論文發表人：林昌億（新墨西哥大學光電所博士班）
http://spie.org/x19316.xml
在這篇論文中，我們報告了在磷化銦基版上生長的砷化銦量子段單積體1.58微米波段被動鎖模雷射元件。此雷射元件的重複頻率可達到18.5千兆赫。Dashes-in-a-well作用區域結構包括了五層受壓應變的AlGaInAs量子井包覆的砷化銦量子段，外圍有30奈米受張力應變的AlGaInAs層。雷射元件共振腔長度為二至三公釐，有著4微米寬的脊形波導管，其波導每隔0.5公釐劃分著電絕緣的正極接觸區塊。我們經由改良的分節觸點測量法得到砷化銦作用區域的模式增益及耗損譜，並確認砷化銦量子段的光電特性是半導體鎖模雷射所需求的。分節的波導管在同樣的DWELL作用區域下被重新焊接成分隔的增益及吸收區塊。我們在在吸收區塊旁的刻面鍍上一高反射膜(95%)，而另一刻面則是自然斷面。為了解共振腔設計及決定增益與吸收段長度的比例關係，我們以微波光子學的角度推導出一個針對兩段式被動鎖模雷射器件的共振腔設計模型。新推導出的理論方程式可經由量測的模式增益與損耗特性數據找出最佳雷射元件腔長設計。
Monolithic InAs quantum dash 1.58-micron passively mode-locked lasers grown on an InP substrate are reported. A repetition rate of up to 18.5 GHz has been realized. The dashes-in-a-well (DWELL) active region consists of 5 stacks of InAs quantum dashes embedded in compressively strained Al0.20Ga0.16In0.64As quantum wells separated by 30-nm undoped tensile-strained Al0.28Ga0.22In0.50As spacers on both sides of the DWELL. 4 micron-wide ridge waveguides with cavity lengths in the range 2-3 mm were fabricated with equal-length, electrically-isolated anode contacts, each 0.5 mm in length. The modal gain and loss spectra of the InAs active region were then measured through the improved segmented contact method, and the characteristics that make InAs quantum dash materials system desirable for semiconductor mode-locked lasers were identified. The segmented waveguides were then reconfigured into mode-locked lasers by wire bonding the segments together to form separate gain and absorber regions that use the same DWELL active region. A highly reflective coating (95%) was applied to the mirror facet next to the absorber while the other facet was cleaved. To assist in the cavity design and determine the relative length of the absorber and gain sections, a model for the cavity geometry of two-section passively mode-locked lasers was studied that is based on a microwave photonics perspective. The new set of theoretical equations was used to find the optimal device layout using the measured modal gain and loss characteristics as input data.
