一氧化碳雷射在波長5~8 μm間有數百條的雷射躍遷譜線，並且已經應用在雷射光譜學、雷射磁共振以及痕量氣體的光聲測量等。在雷射的穩頻方面，最佳的方法為光阻抗蘭姆凹陷穩頻；為利用直流放電的方式將低氣壓的CO、N2、Xe混合氣之放電管置於雷射腔內，以取得光阻抗訊號。在本篇論文中，我們主要研究的是一氧化碳雷射的射頻光阻抗蘭姆凹陷穩頻的可行性。
我們利用6AQ5A真空管所組成之射頻震盪電路來研究一氧化碳之光阻抗效應。此射頻震盪電路可使一氧化碳的放電管在1 torr以下維持穩定的放電。放電管為氣體流動式，並將其置於雷射腔外。我們讓雷射光通過放電管，並利用截光器調制雷射光。由震盪電路的輸出訊號，利用鎖相放大器解調後可得到光阻抗訊號。雖然在一般的情況下無法觀察到光阻抗訊號，但在使用CO、N2及Ar的混合氣體時可觀察到光阻抗訊號。當放電管的氣體比例為CO：N2：Ar=1：1：60時可觀察到訊噪比最佳的光阻抗訊號。在總氣壓低於700 mtorr，雷射波長為5.3~5.6 μm的條件下，讓雷射光近似原路徑反射通過放電管，並藉由PZT改變雷射腔的長度，可觀察到由光阻抗效應所造成的蘭姆凹陷訊號。然後在PZT上疊加交流小振福的電壓訊號以調制雷射光的頻率，於是測得了蘭姆凹陷的一階微分訊號。由此訊號之訊噪比可預估其頻率穩定度約為4×10-9。

CO laser provides several hundreds lines in the wavelength range of 5 to 8 μm with moderate power. It has been applied to laser spectroscopy and photoacoustic detection of trace gases. In the part, the most accurate frequency stabilization methode is the optogalvanic Lamb-dip stabilization using a DC discharge of low pressure CO：N2：Xe mixture inside the laser cavity. In this thesis, we investigate the feasibility of RF optogalvanic Lamb-dip stabilization of CO laser.
A RF Colpitts oscillator with a pentode 6AQ5A is used for the study of the CO optogalvanic effect. The RF power of this oscillator is enough to sustain the CO discharge at pressure lower than 1 torr. By using this oscillator, the radio frequency optogalvanic signal is observed with the gas mixture CO：N2：Ar=1：1：60. Under the discharge pressure lower than 700 mtorr, the Doppler-free optogalvanic Lamb dip is detected at the vibrational levels ν=8 to 11 (5.3 to 5.6 μm). Using the first devirative of Lamb dip signal, the frequency stability better than 4 ×10-9 is expected based on the observed signal-to-noise ratio.

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