Frequency stability improvement of a two-mode stabilized 633-nm He–Ne laser

Abstract

The red side (lower-frequency) mode of a two-mode stabilized 633-nm He-Ne laser has been locked to the hyperfine structure of the P() line of (127)I(2) by means of frequency modulation spectroscopy enhanced by an external optical cavity. Both the red side and blue side (higher-frequency) modes of the laser exhibit a frequency stability of 2.3 x 10(-11) tau(-1/2). In addition, the frequency fluctuations of the blue side mode are detected by a Fabry-Perot cavity and compensated through an acousto-optic frequency shifter. The short-term stability of better than 3 x 10(-11) is attained for integration times of between 2 x 10(-3) and 2 x 10(-1) s.

A simple and low-cost setup for part per billion level frequency stabilization and characterization of red He-Ne laser

“…Primary consideration for building such a setup is selecting an appropriate laser cavity that can be used for frequency stabilization by taking advantage of the orthogonally polarized adjacent longitudinal modes [12] , [10] . Doppler broadened gain profile of a He-Ne laser spans approximately 1.5 GHz (full width half maximum, FWHM) and using a short cavity with a relatively large free spectral range (FSR) of 1 GHz, will lead to two orthogonally polarized longitudinal modes within the gain profile.…”

A simple and low-cost setup for part per billion level frequency stabilization and characterization of red He-Ne laser

“…One of the primary consideration for such a setup is selecting an appropriate laser cavity that can be used for frequency stabilization, taking advantage of the orthogonally polarized adjacent longitudinal modes [7,9]. Doppler broadened gain profile of He-Ne laser spans approximately 1.5 GHz (full width half maximum, FWHM) and using a short cavity with a relatively large free spectral range (FSR) of ∼ 1 GHz, will lead to two orthogonally polarized longitudinal modes within the gain profile.…”

Using coherence properties for frequency stabilizing He-Ne laser

“…In general, the stabilization methods are based on the detection of the frequency change and use it to control the optical path-length of the resonator (mechanically, thermally, electro-optically). Methods implemented for detection of frequency change are numerous: Zeeman effect [10], polarization splitting [11], beat frequency between modes [11,12], interferometry [13,14], saturated absorption [15], referencing to external Fabry-Perot cavity [16]. On the other hand, methods for stabilization of the resonator length are usually based on temperature control in a feedback loop [10,11,17].…”