Fabrication tolerances can significantly degrade the performance of fabricated photonic circuits and process yield. It is essential to include these stochastic uncertainties in the design phase in order to predict the statistical behaviour of a device before the final fabrication. This paper presents a method to build a novel class of stochastic-based building blocks for the preparation of Process Design Kits for the analysis and design of photonic circuits. The proposed design kits directly store the information on the stochastic behaviour of each building block in the form of a generalized-polynomial-chaos-based augmented macro-model obtained by properly exploiting stochastic collocation and Galerkin methods. Using these macro-models, only a single deterministic simulation is required to compute the stochastic moments of any arbitrary photonic circuit, without the need of running a large number of time-consuming circuit simulations thereby dramatically improving simulation efficiency. The effectiveness of the proposed approach is verified by means of classical photonic circuit examples with multiple uncertain variables.

A continuously tunable integrated optical delay line architecture with large bandwidth and bandwidth-delay product is proposed and demonstrated. The non-resonant delay line is based on cascaded Mach-Zehnder interferometers with tunable couplers. The device is operated with a single control signal and outperform the common ring-resonator-based delay lines in terms of bandwidth-delay product. A device with a delay tuning range of 124 ps is experimentally demonstrated over a transmission bandwidth of 4.5 GHz.

Unavoidable statistical variations in fabrication processes can have a strong effect on the functionality of fabricated photonic circuits and on fabrication yield. It is hence essential to consider these uncertainties during design in order to predict and control the statistical behavior of the circuits. In this paper, we exploit elementary effect test and variance-based sensitivity analysis to investigate the behavior of a photonic circuit under fabrication uncertainties, with the aim to identify the most critical parameters affecting circuit performances. As an example, we perform the sensitivity analysis on the 3-dB bandwidth of two different filter designs considering random deviations of the waveguides width and couplers' gap. The information obtained from the analysis is then used to isolate the most critical parameters of the circuits and to estimate and reduce the cost of postfabrication correction of the process variability

An integrated optical delay line is presented and experimentally demonstrated with a true-time delay continuously tuned up to 125 ps. The proposed device is based on a Mach-Zehnder interferometer with tuneable couplers, can be ideally operated with a single control signal and achieves a bandwidthdelay product consistently larger than ring-based delay lines. The device is successfully used in a transmission system to control the delay of a 10 Gbit/s data stream.

We propose an efficient technique based on polynomial chaos expansion and genetic algorithms to enable constrained optimization of photonic integrated circuits subject to fabrication tolerances. Simulations on a realistic SOI design confirm its effectiveness.