D.M. Cooper

Drawing-dependent transmission loss in germania-doped silica optical fibres

Abstract Excess attenuation is reported in germania-doped silica glass fibres, especially those optimised for monomode operation at 1.55 μm. This additional loss is found to be dependent on fibre drawing conditions, and possible origins are discussed.

Sensitivity Of The Performance Of Monomode Fibres To The Fabrication Conditions

The effects of fibre drawing tension on the optical properties of various monomode fibre designs is examined. High drawing tensions were found to give low optical loss. Grading the refractive index profile was found to reduce the drawing-induced loss considerably. Fibres with high germania content show the largest drawing effects.

Silicon Oxynitride Coatings To Reduce Mechanical Fatigue And Hydrogen Induced Optical Ageing In Silica Fibres

Monomode silica fibre has been coated during fibre pulling with silicon oxynitride ceramics using an on-line deposition process. The coatings have been tested for their ability to prevent the mechanical and optical ageing of fibre. The ceramic coated fibres are more fatigue resistant than silica having N values of over 100 compared with an N of 25 for silica. rrus ceramic coated fibre need only be proof tested at about half the level required for silica. While silica fibre saturates with hydrogen in 500 hours no hydrogen has been detected in a ceramic coated fibre stored in hydrogen for 1900 hours. This and other experiments at high temperature suggest that silicon oxynitride coatings can prevent the hydrogen content of fibre from reaching unacceptable levels.

Properties of facet-coated 1.3 mu m InGaAsP/InP MQW lasers

Multiple quantum well (MQW) external cavity lasers and optical amplifiers operating in the 1.3 mu m optical fiber communications window are described. The device designs and fabrications are discussed. It is demonstrated that MQW devices offer enhanced characteristics when compared with conventional bulk devices. An MQW laser with a single facet coat in an external cavity was measured to have a tuning range of 160 nm from 1.255 mu m to 1.417 mu m. The device had a peak power of over 40 mW at 1.336 mu m, and a side mode suppression ratio of more than 40 dB. An optical amplifier with a length of 500 mu m had a bandwidth of 110 nm, a 18 dB single-pass gain, and saturated output power of 14 dBm (25 mW).<<ETX>>

Linearity and noise of InGaAs multi-quantum-well lasers

Measurements are presented which demonstrate that multiple-quantum-well (MQW) lasers can offer significantly lower noise and distortion levels than equivalent double-heterostructure lasers. Improvements of approximately=10 dB in the laser intensity noise and approximately=8 dB in the second-harmonic distortion have been achieved. These figures are close to the predicted improvement of approximately=12 dB expected in MQW lasers as a result of doubling the laser resonant frequency.<<ETX>>

Recent progress in high performance InGaAsP optical amplifiers and multiple quantum well devices

Techniques for reducing the polarization sensitivity and suppressing the facet reflectivity of semiconductor optical amplifiers are reviewed. Results for 1.3- and 1.5- mu m amplifiers are discussed. The benefits of multiple-quantum-well (MQW) devices are demonstrated by enhanced tuning range external cavity devices and by high-saturated-output-power, fast-gain-recovery amplifiers.<<ETX>>