Gas-lens effect and cavity design of some frequency-stabilized He–Ne lasers

Abstract

It is shown that there exists an optimal cavity length which should minimize the frequency shifts induced by lenslike effects in intracavity saturated absorption lasers. Ideas are developed which provide a satisfactory explanation for the dispersion in modulation shifts observed in some recent laser intercomparisons.

Spectral-line asymmetry in double-output-cavity lasers

“…It is important to note that this effect has already been accidentally observed [27,28]. It is also important to highlight that to the best of our knowledge, no theoretical explanation has been given to such effect.…”

“…Line shape at the output 2 (c) with its zoomed view (d). [16,26,27]. In these conditions, his Lamb-dip frequency is coincident with the resonance frequency.…”

“…In some cooperative cases, the cavity geometry favours mutual compensation between population and saturation effects [26,27]. These critical cases exhibit symmetric line shapes.…”

A transportable methane stabilized He-Ne laser

“…The curvature radius of the laser mirror is 7 m for the methane cell side and 2 m for the other side. Therefore a beam waist in a laser cavity without the gas lens effects [5] has been calculated to be very close to the center of the methane cell. On the other hand, a transmittance of the laser mirror is, respectively, 2 percent for the cell side and 5 percent for the other side.…”

“…The Allan variance in the stabilized case increases for an average time of shorter than 10 ms owing to an effect of a modulation. But it decreases with 10-1 10' Averaging Time (5) an inclination of 2.5 x 10-12 7 -1 / 2 between 10 ms and 1000 s. The frequency difference between two stabilized lasers which were continuously operated for six days (from February 24, 1986) was measured at the same time during each day. The results are the mean values of 20 samples measured at I-s gate time.…”