Gain recovery in semiconductor optical amplifiers

Pump-probe measurements are presented of gain compression and recovery in a series of four semiconductor optical amplifiers of different lengths but otherwise identical structures. A continuous wave probe beam from a tunable laser is used to measure the wavelength dependence of gain compression and recovery times. A good level of agreement is obtained when these results are compared with numerical simulations using a model that includes the material gain spectrum, saturation effects and the variation of optical intensities with longitudinal position in the device. In addition the experimental results are interpreted in terms of a recent theory that offers approximate analytic expressions connecting recovery time with transmission gain. The spectral dependence of the recovery time and the gain are used to verify the correlations between these quantities and their dependence on device length. The results for recovery time show a strong dependence on probe wavelength with a pronounced minimum which is coincident with the peak of the gain spectrum for each device. A rather weak correlation of speed with length is found. © 2008 Elsevier B.V. All rights reserved

Passive alignment of second generation optoelectronic devices

This paper details how expanded-mode semiconductor devices and passive alignment techniques can be used to realize low-cost high-performance fiber grating laser and laser amplifier packages for future generations of optical telecommunication system

Polarisation insensitive, 25 dB gain semiconductor laser amplifier without antireflection coatings

An angled facet strained MQW semiconductor laser amplifier with integrated mode expanders has been designed and fabricated. A device without antireflection coatings had <0.5 dB gain ripple and 0.5 dB polarisation sensitivity at 25 dB gain

Improved gain block for long wavelength (1.55 µm) hybrid integrated devices

A curved waveguide, strained multiple quantum well reflective amplifier with an integrated front facet mode expander has been designed and fabricated. A device without facet coatings has been found to have a chip gain of 36 dB with 6 dB of gain ripple. This equates to an effective facet reflectivity of 8×10<sup>-6</sup&gt

Low noise figure (7.2 dB) and high gain (29 dB) semiconductor optical amplifier with a single layer AR coating

An angled facet strained MQW semiconductor laser amplifier with integrated mode expanders has been designed and fabricated. A device with simple single layer antireflection coatings exhibited a maximum of 29 dB fibre-to-fibre gain with a minimum noise figure of 7.2 dB at 26 dB gain and a saturation output power of 7.5 dBm. This gain is equal to the highest reported for an SLA operating at 1.5 μm while the noise performance is superior to that in any published work

Improved fibre grating lasers using large spot, curved waveguide semiconductor reflective amplifiers

High performance operation is reported of fibre grating lasers which have a large spot, curved waveguide semiconductor reflective amplifier as the gain block. Devices incorporating both uncoated and antireflection coated chips show good linearity and temperature stability. Direct modulation at rates to 2.5 Gbit/s is demonstrated