Optically Enabled ADCs and Application to Optical Communications

Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-the-art 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-and-hold 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

Photonic Analog-to-Digital-Converters –Comparison of a MZM-Sampler with anOptoelectronic Switched-Emitter-Follower Sampler

In this paper two integrated photonic Analog-to-Digital Converter architectures are modeled and simulated. The results are compared in terms of bandwidth, linearity, and jitter performance. The Mach-Zehnder-Modulator based sampler is implemented on system level in Lumerical Interconnect. The effective resolution is dependent on the average optical power, the modulation index, and the applied post-processing. It stays above 7 Bit for a modulation index of m=0.31 up to 20 GHz. The optoelectronic Switched-Emitter-Follower architecture is designed in a 250nm SiGe BiCMOS photonic process and the post-layout transient noise simulations show an effective resolution of over 7 Bit for an input amplitude of 200mVpp up to 50 GHz

Optically clocked switched-emitter-follower THA in a photonic SiGe BiCMOS technology

In this paper a novel opto-electronic Track-and-Hold Amplifier (OE-THA) is presented.The OE-THA can be used as a sampler in a photonic analog-to-digital-converter (ADC). Itis fabricated in a silicon photonic 250 nm SiGe BiCMOS technology to allow for monolithicintegration of photonic and electronic components. The OE-THA chip exhibits a small signalbandwidth of over 65 GHz, a total harmonic distortion below −34 dB up to 75 GHz and asignal-to-noise and distortion ratio (SINAD) of over 35 dB (5.5 effective bits, ENOB) up to45 GHz. The measured resolution bandwidth products result in a corresponding equivalent jitterof below 80 fs rms from 20 to 70 GHz. The best equivalent jitter is achieved at 41 GHz with avalue of 55.8 fs rms. This is enabled by using a low-jitter optical pulse train, generated by aMode-Locked-Laser (MLL), as an optical sampling clock. The circuit integrates all optical andelectronic components besides the MLL. It draws 110 mA operated from a supply voltage of−4.6 V and occupies a silicon area of only 0.59 mm$^2$