METHOD FOR OPTICAL AND ELECTRICAL SIGNAL PROCESSING OF A MULTI-HETERODYNE SIGNAL GENERATED BY A MULTI-MODE SEMI-CONDUCTOR LASER AND DETECTION DEVICE UTILIZING THAT METHOD

摘要

The invention relates to a method for optical and electrical signal processing of a multi- heterodyne signal generated by a multi-mode semi-conductor laser, where the system comprises two laser sources and a sample interaction unit, wherein at least the beam of one of the lasers passes through said interaction unit before being combined on a detector. Both lasers are tuned to overlap the spectra in order to generate the heterodyne signal in the bandwidth of the detector (20). Then, the first laser is tuned (40=>42) by an amount keeping the tuning result within the available bandwidth (55) of said detector. Then the second laser is roughly tuned the by same amount as the tuning of the first laser to bring back the signal to the vicinity (48) of the original place in the RF-domain and within the bandwidth (55) of the detector. Finally, the tuning steps are repeated for a number of times with different value of mode spacing for reconstructing the sample spectrum and provide a high resolution image of the dip (41) absorption line (40).