Injection-induced modulation of laser light by the interaction of laser diodes

The experimental investigation of laser-light modulation by injecting laser light of a frequency, which is slightly different from the cavity resonant frequency, into a laser-diode cavity is reported. For this investigation, the interaction of two laser diodes was used and the relation between the oscillation frequency spectra and the lasing frequency difference of the two diodes was measured where the frequency difference was greater than the locking frequency range. The sidebands generated by the injection of laser light were measured to judge an appearance of the injection-induced modulation of light intensity. Modulation in the frequencies from 10 to 90 GHz was achieved by using laser diodes of
60-130-\mu
m length. It was experimentally shown that the upper frequency limit of the injection-induced modulation was related to the
Q
value of the laser-diode cavity.