US Patent 7468996 External cavity laser tuning element dither servo control

According to embodiments of the present invention, an external cavity laser includes one or more tuning elements. At least one modulated voltage signal or dither is used to lock the transmission peak of the two tuning elements to each other. The wavelength of the laser also may lock onto the lock transmission peaks. In embodiments in which two dither signals are used, the dither signals may be orthogonal to or independent of each other. The two dither signals may produce two control signals to align the transmission peak of one filter to the transmission peak of another filter and the lasing mode of the laser to the aligned filters.