Daan Lenstra

Learn More
We demonstrate the generation of sub-picosecond optical pulses using a semiconductor optical amplifier (SOA) and a linear polarizer placed in a ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the passive mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz.(More)
We use a new rate-equation model for the propagation of sub-picosecond polarized optical pulses in a semiconductor optical amplifier (SOA). This model is based on the decomposition of the polarized optical field into TE and TM components that interact via the gain saturation, and accounts for two-photon absorption, free-carrier absorption, self-and(More)
We present a theoretical study of unnested period-doubling islands in three-dimensional rate equations modeling a semiconductor laser subject to external optical injection. In this phenomenon successive curves of period doublings are not arranged in nicely nested islands, but intersect each other. This overall structure is globally organized by several(More)
We consider a model of two mutually delay-coupled semiconductor lasers in a face to face configuration. The lasers are coherently coupled via their optical fields, where the time delay τ arises from the finite propagation time of the light from one laser to the other. This system is described well by single mode rate equations, which are a system of delay(More)
We investigate an all-optical switch that is operated by the nonlinear phase-shift introduced by optical pulses with duration of 200 fs in a semiconductor optical amplifier (SOAs). The gate is made out of a commercially available InGaAsP–InGaAs multi-quantum-well (MQW) SOA placed in a Mach–Zehnder interferometer. We have measured the nonlinear phase-shift(More)
We report the first experimental observation of irregular picosecond light pulses within the coherence collapse of a semiconductor laser subject to delayed moderate optical feedback. This pulsing behavior agrees with the recent explanation of low frequency fluctuations as chaotic itinerancy with a drift. Theory and experiments show very good agreement.(More)
We show that a laser with a saturable absorber, described by the Yamada model, displays excitability just below threshold. A small perturbation, for example, a small input pulse, can trigger a single high output pulse, after which the system relaxes back to the off state. In order to study possible applications, such as pulse reshaping and clock recovery,(More)
We show that if gain anisotropy in a bulk semiconductor optical amplifier (SOA) is attributed to different confinement factors for the TE and TM modes, the anisotropy as a function of pump current is quite different from the case when another mechanism, material gain anisotropy due to weak strain in the active layer, is the cause of anisotropy. With a(More)
— We report detailed measurements of the pump-current dependency of the self-pulsating frequency of semiconductor CD lasers. A distinct kink in this dependence is found and explained using a rate-equation model. The kink denotes a transition between a region where the self-pulsations are weakly sustained relaxation oscillations and a region where(More)