以半導體光放大器實現波長可調外腔式雷射

Abstract

本篇論文主要使用半導體光放大器做為外腔式雷射的增益介質，藉由傾斜的波導降低反射率以壓制晶片本身的Fabry-Perot模態，避免因為電流增加使得模態淨增益太早到達閥值增益，藉此增加可調波長的範圍。我們使用十層自聚性銦化鉮量子點做為此半導體光放大器的主動層，且這十層量子點其披覆層厚度不完全相同，藉此方法得到較寬且較平滑的增益頻譜，也就是所謂的啁啾式多層堆疊量子點。藉由啁啾式多層堆疊量子點且壓制晶片本身的Fabry-Perot模態後，我們得到範圍1140 nm ~ 1271 nm共131 nm的可調範圍，且閥值電流密度在0.4 kA⁄cm^2 ~2.5 kA⁄cm^2 。所有的雷射其強度都高於旁邊的放大自發性輻射約16dBm。

In this thesis, we used the semiconductor optical amplifier(SOA) as the gain material of external cavity lasers. For successfully suppressed the Fabrt-Perot mode of laser chirp, we reduced the reflectivity between GaAs and air by tilted waveguide. This could be advance the tunable wavelength range by avoiding the net mode gain over the threshold gain. There are ten layers self-assembled InAs QDs which have various thickness of capper laser in our active region of semiconductor optical amplifier. There are different thickness to get wider and more smooth gain spectrum, and this is so called Chirped-Multilayer Quantum Dot Laser(CMQD). By suppressing the Fabrt-Perot mode of laser chirp and the Chirped-Multilayer Quantum Dot Laser, we got the tunable range of 1140 nm to 1271 nm which is about 131 nm adjustable range and the threshold current density is between 0.4 kA⁄cm^2 and 2.5 kA⁄cm^2 . By the way, all of the lasing power are highr than the amplify spontaneous radiation 16dBm.