Tailoring the dynamics of multisection lasers for 40 Gb/s direct modulation
We demonstrate theoretically how a proper tailoring of the longitudinal structure of multisection semiconductor laser help to achieve the required device performance when modulating current with 40 Gbit/s PRBS signal. For this reason we simulate and analyze the longitudinal dynamics with the software package LDSL-tool.
Design optimization of InGaAsP-InGaAlAs 1.55 /spl mu/m strain-compensated MQW lasers for direct modulation applications
A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 /spl mu/m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.
Optical speedup at transparency of the gain recovery in semiconductor optical amplifiers
Experimental demonstration of optical speedup at transparency (OSAT) has been performed on a 1 mm long semiconductor optical amplifiers (SOA). OSAT is a recently proposed scheme that decreases the recovery time of an SOA while maintaining the available gain. It is achieved by externally injecting into the SOA the beam of a separate high power laser at energies around the transparency point. Even though the experimental conditions were not optimal, a beam of 100 mW decreases the recovery time by a third when it is injected in the vicinity of the material transparency point of the device. This acceleration of the device response without detrimental reduction of the gain is found to be effective over a broad wavelength window of about 20 nm around transparency. The injection of the accelerating beam into the gain region is a less efficient solution not only because the gain is then strongly diminished but also because speeding is reduced. This originates from the reduction of the amplified spontaneous emission power in the device, which counterbalances the speeding capabilities of the external laser beam. Another advantage of the OSAT scheme is realized in relatively long SOAs, which suffer from gain overshoot under strong current injection. Simulations show that OSAT decreases the gain overshoot, which should enable us to use OSAT to further speedup the response of long SOAs.