arXiv subjects

Markus Peil

Publications and source records attributed to Markus Peil.

6 recordsLinked to original sources

arXiv2026

Temperature Dependence of the Refractive Index for AlAsGaSb

Accurate design and optimization of photonic multilayer structures like distributed Bragg reflectors (DBRs) require precise knowledge of material optical constants, particularly the temperature dependence of the refractive index. While these parameters are well established for widely used semiconductors, for emerging materials such as antimonides they are often limited to room-temperature data, especially for new spectral ranges of interest. Antimonide compounds, in particular GaSb-based alloys, are promising for quantum photonics applications. In this work, we investigated DBRs lattice-matched to GaSb and designed for operation in the third telecommunication window. Reflectivity spectra were measured in the temperature range from 11.5 K to 300 K, and then fitted using the transfer matrix method (TMM), combined with a dedicated recursive numerical fitting algorithm. Initial parameters included layer thicknesses determined by scanning electron microscopy (SEM) and literature values of refractive indices at room temperature. This approach enabled extraction of the temperature-dependent refractive indices of two AlGaAsSb alloys suitable for forming DBR mirrors for 1.5 um wavelengths. The obtained results provide essential input for reliable DBR design, ensuring proper stopband positioning and high reflectivity under cryogenic operating conditions required for efficient quantum emitter performance.

cond-mat.other↗

arXiv2026

Predictive wavelength tailoring of uniform GaSb-based quantum dots for emission at 1.55 um

A detailed study of emission wavelength tailoring of GaSb-based QDs formed by InGaSb-filling of droplet-etched nanoholes in AlGaSb is presented. The study shows that the emission wavelength can be modified from 1.48 um to the center of the telecom C-band at 1.55 mm by independently varying the QD composition and size. More specifically, the optical transition energy shifts linearly as a function of In-content of the QD material at a rate of -4.4 meV/In-percentage, and with the number of monolayers (ML) of material used for filling the nanoholes, at -2.0 meV/ML. These experimentally observed energy shifts are well predicted by simulations yielding rates of -4.3 meV/In-percentage and -2.1 meV/ML, respectively. For the simulation, a uniform In composition, low intermixing, and microscopically measured QD geometry is considered. Additionally, excellent ensemble QD uniformity, with unprecedented inhomogeneous broadening well-below 7 meV across all samples is demonstrated. Finally, photoluminescence of single-QDs reveals narrow excitonic emission lines of 13.8+/-6.7 ueV and low fine-structure splitting values reaching <10 ueV. These results identify GaSb-based LDE QDs as a tunable telecom platform for scaling quantum-photonic applications over long-haul optical fiber networks.

cond-mat.mes-hall↗

arXiv2026

Time-domain optical coherence tomography at 2 $\mu\mathrm{m}$ using GaSb-based broadband superluminescent diode

We report a time-domain optical coherence tomography (TD-OCT) system operating in the 2 $\mu\mathrm{m}$ spectral region, enabled by a GaSb-based superluminescent diode (SLD). The spectrum emitted by the SLD exhibits a full-width half-maximum (FWHM) of $\sim$80 nm centred near 2.1 $\mu\mathrm{m}$. For OCT operation, stable amplified spontaneous emission with low spectral ripple ($<20\%$) is maintained at drive currents below 150 mA. The SLD is fiber coupled and integrated into a fiber-based Michelson interferometer. In the OCT system, the measured coherence envelope yields an axial resolution of approximately 300 $\mu$m in air and enables depth-resolved imaging of scattering paint-based coating samples. In contrast to OCT implementations at 2 $\mu\mathrm{m}$ wavelength region that commonly rely on supercontinuum sources, the use of GaSb-based SLDs offers a compact practical alternative, leveraging the maturity and scalability of electrically driven semiconductor light sources packaged in a standard "butterfly" module. This report represents the first demonstration of TD-OCT imaging at 2 $\mu\mathrm{m}$ using a GaSb-based SLD source and establishes its suitability for compact and scalable mid-IR OCT instrumentation targeting non-biological, low-water-content materials.

physics.optics↗

arXiv2025

Design of broadband optical gain in GaSb-based waveguide amplifiers with asymmetric quantum wells

