Zone-addressable 20 × 20 940 nm VCSEL array with a 5-bit binary number pattern.

This article presents a monolithically zone-addressable 20 × 20 940 nm vertical-cavity surface-emitting laser (VCSEL) array with a binary number pattern design for sensing applications. The emitters in this VCSEL array have a uniquely designed binary pattern design, with each row representing a 5-bit pattern designed to aid pattern-matching algorithms to deduce the shape and depth information efficiently. Approximately 200 VCSELs are arranged in four individually addressable light-emitting zones, with ∼50 emitters in each zone. Each zone generates laser pulses up to 7.2 W in peak power.

High uniformity red µ-LED array with a current efficiency of 2.6 cd/A and ns-level response time.

This paper demonstrates an AlGaInP-based 620-nm red micro-light-emitting-diode (µ-LED) array and studies the enhancement effect of the surface treatments using (NH4)2Sx solutions by comparing the characteristics of µ-LED arrays with and without the (NH4)2Sx treatment. Furthermore, our µ-LED array demonstrates a measurement of the current efficiency (2.6 cd/A), which improves the light output uniformity. Also, we apply a setup for measuring the response time at the fast ns-level to analyze the effect of passivation in AlGaInP-based µ-LED arrays.

Achieving ns-level pulsed operation of up to 6.27 W with a 1.55-µm BH-DFB laser for LiDAR applications.

In this Letter, we present a highly efficient 1.55-µm buried heterostructure distributed feedback (BH-DFB) laser diode. The optimized epitaxial structure resulted in a threshold current of 12 mA and a differential slope efficiency of 0.433 W/A. The laser exhibited stable single longitudinal mode characteristics in both high current injection and broad temperature range testing. Additionally, the ns-level pulsed operation characteristics of the BH-DFB laser were verified, achieving a pulse peak power of 6.27 W with a pulse optical width of 20.4 ns. The watt-level pulse optical power was achieved with a single active region. With its eye-safe wavelength, high operating efficiency, stable single-mode spectral characteristics, and high pulse optical power, the 1.55-µm BH-DFB laser is a promising light source for LiDAR systems.

40.1-GHz sub-freezing 850-nm VCSEL: microwave extraction of cavity lifetimes and small-signal equivalent circuit modeling.

We present an 850-nm vertical-cavity surface-emitting laser (VCSEL) constructed for a wide operating temperature range from 25°C to -50°C sub-freezing temperature, demonstrating 40.1-GHz at -50°C. The optical spectra, junction temperature, and microwave equivalent circuit modeling of a sub-freezing 850-nm VCSEL between -50°C and 25°C are also discussed. Reduced optical losses, higher efficiencies, and shorter cavity lifetimes at sub-freezing temperatures are the leading causes of the improved laser output powers and bandwidths. The e-h recombination lifetime and the cavity photon lifetime are shortened to 113 and 4.1 ps, respectively. Could potentially supercharge VCSEL-based sub-freezing optical links for applications in frigid weather, quantum computing, sensing, aerospace, etc.

29 GHz single-mode vertical-cavity surface-emitting lasers passivated by atomic layer deposition.

The fabrication processes of high-speed oxide-confined single-mode (SM)-vertical-cavity surface-emitting lasers (VCSELs) are complex, costly, and often held back by reliability and yield issues, which substantially set back the high-volume processing and mass commercialization of SM-VCSELs in datacom or other applications. In this article, we report the effects of Al2O3 passivation films deposited by atomic layer deposition (ALD) on the mesa sidewalls of high-speed 850-nm SM-VCSELs. The ALD-deposited film alleviates the trapping of carriers by sidewall defects and is an effective way to improve the performance of SM-VCSELs. The ALD-passivated SM-VCSELs showed statistically significant static performance improvements and reached a believed to be record-breaking SM-modulation bandwidth of 29.1 GHz. We also propose an improved microwave small-signal equivalent circuit model for SM-VCSELs that accounts for the losses attributed to the mesa sidewalls. These findings demonstrate that ALD passivation can mitigate processing-induced surface damage, enhance the performance of SM-VCSELs, and enable mass production of high-quality SM-VCSELs for mid- to long-reach optical interconnects.

Performance Analyses of Photonic-Crystal Surface-Emitting Laser: Toward High-Speed Optical Communication.

This study conducts comprehensive performance analyses of a commercial photonic-crystal surface-emitting laser (PCSEL) via small-signal measurement and the bit-error-rate test. Meanwhile, the radio frequency characteristics of the PCSEL are unveiled for the first time. Compared to the vertical-cavity surface-emitting lasers, the PCSEL shows great potential for a broader optical bandwidth that is benefited from the high optical-confinement factor. A maximum bandwidth of around 2.32 GHz is experimentally observed when the PCSEL was biased at 340 mA. Moreover, a theoretical calculation was applied to shed light on the characteristics of the small-signal measurement, providing a deep insight into the corresponding intrinsic response model. The signal transmission capability of the PCSEL was investigated as well. The maximum bit rate and corresponding rise time transmitted at 500 Mbps are 1.2 Gbps and 186.16 ps, respectively. Thus, a high-speed PCSEL can be realised with a shrunk form factor, serving as a promising candidate for the next-generation light sources in high-speed optical communication.

Investigation of the current influence on near-field and far-field beam patterns for an oxide-confined vertical-cavity surface-emitting laser.

This experiment presents dynamic behaviors between the operating current and the optical beam images of vertical-cavity surface-emitting lasers (VCSELs) with two different aperture diameters of 3 µm (single-mode) and 5 µm (multi-mode). These VCSELs exhibit complex optical phenomena under current injection such as thermal effects, modal competition, carrier distribution, and laser coherence which make the light field distribution difficult to predict. In this report, the DC properties, optical spectrum, and optical images were measured together at different operating currents to accurately evaluate the characteristics of the lasers. Unlike previous works, the variations of the far-field angle were precisely evaluated by the side-mode-suppression ratio (SMSR) of the optical spectrum. In addition to commonly used transform functions such as the Gaussian beam formula, the SMSR provides another tool for the judgment of far-field divergence which could prevent inaccurate analysis. Moreover, the impact of thermal lensing was calculated by the DC measurement and demonstrated by the far-field measurement at high injection current. Through this experiment, the interaction between the injection carrier, thermal lens effect, and current spreading was described as fully as possible.