Frequency-locking of a 1.3μm DFB laser using a miniature argon glow lamp

Abstract

The frequency of an InGaAsP distributed-feedback (DFB) laser was locked to the 2p10 - 3d5 transition of argon atoms at 1.2960 μm using the optogalvanic signal obtained from a commercial miniature glow lamp. At a discharge current of 500 μ A, the signal-to-noise ratio of the optogalvanic signal corresponding to the Ar transition was about 18 dB. The peak-to-peak width of the first derivatave signal was 650 MHz. The slope of the signal was 0.32 μ V/MHz near the center of the transition. By using the linear portion of the first-derivative signal, the laser frequency was locked to the Ar 2p10 - 3d5 transition. The peak-to-peak frequency fluctuations in the free-running condition were estimated to be 650 MHz, which is mainly due to laser temperature fluctuations. When the servo-loop was closed, the frequency stability was improved to better than 13 MHz.