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Peter W E Smith

Publications and source records attributed to Peter W E Smith.

7 recordsLinked to original sources
PubMed2006

All-fiber multimode interference bandpass filter.

A novel design for an all-fiber bandpass filter based on a multimode interference reimaging phenomenon is presented. The filter has achieved low insertion loss with adequate bandwidth and isolation for coarse wavelength-division multiplexing. The filter can easily be made with any central wavelength that is compatible with the single-mode fiber used for its construction. The measured filter performance matches the theoretical predictions well. The filter can have broad applications in fiber-optic telecommunications, spectroscopy, and sensing.

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PubMed2005

Efficient Raman shifting of high-energy picosecond pulses into the eye-safe 1.5-microm spectral region by use of a KGd(WO4)2 crystal.

We report an efficient transient stimulated Raman conversion of high-energy picosecond pulses at 1350 nm into the eye-safe 1500-nm wavelength range by use of a KGd(WO4)2 crystal. The conversion efficiency into either 1503- or 1537-nm radiation (767- or 901-cm(-1) Raman modes, respectively) is measured to be approximately 10% in a single-pass configuration. The transient Raman gain coefficient is found to be approximately 0.8 cm/GW. Simultaneous generation of multiple Raman lines is also observed.

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PubMed2004

Coherent two-photon absorption spectroscopy of the Raman-active KGd(WO4)2 crystal.

We report on the systematic open-aperture Z-scan characterization of the two-photon absorption properties in one of the most efficient solid-state Raman frequency shifters, the crystal potassium gadolinium tungstate [KGd(WO4)2]. The two-photon absorption coefficient was determined in the 370-600-nm wavelength range, with the highest value found to be approximately 1.9 cm/GW at 370 nm. Nonlinear losses are crucial in determining the conversion efficiency of the stimulated Raman scattering process when it is excited with ultrashort laser pulses with photon energy exceeding half of the bandgap. In addition, the results were analyzed within the context of a simple two-parabolic-band theoretical model to yield an effective bandgap energy value for the crystal.

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PubMed2004

Wide spectral range third-order autocorrelator based on ultrafast nonresonant nonlinear refraction.

We demonstrate a simple scheme for a wide spectral range, third-order autocorrelator based on ultrafast nonlinear Kerr-type refraction. The technique was successfully used to characterize high-energy ultrashort pulses at 1550 and 1300 nm, where the pulse's shape and width are two of the most critical parameters. Because of its simplicity, this technique is also a powerful tool for the optimization of high-power chirped-pulse amplified laser systems, in which slight misalignment of the stretcher-compressor gratings can lead to spatiotemporal pulse distortions. In addition, it can be extended to low-power mode-locked oscillators.

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PubMed2004

Dispersion of the nonlinear refractive index in sapphire.

The nonlinear refractive index, n2, of sapphire was experimentally measured in the 550-1550-nm wavelength range by use of a picosecond Z-scan technique. It was found that in this spectral region the value of n2 decreases monotonically from approximately 3.3 x 10(-16) to approximately 2.8 x 10(-16) cm2/W. An empirical expression for the wavelength dependence of the nonlinear refractive index in the 270-1550-nm range was obtained.

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PubMed2002

Analysis of chirped-sampled and sampled-chirped fiber Bragg gratings.

We analyze sampled fiber Bragg gratings that have chirp in the grating period, in the sampling function, or in both. In the last-named case the sampling period can be chirped, the sample length can be chirped, or both. We explain the features in the spectral and group-delay (dispersion) responses for gratings that have a single chirp parameter. We then show how the response of sampled gratings that have multiple chirp parameters can be explained in terms of the single-chirp parameter cases.

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