High-Efficiency 808-nm InGaAlAs–AlGaAs Double-Quantum-Well Semiconductor Lasers With Asymmetric Waveguide Structures

Evstropov

et al. 2019

Appl. Phys. Express

Temperature photovoltaic dependencies have been measured at 90–350 K for a single-junction GaAs-based p-i-n solar cell and for a similar solar cell with imbedded in i-region In0.4Ga0.6As quantum objects. A theoretical approach for analyzing temperature dependencies of open circuit voltage has been proposed. A dethermalization of quantum objects has been observed at temperatures below 170 K, and the temperature of full dethermalization is estimated to be 80 K. It has been shown that dethermalized quantum objects are not involved in the photovoltaic process and may cause photocurrent losses, while, when thermalized, quantum objects give a photocurrent increment. It has been found that the energy difference between optic transitions in GaAs and in quantum objects is independent on temperature. Analysis of the temperature dependencies has allowed for the estimation of effective band gap energy of quantum objects which, at room temperature, was found to be 1.2 eV.

mentioning

confidence: 99%

Dethermalization of carriers in GaAs solar cells with quantum objects

Evstropov

et al. 2019

Appl. Phys. Express

“…The parameters of this system are listed in Table II. Note that the combined pumping efficiency is comprised of a series of efficiency factors, including the quantum efficiency η Q = 95%, the Stocks factor η S = 76%, the overlap efficiency η B = 90%, the pump source efficiency η P = 75%, the pump source transfer efficiency η t = 99%, and the pump absorb efficiency η a = 91% [32,36]. Such parameter setting is under the assumption of multiple-transverse-mode operation.…”

Section: A Parameter Settingmentioning

confidence: 99%

Mobile Optical Communications Using Second Harmonic of Intra-Cavity Laser

Xiong,

Liu,

Wang

et al. 2021

Preprint

Optical wireless communication (OWC) meets the demands of the future six-generation mobile network (6G) as it operates at several hundreds of Terahertz and has the potential to enable data rate in the order of Tbps. However, most beam-steering OWC technologies require high-accuracy positioning and high-speed control. Resonant beam communication (RBCom), as one kind of nonpositioning OWC technologies, has been proposed for high-rate mobile communications. The mobility of RBCom relies on its self-alignment characteristic where no positioning is required. In a previous study, an external-cavity second-harmonic-generation (SHG) RBCom system has been proposed for eliminating the echo interference inside the resonator. However, its energy conversion efficiency and complexity are of concern. In this paper, we propose an intra-cavity SHG RBCom system to simplify the system design and improve the energy conversion efficiency. We elaborate the system structure and establish an analytical model. Numerical results show that the energy consumption of the proposed intra-cavity design is reduced to reach the same level of channel capacity at the receiver compared with the external-cavity one.

Springer Series in Optical Sciences

“…For these reasons, VCSEL conversion efficiency curves, as displayed below, show rollover at smaller ratiosÎ c /I th compared to, e.g., broad-area EELs for high-power applications. Figure 2.12 contains data points for a record EEL withη c = 75% and I c /I th ≈ 12 [59] and an optimized VCSEL withη c = 62% andÎ c /I th ≈ 7 [24,25]. Since there exists a tradeoff between increasing layer conductivity (leading to small R d ) and decreasing threshold gain (leading to small I th ) while maintaining high differential efficiencies, it becomes clear that obtaining peak conversion efficiencies above 70% is one of the most challenging topics in VCSEL research.…”

Section: Conversion Efficiencymentioning

confidence: 99%

VCSEL Fundamentals

Michalzik

2012

In this chapter we outline major principles of vertical-cavity surfaceemitting laser (VCSEL) design and operation. Basic device properties and generally applicable cavity design rules are introduced. Characteristic parameters like threshold gain and current, differential quantum efficiency and power conversion efficiency, as well as thermal resistance are discussed. We describe the design of Bragg reflectors and explain the transfer matrix method as a convenient tool to compute VCSEL resonator properties in a one-dimensional approximation. Experimental results illustrate the emission characteristics of high-efficiency VCSELs that apply selective oxidation for current and photon confinement. Both the 850 and 980 nm wavelength regions are considered. The basic treatment of laser dynamics and noise behavior is presented in terms of the small-signal modulation response as well as the relative intensity noise. Finally we give some examples of VCSEL applications in fiber-based optical interconnects, i.e., optical data transmission over short distances. IntroductionVCSELs have undergone an extraordinary evolution over the past three decades. Suggested by Prof. Kenichi Iga and first demonstrated by the research group at Tokyo Institute of Technology in the late 1970s [1-3], VCSELs are a commodity item today [4] and already serve millions of computer users as the key component in modern navigation devices such as the optical mouse. In even larger quantity, this laser type has entirely replaced edge-emitting laser diodes for use in multimode fiber-based Gbit/s speed optical data transmission in premises networks and for the interconnection of various kinds of computer clusters. Several books entirely devoted R. Michalzik (B)