1. Semiconductor Laser Diodes 2. Basic Concepts 3. Free-Carrier Theory 4. Coulomb Effects 5. Many-Body Gain 6. Band Mixing and Strain in Quantum Wells 7. Semiclassical laser Theory 8. Multimode Operation 9. Quantum Theory of the Laser 10. Propagation Effects 11. Beyond Quasiequilibrium Theory, Appendices A-e, Index

Semiconductor-Laser Physics

The propagation of strong picosecond optical pulses in semiconductor optical amplifiers (SOAs) is investigated numerically by taking into account carrier heating, spectral hole-burning, and two-photon absorption, as well as ultrafast nonlinear refraction. Very good agreement with published experimental results are observed in both the time and frequency domains. It is shown that the effects of two-photon absorption and ultrafast nonlinear refraction are very important in determining the output pulse properties for pulse energy larger than 1 pJ.

Strong picosecond optical pulse propagation in semiconductor optical amplifiers at transparency

Single-stripe GaAs/AlGaAs semiconductor optical amplifiers which simultaneously generates from four to more than twenty tunable WDM channels. A four channel version transmits approximately 12 picosecond pulses at approximately 2.5 GHz for an aggregate pulse rate of 100 GHz. Wavelength tuning over 18 nm has been demonstrated with channel spacing ranging from approximately 0.8 nm to approximately 2 nm. A second version uses approximately 20 wavelength channels, each transmitting approximately 12 picosecond pulses at a rate of approximately 600 MHz. A spectral correlation across the multiwavelength spectrum which can be for utilizing single stripe laser diodes as multiwavelength sources in WDM-TDM networks. A third version of multiple wavelength generation uses a fiber-array and grating. And a fourth version of wavelength generation uses a Fabry-Perot Spectral filter. Also solid state laser sources and optical fiber laser sources can be used.

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Multiwavelength modelocked semiconductor diode laser

We investigate nonlinear carrier dynamics in a multiquantum-well semiconductor optical amplifier (SOA) in the context of ultrafast all-optical logic. A rate-equation model is presented that accounts for two-photon absorption, free-carrier absorption, self- and cross phase modulation, carrier heating, spectral, spatial hole burning, and self- and cross polarization modulation. The nonlinear refractive index dynamics is investigated theoretically and experimentally. We find nonlinear phase changes larger than /spl pi/ radians, which recovers on a timescale in the order of 1 ps. We also investigate a nonlinear AND gate that consists of an SOA that is placed in an asymmetric Mach-Zehnder interferometer. We show that the gate can be operated using 800-fJ optical pulses with duration of 200 fs while having a contrast ratio larger than 11 dB.

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All-optical logic based on ultrafast gain and index dynamics in a semiconductor optical amplifier

We present experimental and theoretical results on ultrafast nonlinear dynamics in InGaAsP semiconductor optical amplifiers (SOAs). Carrier heating, spectral hole burning, and two-photon absorption are analyzed by heterodyne pump-probe experiments which deliver basic model parameters like gain-phase coupling parameters of the material. The impact on the device performance induced by these physical effects is verified by cross-gain/cross-phase experiments on InGaAsP-based SOAs and Mach-Zehnder interferometer switches. In the co-propagation arrangement, the switching window with maximum transmission is shown to be 1.5 ps which translates into demultiplexing capabilities beyond 600 Gb/s. Calculations based on a distributed rate equation model show that, for high-speed applications, the switching window can be limited by pulse saturation and by subpicosecond nonlinear effects.

All-optical switching at multi-100-Gb/s data rates with Mach-Zehnder interferometer switches

We present detailed derivation of our new model for femtosecond pulse amplification in semiconductor laser amplifiers. The various dynamic nonlinear terms of gain compression and associated self-phase modulation are derived semiphenomenologically, and are discussed physically. Included are the effects of carrier depletion, carrier heating and spectral hole-burning, as well as linear and two photon absorption and the instantaneous nonlinear index. Additionally, we account for dynamically changing gain curvature and slope. We apply the theory to strong signal cross-phase-cross-gain modulation experiments with /spl sim/500 fs pulses in a broad area GaAs amplifier and show that the model accurately describes the observed complex phenomena. We also present experimental results on single beam strong signal amplification in two different quantum-well amplifiers using 150-200 fs duration pulses. For such pulse lengths, carrier heating becomes an integrating nonlinearity and its self-phase modulation is similar to that due to carrier depletion. Additionally, since the pulse spectrum is broad, the gain slope and curvature shift and narrow it. The resultant spectral distortions are very different than observed (and modeled) earlier for the /spl sim/500 fs pulses. The model is again able to correctly describe the evolution of these ultrashort pulses, indicating that it remains valid, even though pulse durations approach the intraband relaxation time.

S. Dijaili

Papers

Femtosecond self- and cross-phase modulation in semiconductor laser amplifiers