新穎光纖載毫米波系統與技術之整合研究-總計畫暨子計畫七：超高重複率鎖模光纖雷射光源及其光頻穩定技術之研究

Abstract

本計畫為【新穎光纖載毫米波系統與技術之整合研究】群體研究計畫之總 計畫與子計畫七：【超高重複率鎖模光纖雷射光源及其光頻穩定技術之研究】。 １、總計畫摘要 本群體研究計畫將針對未來光纖載毫米波通訊系統所需要的關鍵光電技 術（如高頻、高品質光電調變訊號之產生、傳輸、處理、與偵測等）來進行整 合性研究，並發展重要的相關應用。其中有三個子計畫屬傳輸與系統應用層 次，四個子計畫屬元件與模組層次，從而可以達到較全面的技術涵蓋性﹐整體 計畫研究也可來進行不同層次間之互動式發展。在元件與模組層次主要是以發 展微波光電之新穎光偵測、光調變、與光源技術（包括半導體雷射、鎖模光纖 雷射）為主，期能幫助開啟很多光纖載毫米波通訊及微波光電之新穎研究與應 用。在訊號傳輸與系統應用層次則主要是以發展67~ 300 GHz 的光纖載毫米波 通訊技術、基於第四代行動通訊長期演進技術(LTE)之光纖載毫米波系統、以 及如拍擊干擾補償與多天線輸入多天線輸出等技術為主，希望來更進一步提升 光纖載毫米波系統之資料傳輸速率與距離。各子計畫間的整合性將透過總計畫 的居間協調來進行，一方面儘可能結合各子計畫的成果來進行整合性的研究及 系統展示，一方面也在計畫管理與行政業務上來協助各子計畫。 ２、子計畫摘要 本子計畫將發展超高重複率鎖模光纖雷射及其光頻穩定技術﹐可以來作為 光纖載毫米波通訊與微波光電等應用之光源。透過適當的鎖模機制﹐鎖模光纖 雷射可產生由tens GHz 到hundreds GHz 脈衝重複率之光脈衝序列，相當適合 來作為超高重複率之脈衝光源。不過此種類型之超高重複率鎖模光纖雷射通常 都會需要配合一些穩定機制來產生穩定的雷射輸出，包括脈衝重複率之穩定及 光頻率諧波分量上之穩定。在本子計畫中我們將透過結合多種主、被動鎖模技 術來建構穩定之超高重複率鎖模光纖雷射光源，然後透過創新之精密回饋控制 機制來達到光頻穩定之雷射輸出。在鎖模技術方面﹐我們將透過腔內光學濾波 的方式來幫助光纖雷射可以更容易地鎖模在超高重複率﹐同時透過主被動混合 式鎖模機制來增加雷射的輸出頻寬。在光頻穩定方面﹐我們則將嘗試透過我們 最近所新發現的Repetition frequency pulling effect 來進行﹐此效應能微調鎖模 光纖雷射之脈衝重複率而不需改變共振腔長﹐將能相當有助於光頻回饋控制之 進行。我們也將配合其他子計畫來發展此種超高重複率鎖模光纖雷射光源在光 纖載毫米波傳輸與微波光電等方面之應用。

This project is the main project of the NSC integrated project “Novel millimeter-wave-over-fiber systems and technologies” and the sub-project 7 “Ultra-high repetition rate mode-locked fiber lasers and their optical frequency stabilization techniques”. 1. Main project: The present integrated project will perform integrated investigation on the important development trends for Millimeter-Wave-Over-Fiber communication systems and technologies. There are four sub-projects focused on the device/module level and three sub-projects focused on the transmission/system level. The main research topics in the device/module level include: novel detection, modulation, and light sources (semiconductor and fiber lasers) for generating high frequency/high quality millimeter-wave-over-fiber signals. These studies should help to open up many new possibilities for Millimeter-Wave-Over-Fiber technologies. The main research topics in the transmission/system level include: 67-300GHz millimeter-wave-over-fiber systems, LTE-based millimeter-wave-over-fiber systems, beating interference compensation techniques, MIMO techniques, and so on. These studies should help to improve the transmission speed and distance for future Millimeter-Wave-Over-Fiber communication systems. We will enforce the cooperation between different sub-projects through the coordination of the main project and perform some integrated researches and demos. 2. Sub-project: The main focus of the present sub-project is to investigate ultra-high repetition rate mode-locked fiber lasers and their optical frequency stabilization techniques. These lasers can be used as the light sources for the possible applications of Millimeter-Wave-Over-Fiber communication and microwave photonics. With suitable mode-locking mechanisms, fiber lasers can be mode-locked at very high repetition rates from tens GHz to hundreds GHz. Typically these high repetition rate fiber lasers will require some stabilization schemes to achieve stable pulse repetition rate as well as stable optical wavelength for the laser outputs. We will utilize intra-cavity optical filtering for helping the lasers to mode-lock at ultra-high repetition rates and utilize the hybrid active/passive mode-locking mechanisms to achieve wider output bandwidth (shorter pulse-width). The optical wavelength stabilization will be achieved through the new repetition frequency pulling effect we recently discovered. The effect allows us to fine-tune the pulse repetition rate without changing the cavity length. This is very helpful for feedback stabilization of the optical wavelength of mode-locked fiber lasers. We will also cooperate with other sub-projects to investigate the possible applications of the developed mode-locked fiber laser sources on Millimeter-Wave-Over-Fiber communication systems as well as the microwave photonics.