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The constraints on dilute-nitride Semiconductor Optical Amplifiers (SOAs) for multi-wavelength amplification have been evaluated. SOAs have been fabricated by angling the facets of a GaInNAs/GaAs edge emitting laser using gas enhanced focused ion beam etching. The original laser has been characterized in terms of its temperature dependence and net modal gain. A full width half maximum (FWHM) of 40nm has been found at 298K. Good temperature stability has also been found with a value of 0.35nm/K for the lasing wavelength. The good temperature stability of the device has been explained in terms of the role that the monomolecular recombination plays in the temperature dependence of the device. The monomolecular recombination has been reported temperature independent having two key effects; reduction of the temperature performance and reduction of the dynamic performance in terms of an increase in the threshold current and a decrease of the high speed potential. Iodine gas enhanced focused ion beam etching (GAE-FIB) has been used for the fabrication of the SOA, the iodine gas increasing the etching rate by a factor of 2.5. The fabrication has been completed in two steps; in the first one the facets have been angled and in the second step a cross-section procedure has been employed for smoothing of the facets. Once the SOA has been fabricated its potential for simultaneous multiple channel amplification has been studied. A flat gain spectrum over a range of 40nm has been obtained. This value and the wavelength range have good agreement with the net modal gain measured in the original laser device. In addition, minimum channel interspacing has been achieved with no wavelength degradation.

The potential of 1.3µm GaInNAs SQW laser diodes for high speed operation is experimentally investigated in this paper, computing the differential gain, dg/dn, at a temperature range suitable for most network applications (293K -348K) and the small signal modulation bandwidth. The investigation begins with a basic characterization calculating the T 0 , with a value of 56K in a range of temperatures of 293K -318K. The lasing wavelength at 293K is found to be 1250nm with a linear temperature dependence of 0.377nm/K. Secondly, the paper presents a detailed study of the modulation bandwidth of the device, obtaining a value of 6.06Ghz for the maximum modulation bandwidth at 293K with a modulation efficiency of 0.64GHz/ √ mA. In a range of temperatures of 293K -318K, the modulation bandwidth is found to decrease only slightly with the temperature with a slope of 0.0088Ghz/K. Finally, the paper explains the temperature behaviour obtained for the modulation bandwidth studying the temperature dependence of the differential gain, dg/dn. For this evaluation, the value of the differential gain with the current (how the peak gain changes with the sub-threshold bias current applied to the sample), dg/dI, is obtained using the Hakki-Paoli method. 1 Quasi-linear temperature dependence of this value has been obtained with a slope of 3.377cm −1 A −1 /K. Using impedance measurements, a relation between the carrier density, n, and the bias current applied to the laser, I, has been obtained. With this relation, we obtained the differential current with the carrier density, dI/dn. Then, we calculated the differential gain dg/dn = dg/dI · dI/dn. At 293K, the differential gain a value of 1.55 · 10 −15 cm 2 . To conclude we saw how the differential gain, dg/dn, has been found to have similar temperature behaviour as the small signal modulation bandwidth.