Spectral beam combining of a broad-stripe diode laser array in an external cavity

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Laser Engineering

Background:

• Diode laser arrays offer high power but often suffer from poor beam quality.
• Combining beams from multiple laser elements is crucial for high-power laser applications.
• Maintaining beam quality during combining is a significant challenge.

Purpose of the Study:

• To demonstrate effective beam combining of a linear diode laser array.
• To improve the beam quality of a multi-element diode laser system.
• To achieve wavelength control and beam overlap from individual array elements.

Main Methods:

• Utilized an 11-element linear diode laser array with broad stripe emitters.
• Implemented a common external cavity incorporating a diffraction grating.
• The grating spectrally dispersed and aligned beams from each array element.

Main Results:

• Successfully combined the outputs of the 11 diode lasers into a single beam.
• Achieved a beam quality of approximately 20 times diffraction limited in the junction plane.
• The external cavity forced each element to operate at a distinct, controlled wavelength.
• The combined beam power was 50% of the initial bare laser array output.

Conclusions:

• External cavity laser design with a grating is effective for beam combining diode laser arrays.
• This technique allows for simultaneous wavelength control and spatial beam overlap.
• Further optimization is needed to improve power extraction efficiency in the combined beam.