可調式窄線寬外腔半導體雷射穩定度之比較與探討

Comparison and Analysis on the Stability of Tunable Narrow Linewidth External Cavity Diode Lasers

陳麗偉(Li-Wei Chen)

指導教授 ： 莊賀喬

共同指導教授 ： 張銘顯(Ming-Shien Chang)

國立臺北科技大學/機電學院/機電整合研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00936

摘要

本研究設計及自製三台不同結構之外腔半導體雷射系統，並比較其穩定性。第一台為一體成型之Littrow外腔雷射，其共振腔長70mm。另兩台為共軛成像體積布拉格光柵(volume Bragg grating, VBG)外腔雷射，或簡稱為Cat-eye雷射，並且利用類點光源雷射二極體(Virtual Point Source Laser Diode)，能夠修正雷射光成像的像差。其中一台Cat-eye雷射使用彈簧片以及壓電致動器(Piezoelectric transducer, PZT)來控制VBG位置，以達到調變共振腔長以及波長的目的，其共振腔長為48 mm。另一台Cat-eye雷射則使用溫控方式來改變VBG的中心波長，其共振腔長44 mm。我們比較三台雷射長時間穩定度以及譜線線寬。此三台外腔雷射線寬皆低於銣原子D2譜線線寬，我們因此可以觀測到飽和吸收光譜，並進一步利用鎖相迴路以及回饋電路將譜線解調成微分訊號，然後回授給雷射來達到絕對穩頻目的。

關鍵字

外腔雷射(External cavity diode laser) ； Littrow ； 體積全像光柵(Volume Bragg Grating ,VBG) ； 共軛成像 ； 類點光源雷射二極體(Virtual Point Source Laser Diode)

並列摘要

The study presents three designs of external cavity diode lasers (ECDLs). The first ECDL is a Littrow laser with monolithic construction, and it has a cavity length of 70 mm. Two volume Bragg grating (VBG) ECDLs were designed in “cat-eye” configuration, in which two ends of the linear laser cavity form an image conjugation pair. A virtual point source laser diode (VPS diode) is used, in which its astigmatism is largely corrected by a proprietary prism inside the To-can package of the laser diode. In this way, better spatial mode matching for the cat-eye configuration. The first Cat-eye VBG ECDL has a cavity length of 48 mm, and the wavelength is tuned by changing the cavity length. The other Cat-eye VBG ECDL has a cavity length of 44 mm, and the laser wavelength is tuned by changing the temperature of the VBG. The linewidths of those ECDLs are all below 500 kHz, which are lower than the linewidth of the D2 transition of Rubidium atom. All lasers have very good long term passive stability, the drifts were measured less than 500 MHz in 24 hours, and they can be actively frequency stabilized to the Rubidium D2 transition, utilizing FM spectroscopy and P-I servo loops.

並列關鍵字

External Cavity Diode Laser ； Littrow ； Volume Bragg Grating (VHG) ； Cat-eye ； Virtual Point Source Laser Diode

參考文獻

[11] 陳子傑，以市售鏡座為基礎之體積全像光柵外腔雷射之開發，碩士論文，國

[12] 張倉睿，共振腔結構對體積全像光柵外腔雷射穩定度之探討，碩士論文，國

[1] 韓殿君，銣原子之玻色-愛因斯坦凝聚，物理雙月刊廿七卷二期，台灣，2005。

[6] C. J. Hawthorn, K. P. Weber, and R. E. Scholten, “Littrow configuration tunable external cavity diode laser with fixed direction output beam”, Review of Scientific

[7] Sebastian D. Saliba and Robert E. Scholten, “Linewidths below 100 kHz with external cavity diode lasers”, APPLIED OPTICS, Vol. 48, No. 36, 20 December 2009