| 尹椿淑,何志毅,邓术,梁仕,何宁.大功率LED的脉冲响应及其大电流光调制技术研究[J].光电子激光,2015,26(6):1041~1047 |
| 大功率LED的脉冲响应及其大电流光调制技术研究 |
| Investigation on pulse response and the large current optical modulation of high power LEDs |
| 投稿时间：2015-01-26 |
| DOI： |
| 中文关键词: 大功率LED 光调制 脉冲调制 可见光通信(VLC) FPGA |
| 英文关键词:high power LED optical modulation pulse modulation visible light communicatio n (VLC) FPGA |
| 基金项目:国家自然科学基金(61077036,61461014)、无线宽带通信与信号处理重点实 验室开放基金(12108)和桂林电子科技大学研究生科研创新(XY130212)资助项目 (桂林电子科技大学 信息与通信学院,广西 桂林 541004) |
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| 中文摘要: |
| LED作为可见光通信(VLC)的发射光源时为保证足够 大的光信号覆盖范围和信号强度,应采用大电流脉冲调制。本文研究了大功率LED的光 -电脉冲响应比小功率器件较慢、从而造成光调制带宽降低的原因,以及LED注入电 子和空穴的缓慢复 合与驱动电路晶体管在大电流工作时的存储效应；由此设计了FPGA控制下的光脉冲整形方案 ,信号脉冲经由FPGA再生同时产生另外两路相位关联的短脉冲,同步控制驱动电路分别 在信号脉冲上 升沿施加一个瞬时高压加速载流子注入,在脉冲下降沿使LED两端短路将剩余载流子泄放, 使光脉冲边沿加速进行整形。对接收信号 的眼图和误码率(BER)的测试结果表明,在接近安培量级的 峰-峰值调 制电流下,通过这种同步控制方法使光信号质量得到有效改善,传输速率得到明显提高。 |
| 英文摘要: |
| Light emitting diodes (LEDs) can be used as the light sources for wireless op tical communication,which are expected to be developed into optical local area n etwork.In terms of a specific transmission speed requirement,large current modulation should be adopted to ensure large area of signal coverage and signal intensity.In this paper,the mechanisms of the slower photo-electric response and smaller optical modulation bandwidth of the high power LEDs than those of th e lower power ones are investigated.The slow recombination of the electrons/holes injected into the LE D and the carrier storage effect of the transistor in the driving circuit are analyzed.The optical pulse shaping technique is selected to promote the transmission speed.FPGA is used to generate the two outputs of additional short pulses with their phases correlated to the signal pulses regenerated by th e FPGA.The two pulses synchronously control a driving circuit to apply a transient over -voltage at the pulse rising edge to speed up the carrier injection,and a short circuit to the LED at the pu lse falling edge discharging the remaining carriers.The measurement results of eye-diagram and bit error ra te (BER) of the received signals demonstrate that the optical signal quality and the transmission rate ar e significantly improved,at the nearly ampere level of the peak-peak modul ating current. |
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