Abstract

We demonstrate a technique for tunable single-mode operation of high-power laser-diode arrays. A spatially filtered part of the far field from a gain-guided GaAlAs laser-diode array is directed to a diffractive grating and is coupled to a phase-conjugating self-pumped barium titanate crystal. The interaction among the grating, the dynamic gratings in the photorefractive crystal, and the spatial filter forces the laser-diode array with poor spatial and temporal coherence to oscillate in a single spatial and single longitudinal mode. At a drive current of two times the threshold, the array operates in a single-lobed far-field pattern that is only 1.5 times the diffraction limit. The bandwidth of the enhanced output beam is measured to be less than 0.03 nm, and the coherence length of the output is increased 45 times, to at least 16 mm. Once single-mode operation has been obtained, one can continuously tune the frequency over a range of 5 nm around a center wavelength of 811 nm by tilting the grating. More than 50% of the radiated energy of the free-running laser is coupled out of the system. The significantly enhanced coherence properties of the output may lead to a number of new or improved applications in areas such as second-harmonic generation, coupling into single-mode fiber, and pumping of solid-state lasers.

© 1998 Optical Society of America

Single-mode operation of a laser-diode array with frequency-selective phase-conjugate feedback

Martin Løbel, Paul M. Petersen, and Per M. Johansen
Opt. Lett. 23(11) 825-827 (1998)

Improvement of spatial and temporal coherence of a broad area laser diode using an external-cavity design with double grating feedback

Eva Samsøe, Peter E. Andersen, Stefan Andersson-Engels, and Paul M. Petersen
Opt. Express 12(4) 609-616 (2004)

Volume Bragg grating external cavities for the passive phase locking of high-brightness diode laser arrays: theoretical and experimental study

David Pabœuf, Deepak Vijayakumar, Ole Bjarlin Jensen, Birgitte Thestrup, Jun Lim, Slawomir Sujecki, Eric Larkins, Gaëlle Lucas-Leclin, and Patrick Georges
J. Opt. Soc. Am. B 28(5) 1289-1299 (2011)

Rhodium-doped barium titanate phase-conjugate mirror for an all-solid-state, high-repetition-rate, diode-pumped Nd:YAG master-oscillator power amplifier laser

Arnaud Brignon, Stéphane Sénac, Jean-Luc Ayral, and Jean-Pierre Huignard
Appl. Opt. 37(18) 3990-3995 (1998)

Laser-diode injection locking with a double phase-conjugate mirror in photorefractive Bi₁₂TiO₂₀ fiberlike crystal under external alternating voltage

Alexei A. Kamshilin, Timo Jaaskelainen, Vasilii V. Spirin, Leonid Yu. Khriachtchev, Ribun Onodera, and Yukihiro Ishii
J. Opt. Soc. Am. B 14(9) 2331-2338 (1997)