M. Yu. Morozov

Pulsed difference frequency generation regime in dual-wavelength vertical-external-cavity surface-emitting laser

The parameters of middle-IR radiation (λ ∼ 17 μm) generated as a result of the intracavity nonlinear optical interaction in a semiconductor dual-wavelength vertical-external-cavity surface emitting laser operating in a pulsed regime have been numerically analyzed. The dependence of the peak output radiation power on the length of the nonlinear crystal has been studied for various values of the loss factor.

Effect of pump wave reflections on the excitation of a dual-wavelength vertical-cavity surface-emitting laser

The effect of pump wave reflections on the carrier generation rate and uniformity of carrier population in quantum wells (QWs) of a dual-wavelength vertical-cavity surface-emitting laser has been numerically analyzed. The laser’s active region has been described within a mathematical model allowing any number of QWs and arbitrary distribution of carrier generation rate. It is shown that the optimal arrangement of blocking layers in the active region of a dual-wavelength vertical-cavity surface-emitting laser allows one to obtain a very uniform QW population. It is established that pump wave reflections significantly affect the local carrier generation rate and, therefore, the distribution of excited carriers in the laser structure.

Features of dual-wavelength generation in a vertical-external-cavity surface-emitting laser

The steady-state stability of a dual-wavelength vertical-external-cavity surface-emitting laser has been analyzed. It is shown that, in the laser with independent active regions containing quantum wells (QWs) of different depths, this state is always stable. The increment of growth and the frequency of oscillations of small deviations from the steady state are determined in the presence of coupling between the active regions, which is caused by the absorption of short-wavelength radiation in deep QWs. In the region of violation of the steady-state stability, the generation proceeds in the form of short pulses, with the almost simultaneous excitation of the optical fields at both frequencies.

Negative terahertz conductivity of graphene when pumping by optical plasmons

The diffusion pumping of graphene by optical plasmons, propagating in metal, and separated from the graphene by a semiconductor layer has been investigated theoretically. It is shown that pumping of graphene with optical plasmons provides maximum negative terahertz conductivity of graphene at a lower (approximately by 25%) pumping power compared to a diffusion pumping of graphene with optical radiation.

Amplification of plasma waves in shielded active graphene

Amplification of plasma waves in shielded graphene with inverted energy distribution of charge carriers is investigated theoretically. It is shown that graphene shielding allows one to increase an amplification factor of terahertz plasmons in several times compared to the case of amplification of unshielded plasmons due to strong field confinement of the shielded plasmons near graphene.

Control of light polarization in a semiconductor dual-wavelength vertical external cavity surface-emitting laser

A method for controlling the polarization characteristics of the radiation of a dual-wavelength vertical external cavity surface-emitting laser (VECSEL) is proposed. It is shown that a retarder of a special kind used as a part of the laser cavity allows the excitation of laser radiation with components in nearly mutually transverse polarization planes.

Spatio-temporal carrier dynamics of a dualwavelength vertical external cavity surface-emitting laser

The mathematical model of a dual-wavelength emission from a vertical external cavity surface-emitting laser taking into account the transverse distribution both of optical fields and pump carrier flux density is built. Spatio-temporal dynamics of charge carriers and photons is analyzed. It is shown that the most pronounced optical hole-burning can be observed near the optical axis of the laser.

Mid-infrared pulsed radiation in a dual-wavelength vertical external cavity surface-emitting laser

Parameters of mid-infrared pulsed radiation (∼17.1 µm) being emitted due to intracavity nonlinear optical frequency conversion in the dual-wavelength vertical external-cavity surface-emitting laser are analyzed. Nonlinear optical frequency conversion is supposed to be realized in the quasi-phase-matched crystal. The dependence of peak pulse power at the wavelength corresponding to the mid-infrared range on the nonlinear crystal length at various values of a loss factor is obtained.

Dynamic regimes of a dual-wavelength vertical external cavity surface-emitting laser

The map of dynamic regimes of a dual-wavelength vertical external cavity surface-emitting laser is built. The areas of continuous wave operation as well as of time-periodic, quasi-periodic and chaotic operation can be marked out in the map. A possible explanation of quite different laser behavior in those area is given.

Optical excitation of nonidentical quantum wells in the active region of a vertical-external-cavity laser

Optical excitation of a semiconductor structure comprising two nonidentical quantum wells (QWs) separated by barriers absorbing the pump radiation has been numerically simulated. It is shown that the equalization of populations in the QWs can be achieved in two ways: (i) shift of the deeper QW to a region of weak carrier generation and (ii) introduction of a blocking layer preventing the transport of carriers.