Narrow-band Polarization Research Articles

All-fiber narrowband polarization controller based on coherent acousto-optic mode coupling in single-mode fiber

An all-fiber, narrowband, tunable polarization controller is proposed and demonstrated. The device is based on coherent acousto-optic mode coupling induced by two orthogonal acoustic waves on a dispersion-compensating fiber. The cooperative coupling between the two polarizations of the core mode and the TE01 cladding mode through the two gratings permits indirect coupling between the two polarizations of the core mode with nearly 100% efficiency, which makes the polarization-controlling function possible. Experimental results verify the operation of the polarization controller with an insertion loss of <1 dB.

Large enhancement of fully resonant sum-frequency generation through quantum control via continuum states

A theory of quantum control of short-wavelength sum-frequency generation, which employs the continuum states, is developed. The proposed scheme employs all-resonant coupling and trade-off optimization of the accompanying constructive and destructive quantum interference effects in the lower-order and higher-order polarizations controlled by the overlap of two autoionizinglike laser-induced continuum structures. The scheme does not rely on adiabatic passage, coherent population trapping or maximum atomic coherence as a means to facilitate maximum output. The opportunities for manipulating transparency of the medium and refractive index for the fundamental and generated radiations, as well as nonlinear polarization in the multiple-resonant medium, are shown. This opens the feasibility of creating frequency-tunable narrowband filters, polarization rotators, and dispersive elements for vacuum ultraviolet radiation. The features specific for quantum interference in Doppler-broadened media are investigated. The feasibility of almost complete conversion of long-wavelength fundamental radiation into generated short-wavelength radiation, and of a dramatic decrease in the intensity of required fundamental radiations, is shown.

Isogyration birefringent filter

A new narrow-band polarization spectral filter with an infinitely wide free spectral range is proposed. This filter utilizes the characteristics of propagation of light in a gyrotropic birefringent medium exhibiting reversal of the sign of gyration (isogyration medium). It is shown that the width of the spectral transmission maximum may reach a few angstroms and that the angle of view is limited only by the aperture of polarizing prisms.

Wavelength dependence of polarization. XXXII. Narrow-band polarization effects in cool stars.

Wavelength dependence of polarization. XXXII. Narrow-band polarization effects in cool stars.