Scalable orthogonal delay-division multiplexed OEO artificial neural network trained for TI-ADC equalization

We propose a new signaling scheme for on-chip optical-electrical-optical artificial neural networks that utilizes orthogonal delay-division multiplexing and pilot-tone-based self-homodyne detection.This scheme offers a more efficient scaling of the optical power budget with increasing network complexity.Our simulations,based on220 nm silicon-on-insulator silicon photonics technology,suggest that the network can support 31×31 neurons,with 961 links and freely programmable weights,using a single 500 m W optical comb and a signal-to-noise ratio of 21.3 d B per neuron.Moreover,it features a low sensitivity to temperature fluctuations,ensuring that it can be operated outside of a laboratory environment.We demonstrate the network’s effectiveness in nonlinear equalization tasks by training it to equalize a time-interleaved analog-to-digital converter(ADC)architecture,achieving an effective number of bits over 4 over the entire 75 GHz ADC bandwidth.We anticipate that this network architecture will enable broadband and low latency nonlinear signal processing in practical settings such as ultra-broadband data converters and real-time control systems.

Hybrid multi-chip assembly of optical communication engines by in situ 3D nanolithography

Three-dimensional(3D)nano-printing of freeform optical waveguides,also referred to as photonic wire bonding,allows for efficient coupling between photonic chips and can greatly simplify optical system assembly.As a key advantage,the shape and the trajectory of photonic wire bonds can be adapted to the mode-field profiles and the positions of the chips,thereby offering an attractive alternative to conventional optical assembly techniques that rely on technically complex and costly high-precision alignment.However,while the fundamental advantages of the photonic wire bonding concept have been shown in proof-of-concept experiments,it has so far been unclear whether the technique can also be leveraged for practically relevant use cases with stringent reproducibility and reliability requirements.In this paper,we demonstrate optical communication engines that rely on photonic wire bonding for connecting arrays of silicon photonic modulators to InP lasers and single-mode fibres.In a first experiment,we show an eight-channel transmitter offering an aggregate line rate of 448 Gbit/s by low-complexity intensity modulation.A second experiment is dedicated to a four-channel coherent transmitter,operating at a net data rate of 732.7 Gbit/s-a record for coherent silicon photonic transmitters with co-packaged lasers.Using dedicated test chips,we further demonstrate automated mass production of photonic wire bonds with insertion losses of(0.7±0.15)dB,and we show their resilience in environmental-stability tests and at high optical power.These results might form the basis for simplified assembly of advanced photonic multi-chip systems that combine the distinct advantages of different integration platforms.

Modeling of a SiGeSn quantum well laser

We present comprehensive modeling of a Si GeSn multi-quantum well laser that has been previously experimentally shown to feature an order of magnitude reduction in the optical pump threshold compared to bulk lasers.We combine experimental material data obtained over the last few years with k·p theory to adapt transport,optical gain,and optical loss models to this material system (drift-diffusion,thermionic emission,gain calculations,free carrier absorption,and intervalence band absorption). Good consistency is obtained with experimental data,and the main mechanisms limiting the laser performance are discussed. In particular,modeling results indicate a low non-radiative lifetime,in the 100 ps range for the investigated material stack,and lower than expectedΓ-L energy separation and/or carrier confinement to play a dominant role in the device properties. Moreover,they further indicate that this laser emits in transverse magnetic polarization at higher temperatures due to lower intervalence band absorption losses. To the best of our knowledge,this is the first comprehensive modeling of experimentally realized Si GeSn lasers,taking the wealth of experimental material data accumulated over the past years into account. The methods described in this paper pave the way to predictive modeling of new (Si)GeSn laser device concepts.