FOURIER DOMAIN MODE LOCKING: METHOD AND APPARATUS FOR CONTROL AND IMPROVED PERFORMANCE
A control system for improving and stabilizing Fourier domain mode locking (FDML) operation. The control system may also provide regulation of FDML operational parameters such as filter tuning, laser gain, polarization, polarization chromaticity, elliptical polarization retardance, and/or dispersion. The control system may be located internal to or external from the FDML laser cavity.
1 . A system to generate control signals for FDML operation in a Fourier Domain Mode Locking (FDML) laser comprising:
a light measurement device configured to receive a periodically wavelength swept light-field from a laser output of the FDML laser and determine a measured parameter; and
an electronic processing device configured to generate non-sinusoidal output control signals, based on the measured parameter, to adjust a time versus wavelength tuning characteristic of a tunable wavelength selective filter of the FDML laser.
2 . The system of claim 1 wherein the electronic processing device is an electronic waveform synthesizer.
3 . The system of claim 1 wherein the control signal generates a quasi periodic drive waveform.
4 . The system of claim 3 wherein the quasi periodic drive waveform is configured to compensate dispersion effects in a FDML laser cavity.
5 . The system of claim 1 wherein the drive waveform generates a wavelength swept output with a linear dependence of an optical frequency on time.
6 . The system of claim 5 wherein the filter control signal adjusts the drive waveform to a predetermined and numerically optimized waveform that is applied to the filter.
7 . The system of claim 5 wherein the predetermined waveform applied to the filter is controlled in a closed loop.