Double Phase Conjugate Mirror Geometry Research Articles

Injection locking semiconductor lasers with phase conjugate feedback

Phase conjugate injection locking is shown to couple coherently two semiconductor lasers through a double phase conjugate mirror geometry. The mutual coherence and stability of the lock band are characterized from the visibility and relative intensity noise measurements for various levels of phase conjugate coupling and frequency detunings. Side mode phase conjugate injection locking is demonstrated by high mutual coherence with visibility ∼0.93 and detunings up to nine longitudinal mode spacings at injection levels of −22 dB. Central mode phase conjugate injection locking with high mutual coherence is also possible for feedback levels of −36 dB and exhibiting an asymmetric stable locking region of 350 MHz bandwidth within the locking band. The phase locking is unstable though, the reasons for which are discussed. Increased phase conjugate feedback extends the lock band to greater detunings and asymmetry as in direct injection locking with only a small region showing high mutual coherence. Intensity noise measurements are also discussed.

Injection locking characteristics of semiconductor lasers in double phase conjugate mirror geometry

Phase locking of two semiconductor lasers is demonstrated by injection of the feedback from a double phase conjugate mirror. The stability or quality of the locking is characterised from fringe visibility measurements. Phase conjugate injection into the central mode exhibits an asymmetric stable locking region which extends to greater detunings and asymmetry with increased feedback. High quality locking is also demonstrated by phase conjugate injection into sidemodes up to nine longitudinal mode spacings from the target mode.

Photorefractive oscillator with a double phase-conjugate mirror geometry and orthogonally polarized pump beams

The first observation of oscillation via four-wave mixing in a double phase-conjugate mirror geometry with orthogonally polarized pump beams is reported. It is shown that generation of the waves deviating by a small angle from the plane pump beams can be adequately described by a set of equations for conventional four-wave mixing geometry with tilted pump beams. The experiments were carried out using the photorefractive Bi 12TiO 20 crystal in an external alternating electric field at the wavelength of a HeNe laser ( λ=633 nm).

Double phase-conjugate mirror using a photorefractive Bi_12TiO_20 crystal

Experimental results are reported for four-wave mixing at 633 nm with a photorefractive Bi(12)TiO(20) crystal in a double phase-conjugate mirror geometry. Recording in the presence of an alternating electric field with optimum focusing of interacting Gaussian beams yields up to 40% diffraction efficiency for the hologram.