Carrier dynamics of type-II InAsSb/GaAsSb W-quantum wells emitting in mid-infraredSmołka, Tristan; Rygała, Michał; Ryczko, Krzysztof; Bader, Andreas; Hartmann, Fabian; Petrovic, Borislav; Höfling, Sven; Motyka, Marcin
doi: 10.1117/12.3001654pmid: N/A
Interband cascade lasers (ICLs) are highly efficient semiconductor lasers operating in the mid-infrared range. Their cascade structure of multiple quantum wells enables continuous operation at room temperature with low threshold current. This study explores the impact of tensile and compressive strain on W-QWs' electronic structure and carrier dynamics. Using transient absorption measurements on specific material structures, researchers investigated carrier lifetimes and fundamental transitions. Photoreflectance and photoluminescence measurements were also employed to study band structure and optical properties. The findings provide insights into optimizing ICL performance, improving their performance in application for gas sensing, spectroscopy, medical diagnostics, and communication.
Direct optical wiring (DOW)-based optical interconnects for optical communications using LD and LED devicesKim, Chongcook; Kim, Taeyong; Kim, Jong Kyu
doi: 10.1117/12.3000575pmid: N/A
We have developed Direct Optical Wiring (DOW) technology and successfully implemented it in chip-to-chip optical links in the form of commercially available products. The chip-to-chip optical coupling efficiencies using the DOWbased optical links exceed 93% in both in-plane and out-of-plane optical system, where the in-plane optical link includes vertical-cavity surface-emitting lasers (VCSELs) and photodiodes (PDs); and the out-of-plane one directly connects an edge-emitting laser diode to a PD. Such outstanding optical coupling is attributed to the minimized optical reflection and/or scattering in the end-to-end optical link, resulting in an improved bit error rate (BER). LESSENGERS® 800G QSFP-DD SR8 and 400G QSFP112 SR4 optical transceiver modules featuring DOW technology demonstrate the BER of ~ 5 10-10 even at an elevated device temperature of 57C.
Segmented red, green, and blue light sources for energy efficient LCoS AR displaysYoung, Erik; Lopez, Toni; Monestir, Florent; Liu, Shih Chun; Loh, Cheng Hou; ., Saraswati; Shapiro, Noad; Mihopoulos, Ted; Pathak, Rajiv
doi: 10.1117/12.3001621pmid: N/A
We have investigated the use of segmented red, green, and blue LED emitters for use in LCoS projection systems. We find that segmenting the light emitting area has a minimal impact to the efficacy and wall plug efficiency of the die thus validating that these devices could help in significantly reducing the power consumption of LCoS systems by enabling local dimming strategies.
High-power multijunction VCSELs for LiDAR and related sensing applicationsGhods, Amirhossein; Johnson, Klein; Tatah, Karim; Stocker, Mary; Miglo, Alex
doi: 10.1117/12.3003210pmid: N/A
Increasing the number of active regions is an effective approach for scaling optical output power in vertical cavity surface emitting lasers (VCSELs). This, in addition to high power conversion efficiency, miniaturized packaging, addressability, fast pulse rise time, and minimal spectral shift with temperature, make multijunction VCSELs an attractive alternative to conventional edge-emitting lasers (EELs) for variety of automotive, industrial, and consumer markets. Especially, LiDAR applications using Time of Flight (ToF) mapping methods require power efficient VCSELs with high throughput and fast rise times for achieving high spatial resolution and longer detectable ranges. However, with greater available optical gain in multijunction VCSELs, comes a more complex cavity structure which includes multiple active regions, tunnel junctions, and optical confinement layers. These can interconnectedly affect the optical, spectral, and electrical characteristics of these devices. For example, wider far-field beam divergence angle for multijunction VCSELs than those of the single-junction structure has been observed, which could be due to structural design parameters, in addition to device processing variability. This can severely reduce the usable output power from these devices, which is typically defined to be enclosed within certain angular limits. In this paper, we will demonstrate the recent advances in the development of high power multijunction VCSELs with up to eight active junctions, lasing in the wavelength range of 850-940nm. Both continuous-wave and short pulse characteristics of these devices measured at room temperature and wider temperature range show their reliable performance and demonstrate their suitability for integration in variety of LiDAR and other high-power sensing applications.
