Self-induced frequency scanning and distributed Bragg reflection in semiconductor lasers with phase-conjugate feedback

A GaAlAs semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. We also report similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case

Semi-self-pumped phase-conjugate mirrors

We describe semi-self-pumped photorefractive phase-conjugate mirrors based on the unidirectional ring resonator and the double phase-conjugate mirror. Their applicability to thresholding phase conjugation and one-way imaging through distortions is discussed

Plane-wave theory of nondegenerate oscillation in the linear photorefractive passive phase-conjugate mirror

We present a plane-wave theory of nondegenerate oscillation in the linear passive (self-pumped) phase-conjugate mirror (PPCM). The circumstances under which the plane-wave theory permits spontaneous nondegenerate oscillation in this and other PPCM's are discussed

Passive (self-pumped) phase conjugate mirror: Theoretical and experimental investigation

We report the results of a theoretical and experimental investigation of a passive (self-pumped) phase conjugate mirror. This device is based on real time holography in materials which allow a spatial phase shift between the refractive index grating and the light interference pattern. An imaging experiment is reported showing the phase conjugating nature of the device. The holographic medium used was a single crystal of barium titanate

Amplified reflection, transmission, and self-oscillation in real-time holography

A theory of phase conjugation in asymmetric materials that allow a phase shift between the grating and the light-interference pattern is developed. We find that when this phase is nonzero, maximum phase-conjugate reflectivity occurs for unequal pump intensities. The conditions for self-oscillation are studied

Passive phase conjugate mirror based on self-induced oscillation in an optical ring cavity

A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self-starting by four-wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported

Combining 3D printing and liquid handling to produce user-friendly reactionware for chemical synthesis and purification

We use two 3D-printing platforms as solid- and liquid-handling fabricators, producing sealed reactionware for chemical synthesis with the reagents, catalysts and purification apparatus integrated into monolithic devices. Using this reactionware, a multi-step reaction sequence was performed by simply rotating the device so that the reaction mixture flowed through successive environments under gravity, without the need for any pumps or liquid-handling prior to product retrieval from the reactionware in a pure form

Coherent oscillation by self‐induced gratings in the photorefractive crystal BaTiO_3

We report here the demonstration of several new optical oscillator configurations including a unidirectional ring oscillator and a self‐pumped phase conjugate mirror. The gain medium is BaTiO_3, pumped by a 632.8‐nm He‐Ne laser at power levels down to 50 μW

Exact solution of a nonlinear model of four-wave mixing and phase conjugation

An exact solution of a nonlinear model of holographic four-wave mixing is derived. An expression for the reflectivity of a phase-conjugate mirror with depleted pumps is presented. We find that such a phase-conjugate mirror may exhibit bistability