Abstract

A technique to phase lock CO₂ lasers with spatially separated active media was investigated. Only reflective optics (except for the output coupler) were used, in view of applications of this method in the field of high-power lasers. Phase locking was established when the beams of two resonator branches were made to propagate very close to each other along the so-called coupling path. As a result of diffraction effects both resonators were exchanging energy, establishing a phase-locked operation mode when several locking conditions were fulfilled. A maximum coupling coefficient (the ratio between the diffracted intensity in the second cavity and the intercavity intensity in the first resonator) of 2.6% could be achieved. Because phase locking was highly dependent on the difference between the two resonator lengths, a length control that uses a piezoelectric translator connected to one of the resonator mirrors was used. To detect phase locking, the intensity maximum of the interference pattern of the two laser beams was monitored with a fast detector. By application of a ramp signal to the piezoelectric translator and detection of the peak intensity, the locking range could be measured. Up to a mismatch of the resonator lengths of λ/130, locking could be maintained. The measurements were compared with results of a computer simulation with Huygens–Fresnel integrals to describe diffraction and the one-dimensional Maxwellian equations to calculate supermodes and to analyze their stability. The numerical results showed an excellent agreement with the measured values.

© 1995 Optical Society of America

Phase locking of CO₂ lasers

Wendelin Weingartner, Kurt Schröder, and Dieter Schuöcker
Appl. Opt. 40(15) 2453-2460 (2001)

Design and performance of diffractive optics for custom laser resonators

James R. Leger, Diana Chen, and Greg Mowry
Appl. Opt. 34(14) 2498-2509 (1995)

Modal properties of an external diode-laser-array cavity with diffractive mode-selecting mirrors

James R. Leger, Greg Mowry, and Xu Li
Appl. Opt. 34(21) 4302-4311 (1995)

Influences of misalignment of control mirror of axisymmetric-structural CO₂ laser on phase locking

Yonggen Xu, Yude Li, Yi Qiu, Ting Feng, Fuxing Fu, and Wei Guo
Appl. Opt. 47(33) 6291-6299 (2008)

Investigation of computer-generated diffractive beam shapers for flattening of single-modal CO₂ laser beams

M. Duparré, M. A. Golub, B. Lüdge, V. S. Pavelyev, V. A. Soifer, G. V. Uspleniev, and S. G. Volotovskii
Appl. Opt. 34(14) 2489-2497 (1995)