A 4.26-μm RCLED and a fast low-power CO 2 sensor

Resonant cavity light-emitting diodes (RCLEDs) which composed of active region surrounded by two distributed Bragg reflector (DBR) mirrors have been reported in the communication system based on Plastic Optical Fiber (POF) and high brightness application. However, high performance of 650nm AlGaInP RCLED, which is strongly depends on the optimization of DBRs, especially the matched reflectivity between p-type and n-type DBR mirrors, is still difficult to obtain. In this paper, the performance of 650nm RCLEDs including 34-pair AlGaAs/AlAs n-type DBRs and different pairs of AlGaInP/AlInP p-type DBRs have been investigated both theoretically and experimentally. Top emitting chips with the size of 225×225μm 2 without encapsulation were fabricated under the same conditions, experimental results reveal that the device of optimized DBR mirrors with 10-pair p-type DBRs obtain high efficiency, low turn-on voltage and forward resistance, good temperature stability. INTRODUCTIONTraditional red LEDs suffered from poor extraction efficiency which is limited to 2 -4% by Snell's law. To solve this problem, different approaches have been developed, which can be separated into two categories. One is to optimize the device's geometry by texturing the surface of the chip, undercutting the sidewalls or changing the structures of geometries [1][2][3][4][5] , but these optimum structures may need complex processes or auxiliary structures; The other is concentrating on forcing the internal emission redirect into the escape cones and enhancing them, resulting in a modification of the spontaneous emission process, such that the internal emission is no longer isotropic, it results in improved extraction efficiency. This leads to the concept of the RCLED [6,7] , which is composed of a light-emitting active layer sandwiched between two mirrors forming a Fabry-Pérot (F-P) resonator.Resonant-cavity light-emitting diode (RCLED) is a novel light-emitting diode with high extraction efficiency. Since Schubert et.al [7] presented the first RCLED in 1992, the development of RCLED has been continuously increased in many applications, especially in the short-haul data communication system based on POF. The external quantum efficiency has been improved by optimizing the structure of RCLED, which can be up to 27% [8,9] , and the best simulated extraction efficiency has been reported over 40% [10] , by diminishing the loss of power in the unextractable modes.

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“…According to the principle of Fermi's Golden Rule (F-G), at the resonance wavelength, the emission enhancement factor e G is given by [6,14] :…”

Section: Theoreticl Analysis and Simulationmentioning

confidence: 99%

Performance of 650 nm AlGaInP RCLEDs with different P-type DBRs

Tang

Chen

et al. 2009

SPIE Proceedings

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“…These requirements are difficult to meet with the most prominent/conventional industrial solution for CO 2 detection: NDIR spectrometry (Non-dispersive infrared spectrometry). It uses a broadband lightsource (glow lamp, LED) a filter and a detector to detect the light attenuation due to the fundamental CO 2 absorption band at 4.3 µm wavelength [1,2]. Also electro-chemical sensors [3] and experimental chemical sensing techniques for CO 2 exist.…”

Section: Introductionmentioning

confidence: 99%