PubMed Health⌕ Search

Biomedical subjects

Benjamin J Eggleton

Publications and source records attributed to Benjamin J Eggleton.

13 recordsLinked to original sources
PubMed2006

2R optical regenerator in As2Se3 chalcogenide fiber characterized by a frequency-resolved optical gating analysis.

We present a detailed analysis of a 2R optical regenerator based on self-phase modulation in As(2)Se(3) chalcogenide glass fiber using frequency-resolved optical gating (FROG). We obtain good agreement between the FROG measurements and theory, and confirm that the output pulses are near-transform limited. We show that two-photon absorption improves the profile of the power transfer function while not degrading the temporal performance.

Journal Article↗
PubMed2006

Photothermal effects in fiber Bragg gratings.

Writing a fiber Bragg grating in optical fiber generates an intrinsic broadband absorption term that can result in photothermal heating during subsequent use with fiber core guided light. This, in turn, can cause a significant shift of a grating resonance via the thermo-optic coefficient, even at low in-fiber light powers. The magnitude of the absorption term and its dependence on the grating strength are detailed. We further show how the degree of heating can be influenced by the particular environment in which the grating is placed and that, while the shift can be quite deleterious for some applications, its effect can be mitigated. A simple conductive model is developed.

Journal Article↗
PubMed2005

Integrated all-optical pulse regenerator in chalcogenide waveguides.

We report a fully integrated, passive, all-optical regenerator capable of terabit per second operation, based on a highly nonlinear chalcogenide (As2S3) glass rib waveguide followed by an integrated Bragg grating bandpass filter. We demonstrate a clear nonlinear power transfer curve with 1.4 ps optical pulses, capable of improving the signal-to-noise ratio and reducing the bit error rate for digital signals.

Journal Article↗
PubMed2005

Soliton compression and pulse-train generation by use of microchip Q-switched pulses in Bragg gratings.

Pulse compression and pulse-train generation are demonstrated by use of kilowatt 580 ps pulses generated by a compact (15 cm x 3 cm x 3 cm) microchip Q-switched laser followed by a fiber Bragg grating. A 12-fold pulse compression to 45 ps with five times peak power enhancement is achieved at 1.4 kW through soliton effect compression in the fiber grating. At 2.5 kW, modulational instability leads to a train of high-contrast sub-100 ps pulses. These demonstrations take advantage of the ultrastrong dispersion at frequencies close to the edge of the photonic bandgap. Experimental results are discussed in the context of the nonlinear Schrödinger equation and are compared with simulations of the nonlinear coupled-mode equations.

Journal Article↗
PubMed2005

Effect of group delay ripple on picosecond pulse compression schemes.

We show experimentally, through autocorrelation and frequency-resolved optical gating measurements, that a simple dispersive fiber Bragg grating with group delay ripple approximately 10 ps peak-to-peak may be used effectively to stretch ultrashort optical pulses for linear amplification before recompression to a higher-power pulse. We further investigate, through simulations, the effect of group delay ripple on the pulses and show that there are regimes, defined by both ripple magnitude and ripple period as a function of wavelength, in which the pulses are nearly perfectly compressed. A map with contours of equal figures of merit indicates favorable regions of operation.

Journal Article↗
PubMed2005

Transverse characterization of high air-fill fraction tapered photonic crystal fiber.

We demonstrate tapering of a high air-fill fraction photonic crystal fiber by using the flame-brushing technique. Transverse probing along the taper allows us to ascertain how the microstructure is preserved during tapering. Experimental results are compared with numerical simulations performed with the finite-difference time-domain and plane-wave expansion methods. Through this investigation we find that the fiber geometry is well preserved throughout the tapering process and we resolve the apparent discrepancies between simulation and experiment that arise through the finite extent of the fiber microstructure.

Journal Article↗
PubMed2005

Leakage of the fundamental mode in photonic crystal fiber tapers.

We report detailed measurements of the optical properties of tapered photonic crystal fibers (PCFs). We observe a striking long-wavelength loss as the fiber diameter is reduced, despite the minimal airhole collapse along the taper. We associate this loss with a transition of the fundamental core mode as the fiber dimensions contract: At wavelengths shorter than this transition wavelength, the core mode is strongly confined in the fiber microstructure, whereas at longer wavelengths the mode expands beyond the microstructure and couples out to higher-order modes. These experimental results are discussed in the context of the so-called fundamental mode cutoff described by Kuhlmey et al. [Opt. Express 10, 1285 (2002)], which apply to PCFs with a finite microstructure.

Journal Article↗
PubMed2005

Optimization of distributed resistive metal film heaters in thermally tunable dispersion compensators for high-bit-rate communication systems.

Tunable dispersion compensators are an essential component for optical networks operating at 40 Gbits/s and beyond. One fiber-based tunable dispersion compensator that has proved to be effective consists of a chirped fiber Bragg grating tuned by a thin-film distributed resistive heating element. We describe several modifications to the heater design that minimize temperature-induced higher-order dispersion, eliminate the need for a second stabilization heater when the device is operated at constant ambient temperature, and significantly lower its maximum operating temperature. We demonstrate a tunable dispersion compensator with a single thin-film heater that provides over 500 ps/nm of tunable dispersion over a fixed 100-GHz bandwidth with a maximum operating temperature of less than 125 degrees C above ambient.

Journal Article↗
PubMed2003

Interferometric characterization of phase masks.

We demonstrate a novel interferometric technique for highly accurate characterization of phase masks used in optical fiber grating fabrication. The principle of the measurement scheme is based on the analysis of the interference pattern formed between the first- and zero-order beams transmitted through or reflected from the grating under test. For spatial resolution of a few millimeters, our methods allow the determination of local variations of the order of 1-microm grating period with an accuracy of a few picometers. These methods are applicable to a broad class of diffractive grating structures.

Journal Article↗
PubMed2003

Wavelength-tunable semiconductor pump diode for reconfigurable Raman amplification.

We demonstrate a wavelength-tunable semiconductor pump diode for Raman amplification. Thediode is stabilized by a fiber Bragg grating (FBG) that can be continuously tuned over more than 20 nm. Tuning of the diode output wavelength is achieved by varying the center wavelength of the FBG, since the diode preferentially lases within the FBG bandwidth. We investigate the effects of wavelength tuning on the diode spectrum on its corresponding Raman gain, and on pump-pump four-wave mixing in fiber having zero-dispersion wavelength coincident with the Raman pumps.

Journal Article↗
PubMed2002

Influence of scattering on transmission through long-period fiber gratings and tunable microstructure fibers.

Controlled optical scattering within or around an optical fiber provides a potentially useful mean for adjusting its transmission characteristic. This approach can complement conventional methods based on the establishment of well-defined variations in the index of refraction of the core or the cladding of the fiber. We describe the use of a highly scattering submonolayer of nanoparticles deposited onto the fiber surface for adjusting the resonance wavelength, depth, and width of an in-fiber long-period grating filter. We also introduce a polymer-dispersed liquid-crystal material that has a thermally tunable scattering cross section and can be incorporated into the channels of a microstructure optical fiber; this system may provide the means for a fiber-based scattering switch.

Journal Article↗