Characterization of GaAs/(GaAs)n(AlAs)m surface-emitting laser structures through reflectivity and high-resolution electron microscopy measurements

Abstract

Careful investigation of the reflectivity of two very high finesse integrated Fabry–Perot interferometers is reported. These two structures, made of GaAs active layer (1.7 μm thick) surrounded by two superlattice/AlAs Bragg reflectors, exhibit vertical cw lasing action at and above room temperature when photopumped with thresholds of 16 mW at 300 K and 56 mW at 380 K. Reflectivity measurements together with theoretical calculations show that layer regularity, accurate thickness control, and low interface roughness are key parameters for high-performance structures. Transmission electron microscopy on cleaved wedges and reflection electron microscopy are shown to be unique tools for measuring and characterizing these layers. Electron microscopy, optical reflection, and laser linewidth measurements are correlated and show that the layer flatness is dramatically increased by the introduction of six (2.5 Å) GaAs wells in the AlAs growth of the integrated dielectric reflectors. Reflectives of 97%, Fabry–Perot finesse as high as 100 (61 for direct measurements), and laser linewidths as small as 1.2 Å are reported.

A new approach based on transfer matrix formalism to characterize porous silicon layers by reflectometry

“…(1), means that all reflection and transmission coefficients (in complex amplitude) of the PS/substrate interface are reduced as exp(-S), whatever the direction of propagation of the incident wave. This approach is consistent with the approximation sometimes used for describing roughness effects in Molecular Beam Epitaxy [10,11]. The same treatment can be extended to the first air/PS interface.…”

Huge Enhancement of Magneto-Optical Faraday Effect in YIG Films with Disordered Multilayer Structures

“…This is indeed demonstrated in films with the structure of onedimensional photonic crystal (ID-PC) with a defect, or equivalently referred to as integrated Fabry-Perot resonator [4], in which strong localization of light occurs. In FigA, we show T and OF spectra of the film with ID-PC structure: the film structure is expresses by (Bi:YIG/SiO z )x8/Bi:YIG x2/(SiOz/Bi:YIG)x8 and is designed under the condition of n~M= n s d s =A!4 (A=1.15!lm) with refraction indices n M and ns of the Bi:YIG and SiO z layers, respectively.…”

Control of the average light transmission in one-dimensional photonic structures by tuning the random layer thickness distribution

“…It has been theoretically proposed [21] and experimentally demonstrated [22] that the average transmission of a photonic structure characterized by a random layer thickness is lower with respect to the one of a periodic photonic crystal. But in these two studies an analysis of the influence of the distribution of the random layer thicknesses on the optical properties of the disordered structures is missing.…”