Phase-locking characteristics of coupled ridge-waveguide InP/InGaAsP diode lasers

Abstract

The phase-locking characteristics of two coupled, ridge waveguide InP/InGaAsP diode lasers emitting at 1.2 μm were investigated experimentally. The phase locking of the lasers was verified by the observation of phase-locked modes (supermodes) in the spectrally resolved near fields and distinct diffraction patterns in the far field. By independent control of the laser currents it was possible to vary continuously the mutual phase shift between the two phase-locked lasers and thus steer the far-field diffraction lobes. In addition, the separate current control could be utilized to obtain single longitudinal mode oscillation of the phase-locked lasers. Variation in one of the laser currents resulted then in tuning of the wavelength of this single mode over a range of 90 Å.