Patent ID: 8861970
Filing Date: 2014-10-14
Classification: G02B,H04B

Abstract:
1. A bidirectional optoelectronic device comprising: (a) a photodetector arranged (i) to receive an input optical signal modulated to encode first transmitted information and (ii) to generate in response to the input optical signal an output electrical signal modulated to encode the first transmitted information; (b) a light source arranged (i) to receive an input electrical signal modulated to encode second transmitted information and (ii) to generate in response to the input electrical signal an output optical signal modulated to encode the second transmitted information, which light source has first and second electrical leads for receiving the input electrical signal; (c) a drive circuit arranged to apply a first portion of the input electrical signal to the first electrical lead of the light source and to apply a second portion of the input electrical signal to the second lead of the light source, wherein the second portion of the input electrical signal is a scaled, inverted substantial replica of the first portion of the input electrical signal; and (d) a protective encapsulant arranged to encapsulate the photodetector and the light source, wherein: (e) the encapsulant includes hollow dielectric microspheres dispersed within its volume so as to reduce a cross-talk penalty arising from unwanted electrical signals present in the encapsulant to a level below that exhibited by the bidirectional device without the microspheres in the encapsulant; (f) the encapsulant further includes an optical absorber dispersed within its volume so as to reduce a cross-talk penalty arising from unwanted optical signals present in the encapsulant to a level below that exhibited by the optoelectronic device without the optical absorber in the encapsulant; (g) the optical absorber comprises carbon particles dispersed in the encapsulant; and (h) the photodetector exhibits a cross-talk penalty less than about 3 dB, and the light source and the photodetector are positioned on a common substrate within about 2 mm of one another.