Strong exciton–photon coupling in organic materials

Performance characteristics of resonant cavity light-emitting diodes operating at the wavelength of 650 nm have been studied. It has been shown that a variation in device temperature significantly modifies the far-field pattern and thus the fibre coupling efficiency, due to a cavity detuning effect. Temperature dependences of output power and emission wavelength are also studied. Modulation bandwidth of >120 MHz and light power of 2 mW (cw) have been achieved for 84 µm devices driven at a 40 mA current. Accelerated ageing tests for 36 000 device hours indicate no degradation in output power.

Temperature behaviour of resonant cavity light-emitting diodes at 650 nm

Pillar microcavities based on CdMnTe/CdMgTe heterostructures have been investigated by means of spatially resolved optical spectroscopy. Strong coupling with a Rabi splitting of about 15.8 meV is demonstrated by performing microreflectivity measurements on a single pillar with three-dimensional optical confinement. Analyzing the temperature and the power dependent photoluminescence signal after nonresonant excitation, clear evidence of strong coupling in the nonlinear emission regime is obtained even at elevated temperatures.

Nonlinear emission in II–VI pillar microcavities: Strong versus weak coupling

High-performance InGaN-based green resonant-cavity light-emitting diodes (RCLEDs) with a plating Cu substrate for plastic optical fiber communication applications are reported. Good stability of emission wavelength was obtained at 0.016 nm/mA . The RCLEDs presents low temperature dependence, showing only a 3% drop in light output power as the temperature increasing from 25 to 85degC. The superior performance can be attributed to the decreased dynamic series resistance and the enhanced thermal dissipation of the heat sink substrate.

https://ir.nctu.edu.tw:443/bitstream/11536/6673/1/000269214900003.pdf

High-Performance InGaN-Based Green Resonant-Cavity Light-Emitting Diodes for Plastic Optical Fiber Applications

We present a quantum-dot microcavity light-emitting diode emitting at 1.3 μm at room temperature. The long wavelength emission is achieved by using InGaAs quantum dots directly grown on GaAs, by metalorganic chemical vapor deposition. The device exhibits electroluminescence bright emission, peaked at 1298 nm and with a full width at half maximum of 6.5 meV.

Electrically injected InGaAs/GaAs quantum-dot microcavity light-emitting diode operating at 1.3 μm and grown by metalorganic chemical vapor deposition

Temperature dependence of the cavity-polariton mode splitting in a semiconductor microcavity

We report a systematic investigation of the emission properties of semiconductor microcavity light-emitting diodes (MC-LEDs) with different cavity detuning. Evidence that varying the cavity detuning leads to temperature insensitive output characteristics is provided by changes in the temperature dependence of the slope efficiency extracted from the light output versus current characteristics. For resonantly tuned devices the slope efficiency decreases monotonically with increasing temperature. However when the cavity peak is detuned to long wavelength with respect to the room temperature quantum well (QW) emission, temperature insensitive characteristics are achieved. Compared to a noncavity type LED, enhanced efficiency and narrow spectral linewidth have been observed for the MC-LEDs with the highest output efficiency achieved when the QW emission and cavity peak are exact resonant.

Temperature dependence of InGaAs/GaAs quantum well microcavity light-emitting diodes

Light output power versus current, emission spectroscopy and far-field emission patterns have been used to characterize microcavity light emitting diodes (MC-LEDs). Evidence that microcavity effects lead to enhanced emission properties is provided by changes in the total emitted light output power, as well as the electroluminescence spectra of the MC-LEDs. Compared to a conventional noncavity type LED structure, enhanced efficiency and narrow spectral linewidths have been observed for the MC-LEDs over a wide range of cavity detunings and cavity Q values. Evidence that control of the cavity detuning leads to temperature insensitive output characteristics is provided by changes in the temperature dependence of the slope efficiencies extracted from the light output versus current characteristics. Variations in the emitted radiation patterns as a function of current injection are also reported demonstrating the important role of the cavity detuning on the emission properties of MC-LEDs.

Cavity detuning effects in semiconductor microcavity light emitting diodes

Photoluminescence (PL) has been used to study cavity-polariton-mode splitting in a strongly coupled microcavity that utilizes high-contrast oxidized AlAs/GaAs mirrors. The cavity structure was specifically designed to reduce nonradiative recombination at the oxide–semiconductor interfaces and takes full advantage of the high-contrast mirrors to reduce the effective cavity length, and increase the exciton–photon coupling strength. The cavity-polariton splitting measured at room temperature was 6.2 meV, which we believe to be the first ever reported PL splitting measured at room temperature using an oxide-based microcavity. The temperature dependence of the cavity-polariton splitting has also been measured and is well described within a semiclassical polariton model.

Photoluminescence study of cavity-polariton-mode splitting using high-contrast selectively oxidized AlAs/GaAs mirrors

Photoluminescence (PL) has been used to characterize an InGaAs/GaAs single quantum well (SQW) adjacent to a selectively oxidized AlAs layer. For a direct interface between the SQW and AlAs, the room temperature PL intensity is drastically reduced after oxidation indicating the presence of an efficient non-radiative pathway. However, a 20 nm AlGaAs layer grown between the SQW and the AlAs effectively isolates the SQW and yields a luminescence efficiency after oxidation identical to that of the as grown material.

A. R. Pratt

Papers

Temperature dependence of the cavity-polariton mode splitting in a semiconductor microcavity

Temperature dependence of InGaAs/GaAs quantum well microcavity light-emitting diodes

Cavity detuning effects in semiconductor microcavity light emitting diodes

Photoluminescence study of cavity-polariton-mode splitting using high-contrast selectively oxidized AlAs/GaAs mirrors

Photoluminescence of InGaAs/GaAs single quantum well adjacent to a selectively oxidized AlAs layer