Automatic Phase Compensation for Extremely Short Optical-Pulse Generation Using Wavelet Transform

We introduce the wavelet transform (WT) method to automatic phase compensation for the generation of extremely short optical pulses with a duration of a few to several femtoseconds. This method is based on the immediate negative feedback of the spectral phase which is directly reconstructed by the wavelet-transform analysis with no uncertainty in phase retrieval without any manual decision, unlike the Fourier transform method. It is shown that the wavelet-transform method is useful for automatic compensations for three types of ultrabroadband pulses with different characteristics, such as: 1) a strong chirp; 2) a 600-rad spectral-phase variation over one octave bandwidth; and 3) a complicated spectral phase as well as a structured intensity spectrum.