arXiv subjects

Jukka Viheriala

Publications and source records attributed to Jukka Viheriala.

3 recordsLinked to original sources

arXiv2026

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

We report a time-domain optical coherence tomography (TD-OCT) system operating in the 2 $μ\mathrm{m}$ 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 $μ\mathrm{m}$. 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 $μ$m in air and enables depth-resolved imaging of scattering paint-based coating samples. In contrast to OCT implementations at 2 $μ\mathrm{m}$ 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 $μ\mathrm{m}$ 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 μm 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↗

arXiv2022

Widely tunable 2 $μ$m hybrid laser using GaSb semiconductor optical amplifiers and Si3N4 photonics integrated reflector

Tunable lasers emitting at a 2-3 $μ$m wavelength range and compatible with photonic integration platforms are of great interest for sensing applications. To this end, combining GaSb-based semiconductor gain chips with Si$_3$N$_4$ photonic integrated circuits offers an attractive platform. Herein, we exploit the low-loss features of Si$_3$N$_4$ waveguides and demonstrate a hybrid laser comprising a GaSb gain chip with an integrated tunable Si$_3$N$_4$ Vernier mirror. At room temperature, the laser exhibited a maximum output power of 15 mW and a tuning range of 80 nm (1937-2017 nm). The low-loss performance of several fundamental Si$_3$N$_4$ building blocks for photonic integrated circuits is also validated. More specifically, the single-mode waveguide exhibit transmission loss as low as 0.15 dB/cm, the 90$^\circ$ bend has 0.008 dB loss, and the 50/50 Y-branch has an insertion loss of 0.075 dB.

physics.optics↗