An optical technique for photonic millimeter-wave generation is based upon passively mode-locked laser diodes (passive MLLD, please see the attached image), where the mode locking frequency of a multimodal emitting laser is determined by the length of the cavity. Mode locking can be achieved e.g. by integrating a saturable absorber in the resonator which is typically placed at the end of a cavity.
So my confusion is it possible to change the “length of the cavity”..? what is the relation between mode locking frequency and length of the cavity..?
is it possible to put a saturable absorber at the end of the cavity in case of CW laser…?
in the attached image the n represents the nth optical mode.
Regards,
Dhiman
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