤干涉仪作为梳状滤波器,并和复合腔共同选模,在常温下我们获得了两个波长同时输出的掺铒光纤环形腔激光器。这一装置具有结构简单,器件价格低,实现容易等优点。
Because there is gain material in the resonator, the active fiber ring resonators show polymorphic characteristics in their different working state. Under the threshold, the active fiber ring resonator can be used as scanning optical spectrum analyzers, optical filters or delay-line and so on. Upper the threshold, the active fiber ring resonator could become the fiber ring laser or fiber ring Cyroscope etc. According to different applications, some varied kinds of material can be implanted into the resonator. And among these structures, the active fiber ring resonator with Erbium-doped fiber pumped by laser diode (LD) is one of the most important ones.
Basing on the Erbium-doped fiber ring resonator,Erbium-doped fiber laser was researched theoretically and experimentally, Which include:
(1)Gain and output power of EDFL are discussed based on the two energy level modeling method. Some analytical equations of important parameters such as gain, fiber length, erbium concentration, coupling coefficient are derived. The factors that influenced the output of the laser are analyzed theoretically. The output power of the laser is observed to be related with the length of EDF, the coupled-ration of the output coupler and the loss of splicing.We carried out the steady state experiments by employing the existing experiment equipments. The spontaneous-emission spectrum of erbium-doped fiber was measured. We developed an erbium-doped fiber ring laser which the line-width and the output power of this laser are 0.93nm and -1dBm, respectively.
(2)The technique of injection locking was analyzed theoretically. The line-with is deduced under this modulation. An injection locking Erbium doped fiber ring laser has been researched experimentally. We gained a laser with the line-width and the output power of this laser being 0.64nm and 2dBm, respectively. Finally, we analyzed the result of the experiment.
(3)Thorough analyzed the work principle of the single/double channels Mach-Zehnder (M-Z) fiber interferometer and choosing modes with composite cavity. And we demonstrate experimentally a two-wavelength Erbium-doped fiber ring laser by using a Mach一Zehnder fiber interferometer and composite cavity. As a result, a fiber ring resonator laser with simultaneous two-wavelength oscillations are obtained in room temperature. This device has advantageous of simple design fabrication and low cost et al.
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