US Patent 7428254 Athermalisation of tuneable lasers

This invention describes a technique and apparatus to use any tuneable laser to generate a specified output frequency without controlling its temperature. This technique only involves a thermal sensor and a controller a determine the current(s) of voltage(s) applied to the grating or tuning section(s) to obtain the required wavelength. The control loop can be implemented using a programmed microprocessor, an amplifier and a low pass filter.