GaAs/AlGaAs photonic crystals for VCSEL-type semiconductor lasers

The results of modelling of the influence of photonic crystal on the performance of VCSEL-type semiconductor laser structure are shown and indicate that the use of those structures would significantly improve the working parameters of the devices. The method of fabrication of photonic crystals in the Bragg mirrors of GaAs/AlGaAs-based VCSELs is presented.     

How exact are simplified scalar approaches to optical fields in oxide-confined stripe-geometry diode lasers?

Optical model, scalar or vectorial one, describing behaviour of an optical field within a diode-laser cavity, is one of the most important parts of modelling of a diode-laser operation. As compared to more accurate vectorial optical approaches, scalar ones are known to be less exact but simultaneously they need much less computation time. Besides, they have been sometimes found to be surprisingly exact even beyond their confirmed range of validity. Therefore, in this paper, real validity limits of their application have been determined by comparing their simplified results with more exact results obtained with the aid of vectorial models. The analysis comprises a comparison of an application of the most popular scalar approach to optical properties of diode lasers, i.e., the effective index method, and the vectorial method of lines for the standard 1.3-μm GaAs-based stripe-geometry diode laser. The scalar model has been found to be quite exact in the case of a determination of the effective refractive index, i.e., the wavelength of emitted radiation, whereas its exactness in the lasing threshold analysis is much worse, especially in the case of higher-order modes. Our analysis is concluded with a determination of the regions where both models give satisfactorily close results.     

Modal behavior of photonic-crystal vertical-cavity surface-emitting diode laser analyzed with Plane Wave Admittance Method

A three-dimensional, full vectorial model has been applied for investigation the modal characteristics of a phosphide photonic-crystal vertical-cavity surface-emitting diode laser. The photonic crystal has been defined as a regular, hexagonal net of holes, etched in the upper, p-type Distributed Bragg Reflector of the laser. The electromagnetic field has been confined to the active region by a single defect of the photonic crystal providing overlapping with carriers funneled by a tunnel junction. We have determined the range of design parameters, which provide single mode operation.     

Thermal properties and wavelength analysis of telecom oriented photonic-crystal VCSELs

Results of the self-consistent comprehensive analysis of a room-temperature operation of InP-based 1300-nm AlInGaAs photonic-crystal (PhC) VCSELs are presented. In particular, an influence of PhC parameters on thermal effects within VCSEL volume and its emission wavelength are analysed. The PhC has been found to introduce a number of opposite effects including a possible light leakage through PhC holes. From one side, PhC holes make more difficult heat-flux extraction from VCSEL volume leading to higher temperature increases within it. But, from the other side, a properly manufactured PhC creates an efficient radial confinement mechanism for VCSEL radiation field. It enhances an interaction between the field and the active-region carriers leading to a decrease in both the VCSEL lasing threshold and temperature increases. Seemingly both effects may similarly affect VCSEL operation, but our analysis revealed, that thermal properties of the PhC VCSEL are mainly dependent on an efficient confinement of its radiation field within the active region impeding a mode leakage through PhC holes, whereas an importance of deterioration of heat-flux extraction from VCSEL volume is much less essential. The wavelength shift induced by a change of PhC parameters has been found not to exceed 4×10⁻³ μm.     

Validity of Scalar Approaches to Radiation Modes of the GaAs-Based 1.3-μm Diode Lasers Designed for the Optical–Fibre Communication

The work presents a comparison between results of optical simulations based on the scalar and vectorial models applied to both stripe – geometry Fabry-Perot (FPL) as well as vertical-cavity surface-emitting (VCSEL) diode lasers designed for the 1.3-μm optical–fibre communication. As compared to vectorial optical approaches, scalar ones are known to be less exact but simultaneously they need as many as approximately 100 times shorter computation time, which favours those models in many applications. Therefore, vectorial models should be applied only in cases of confirmed faulty performance of scalar ones. While the Effective Index Method and the Effective Frequency Method have been chosen as scalar approaches to FPLs and VCSELs, respectively, simulations, the Method of Lines has been used in both cases as a vectorial one. Scalar models have been found to be quite exact in the case of a determination of the effective refractive index and wavelength of emitted radiation, whereas their exactness in the lasing threshold analysis is much worse, especially in the case of higher-order modes. Our analysis is concluded with the determination of the regions where both models give satisfactorily close results.     

Threshold characteristics of bottom-emitting long wavelength VCSELs with photonic-crystal within the top mirror

We present self-consistent modeling of InP-based 1300-nm AlInGaAs photonic-crystal vertical-cavity surface-emitting diode laser. We investigate the influence of photonic-crystal parameters on threshold characteristics. We show that a shallow photonic crystal can significantly deteriorate the VCSEL threshold current. The significant reduction of threshold current can be assured by the photonic-crystal etched through the whole top DBR mirror.     

Numerical analysis of high Q-factor photonic-crystal VCSELs with plane-wave admittance method

The paper presents the application of a novel plane-wave admittance method (PWAM) to the three-dimensional and fully vectorial modeling of vertical-cavity surface-emitting lasers with incorporated photonic crystal. The basic mathematical details of the method are given and its convergence is verified for a sample structure. Then the simulations performed with PWAM are used to determine the optimal photonic crystal parameters for low-loss, high-Q-factor regime.     

Highly birefringent and dichroic photonic crystal VCSEL design

We analyse the possibility to stabilise the polarisation of light emitted by photonic crystal vertical-cavity surface-emitting lasers (PC-VCSELs). We consider two different photonic crystal configurations in a GaAs/AlGaAs VCSEL: with elliptical holes and with selectively enlarged holes and a small central hole. Very large birefringence (∼400 GHz) and dichroism (∼7%) are demonstrated for the second PC-VCSEL design.     

Threshold simulation of 1.3-μm oxide-confined in-plane quantum-dot (InGa)As/GaAs lasers

In the paper, the self-consistent optical–electrical–thermal-gain model of the oxide-confined long-wavelength 1.3-m quantum-dot (InGa)As/GaAs diode laser is demonstrated. The model has been applied to analyse room-temperature (RT) threshold-operation characteristics of the advanced laser of this kind. It may be used to describe physics of the above arsenide-based diode lasers to better understand their threshold performance and finally to optimize their structures.