Integrating-sphere diffuser for wireless infrared communication

The application of an integrating sphere (IS) as a diffuser in a wireless infrared (IR) network is investigated. Going beyond the simplified analytical model, it is shown that ray-tracing simulations provide realistic data for the optical insertion loss, the transfer function and the far-field light distribution. As an example, a sphere diffuser for a 155 Mbit/s 16-PPM IR transmitter is investigated with an insertion loss of 0.66 dB, a cutoff frequency of 570 MHz and a 104° full width at half-maximum (FWHM) angle of the intensity distribution. The device has also been manufactured using a proprietary material and good agreement between simulation and experimental data is found. A method to increase the FWHM angle and some aspects of eye safety are discussed.