超高重複頻率鎖模光纖雷射之研究

Abstract

在本論文中我們研究數種可實現高重複頻率之光纖鎖模雷射架構，包括非 同步約分諧波鎖模摻鉺光纖雷射，100 GHz 脈衝束縛態非同步諧波鎖模摻鉺光纖 雷射，以及利用 110 GHz 和 250 GHz 矽基微環共振腔之鎖模摻鉺光纖雷射 等。在非同步約分鎖模雷射方面，我們成功將11 GHz 的相位調變頻率透過約分 鎖模技術升頻至33 GHz 並且操作在非同步鎖模狀態。在100 GHz 脈衝束縛態非 同步鎖模雷射方面，我們利用適當長度的偏振保持光纖和非線性光纖，可在 10 GHz 和 20 GHz 的非同步鎖模頻率下產生內在重複率100 GHz、脈衝間距10 ps 的束縛態脈衝序列。在矽基微環共振腔鎖模光纖雷射方面，我們利用基於成熟矽 晶圓製程技術之高Q 值毫米尺度微環共振腔成功讓光纖雷射穩定鎖模在110 GHz 與250 GHz 之超高重複率，同時透過矽製光柵耦合技術之使用來達到單模光纖 與微環共振腔的有效光耦合。在雷射動力學之研究方面，我們也提出以調整相位 調製深度來微調非同步鎖模雷射脈衝重複頻率的新方法，無需改變雷射共振腔之 長度，可有助於高重複率鎖模光纖雷射之穩定控制。我們也發展出可在雷射操作 時量測非同步約分鎖模雷射等效相位調變深度之新方法，有助於釐清非同步約分 鎖模雷射之鎖模機制及特性改善。整體而言，藉著我們所發展出來的技術已可以 將光纖鎖模脈衝雷射之重複頻率推升至100 GHz 以上，未來也可以利用這些研 究結果來發展光通訊及微波光電等方面之應用。

We have investigated several configurations of mode-locked fiber lasers for achieving ultra-high pulse repetition rate. These lasers include the 33 GHz asynchronous rational harmonic mode-locked Er fiber laser, the 100 GHz bound state asynchronous mode-locked Er fiber laser, and the 110 & 250 GHz mode-locked Er fiber lasers based on a silicon micro-ring resonator. For asynchronous rational harmonic mode-locking, we have successfully boosted the repetition rate from 11 GHz to 33 GHz. For bound state asynchronous mode-locking, we have successfully generated internally 100 GHz bound pulses at the 10 & 20 GHz asynchronous mode-locking frequencies by using suitable lengths of polarization maintain fiber and high nonlinearity fiber. For micro-ring resonator mode-locking, we have successfully achieved stable 110 & 250 GHz mode-locked fiber lasers by using a silicon micro-ring resonator with the high quality factor (Q value). The grating coupling technique has been utilized to effectively couple lights between the silicon micro-ring and the single-mode fiber. For the investigation of laser dynamics, we have developed a new method to fine-tune the laser pulse repetition rate by adjusting the phase modulation depth without changing the cavity length. It should be helpful for stabilizing the high repetition rate asynchronous mode-locked fiber lasers. We have also developed a new method for in-situ monitoring the effective phase modulation III depth in an asynchronous rational harmonic mode-locked laser. It should be useful for clarifying the mode-locking mechanism of asynchronous rational mode-locking and for further improving the performance. Overall speaking, based on the techniques we have developed, the repetition rate of mode-locked fiber lasers can be successfully increased beyond the 100 GHz level. These lasers should find useful applications in the area of optical communication and microwave photonics.