A design strategy for achieving broadband optical gain in GaSb-based semiconductor amplifiers operating beyond 2 \mu m is presented. By employing asymmetric GaInSb/AlGaAsSb quantum wells (QWs) of varying thicknesses, a flat and wide gain spectrum is demonstrated. The approach leverages carrier density and transition energy tuning across QWs to access various energy levels at specific current densities. Simulations using "Harold" self-consistent environment predict a full-width at half-maximum (FWHM) gain bandwidth exceeding 340 nm for a structure comprising one 7 nm and three 13 nm-thick QWs. The modelling parameters were validated against experimental data, ensuring a robust framework for designing broadband amplifiers and superluminescent diodes for mid-infrared applications.

physics.optics↗

arXiv2025

Fast Recovery Dynamics of GaSbBi-based SESAMs for high-fluence operation

Modelocked lasers operating at 2-3 um wavelength region are interesting for various spectroscopic applications. To this end, GaSb-based semiconductor saturable absorber mirrors (SESAMs) are developing fast as a practical technology for passive modelocking. Yet, such SESAMs suffer from either too high two-photon absorption or slow absorption recovery dynamics. This study introduces GaSbBi quantum wells (QWs) as a novel platform to ensure a larger material selection for engineering GaSb-based SESAMs with decreased two-photon absorption and ultrafast absorption recovery time. Three GaSbBi QW SESAM designs were fabricated to compare their performance against conventional GaInSb QW SESAMs. The first structure makes use of typical GaSb barriers and exhibits comparable characteristics to the conventional design, including a saturation fluence of 1.09 uJ/cm^2, modulation depth of 1.41%, and a fast interband recovery time of 6.03 ps. The second design incorporated AlAs0.08Sb0.92 barriers, achieving reduced two-photon absorption, though at the cost of higher non-saturable losses due to unintended Bi droplet formation during growth of the AlAs0.08Sb0.92/GaSbBi QW heterostructure. Importantly, it maintained a fast interband recovery time (30 ps), overcoming the slow recovery dynamics exhibited by standard GaInSb QW SESAMs with AlAs0.08Sb0.92 barriers. The third design explored GaSbBi QWs with higher Bi content targeted for longer wavelength operation at 2.3 um, which exhibited fast recovery times and good nonlinear reflectivity characteristics. However, the higher Bi content resulted in elevated non-saturable losses. These results highlight the potential of GaSbBi QWs for SWIR SESAMs, opening the path for further epitaxial optimization to enhance their performance.

physics.optics↗

arXiv2024

Telecom wavelength single-photon emission from quasi-resonantly excited InGaSb/AlGaSb quantum dots

Deterministic light sources capable of generating quantum states on-demand at wavelengths compatible with fiber optics and atmospheric transmission windows are essential for practical applications in quantum communication, distributed photonic quantum computing, and quantum metrology. Currently, the technology providing semiconductor quantum emitters with the most promising properties is based on filling droplet-etched nanoholes to form quantum dots (QDs). However, the standard GaAs/AlGaAs material system does not offer telecom window emission. Here, we combine this growth method with antimonide-based materials to demonstrate single-photon emission at 1500 nm from a droplet-etched InGaSb QD. Our device with an antimony-based high refractive index contrast back-reflector designed for cryogenic operation and a solid immersion lens improves photon extraction. QD states are protected by a potential barrier limiting the influx of surrounding carriers, which however prevents revealing excitonic fine structure under nonresonant excitation. In this work, we employ a frequency-tunable continuous wave laser to achieve longitudinal optical (LO) phonon-assisted excitation of the QD ground state and resonant excitation of an excited state. These direct approaches for exciting a single InGaSb QD unlock access to its excitonic fine structure. The typical neutral biexciton-exciton cascade exhibits a negative binding energy of 1.4 meV (2.6 nm) and a fine structure splitting of 24.1+/-0.4 ueV. Furthermore, we obtain spectrally isolated emission from a charged exciton with a multi-photon probability of 5 % with LO phonon-assisted two-color excitation. These results represent a major step towards using this novel antimonide-based QD emitters as deterministic quantum light sources in complex quantum secure networks exploiting the wavelength compatibility with standard telecom fibers.

cond-mat.mes-hall↗