Coherent Beam Combining of Laser Amplifiers

Abstract

The University of Central Florida invention provides a system for coherently combining laser amplifiers, including fiber and solid-state ones, to provide a coherent output laser beam using diffractive optical elements. For different applications, more laser power is required, and there are different means to achieve this. Some are based on combining lasers with different wavelengths, but some require the final laser beam to have a relatively narrow spectrum. To achieve this result, coherent beam combination is one approach. While separate laser resonators can be combined coherently, only a few attempts have been made to combine laser amplifiers. For the beam combining to be called "coherent" the light propagating through the amplifiers and consequently combined into a single beam should have the same phase and wavelength characteristics (central wavelength and spectral width). It basically behaves as though it was emitted from a single laser source.

As a solution, UCF researchers developed a technique for combining laser amplifiers and providing a robust source of coherent laser light. The high power from the combined outputs of laser amplifiers does not need additional phase control (active phase control) techniques.

Technical Details: In some embodiments, a laser source includes multiple laser amplifiers operating in parallel (for example, in different channels) between two nonpolarizing beamsplitters (the first and second nonpolarizing beamsplitters). The laser source may further include a seed laser source to generate a seed beam. This seed beam may be split by the first nonpolarizing beamsplitter into the multiple channels for a first pass of amplification, combined along a common path by the second beamsplitter, and retroreflected back to the second nonpolarizing beamsplitter by a Faraday mirror. The retroreflected light may then be split between the multiple channels by the second beamsplitter for a second pass of amplification and recombined by the first beamsplitter as a coherent output beam.

In other embodiments, the laser source can further include a polarizing beamsplitter between the seed laser and the first beamsplitter. In this way, the polarizing beamsplitter may pass linearly polarized seed light for amplification and direct the output beam along a separate path.

Partnering Opportunity: The research team is seeking partners for licensing, research collaboration, or both.

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