The effect of phase noise introduced by optical sources in spectrally-sliced optically enabled DACs and ADCs is modeled and analyzed in detail. In both data converter architectures, a mode-locked laser is assumed to provide an optical comb whose lines are used to either synthesize or analyze individual spectral slices. While the optical phase noise of the central MLL line as well as of other optical carriers used in the analyzed system architectures have a minor impact on the system performance, the RF phase noise of the MLL fundamentally limits it. In particular, the corresponding jitter of the MLL pulse train is transferred almost one-to-one to the system-level timing jitter of the data converters. While MLL phase noise can in principle be tracked and removed by electronic signal processing, this results in electric oscillator phase noise replacing the MLL jitter and is not conducive in systems leveraging the ultra-low jitter of low-noise mode-locked lasers. Precise analytical models are derived and validated by detailed numerical simulations.

Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-theart all-electrical data converters. In addition to ultra-broadband signal processing, it allows leveraging ultra-low jitter mode-locked lasers and thus increasing the aperture jitter limited effective number of bits at high analog signal frequencies. In this paper, we review our recent progress towards optically enabled time-and frequency-interleaved analog-to-digital converters, as well as their monolithic integration in electronic-photonic integrated circuits. For signal frequencies up to 65 GHz, an optoelectronic track-andhold amplifier based on the source-emitter-follower architecture is shown as a power efficient approach in optically enabled BiCMOS technology. At higher signal frequencies, integrated photonic filters enable signal slicing in the frequency domain and further scaling of the conversion bandwidth, with the reconstruction of a 140 GHz optical signal being shown. We further show how such optically enabled data converter architectures can be applied to a nonlinear Fourier transform based integrated transceiver in particular and discuss their applicability to broadband optical links in general.

We demonstrate optical arbitrary waveform measurement (OAWM) using a silicon pho-tonic spectral slicer. Exploiting maximal-ratio combining (MRC), we demonstrate the viability of the scheme by reconstructing 100-GBd 64QAM signals with high quality.

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We present optimized hourglass-shaped resonator CROW filters showing an improved power consumption of up to 30% when compared with standard circular ring shapes. Metal and doped waveguide heaters are compared in terms of efficiency, crosstalk and insertion losses.

Combining photonic integrated circuits (PIC) with millimeter-wave electronics opens novel perspectives in generation and detection of ultra-broadband signals with disruptive potential for a wide variety of applications. Here, we will give an overview on our recent progress in the field of ultra-broadband photonicelectronic signal processing, covering device concepts such as silicon plasmonic integration, signal processing concepts such as Kramers-Kronig-based phase reconstruction of THz signals, as well as application demonstrations in the field of high-speed wireless data transmission.

We present the design and experimental characterization of a silicon nitride pulse interleaver based on coupled resonator optical waveguide filters. In order to achieve a targeted free spectral range of 1.44 THz, which is large given the reduced optical confinement of the silicon nitride platform, individual ring resonators are designed with tapered waveguides. Its application to time-interleaved photonically-assisted ADCs is analyzed by combining experimental characterization of the photonic integrated circuit with a comprehensive model of the entire ADC. The impact of fundamental signal distortion and noise sources affecting the converter is investigated and suitable equalization techniques at the digital signal processing level are evaluated. The novel application of a simple but powerful equalization filter in the DSP domain allows for a significant improvement of the digitized signal SNR. An ENOB of 5 over a 75 GHz bandwidth (150 GS/s) and an ENOB of 4.3 over a 100 GHz bandwidth (200 GS/s) are expected to be achievable with compact and off-the-shelf single-section semiconductor mode locked lasers, that can be further improved with lower noise light sources.