Rugged optical data distribution network for avionics

Abstract

There is a rapidly increasing data flow between sensors and on-board processors in avionic platforms. Electro-optic (EO) sensors are moving to hyperspectral and radar to phased array to enable precision targeting, wide field of view surveillance and navigation. These trends call for next generation optical network technology which has to provide increasing high speed data transmission under harsh conditions. Recent developments go beyond simple point-to-point fiber links towards establishing optical distribution networks to deal with the data traffic [1]. A flexible and potentially low-cost implementation is the passive optical network (PON) which scales easily to increasing needs simply by upgrading the peripheral units without need to change the fiber connections and infrastructure. PONs are well established in the commercial access market with the increasing push to fiber-to-the-home (FTTH) technologies which has led to the development of a variety of low-cost devices for these networks. A key enabler in our development of an avionics PON is the reflective semiconductor optical amplifier (RSOA) which combines amplification and modulation into a single device [2]. The RSOA is a non-resonant device, thus wideband with the potential for ruggedness, especially high temperature operation with small or no need for cooling. At higher data rates up to 20 Gbps a related device, the reflective electro-absorption modulator with integrated amplification (R-SOA-EAM) can be used instead. To complete the adaptation we replaced the laser, commonly used to provide optical input power in a PON architecture with another non-resonant device, the superluminescent LED (SLED). To create upgrade flexibility we utilized wavelength division multiplexing (WDM) which allows addition and subtraction of channels without changing hardware. Coarse WDM (CWDM) was chosen over Dense WDM (DWDM) for two reasons: the large channel width (20nm) of CWDM reduces cost by relaxing fabrication tolerance and renders the use of temperature control unnecessary, thereby increasing reliability. The concept and current state of development of our optical network is described in this paper.