Fundamental limitations of spectrally-sliced optically enabled data converters arising from MLL timing jitter

Abstract

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.

Optimized hourglass-shaped resonators for efficient thermal tuning of CROW filters with reduced crosstalk

“…Here, our objective is to realize a bank of 3 rd order CROW filters dividing a wideband signal into eight individual slices of 30 GHz each, as part of the optical processing in an integrated photonically-assisted broadband ADC [4], [9]. The free spectral range (FSR) needs to be of at least 240 GHz (8 x 30 GHz).…”

Photonic-Electronic Ultra-Broadband Signal Processing: Concepts, Devices, and Applications

“…When it comes to synthesis and analysis of arbitrary ultrabroadband waveforms, optical frequency combs can act as highly precise sources of well-defined optical carriers that may be used for spectrally sliced detection of optical signals [17], [18]. In this context, chip-scale frequency comb generators are of particular interest, combining compact footprint with high robustness and comb-line spacings of tens of gigahertz.…”

“…Over the recent years, we have explored the viability of such devices in the field of massively parallel optical communications [19], where so-called dissipative Kerr-soliton (DKS) frequency combs [20] and quantum-dash mode-locked lasers [21], [22], [23] have proven particularly useful. In the future, these devices may be exploited for ultra-broadband photonic-electronic analogue-to-digital converters (ADC) that rely on spectrally sliced detection of signals using optical frequency combs as highly precise multi-wavelength local oscillators (LO) [17].…”

“…When it comes to detection of sub-THz band-pass signals, down-conversion to the baseband can be accomplished by optical local-oscillator signals in combination with highspeed PIPED [8] or with photoconductors based on lowtemperature-grown InGaAs/InAlAs heterostructures [6], [25]. Alternatively, ultra-broadband electro-optic modulators that exploit, e.g., the POH approach, can be used for first transferring electrical signals to an optical carrier [16], where they can then be processed further, e.g., by spectrally sliced detection in ultrabroadband photonic-electronic ADC [17]. Conversion of THz data signals to optical carriers lends itself to realizing seamless interfaces between sub-THz point-to-point links and fiber optic infrastructures in future wireless access networks [16], see Figure 1.…”

Optical Arbitrary Waveform Measurement (OAWM) on the Silicon Photonic Platform

“…Optical arbitrary waveform measurement (OAWM) [1] has the potential to unlock a wide variety of applications, ranging from investigation of ultra-short events [2] and photonic-electronic analog-to-digital convertors (ADC) [3] to reception of communication signals with ultra-high symbol rates [4], elastic optical networking [5], and sliceablebandwidth-variable transponders (SBVT) in cloud radio-access networks (C-RAN) [6]. OAWM has previously been demonstrated with an overall bandwidth of 228 GHz [4], exploiting spectral slicing of the incoming waveform into six tributaries that are coherently detected using an optical frequency comb (OFC) as multi-wavelength local oscillator (LO).…”