Dejan M. Gvozdić

Injection Power and Detuning-Dependent Bistability in Fabry–Perot Laser Diodes

In this paper, we investigate the range of injection power and frequency detuning for which bistability of the injection-locked semiconductor Fabry-Perot laser diode can be achieved and preserved. The analysis is based on a detailed model of the multimode rate equations and material gain. The stationary analysis shows that there is a region of the injection power and detuning for which the laser has three stationary states. However, the stability analysis shows that for a wide range of injection powers and detuning, the two of three stationary states are stable and provide bistability. One of these states is the result of injection locking, whereas the other is mainly a consequence of the interplay between injection-locked and unlocked modes. The difference of the side-mode-suppression ratio between the stable states is of the order of 20 dB and it can increase with detuning and decrease with mode order.

Superefficient electric-field–induced spin-orbit splitting in strained p-type quantum wells

We investigate theoretically the efficiency of the Rashba effect, i.e. the spin-orbit splitting resulting from an electric field. In contrast to previous studies, where the carriers have usually been taken to be electrons, we focus on holes and are able to demonstrate remarkable improvements of the effect by several orders of magnitude. We also show that the frequently-neglected lattice-mismatch between GaAs and AlGaAs can be used to further enhance the efficiency of the wave vector splitting mechanism. The Rashba effect is the fundamental mechanism behind the Datta-Das spin transistor and we find that for a small electric field of 2 kV/cm the spin precession length becomes only 36 nm.

The influence of nonstationary carrier transport on the bandwidth of p-i-n photodiode

The influence of nonstationary carrier transport on the bandwidth and the bandwidth quantum efficiency product of p-i-n photodiodes is analyzed using the complete phenomenological model for two-valley semiconductors. The analysis has been made for various submicron and micron dimensions, for different bias voltages and for several energies of incident pulse excitation, including the variation of the active area of the p-in photodiode. The analysis shows that, as the thickness of the absorption layer varies, the bandwidth could have more than one maximum, especially for smaller bias voltages. The optimal thickness of the absorption layer versus bias voltage and device area is determined, providing maximal bandwidth and maximal bandwidth-quantum efficiency product.

Gain and threshold-current calculation of V-groove quantum-wire InGaAs-InP laser

This paper presents material-gain and threshold-current calculation of a InGaAs-InP quantum-wire laser in the framework of the k/sub /spl middot//p method, with included conduction-band nonparabolicity for the first time. The method for band-structure calculation is based on conformal mapping and Fourier expansion. The calculation shows that high material gain (7000 cm/sup -1/) can be achieved at room temperature for polarization along the free axis of the quantum wire. We propose an optimized laser structure, based on a stack of quantum wires.

Efficient switching of Rashba spin splitting in wide modulation-doped quantum wells

The authors demonstrate that the size of the electric-field-induced Rashba spin splitting in an 80 nm wide modulation-doped InGaSb quantum well can depend strongly on the spatial variation of the e ...

Electronic states in the conduction band of V-groove quantum wires

The article proposes a method to calculate eigenstates and eigenfunctions of the conduction band in V-groove quantum wires, which is based on conformal mapping and Fourier expansion. Consequently, the method relies essentially on an analytical calculation with input data as measured with V-groove quantum wires. The method allows one to take into account the hermiticity of the Schrodinger equation as well as the nonparabolicity of the effective mass. We analyze the influence of both effects on the calculated results, showing that an error of up to 30% is incurred if both effects are neglected.

A Self-Consistent Numerical Method for Calculation of Steady-State Characteristics of Traveling-Wave and Reflective SOAs

This paper presents a detailed numerical model of reflective and traveling-wave semiconductor optical amplifiers (SOAs), based on a self-consistent iteration method. The method is fully transparent to the input parameters and provides stable and efficient convergence of all relevant SOA variables as long as the sufficient number of previous iterations is taken into account. The model accounts for the detailed spectral and carrier density dependence of the radiative recombination rate, material gain, refractive index, and confinement factor. The analysis of unstrained bulk and strained multi-quantum well polarization insensitive SOAs based on this model provides a deep and detailed insight into the device internal state, confirming that spectral and carrier density material dependencies critically influence the modeling results.

Nonlinear pulse response of p-i-n photodiode caused by the change of the bias voltage

An analytical expression is derived for nonlinear response of a p-i-n photodiode, commonly used in optical communications. Nonlinearity is caused only by the change of bias voltage, in case of pulse light excitation. The response time increases slowly with increasing the incident pulse power as a result of this nonlinearity. It is assumed in calculations that the optical excitation is not so strong to cause space charge redistribution.

Multivalued Stability Map of an Injection-Locked Semiconductor Laser

We present a novel and detailed analysis of the locking range and the stability map for side-mode injection-locked in-plane semiconductor multimode lasers. By including the usually neglected unlocked modes in our model, we predict a multivalued locking range and stability map for this type of lasers. We also explain and relate, the previously noticed slave laser bistability phenomenon with the multivalued character of the locking range and stability map, and experimentally validate our findings. Moreover, we find that the unstable operating region, commonly found in literature by stability analysis of the injection-locked mode alone, is actually much smaller.

Switching time in optically bistable injection-locked semiconductor lasers

Switching between states in a dispersive bistable injection-locked slave laser has been theoretically investigated. We show that the switching can be achieved by relatively small and short (≈10-50 ps) variation of the master laser injection power or frequency, which, besides the variation of the slave laser optical power, leads to significant variation of its photon phase (≈5π/6). By using an analytical model, we calculate the switching time dependence on the magnitude of the injection power and the frequency detuning variation.