Longitudinal mode separation tuning in 633 nm helium-neon lasers using induced cavity birefringence

Abstract

The theory of laser cavity birefringence induced by insertion of two quarter-wave plates into the cavity is developed to show how the intermode frequency of a two-mode laser can be tuned through a free spectral range by relative rotation of the plates. Birefringence is demonstrated in a helium-neon laser at 633 nm using an open cavity having a tube with anti-reflection coated windows. The lock-in between modes when the intermodal frequency approaches zero was investigated and found to be smallest when the tube was placed between the plates which were aligned with axes parallel. Active frequency stabilization at a frequency separation of 50 MHz was demonstrated using the mode-balancing technique.

Diode-pumped dual-frequency microchip Nd : YAG laser with tunable frequency difference

“…Cross coupling between modes often causes 'the lockin effect' in He-Ne lasers [18]. When the intermode beat frequency gets smaller than the lock-in threshold, the two modes are too close to coexist because of strong mode competition and the frequency difference collapses to zero sharply.…”

Method for the measurement of retardation of wave plates based on laser frequency-splitting technology

“…6 Some groups in Europe have also done research in similar fields. 7,8 Particularly, a group led by Le Floch at the University of Rennes, France, has done a great deal of relevant work on intracavity anisotropyinduced frequency splitting and beating. [9][10][11][12] In some of their work, quarter-wave plates and half-wave plates are used as birefringent devices or compensators, and their effects are analyzed.…”

“…[9][10][11][12] In some of their work, quarter-wave plates and half-wave plates are used as birefringent devices or compensators, and their effects are analyzed. 7,11,12 However, the wave plates are generally assumed to be perfect in these analyses, and their properties are not measured. The approach presented in this paper can be used to precisely measure the optical retardation of wave plates by investigating the intracavity waveplate-induced frequency splitting.…”

Actively mode-locked fiber lasers for high speed telecommunication systems

“…Besides the pump and lasing medium anisotropies, the birefringence of the cavity may also be the cause of polarization dynamics in the lasers. Laser frequency splitting due to cavity birefringence was reported [141,142]. In [141] two quarter-wave plates were inserted into the cavity to separate the longitudinal modes.…”

“…Laser frequency splitting due to cavity birefringence was reported [141,142]. In [141] two quarter-wave plates were inserted into the cavity to separate the longitudinal modes. By adjusting the rotation angle of the two wave plates, dual-frequency lasing was observed.…”