High Efficiency, Wavelength Stabilized Laser Diode Using AWG's And Architecture For Combining Same With Brightness Conservation

Abstract

The invention relates to high power semiconductor lasers based on a laser diode array waveguide grating (DAWG) in which the wavelength is stabilized using an array waveguide grating (AWG) in an external cavity configuration. Another aspect of the present invention relates to techniques for efficiently coupling optical gain element arrays to an AWG. Another feature provides for the efficient and brightness-conserving combination of multiple high power DAWG lasers into a single output.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority of U.S. Provisional Application No. 60 / 737,925 filed Nov. 18, 2005, entitled “WAVELENGTH STABILIZED LASER DIODE” which is incorporated herein by reference for all purposes.TECHNICAL FIELD [0002] The present invention relates to wavelength stabilized semiconductor laser sources in which array waveguide gratings (AWG) are used as the optical wavelength stabilizing element in an external cavity, in particular to broad-area (multimode) semiconductor laser diode arrays and, more particularly, to a system for scaling power to a 10 watt to kilowatt level into a single fiber output by combining outputs of multiple laser sources using wavelength and polarization multiplexing to conserve brightness. BACKGROUND OF THE INVENTION [0003] Semiconductor high power lasers are interesting as replacements of today's commercially available CW fiber lasers (FL's) for many reasons, among which compact size and high efficiency...

AI Technical Summary

Benefits of technology

"The present invention is about high power semiconductor lasers that use a laser diode array waveguide grating (DAWG) in an external cavity configuration to stabilize the wavelength. The invention also focuses on efficiently coupling optical gain element arrays to the DAWG and combining multiple high power DAWG lasers into a single output while conserving brightness. The technical effects of the invention include stable wavelength, efficient coupling, and brightness conservation."

Problems solved by technology

The power achievable from a single laser module is limited to the range of several watt.

Simple optical combiners do not satisfy the efficiency requirement for fundamental physics reasons.

To obtain high output power and efficiency, broad area laser diodes are generally used, however due to their dimensions they tend to oscillate in multiple transverse modes.

The broad area output facet of these lasers also presents a challenge for coupling into a single mode optical fiber in applications where maximal brightness is called for.

Distributed feedback gratings as well as distributed Bragg reflectors are commonly integrated into the laser structure, but these exhibit a relatively high wavelength shift with temperature, which can be problematic in high power environments.

Similar techniques have been developed also for broad area lasers, however coupling them into an external cavity with the required efficiency is still a major problem.

A disadvantage of this arrangement is that it requires close tracking of the laser wavelength with the passbands of the WDM device under changing temperature conditions.

This has a similar disadvantage to the previous example.

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