CHIRP REDUCTION IN 3-CAVITY SEMICONDUCTOR-LASER DIODES

The oscillation frequency shift ratio (OFSR) of a three-cavity coupled laser diode, which is caused by refractive index changes due to current modulation and temperature variation, has been investigated. It is found that the OFSR is significantly reduced by using a laser with an AR coated facet and a high external-mirror reflectivity, in addition to large external cavity lengths. Also, compared with an external cavity laser, the three-cavity laser has a smaller OFSR provided that the external cavities' reflectivities r0 and r3, are not identical (that is, r3 > r0). The analysis indicates that the structural parameters affect the OFSR of the three-cavity laser, which was shown to have a high longitudinal mode discrimination'.