Method for Manipulating Optical Phase of a Laser Beam

The field of laser technology is consistently on the hunt for more precise and controllable laser beams. Lasers play a significant role in diverse fields, including communication, manufacturing, medicine, and scientific research. One aspect that requires meticulous attention is the linewidth of the laser, which affects the coherency and phase noise of the light. Therefore, techniquesare needed for effectively controlling and narrowing the laser linewidth. Existing methods to produce high-power, narrow-linewidth lasers can often be complex and inefficient, with limitations on the achievable power and linewidth. It's challenging to maintain a narrow linewidth while increasing the power level, and this problem escalates when the target wavelength range expands. The more diverse the wavelength range, the harder it is to manage the linewidth and power balance. Hence a synchronization of these aspects is a key issue in current scenarios.

Technology Description

This innovation involves the use of binary-phase-shift-key, phase-modulated waveforms that have gigahertz bandwidths compatible with kilowatt-class fiber amplifiers. They can be narrowed back to the source laser's linewidth via second-harmonic, sum-frequency, or difference-frequency generation in a second-order nonlinear crystal. A frequency-doubled optical signal phase-modulated with a pseudo-random bit sequence (PRBS) waveform can recover its original optical spectrum, effectively canceling the PRBS waveform and converting the underlying laser spectrum. This technology differentiates itself by its potential for high-power, narrow-linewidth laser development at wavelengths from the visible to the long-wave infrared. It leverages the cancellation capabilities through sum-frequency generation (SFG) and difference frequency generation (DFG). Utilizing ytterbium-, erbium-, thulium-, and neodymium-doped fibers with SHG, SFG, and DFG processes results in beams with very narrowband optical spectra and wavelengths from below 400 nm to beyond 5 µm. This technique offers a unique avenue to construct lasers that hold promise for a wide range of applications.