THz-Range All-Optical Wavelength Conversion using a Feedback-Controlled Multi-Wavelength Laser

All-optical wavelength conversion is a key functionality for microwave photonics [1], and large wavelength division multiplexing (WDM) networks with dynamic traffic [2], e.g., to enable flexible wavelength allocation within the subnetworks. All-optical techniques mostly rely on exploiting the nonlinearities in semiconductor lasers or amplifiers, such as gain-saturation and difference-frequency generation. These methods, however, require additional probe laser [3], or phase matching [2]. Recently, P1 dynamics of a semiconductor laser have been proposed for frequency conversion, relying on the injection of the optical signal [4]. However, these systems are limited due to the reduced interaction between the injected signal and the laser process beyond 100 GHz. Here we propose an alternative approach based on a feedback-controlled multi-wavelength laser (MWL), described in [5], which enables signal regeneration and simultaneous wavelength conversions. The MWL features emission at multiple and controllable modes, thus removing the need for an additional external probe light. By injecting the low-power signal around one of the MWL modes, we achieve a frequency shift of 1.36 THz (10.5 nm) and recover the data. By varying the phase and amplitude of the feedback we show simultaneous frequency conversion at offsets of 28 GHz and 1.36 THz. In fact, our approach does not shift the wavelength of the signal but instead copies the data onto the other MWL modes thereby allowing also simultaneous conversion at different wavelengths, controlled by the feedback phase and amplitude. This approach is, in principle, only limited by the gain bandwidth of the active medium, e.g. up to 10 THz in InP.