Monte Carlo markovian models of a dual-mode semiconductor laser with quantum well (QW) or quantum dot
(QD) active regions are proposed. Accounting for carriers and photons as particles that may exchange energy in
the course of time allows an ab initio description of laser dynamics such as the mode competition and intrinsic
laser noise. We used these models to evaluate the stability of the dual-mode regime when laser characteristics
are varied: mode gains and losses, non-radiative recombination rates, intraband relaxation time, capture time in
QD, transfer of excitation between QD via the wetting layer. . . As a major result, a possible steady-sate dualmode
regime is predicted for specially designed QD semiconductor lasers thereby acting as a CW microwave or
terahertz-beating source whereas it does not occur for QW lasers.
We present the design and the fabrication of a dual-wavelength micro-photonic resonator combining a photonic crystal
membrane (PCM) and a vertical Fabry Perot (FP) cavity where the former is embedded in the latter. A strong optical
coupling between a PCM Γ-point Bloch mode and a FP mode at the same frequency can be used to provide a dual-wavelength
device with a frequency difference which is analysed in terms of modes overlapping. We propose and
demonstrate a process flow that can be used to provide such a device. Optical reflectivity characterisation is presented
for a monolithic device and photoluminescence dual-wavelength spontaneous emission is demonstrated in an extended
vertical cavity. Finally the dual-mode laser emission stability is examined with numerical Monte Carlo simulation.
Two-dimensional (2D) plasma waves in field effect transistors are well known since the pioneer work of Dyakonov
and Shur. The application to terahertz (THz) detection was proven recently both at cryogenic and room temperatures.
Aside from these experiments, we used the interband photoexcitation brought by the difference-frequency
component of a photomixed laser beam to excite very efficiently plasma waves in HEMT channel at room temperature.
Owing to a specific experimental setup avoiding unwanted high-frequency electrical oscillations of the
HEMTs, we obtained the spectral profiles of THz 2D plasma waves resonances of InGaAs HEMTs for many
experimental conditions. The effect of geometrical HEMTs parameters (lengths of the gate and surrounding
regions) as well as biasing conditions (drain and gate voltages) was evaluated on both plasma oscillations frequencies
and amplitudes. Simultaneously, a numerical approach, based on hydrodynamic equations coupled to a
pseudo-2D Poisson solver, was developed that compares well with experiments. Using this unique combination
of experiments and numerical simulations, a comprehensive spectroscopy of plasma waves in HEMTs is thus
obtained. It provides a deeper insight into the physical processes involved in plasma wave excitation and allows
predicting for mixer operation at THz frequency only using the plasma wave nonlinearity. Mixing experiments
are under progress.
The stable two-mode operation of a 4-sections semiconductor laser emitting at 1.55 μm is experimentally demonstrated and analysed. An interpretation of the two-mode regime involving a saturable absorber is theoretically developed and the characteristic parameters of this saturable absorber deduced. This work exhibits the possibility of terahertz wave generation by photomixing using this device.
The stable two-mode operation of a 4-sections semiconductor laser emitting at 1.55 μm is demonstrated and analysed. The two-mode operation only depends on the current feed in the Bragg section. The characterization of the two-mode laser operation exhibits the possibility of terahertz wave generation by photomixing using this device. An interpretation of the two-mode regime involving a saturable absorber is discussed.
Using a grating coupler technique, we report on accurate determinations of bulk and mode refractive indexes in the 1.5 micrometers wavelength region. On the one hand, InP bulk refractive index is measured within a relative accuracy of 10<SUP>-3</SUP> as a function of wavelength range, temperature, and for two doping levels. On the other hand, quantum effects are evidenced on index measurements using a GaInAs multiquantum well waveguide. As a result, it is shown that the guided mode birefringence is strongly enhanced as predicted from energy levels and selection rules of fundamental electronic transitions.