Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Oscillation dependence of two-wave mixing gain for unidirectional ring resonator in photorefractive materials

Abstract: Dependence of the coupling strength of two-wave mixing gain in photorefractive materials for the single unidirectional ring resonator on oscillation conditions has been analyzed in the strong nonlinear regime. In this regime, difference between the frequency of the pump beam and oscillating beam is proportional to the cavity-length detuning, which can be explained in terms of the photorefractive phase-shift. This phase-shift results due to slightly non-degenerate two-wave mixing that compensates for cavity detuning and satisfies the round-trip phase condition for the steady-state oscillation. The presence of such a phase-shift allows the possibility of the nonreciprocal steady-state energy transfer between the pump and oscillating beams. If the gain due to the beam coupling is large enough to overcome the cavity losses then the signal beam is amplified in the presence of material absorption. Such amplification is responsible for the oscillations. For the single unidirectional ring resonator, the effects of cavity-length detuning, energy coupling coefficient, crystal thickness of the material, reflectivity of the cavity mirrors and material's absorption coefficient on the frequency and intensity of oscillations have also been studied in detail. It has been found that for the smaller value of absorption coefficient ( α ) of the photorefractive crystal, the unidirectional ring resonator can oscillate at almost any cavity-length detuning (Δ Γ ) whereas for the larger value of α oscillation occurs only when the cavity-length detuning is limited to small region (around Δ Γ =0). But reverse of the case is found for energy coupling coefficient ( γ 0 ).

Optical heterodyne detection and integrated optical component suitable for use in such a device

Abstract: An optical heterodyne or homodyne receiver includes a single constructively integrated optical component which combines a local oscillator beam with a signal beam to derive oppositely phased combined beams and further splits each of the combined beams into orthogonally polarized sub-beams. The integrated optical component has a polarization-sensitive beam-splitting layer in a first plane and a polarization-insensitive beam-splitting layer in a second plane, the two planes being perpendicular or parallel to each other.

Nearly diffraction-limited signal generated by a lower beam-quality pump in an optical parametric oscillator

Abstract: The beam quality of an optical parametric oscillator (OPO) within a singly resonant, confocal-positive branch unstable resonator is investigated. Resonator configurations have been found in which the beam quality of the outgoing signal exceeds the beam quality of the pump. Cavity magnification and pump-pulse duration are found to determine the signal beam quality. It is shown that signal M2 decreases with increasing pump-pulse duration for a given cavity magnification. In an experimental demonstration of a LiNbO3 OPO within an unstable resonator, pumped by a multitransversal mode beam, a signal beam with an almost-single transversal mode has been generated, whereas the multitransversal mode behavior of the pump beam is projected on the idler beam.