Using MOCVD technology to meet key process requirements that enable micro LEDsMcKee, Mark; Mitrovic, Bojan; Armour, Eric; Montgomery, Jay
doi: 10.1117/12.3008901pmid: N/A
MicroLEDs are projected to have triple-digit growth over the next five years and will have significant benefits for new and existing display applications. MicroLEDs will see high demand in applications such as smartwatches, mobile devices, AR/VR, automotive and TVs. Critical in the manufacturing of these devices is MOCVD epitaxial growth technology. This technology must meet industry’s high-performance requirements, including extremely uniform wavelength, thickness and composition, dopant control and low defectivity while reducing costs via high productivity, high yields and lower operating expenses. These requirements must also be met over the whole wafer as well as across the transfer field. Veeco has developed the Lumina™ As/P MOCVD for Red MicroLEDs that meet and exceed industry’s roadmap on 8” substrates. Details of the technology and data will be discussed as part of this presentation.
Fabrication and characterization of quantum dot-based LEDs with enhanced emission properties by micro cavitiesLangenickel, Jörn; Rodríguez, Luis Paniagua; Martin, Jörg; Möbius, Martin; Michaelis, Dirk; Munzert, Peter; Weiß, Alexander; Danz, Norbert
doi: 10.1117/12.3002669pmid: N/A
This paper presents a novel approach to enhance the performance of Quantum dot (QD) based light-emitting diodes (LEDs) by incorporating Bragg resonator substrates. By depositing QD-LED layer stacks on tailored Bragg resonator substrates, the emission spectrum of red-emitting QD-LEDs is narrowed to less than 20 nm, and the emission pattern becomes more directional. Additionally, the modulation characteristics of QD-LEDs on Bragg-substrates are investigated. These findings demonstrate the potential to improve the usability of QD-LEDs in displays, lighting, and sensing applications.
Advancements in UV-C LED technology: improving external quantum and system efficiencyWilm, Alexander
doi: 10.1117/12.3002443pmid: N/A
The use of ultraviolet (UV-C) light for disinfection has been a well-established practice for many years. In recent years, the development of UV-C LED technology has provided a promising alternative to traditional low pressure mercury lamps. One of the most anticipated parameters of UV-C LED technology is the external quantum or wall plug efficiency. This paper reviews the recent progress and prospects of UV-C LED development, focusing on wall plug efficiency and lifetime at different wavelengths which are suitable for germicidal applications. The robustness of UV-C LED packages is also improving significantly and even tests according to the automotive AEC Q102 specification have been passed successfully. Beyond the pure LED parameters there are further factors and features that affect the system efficiency of UV-C LED based disinfection devices. Examples are demonstrating the big differences in system efficiency between conventional lamp and LED based systems. The big steps in development of UV-C LED during the last years justifies an optimistic outlook to target a replacement of conventional low pressure mercury lamps in the coming years.
Traffic signals and cooperative trajectories at urban intersections: leveraging visible light communication for implementationGalvão, G.; Vieira, M. A.; Vieira, M.; Vieira, P.; Louro, P.; Vestias, M.; Lourenço, P.
doi: 10.1117/12.3000529pmid: N/A
This study addresses the challenges and research gaps in traffic monitoring and control, as well as traffic simulation, by proposing an integrated approach that utilizes Visible Light Communication (VLC) to optimize traffic signals and vehicle trajectory at urban intersections. The feasibility of implementing Vehicle-to-Vehicle (V2V) VLC in adaptive traffic control systems is examined through experimental results. Environmental conditions and their impact on real-world implementation are discussed. The system utilizes modulated light to transmit information between connected vehicles (CVs) and infrastructure, such as street lamps and traffic signals. Cooperative CVs exchange position and speed information via V2V communication within the control zone, enabling flexibility and adaptation to different traffic movements during signal phases. A Reinforcement Learning, coupled with the Simulation of Urban Mobility (SUMO) agent-based simulator, is employed to find the best policies to control traffic lights. The simulation scenario was adapted from a real-world environment in Lisbon, and it considers the presence of roads that impact the traffic flow at two connected intersections. A deep reinforcement learning algorithm dynamically control traffic flows by minimizing bottlenecks during rush hour through V2V and Vehicle-to-Infrastructure (V2I) communications. Queue/request/response interactions are facilitated using VLC mechanisms and relative pose concepts. The system is integrated into an edge-cloud architecture, enabling daily analysis of collected information in upper layers for a fast and adaptive response to local traffic conditions. Comparative analysis reveals the benefits of the proposed approach in terms of throughput, delay, and vehicle stops, uncovering optimal patterns for signals and trajectory optimization. Separate training and test sets allow monitoring and evaluating our model.