Beam combining of laser arrays with high efficiency and good beam quality for power and radiance (brightness) scaling is a long-standing problem in laser technology. Recently, significant progress has been made using wavelength (spectral) techniques and coherent (phased array) techniques, which has led to the demonstration of beam combining of a large semiconductor diode laser array (100 array elements) with near-diffraction-limited output (M/sup 2//spl sim/1.3) at significant power (35 W). This paper provides an overview of progress in beam combining and highlights some of the tradeoffs among beam-combining techniques.

Laser beam combining for high-power, high-radiance sources

Fiber lasers are well suited to scaling to high average power using beam-combining techniques. For coherent combining, optical phase-noise characterization of a ytterbium fiber amplifier is required to perform a critical evaluation of various approaches to coherent combining. For wavelength beam combining, we demonstrate good beam quality from the combination of three fiber amplifiers, and we discuss system scaling and design trades between laser linewidth, beam width, grating dispersion, and beam quality.

Beam combining of ytterbium fiber amplifiers (Invited)

A review of studies of the properties of radiation from optically coupled lasers is presented. The methods for phase locking the fields in optically coupled lasers of different types are considered and the methods for supermode selection and correction of the radiation pattern are discussed.

http://iopscience.iop.org/article/10.1070/QE2003v033n04ABEH002415/pdf

Phase locking of optically coupled lasers

Optically coupled lasers are a striking example of a class of self-organized nonlinear dynamic systems which are currently attracting much interest. From a practical standpoint, the coupling of lasers makes it possible to increase relatively simply both the output power and brightness of a light source. The present review gives an account of the current status of the theory and experimental results obtained for two or more optically coupled lasers. The stress is on the structure of collective modes and their stability. Frequency and phase locking of laser arrays is considered. Optical coupling systems tested experimentally are discussed and the agreement between the experiment and theory is considered. A description is given of the operation of systems in which lasers are detuned by an amount exceeding the width of a locking band. Methods for increasing the brightness of the output radiation of systems with a synthesized aperture are also discussed.

http://iopscience.iop.org/article/10.1070/PU1990v033n03ABEH002553/pdf

Radiation emitted by optically coupled lasers

Coherent beam combination is an effective way to develop high-power lasers with high beam quality and high brightness. Coherent combination of six solid-state lasers based on the technique of mutual injection phase locking by using the natural coherent combination property of corner cube is first investigated. The coherent combination with 15.3 J of output energy, 1.7 mrad of divergent angle is obtained, and the combining efficiency is as high as 95.6% at 10 Hz and 85 A. The far-field profile is flattened protuberance.

Mutual injection phase locking coherent combination of solid-state lasers based on corner cube.

A review is given of the main results obtained in the last few years in the course of development and studies of integrated injection laser arrays. The main configurations of such arrays are considered: they differ in respect of the structure of the active elements and methods used to couple the elements optically. The main approaches to calculations of the mode compositions of the output radiation are described. The experimental energy, spectral, spatial, and dynamic parameters of laser arrays are reported to illustrate the attained levels of their technical characteristics. An analysis is made of phase locking of the radiation from laser arrays by injecting an external phase-locking optical signal, and also by using a shared external resonator, spectral–spatial selectors, and other external optical components.

Phase-locked integrated arrays of injection lasers

A review is given of the main results obtained in the last few years in the course of development and studies of integrated injection laser arrays. The main configurations of such arrays are considered: they differ in respect of the structure of the active elements and methods used to couple the elements optically. The main approaches to calculations of the mode compositions of the output radiation are described. The experimental energy, spectral, spatial, and dynamic parameters of laser arrays are reported to illustrate the attained levels of their technical characteristics. An analysis is made of phase locking of the radiation from laser arrays by injecting an external phase-locking optical signal, and also by using a shared external resonator, spectral-spatial selectors, and other external optical components.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Nickolay N. Evtikhiev

Papers

Phase-locked integrated arrays of injection lasers

Phase-locked integrated arrays of injection lasers