Intermode tuning characteristics of an InGaAsP laser with optical feedback from an external grating reflector

The spectral characteristics are reported of one-side antireflection coated 1.3 mu m InGaAsP lasers exposed to strong feedback from an external grating, when the center wavelength of reflection of the grating is tuned continuously from one solitary laser diode longitudinal mode to the adjacent lower frequency mode. The effects of different residual reflectivities of the coated facet on the tuning characteristics of the laser between internal cavity modes are shown to agree with theory. Bistability in the tuning characteristic is explained. A dependence of the stability of single-mode oscillation and of the linewidth on the detuning from the solitary laser modes is theoretically explained.<
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