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Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator
Published on: January 28, 2019
Active coherent beam combining of diode lasers
Shawn M Redmond1, Kevin J Creedon, Jan E Kansky
1Massachusetts Institute of Technology, Lincoln Laboratory, Lexington, Massachusetts 02420, USA. s.redmond@ll.mit.edu
Optics Letters
|March 16, 2011
Summary
We demonstrated active coherent beam combination (CBC) of 218 semiconductor amplifiers, achieving 38.5 W output. This method uses a stochastic parallel gradient descent algorithm for efficient phase locking without a reference beam.
Area of Science:
- Optics and Photonics
- Semiconductor Lasers
Background:
- Coherent beam combination (CBC) is crucial for scaling optical power.
- Semiconductor amplifiers offer compact and efficient light sources but require precise phase control for CBC.
Purpose of the Study:
- To demonstrate active coherent beam combination (CBC) of a large number of semiconductor amplifiers.
- To achieve high output power through efficient phase locking of multiple amplifier arrays.
Main Methods:
- Utilized eleven 1D, 21-element individually addressable diode amplifier arrays (slab-coupled-optical-waveguide semiconductor amplifiers - SCOWAs).
- Employed a master-oscillator, power-amplifier configuration seeded by diffractive optical elements.
- Implemented a stochastic-parallel-gradient-descent (SPGD) algorithm for active phase control and locking.
Main Results:
- Successfully combined beams from up to 218 SCOWAs.
- Achieved a continuous wave (cw) output power of 38.5 W at 960 nm.
- Demonstrated effective phase locking using the SPGD algorithm without a reference beam.
Conclusions:
- Active CBC of numerous semiconductor amplifiers is feasible and scalable.
- The SPGD algorithm provides an efficient method for phase locking in high-power amplifier systems.
- This technique advances the development of high-power, coherent semiconductor laser sources.
