Multi-wavelength external-cavity laser with digital and mode-hope-free fine tuning mechanisms

Abstract

An apparatus for electronically tuning of a single or multi-wavelength external-cavity laser, comprising: an AR-coated diode laser, a collimator, a liquid crystal cell, a dispersion grating, a focusing lens and a liquid crystal pixel mirror. Wavelength channels can be selected by opening the appropriate pixels of the liquid crystal pixel mirror. By turning on several pixels at the same time, the laser can generate output at several wavelengths. Wavelength switching between channels is also possible. Laser wavelength can further be tuned by varying the driving voltages of the liquid crystal cell or the appropriate pixel mirror. The liquid crystal cell and the liquid crystal pixel mirror in the laser cavity can be combined to form a sandwich-type liquid crystal pixel mirror that allows both step (digital) or fine tuning of the laser wavelength.