Geometrical properties of random particles and the extraction of photons from electroluminescent diodes

Abstract

A confined random-particle flux (such as photons in an electroluminescent diode, integrating sphere, or room, music or other phonons in an auditorium. gas molecules in an imperfect vacuum chamber, neutrons in a reactor, etc.) is analyzed, and simple expressions are shown to exist for the mean path length. transit time, surface transmissivity, projected area, absorption rate, etc.. that arise in its description. The results are applied to a theoretical and experimental analysis of the coupling of photons from their source within an indirect-band-gap electroluminescent diode (or within a sufficiently transparent heterostructure direct-band-gap diode) into the ambient or into a multimode optical fiber. We find that about two-thirds of the internally generated photons will reach air from an encapsulated rough-sawed red-emitting GaP(Zn,O) electroluminescent diode of reasonably high purity and contact reflectivity, whereas in a comparable green-emitting GaP(N) diode only about one-fourth of the photons escape while three-fourths are absorbed within the diode bulk and at its contacts.[This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP:

Optical antenna enhanced spontaneous emission

“…Semiconductor experiments (29,30) show weak antenna-emitter coupling, with the antenna enhancement sometimes masked by metal-induced elastic scattering that enhances light extraction from the semiconductor substrate. Light extraction alone can increase optical emission by 4n 2 , as often used in commercial light-emitting diodes (LEDs), without necessarily modifying the spontaneous emission rate (31,32).…”

“…Semiconductor experiments (29, 30) show weak antenna-emitter coupling, with the antenna enhancement sometimes masked by metal-induced elastic scattering that enhances light extraction from the semiconductor substrate. Light extraction alone can increase optical emission by 4n 2 , as often used in commercial light-emitting diodes (LEDs), without necessarily modifying the spontaneous emission rate (31,32).In this article, we elucidate the physics of antenna-enhanced spontaneous emission, using a traditional antenna circuit model, not the Purcell effect (33) nor a local density-of-states model (34). We use the circuit approach to analyze for the maximum possible spontaneous emission enhancement in the presence of spreading resistance losses (35) and the nonlocal anomalous skin effect (36) in the metal.…”

Nanophotonic Devices - Spontaneous Emission Faster than Stimulated Emission

“…Light extraction alone can increase optical emission by 4n 2 , as often employed in commercial LED's, without necessarily modifying the spontaneous emission rate (31,32).…”

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

“…The method has also successfully been applied to the analysis of the LEE of LEDs with different light extraction structures [10,11]. In 1974, Joyce et al [12] presented the concept of the "random particle" to analyze the LEE of LEDs. In 1995, Ting and McGill [13] used the Monte Carlo ray-tracing method to simulate the properties of the light source of the LED based on the randomness of the photons.…”