Biomedical subjects

Sajjad A Khan

Publications and source records attributed to Sajjad A Khan.

2 recordsLinked to original sources

PubMed2004

Liquid-crystal-deflector based variable fiber-optic attenuator.

A compact, low-component-count, no-moving-parts variable optical attenuator (VOA) is demonstrated for the first time by means of beam spoiling that is implemented via an electrically reconfigurable nonpixelated nematic liquid-crystal deflector. The VOA design features an in-line alignment polarization-insensitive design that does not use bulky polarization splitting and combining optics. The proof-of-concept VOA at 1550 nm demonstrates a 30-dB attenuation range, a 2.5-dB insertion loss, a < or = 0.8-dB polarization-dependent loss, and a 1-s maximum attenuation reset time. The VOA design can counter performance-reducing environmental effects such as excess-loss increases due to temperature variations.

Journal Article↗

PubMed2003

Programmable high-speed polarization multiplexed optical scanner.

A fast digital-analog control polarization-based optical scanner with complete three-dimensional beam-forming programmability is described. Its features include low power consumption and large-aperture liquid-crystal-based optics, digital repeatability, and time-multiplexed accurate analog beam forming. Analog frequency and amplitude control of the nematic liquid-crystal beam-former cells permits continuous fine-scan programmability over a 0.66-mrad horizontal deflection, a 0.75 mrad vertical deflection, and an infinity-to-1.84-m focal-length longitudinal scan. First demonstrations included an 8-point volumetric scan and a 2-bit digital lens scan, both at 1310 nm, with a 35-micros random-access time.

Journal Article↗