Showing papers on "Supercontinuum published in 2001"

Supercontinuum generation of higher-order solitons by fission in photonic crystal fibers.

Abstract: The nonlinear pulse propagation in photonic crystal fibers without slowly varying envelope approximation is studied using an improved variant of first-order wave equation. Supercontinuum generation is shown to be caused by a novel mechanism of spectral broadening through fission of higher-order solitons into redshifted fundamental solitons and blueshifted nonsolitonic radiation. Good agreement with experimental observations is found, and subcycle pulse compression is studied.

White-light supercontinuum generation with 60-ps pump pulses in a photonic crystal fiber

Abstract: The generation of a spatially single-mode white-light supercontinuum has been observed in a photonic crystal fiber pumped with 60-ps pulses of subkilowatt peak power. The spectral broadening is identified as being due to the combined action of stimulated Raman scattering and parametric four-wave-mixing generation, with a negligible contribution from the self-phase modulation of the pump pulses. The experimental results are in good agreement with detailed numerical simulations. These findings demonstrate that ultrafast femtosecond pulses are not needed for efficient supercontinuum generation in photonic crystal fibers.

Analysis and design of supercontinuum pulse generation in a single-mode optical fiber

Abstract: We present an analysis and describe the design of supercontinuum (SC) pulse generation in a single-mode optical fiber. SC generation with a dispersion-decreasing fiber with a convex dispersion profile is contrasted with other approaches to obtaining conditions for generating a flat, broadened spectrum. We present general criteria for SC generation by introducing normalized parameters that allow the shape of the SC spectrum to be invariant for several SC-generating fibers and optical pump pulses. Based on these results, we designed a SC fiber and experimentally generated SC pulses that were in good agreement with theory.

Widely wavelength-tunable ultrashort pulse generation using polarization maintaining optical fibers

Abstract: Characteristics of widely wavelength tunable ultrashort pulse generation using several types of polarization maintaining fibers have been experimentally analyzed. Using the diameter reduced type of polarization maintaining fibers, the wavelength tunable soliton pulse is generated from 1.56 to 2.03 /spl mu/m. It is confirmed that the almost transform-limited 340-fs soliton pulse is generated at a wavelength of around 2 /spl mu/m using a frequency-resolved optical gating method. When low-birefringence fibers are used, it is observed that the orthogonally polarized small pulse spectrum is trapped by the soliton pulse and is also shifted toward the longer wavelength side in the process of soliton self-frequency shift. The wavelength of the orthogonally polarized pulse spectrum is 40-50 nm longer than that of the soliton pulse, and the birefringence of the fiber is compensated by the chromatic dispersion. Finally, a polarization maintaining highly nonlinear dispersion-shifted fiber is used as the sample fiber. When the fiber input power is low, the wavelength-tunable soliton and anti-Stokes pulses are generated. As the fiber input power is increased, the pulse spectra are gradually overlapped and the 1.1-2.1 /spl mu/m widely broadened supercontinuum spectra are generated by only 520 pJ pulse energy.

Backward supercontinuum emission from a filament generated by ultrashort laser pulses in air.

Abstract: Backward emission of the supercontinuum from a light filament induced by high-intensity femtosecond laser pulses propagating in air has been observed to be enhanced compared with linear Rayleigh–Mie scattering. This enhancement is interpreted as a nonlinear scattering process onto longitudinal refractive-index changes induced by the laser pulse itself. The spectral dependence of the supercontinuum angular distribution is also investigated.

Polarization dynamics of femtosecond pulses propagating in air.

Abstract: Polarization dynamics of femtosecond light pulses propagating in air is studied by computer simulation. A rich variety of dynamics is found that depends on the initial polarization state and power of the pulse. Effects of polarization on the plasma and supercontinuum generation are also discussed.

150 channel supercontinuum CW optical source with high SNR and precise 25 GHz spacing for 10 Gbit/s DWDM systems

Abstract: A 150 channel multi-wavelength continuous wave (CW) optical source with precise 25 GHz spacing is successfully realised by longitudinal mode slicing of a supercontinuum spectrum. Confirmation is provided of the generation of more than 150 CW channels ranging from 1530 to 1560 nm with SNRs>28.2dB and Q-factors >20.8 dB which are sufficient for 10 Gbit/s multi-span dense wavelength division multiplexing transmission.

Method and apparatus for arbitrary waveform generation using photonics

Abstract: An apparatus and method for synthesizing waveforms with arbitrary amplitude, frequency, and phase modulation. Pulses from a broadband (supercontinuum) optical source are filtered into a plurality of wavelength channels, and the intensity of each wavelength channel is adjusted to an appropriate level depending on the desired shape of the envelope of the output pulse. The envelope of the sampling wavelength channels can be stretched, compressed, or inverted in the time domain later using a dispersive medium. After time domain manipulation, the optical pulse train is observed with a combination of high-speed photodetectors and a radio frequency low-pass filter, a low-speed photodetector.

