F.N. Timofeev

Transmission passband, optical crosstalk and cascadability of free-space concave grating demultiplexer for dense WDM networks

We describe the performance of a 100 channel free-space concave grating demultiplexer with 1dB transmission passband of ±7GHz (FWHM 14–22GHz). The influence of optical aberrations and defocusing on the transmission spectrum is demonstrated. Crosstalk between neighbouring channels separated by >0.3nm is lower than −25dB and no penalty due to crosstalk is observed using 2.6Gbit/s directly modulated DFB lasers. Penalty-free transmission through a cascade of 30 demultiplexers is demonstrated in an optical fibre recirculating loop experiment, and the permitted tolerances on the laser frequency misalignments for a larger number of cascaded demultiplexers are investigated.

10 Gbit/s directly-modulated, high temperature-stability, external fibre grating laser for dense WDM networks

We report on the modulation performance and temperature stability of a fast (up to 10 Gbit/s) InGaAsP-InP MQW semiconductor external fibre grating laser. The combination of high speed direct modulation with low static and dynamic chirp makes this laser very attractive for application in dense WDM optical networks.

Modulation bandwidth of high-speed, directly-modulated semiconductor laser with detuned external fibre grating reflector

We have studied theoretically and experimentally the impact of operating wavelength detuning on the modulation performance of high-speed directly modulated semiconductor laser with an external fibre grating resonator. It was shown that FGL modulation bandwidth increases with wavelength detuning and can be doubled, up to /spl sim/18 GHz.

Skew Compensation in All Optical Bit Parallel WDM Systems

A bit skew and dispersion compensation scheme using fibre gratings for a 10 Gb/s-channel, 2-bit, Bit Parallel WDM system over 100 km of standard single-mode fibre is presented. The combination of channelised dispersion, and additional fibre delay, is sufficient to give full compensation.

Use of fibre gratings for bit skew compensation in all optical bit parallel WDM systems

We demonstrate transmission of two wavelength division multiplexed (WDM) bit parallel channels over 100 km of standard single mode fibre link using direct-modulated laser diodes at 10 Gbit/s channel. Step-chirped fibre gratings are used to simultaneously compensate to bit skew and dispersion. Bit skew of approximately 2.5 ns due to the fibre dispersion is completely compensated. Our work show shows that the step-chirped fibre grating technique can eliminate the bit skew for bit parallel WDM systems operating at Gbit rate over hundreds of kilometres of fibre link.

Differential delay compensation for reducing packet lengths in a WDMA/TDMA “switchless” optical network

Abstract Differential delays due to fiber dispersion represent the ultimate limitation on achievable guard times and packet durations for WDMA/TDMA “switchless” optical transport networks. A delay compensator based on fiber gratings is proposed to decrease such delays.

Bit skew and dispersion compensation in 10 Gb/s-channel bit parallel WDM systems

We present results on a two-channel (two-bit) bit-parallel WDM system operating at 10 Gb/s per channel over 100-km of standard single mode fibre. The bit skew and dispersion were compensated using two apodised step chirped fibre gratings.

Free-space grating demultiplexer for densely-spaced, subnanometer wavelength-routed optical networks

We report on the diffraction-limited performance of a free-space aberration corrected concave grating demultiplexer. The fibre-to-fibre loss was less than 9 dB and channel isolation better than 25 dB for channel spacing of 0.4 nm, in the wavelength range 24 nm around 1.5 /spl mu/m. This device has applications in wavelength routing crossconnects and in optical spectrum analysers.