利用液晶反射鏡之電控多波長主動鎖模半導體雷射

Abstract

在本論文中，我們利用半導體之製成技術製作液晶條型反射鏡，經由電極圖形製作、半導體製成、液晶封裝…已完成液晶元件，由自製之外接控制驅動電路，可由電腦控制或手動方式控制液晶元件，且具有可程式化控制之優點，相信對光纖通信、光電取樣等之應用會有很大的幫助、。 將自製的液晶元件，首度應用在外腔式主動鎖模半導體雷射系統中，此種雷射系統可透過外接液晶驅動電路的控制，達到電控多波長的目的。在主動鎖模操作模式下：半導體雷射光束經由光柵分光後，透過液晶元件選取波長，迴授共振放大後輸出，由Bias-T將高頻訊號與直流偏壓操作半導體雷射，並配合雷射主動鎖模時之外腔長度調制波長範圍達5.94nm，旁模抑制比可達25dB。經由調整腔內之色散補償，可得之最短脈衝為23.4ps。我們並量測其單波長與多波長之時序混亂度，約為2.5ps與3ps。

Tunable, multi-wavelength mode-locked semiconductor lasers have potential applications in DWDM and ultrafast signal processing such as photonic analog/digital conversion. These functions require pulse-to-pulse timing stability in each of the wavelength channels. In this work, we first demonstrate a new type of electronically tunable single and multi- wavelength external cavity semiconductor laser. This is based on our previous design, which allows multi-wavelength lasing and a liquid crystal pixel mirror (LCPM) for electronic tuning. The active device is an anti-reflection (AR)-coated laser diode (SDL-2360) with a nominal center wavelength, l » 830 nm. Light emitted from the AR-coated (R < 0.1%, estimated) front facet of the LD is collimated and incident at the grazing angle on a diffraction grating (1800 lines/mm). In mode-locked operation, we have achieved single-wavelength tuning over 5.94nm and the SMSR is as high as 25dB. The rising time and falling time are 0.17s and 0.35s correspondingly. The laser pulse-width is compressed by an intra-cavity dispersion compensator from 52.3ps to 23.4ps. The jitter performance of the laser for each of the wavelength channels is about 2.5ps. In multi-wavelength operation, the laser exists higher timing jitter, which is about 3ps.