Arbitrary Digital Processing of THz-Bandwidth Signals Based on Optic-Electronic-Optic Interferometers - Phase 2 (INTERFERE2)

An optic-electronic-optic (OEO) interferometer flexibly extends the functionality of conventional Mach-Zehnder interferometers (MZI) to include linear, non-linear, and even time-variant transfer functions for optical waves. While a conventional MZI splits and recombines an optical signal after rather simple optical operations either in one or in both of its interferometer arms, an OEO interferometer comprises a digital coherent receiver in one of its arms, followed by digital signal processing and subsequent electrical-to-optical inphase-quadrature modulation. Such a structure can be utilized whenever a certain spectral content within an ultrabroadband optical signal is to be modified without affecting remaining signal. With the OEO interferometer it will become possible to interferometrically drop and replace, e.g., individual spectral subcarriers of an optical ODFM signal, an approach which would not be feasible with a conventional filter-based optical add-drop multiplexer. After the first experimental proof-of-concept of an OEO interferometer with an optically opaque processing path within the INTERFERE project of the first phase of the priority programme, the requested INTERFERE2 project has the following objectives for demonstrating advanced operations with OEO-interferometers: 1. Exploring novel algorithms for real-time operation of an OEO interferometer as add-drop multiplexer with phase-control loop.2. Monolithically integrated photonic transceiver circuit with phase-stabilized external fiber delay line.3. Proof-of-concept demonstration of the ultrabroadband operation range of a single OEO interferometer, e.g. in a colorless WDM experiment with widely tunable local oscillator 4. Study on the parallel operation of two or more OEO interferometers with simultaneous accessing and broadband modification of a contiguous optical spectrum 5. Demonstration and evaluation of an OEO interferometer combining the integrated chip with the real-time FPGA implementation With the OEO interferometer, an advanced combined electronic-photonic system is the core of the project, allowing access to the huge optical bandwidth by utilizing leading edge photonic integration technology in combination with efficient digital electronic signal processing, allowing to overcome fundamental limitations of purely electronic signal processing.