Green photonics integrated circuit for NGOA coherent receivers

The recent advances in coherent optical systems enable the use of efficient modulation formats, such as quadrature phase shift keying (QPSK). In this framework, we present an integrated 90° hybrid 2 × 4 coupler based on self-patternable organic–inorganic hybrid thin films fabricated using direct laser writing. The device was coupled to balanced photodiodes, resulting in an optical coherent receiver with capacity to extract the modulated data. The device performance was demonstrated for a transmission over 40 km (G.652 fiber) with a 20 Gb/s QPSK, yielding a 2.5 dB power penalty (BER = 3.8 × 10−3), being the best figures of merit for waveguides processed by low-cost patterning techniques. Furthermore, the hybrid materials are thermally and mechanically stable than polymers, with lower fiber-to-device insertion losses. Therefore, the proposed optical coherent receiver is an easy processed and cost-effective approach for the next generation of optical access networks.