CMOSイメージセンサによる空間光通信システム

摘要

AlGalnAs lasers are suitable for element devices of optical communication systems. However, degradations in forward-biased ESD tests and accelerated aging tests were found. Since both degradations occurred at the facet of the laser, we improved facet-coating processes. In forward-biased ESD tests, we introduced a passivation of an Al ultrathin layer just before facet-coating. The Al ultrathin layer prevents oxidation of the facet from oxygen atmosphere. The degradation ratio of 1 kV ESD tests was decreased from 40% to 0% by introducing the passivation. In accelerated aging tests of 200 mA at 85 °C, we introduced facet-coating with compressive strain. This degradation differed completely from that caused by ESD; dislocation loops covered the entire active layer at the facet. The degradation ratio of 800 h aging was decreased from 5% to 0% by introducing the compressively strained facet-coating.%車車間および路車間通信への応用を目指し，LEDを送信機，カメラ（イメージセンサ）を受信機とする無線型の空間光通信システムを提案する．本システムのイメージセンサには，高速なLEDの光信号を受信できる性能と，車載であるためLEDが画像空間内で動いてもそれを追跡して通信を継続できる機能が求められる．本稿ではこれらの性能および機能を備えた従来にない空間光通信用イメージセンサを開発したので報告する．また屋内および屋内で通信性能実験を実施し，通信レート10Mbps，BER＜10~(15)が得られたので併せて報告する．