Nigel Edward Jolley

An analysis of the improvements in OSNR from distributed Raman amplifiers using modern transmission fibres

We present measurements of the Raman efficiency spectra for recent transmission fibres and model the improvement in DWDM system performance using distributed Raman amplification. For 5 spans of 25 dB fibre loss and 1 dB of connector loss, we predict 4.5-6.5 dB improvement in optical signal to noise ratio (OSNR) when using a 500 mW pump, a variation of up to 2 dB depending on fibre type.

Generation and propagation of a 1550 nm 10 Gbit/s optical orthogonal frequency division multiplexed signal over 1000m of multimode fibre using a directly modulated DFB

OFDM is a spectrally efficient, robust and flexible modulation format. We have theoretically and practically investigated optical OFDM at the highest ever data rate of 10 Gbit/s and successfully transmitted a signal over 1000 m of multimode fibre using a directly modulated laser transmitter.

Ultra-broadband high performance distributed Raman amplifier employing pump modulation

A novel 110 nm, ultra-broadband distributed Raman amplifier has been constructed where pumps may be modulated to reduce non-linear interactions between pump wavelengths. This gave about I dB improvement in effective noise figure for shorter signal wavelengths channels and eliminated noise from an in-band four-wave mixing product produced by beating of pump wavelengths in the low dispersion transmission fibre.

Out-of-band electronic gain clamping for a variable gain and output power EDFA with low dynamic gain tilt

In conclusion, the Er-doped fibre amplifier (EDFA) configuration presented allows variable gain or output power with minimal dynamic gain tilt. The use of an out-of-band probe laser and electronic feedback makes efficient use of the pump power while allowing fine control and adjustment of the EDFA gain but without sacrificing any of the EDFA transmission bandwidth.

Inline loopbacks for improved OSNR and reduced double Rayleigh scattering in distributed Raman amplifiers

We present a novel transmission system configuration, using passive components in a loopback topology, to improve counter-pumped distributed Raman amplification. This improves system performance, reduces double Rayleigh scattering and increases the efficiency of pump usage.

980 nm band pump wavelength tuning of the gain spectrum of EDFAs

We report 2-3 dB changes in the gain spectra of EDFAs in response to nanometer changes in pump wavelength within the 980 nm pump band. The pump wavelength induced gain changes are characterized and several techniques are presented to use them to improve the gain flatness of EDFAs.

Ultra low noise long wavelength EDFA with 3.6 dB external noise figure

A long-wavelength erbium-doped fiber amplifier (LW-EDFB) is reported showing a near-quantum-limited external noise figure as low as 3.6 dB. The amplifier configuration uses a buried optical filter and optical isolator to achieve this performance.

A Bragg grating optically gain-clamped EDFA with adjustable gain, low noise figure and low multipath interference

Summary form only given. In conclusion we have demonstrated an optically gain-clamped EDFA with high-performance fibre Bragg gratings (FBGs). The EDFA exhibits very low multipath interference (MPI), excellent noise figure, and a widely variable gain.