|
Resonant-cavity-enhanced photo detectors (or, RCE photo detectors) enable improved performance over their predecessors by placing the active device structure inside a Fabry–Pérot resonant cavity. Though the active device structure of the RCE detectors remains close to other conventional photodetectors, the effect of the optical cavity, which allows wavelength selectivity and an enhancement of the optical field due to resonance, allows the photo detectors to be made thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. ==Advantages== The quantum efficiency of conventional detectors is dominated by the optical absorption (electromagnetic radiation) of the semiconductor material. For semiconductors with low absorption coefficients, a thicker absorption regions is required to achieve higher quantum efficiency, but at the cost of the Bandwidth (signal processing) of photodetectors. A RCE detector improves the bandwidth significantly. The constructive interference of a Fabry–Perot cavity enhances the optical field inside the photodetector at the resonance wavelengths to achieve a quantum efficiency of close to unity. Moreover the optical cavity makes the RCE detectors wavelength selective. This makes RCE photodetectors attractive for low crosstalk wavelength demultiplexing. Improved quantum efficiency gives less power consumption. Higher bandwidth gives faster operation. The RCE photodetectors have both wavelength selectivity and high speed response making them ideal for wavelength division multiplexing applications. Optical modulators situated in an optical cavity require fewer quantum wells to absorb the same fraction of the incident light, and can therefore operate at lower voltages. In the case of emitters, the cavity modifies the spontaneous emission of light-emitting diodes (LED) improving their spectral purity and directivity. Thus optical communication systems can perform much faster, with more bandwidth and can become more reliable. Camera sensors could give more resolutions, better contrast ratios and less distortion. For these reasons, RCE devices can be expected to play a growing role in optoelectronics over the coming years. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Resonant-cavity-enhanced photo detector」の詳細全文を読む スポンサード リンク
|