106 channel × 10 Gbit/s, 640 km DWDM transmission with 25 GHz spacing with supercontinuum multi-carrier source

Abstract: The first transmission experiment employing a high SNR supercontinuum multi-carrier source is presented. A 106 /spl times/ 10 Gbit/s, 25 GHz spaced DWDM signal has been transmitted over 640 km (8 /spl times/ 80 km).

Low-noise multiwavelength transmitter using spectrum-sliced supercontinuum generated from a normal group-velocity dispersion fiber

Abstract: Aiming at the application of supercontinuum (SC) generated from a fiber with a normal group-velocity dispersion (GVD) to multiwavelength transmitters, we theoretically study the enhancement of optical-amplifier noise in the SC-generation and spectrum-slicing processes. We find that significant enhancement of noise is not observed in these processes. The bit error rate measurement actually shows that the power penalty induced by these processes is less than 1 dB in all spectrum-sliced channels. These results assure low noise of the multiwavelength transmitter using spectrum-sliced SC generated in a normal GVD fiber.

A high SNR, 150 ch supercontinuum CW optical source with precise 25 GHz spacing for 10 Gbit/s DWDM systems

Abstract: A 150 channel multi-wavelength CW optical source with precise 25 GHz spacing is successfully realized by longitudinal mode slicing of a supercontinuum spectrum. We confirm the generation of more than 150 CW channels ranging from 1530 to 1560 nm with SNRs over 28.2 dB and Q-factors over 20.8 dB which are sufficient for 10 Gbit/s multi-span DWDM transmission.

Supercontinuum generation and pulse compression in hollow waveguides.

Abstract: We present a theoretical study of temporal and spectral characteristics and pulse compression in hollow waveguides, using a global approach to dispersion without application of the slowly varying envelope approximation. A novel ultrawide self-phase modulation–induced spectral-broadening regime with spectra covering almost 3 octaves is predicted for a pressure at which the group-velocity dispersion parameter is small and anomalous. Compression to subcycle pulses by an appropriate broadband modulator and pulse shortening without chirp control by a spectral filter are studied.

80 Gbit/s simultaneous photonic demultiplexing based on OTDM-to-WDM conversion by four-wave mixing with supercontinuum light source

Abstract: A novel method for all-optical all-channel simultaneous demultiplexing based on OTDM-to-WDM conversion by four-wave mixing with a highly chirped rectangular shaped supercontinuum source is proposed. Error-free 80 to 10 Gbit/s demultiplexing operation in eight channels is experimentally demonstrated.

Spatial Coherence of Supercontinuum Emitted from Multiple Filaments

Abstract: We experimentally show that the supercontinuum beams emitted from multiple filaments by focusing femtosecond laser pulses into a liquid or a crystal are mutually coherent. The time-resolved Schlieren method reveals that the positional correlation of different filaments in an artificial array of a supercontinuum is high.

40 Gbit/s photonic packet compression and decompression by supercontinuum generation

Abstract: 10 Gbit/s-to-40 Gbit/s photonic packet compression and 40 Gbit/s-to-10 Gbit/s photonic packet decompression are experimentally demonstrated by using supercontinuum generation followed by spectrum-slicing and optical time-gating followed by time-shifting.

Single-mode white-light supercontinuum with 60 ps pump pulses in a photonic crystal fiber

Abstract: Supercontinuum generation in a regime where the self-phase-modulation of the pump wave gives a negligible contribution to the spectral broadening reveals the importance of parametric and Raman effects in photonic crystal fibers.

Bi-directional photonic conversion between 4/spl times/10 Gbit/s OTDM and WDM by optical time-gating wavelength interchange

Abstract: Novel photonic conversion and reconversion of 40 Gbit/s (4/spl times/10 Gbit/s) OTDM-to-WDM-to-OTDM by wavelength interchange using optical time-gating of highly chirped supercontinuum and high speed pulse trains are proposed and experimentally demonstrated.

Photonic time-slot and wavelength-grid interchange for 10-Gb/s packet switching

Abstract: A time-space-wavelength-division photonic packet switch is proposed. The switch is based on ultrafast simultaneous time-slot and wavelength-grid interchange of optical packets using data-signal-induced supercontinuum (SC) light and arrayed waveguide gratings to slice the SC light spectrum. The switch was demonstrated at a data rate of 10 Gb/s.

