Circuit design and integration feasibility of a high-resolution broadband on-chip spectral monitor

TL;DR

This paper presents a novel on-chip spectral monitor architecture capable of high-resolution, broadband optical spectrum measurement across the entire C-band, validated through experimental and simulation results, suitable for network telemetry.

Contribution

It introduces a new spectrometer circuit with a scanning ring resonator and parallel AWGs, along with an original data processing algorithm, enabling high-resolution, broadband spectral monitoring on-chip.

Findings

Achieved 1.30 GHz resolution bandwidth over the entire C-band.

Validated the feasibility of a CMOS-compatible silicon nitride ring resonator system.

Demonstrated robustness of the architecture to fabrication variations.

Abstract

Up-to-date network telemetry is the key enabler for resource optimization by a variety of means including capacity scaling, fault recovery, network reconfiguration. Reliable optical performance monitoring in general and specifically the monitoring of the spectral profile of WDM signals in fixed- and flex-grid architecture across the entire C-band remains challenging. This article describes a spectrometer circuit architecture along with an original data processing algorithm that combined can measure the spectrum quantitatively across the entire C-band aiming at 1 GHz resolution bandwidth. The circuit is composed of a scanning ring resonator followed by a parallel arrangement of AWGs with interlaced channel spectra. The comb of ring resonances provides the high resolution and the algorithm creates a virtual tuneable AWG that isolates individual resonances of the comb within the flat pass-band of its synthesized channels. The parallel arrangement of AWGs may be replaced by a time multiplexed multi-input port AWG. The feasibility of a ring resonator functioning over whole C-band is experimentally validated. Full tuning of the comb of resonances over a free spectral range is achieved with a high-resolution bandwidth of 1.30 GHz. Due to its maturity and low loss, CMOS compatible silicon nitride is chosen for integration. Additionally, the whole system demonstration is presented using industry standard simulation tool. The architecture is robust to fabrication process variations owing to its data processing approach.