Biomedical subjects

Y J Rao

Publications and source records attributed to Y J Rao.

4 recordsLinked to original sources

PubMed2007

All-fiber dynamic gain equalizer based on a twisted long-period grating written by high-frequency CO2 laser pulses.

A novel dynamic gain equalizer for flattening Er-doped fiber amplifiers based on a twisted long-period fiber grating (LPFG) induced by high-frequency CO(2) laser pulses is reported for the first time to our knowledge. Experimental results show that its transverse-load sensitivity is up to 0.34 dB/(g.mm(-1)), while the twist ratio of the twisted LPFG is approximately 20 rad/m, which is 7 times higher than that of a torsion-free LPFG. In addition, it is found that the strong orientation dependence of the transverse-load sensitivity of the torsion-free LPFG reported previously has been weakened considerably. Therefore such a dynamic gain equalizer based on the unique transverse-load characteristics of the twisted LPFG provides a much larger adjustable range and makes packaging of the gain equalizer much easier. A demonstration has been carried out to flatten an Er-doped fiber amplifier to +/-0.5 dB over a 32 nm bandwidth.

Journal Article↗

PubMed2006

Fiber-optic Fabry-Perot sensors based on a combination of spatial-frequency division multiplexing and wavelength division multiplexing formed by chirped fiber Bragg grating pairs.

Effective multiplexing for a very large number of fiber-optic fiber-Bragg-grating-based Fabry-Perot (FBGFP) sensors is proposed that is based on wavelength division multiplexing (WDM) and spatial-frequency division multiplexing (SFDM). For WDM, FBGFP sensors are arranged in different wavelength domains formed by a series of chirped fiber Bragg gratings with different central wavelengths while the sensors with different cavity lengths within the same wavelength domain are multiplexed by use of SFDM because they have different spatial frequencies as a result of their different cavity lengths. In principle, a thousand FBGFP sensors could be multiplexed with such an approach. The experimental results show that a strain accuracy of better than +/-10 microepsilon has been achieved with little cross talk.

Journal Article↗

PubMed2006

Demodulation algorithm for spatial-frequency-division-multiplexed fiber-optic Fizeau strain sensor networks.

A demodulation algorithm for spatial-frequency-division-multiplexed fiber-optic Fizeau strain sensor networks with a large number of sensors is proposed to effectively reduce the cross talk between any two adjacent sensors and hence substantially enhance the multiplexing capability of the network, which is based on the Pisarenko algorithm. The cross talk between two fiber-optic Fizeau sensors is investigated experimentally. The experimental results show that a strain accuracy of better than +/-10 micro permittivity can be achieved even when the cavity length difference is approximately 100 microm. It was demonstrated that the multiplexing capability of the spatial-frequency-division-multiplexed fiber-optic Fizeau sensor network can be approximately 5 times greater than that of the conventional fast-Fourier-transform algorithm, and this can lead to achievement of a sensing network with a multiplexing capability of as many as 1000 Fizeau sensors.

Journal Article↗

PubMed1994

Delusions of parasitosis with fatal outcome.

The case of a 40-year-old man with delusions of parasitosis as the presentation of a monodelusional psychosis is reported. In spite of treatment with pimozide and depot neuroleptics the patient committed suicide. Since the introduction of pimozide, this drug has come to be regarded as the specific treatment for this disorder; this case is presented to emphasize the fact that not all cases respond, and that the disorder can have a fatal outcome.

Adult↗