Kamil Pierscinski, Piotr Gutowski, Dorota Pierscinska, Katarzyna Pieniak, Agata Krzastek, Dominika Niewczas, Grzegorz Sobczak, Iwona Sankowska, Aleksandr Kuzmicz, Jan Muszalski, Maciej Bugajski
In this work optimization of technology of QCLs operating at λ~13 µm wavelength is presented. The devices were grown by Molecular Beam Epitaxy and combined MBE and MOVPE overgrowth. Room temperature operation of QCLs was achieved. The influence of the waveguide design in terms of thickness, growth conditions as well as doping has been studied. We have performed electro-optical and spectral characterization of LWIR QCL extracting crucial device parameters. The analysis of laser parameters is presented. Additional results of single mode operation are presented for devices in coupled cavity configuration.
Acknowledgements: This work was supported by Polish National Science Centre (NCN) grant: SONATA BIS: UMO-2021/42/E/ST7/00263
Compact, multi-spectral laser sources emitting in the mid-infrared (mid-IR) are in high demand for applications. Integration of several multi-spectral, mid IR quantum cascade lasers on silicon-based waveguide platforms is a necessary step towards realization of functional and complex mid-infrared photonic integrated circuits. This paper focuses on the thermal aspects of integration of multi-spectral QCLs toward the integration of QCL chips on silicon-based platform. The experimental results registered by means of CCD-thermo-reflectance are supported by numerical simulations of heat dissipation. The effects of thermal cross-talk between individual emitters are presented and discussed, leading to design guidelines for placement of laser chips in mid-infrared integrated photonics systems.
Improving the heat dissipation in Quantum Cascade Lasers (QCLs) is important from the point of view of a growing number of their applications, which require better performance. In this paper, we propose and experimentally demonstrate the possibility of a significant reduction of Active Region (AR) temperature without sophisticated and fabrication-intensive means. We have examined the influence of electroplated gold thickness on thermal and electro-optical properties of InP-based QCLs. Numerical modeling, that we have performed, predicts a significant reduction of the laser core temperature of epi-side up mounted ridge waveguide QCLs with increased thickness of electroplated gold. Predictions of the numerical model have been confirmed experimentally by means of electro-optical, spectral, and thermal characterization.
Single mode emission is one of the crucial requirements for Quantum Cascade Lasers (QCLs), which are compact laser sources of infrared radiation in the mid-IR range (3–20 micrometers) and in the THz range (1–5 THz). This feature is particularly important in all spectroscopic applications such as industrial process monitoring, remote sensing, breath analysis for medical diagnostic or industrial process monitoring.
In this paper, we have proposed a modified approach to coupled cavity QCLs, based on multisection (three section) coupled cavity QCLs. The range of spectral tuning is very important from the point of view of applications in optical sensing techniques based on the intrapulse tuning of the laser emission.
We have designed and fabricated 3-section CC QCLs characterized by intrapulse wavelength tuning of 2.8 cm-1, obtained for 2 mirosecond pulse width. The device operates above room temperature. The improvement of the spectral tuning of 3-section device is compared to 2-section laser. The third section improved significantly the performance of the laser in terms of single mode intrapulse wavelength tuning.
We demonstrate the operation of two optically pumped high-power membrane external-cavity surface-emitting lasers (MECSELs) that emit in 1600–1800 nm spectral region. The region of the MECSEL consisted of eight strained InGaAs quantum wells (QWs) that are enclosed by InGaAlAs barriers. The heterostructures were deposited on InP substrates by molecular beam epitaxy. In order to efficiently dissipate heat, the developed MECSEL technology requires etching-off the epitaxial substrate and bonding two diamond heat spreaders on both sides of membrane. Maximum output powers of 1.6 W at 1640 nm and 2.1 W at 1760 nm were achieved. The mount temperatures were -6°C in both cases. The introduction of a birefringent filter into the resonator of the 1760 nm emitting laser produced a 133-nm wavelength tuning range, from 1695 nm to 1828 nm.
The paper focuses on the design, fabrication and characterization of monolithic, coupled cavity two-section quantum cascade lasers. The devices were fabricated by reactive ion etching from InP-based heterostructure designed for emission in 9.x micrometer range. To make the device attractive for sensing applications, the idea of the coupled-cavity device was employed, giving the possibility of single longitudinal mode operation. We have previously presented devices fabricated by means of focused ion beam post-processing. However, FIB etching is challenging and time-consuming. In order to overcome the relatively low throughput of the FIB process, in this work, gaps separating sections were defined by dry etching during the fabrication process. Careful optimization of the dry etching process resulted in very good control of gap geometry. Quality of mirrors formed by RIE did not introduce high scattering loss into the cavity, as the threshold current density was not increased significantly. Devices routinely exhibited side mode suppression ratio of more than 20 dB. Approach to fabricate two-section devices by dry etching resulted in improved yield as well as high repeatability of the performance of individual devices.
Monolithic, electrically isolated, two-section devices were also fabricated and characterized. We will present a comparison of the performance of different designs and discuss their characteristics, fabrication challenges and stability against operating conditions.
We report recent results of works on quantum cascade lasers at the Institute of Electron Technology. During that time we have developed technology of lasers emitting at wavelengths 9.0–9.5 μm and 4.7 μm, based on InGaAs/AlGaAs/GaAs and InAlAs/InGaAs/InP heterostructures; both lattice matched and strain compensated. The structures were grown by molecular beam epitaxy MBE and by metalorganic vapor phase epitaxy MOVPE. The InGaAs/AlGaAs/GaAs lasers were grown by MBE. For InP based lasers three types of structures were investigated; the one grown exclusively by MBE without MOVPE overgrowth, the second fabricated by hybrid approach combining MBE grown AlInAs/InGaAs active region with MOVPE grown InP top waveguide layer and the third one with both the top and the bottom InP waveguide grown by MOVPE. Regardless of the waveguide construction, the active region was grown by MBE in every case. The lasers were fabricated in double trench geometry using standard processing technology. The buried heterostructure lasers were also investigated.
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