Photonic variable length packet routing based on multi-wavelength label switch using multi-section fiber Bragg gratings and supercontinuum light source

Abstract: A novel photonic variable length packet routing network based on multi-wavelength label switch using fiber Bragg gratings and supercontinuum light source is proposed. 10Gbit/s variable length packet switching with all-optical multi-wavelength label recognition is demonstrated experimentally for the first time.

High resolution OCDR using 1.55μm supercontinuum source and quadrature spectral detection

Abstract: A Supercontinuum source is used with a static Michelson interferometer to perform high-resolution optical coherence-domain reflectometry (OCDR) at 1.551I¼m. Quadrature spectral detection enables compensation for both the undesirable spectral shape of the source and for the dispersion in the system. A resolution of less than 5I¼m in fibre (full width at half maximum) at 1.55I¼m is obtained.

Generation of femtosecond pulses by two-photon pumping supercontinuum-seeded collinear traveling wave amplification in a dye solution

Abstract: Visible femtosecond (fs) laser pulses have been obtained in a dye solution with a very simple traveling wave collinear configuration. A femtosecond Ti:sapphire laser (790 nm) pumps the dye solution by two-photon absorption and simultaneously generates supercontinuum, which seeds a light-amplification mechanism. Cross-correlation frequency-resolved optical gating measurements reveal a chirped structure in the dye pulse. The shortest pulse duration achieved is 170 fs and the overall energy efficiency of the process is typically 25%.

106 /spl times/ 10 Gbit/s, 25 GHz-spaced, 640 km DWDM transmission employing a single supercontinuum multi-carrier source

Abstract: Summary form only given. Future photonic networks will need to generate over one hundred optical carriers (modes) at ITU grids with well-controlled spacing. Supercontinuum (SC) generation is an effective way of obtaining such well-managed optical carriers by broadening the input optical pulse spectrum while maintaining coherency. Some of the advantages of using SC are a fixed channel spacing with an accuracy of a microwave oscillator and super-broadened spectra, and the capability of generating more than 100 channels. So far, WDM transmission experiments using SC-based pulse sources have been demonstrated. However, transmission experiments utilizing SC sources as multi-carrier sources have not been reported yet. In order to apply the SC sources to future photonic networks, the SC sources must be able to generate high power, high SNR optical carriers. Recently, we have generated 1000-channel optical carriers from a single SC source, and improved the output power and the SNR of the optical carriers. This paper describes the first transmission experiment utilizing the advanced SC multi-carrier source (SC-MCS) which generates over 1000 optical carriers with high power and high SNR.

All-optical data addition to a time slot in 160 Gb/s OTDM signal using wavelength conversion by supercontinuum in a nonlinear fiber

Abstract: Simultaneous all-optical signal addition and wavelength conversion in 160 Gb/s OTDM-based WDM data using supercontinuum generation is proposed and first demonstrated using a highly nonlinear fiber. 10 Gb/s data dropped from a 160 Gb/s OTDM signal is successfully added to 15/spl times/10 Gb/s OTDM signals.

Wavelength-tunable soliton generation in the 1400 -1600 nm region using an Yb fiber laser

Abstract: Soliton pulses tunable in the 1400 - 1600 nm region are generated in standard telecom fiber seeded with a continuum produced in a fiber taper using an Yb fiber laser. Here we demonstrate supercontinuum generation in the 500 nm - 1600 nm wavelength region using a compact ultrafast Yb fiber laser as a systems-compatible pump source for the first time. Moreover, by injecting the supercontinuum into a length of standard telecommunications fiber, we can induce Raman-soliton generation to produce near bandwidth-limited pulses tunable in the 1400 - 1600 nm wavelength region. The required pulse energy for supercontinuum and Raman-soliton generation is only of the order of 1 nJ, which demonstrates that this technique is compatible with fiber sources operating at GHz repetition rates.

Simultaneously generated 3.24 Tbit/s (81 WDM /spl times/ 40 Gbit/s) carrier suppressed RZ transmission using a single supercontinuum source

Abstract: A 3.24 Tbit/s (81 WDM /spl times/ 40 Gbit/s) carrier suppressed RZ (CS-RZ) format is simultaneously generated using a single supercontinuum source pumped by optically multiplexed 40 Gbit/s CS-RZ and is transmitted over an 80 km link.

Wideband tunable wavelength conversion of 10-Gbit/s return-to-zero signals by optical time gating of a highly chirped rectangular supercontinuum light source.

Abstract: We propose a novel technique for wideband tunable wavelength conversion of return-to-zero signals by optical time gating of a supercontinuum (SC) light source. A SC pulse generated by nonlinear propagation in a normal-dispersion fiber has a rectangular shape with highly linear upchirping. By control of the optical time-gating position, the center wavelength of time-gated SC pulse can be precisely tuned. Error-free 10-Gbit/s wavelength conversion with a tuning range of 27.1 nm is experimentally demonstrated.