High-Resolution Mode-Spacing Measurement of the Blue-Violet Diode Laser Using Interference of Felds Created with Time Delays Greater than the Coherence Time

It is observed that the multi-mode cw blue-violet diode laser exhibits revival of interference when the interferometric path length difference is much greater than the coherence time of the laser and that the recurring interference peaks are separated by the same distance. We report that this unusual interference phenomenon can be used for high-resolution mode spacing measurement of the multi-mode cw blue-violet diode laser without using a high-resolution spectrometer.