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Physical reservoir computing (PRC) is a recently developed variant of neuromorphic computing, where the output from a nonlinear physical system is utilized to perform various machine learning tasks. In this work, we theoretically analyze the performance of a photonic waveguide mesh (WGM) with electro-optic phase shifters for monolithic-hybrid-photonic-electronic reservoir computing (MHPE RC), where the phase-to-intensity relations in the photonic circuit provide nonlinearity and high dimensionality, while the electronic circuit provides the input and feedback with tunable parameters. First, we numerically demonstrate the efficiency and performance superiority of a parallel architecture comprising fabricated WGM. Next, we present the Lyapunov filtered-minimal redundancy maximal relevance (Lf-mRMR) algorithm, which optimizes the electronic parameters of parallel WGMs by analyzing the Lyapunov exponent and the mutual information between the output of the corresponding WGMs and the required task. The Lf-mRMR algorithm is computationally less complex, substantially improves the performance of MHPE RC, and can tolerate fabrication errors. We present the selective parallel architecture for reservoir computing (SPARC), which, assisted by the Lf-mRMR algorithm, can achieve performance close to convolutional neural networks. Finally, we experimentally employ on-chip silicon photonics with thermo-optical phase shifters and external off-chip digital memory and control unit to validate the advantageous performance of Lf-mRMR-assisted RC. 

The modal dispersion of waveguides typically limits integrated photonic devices to operation with a single polarization state. In this work, we propose a generic mode separation technique we call “interferometric mode splitting” (IMS), which enables guided modes to be separated over wide bandwidths with a large extinction ratio. To demonstrate the general principle of IMS, we show that an unmodified thermally driven silicon photonic Fourier transform spectrometer exhibits a polarization-separating effect in the frequency domain, even though only one polarization-insensitive detector is used. Using this effect, we experimentally demonstrate a simple on-chip spectrometer capable of extracting two-polarization spectra over a wide 1480–1630 nm bandwidth with a greater than 20 dB polarization extinction ratio. These specifications would be highly challenging to achieve using existing, conventional on-chip polarization-splitting techniques. Though we focus on this specific realization of IMS, we also show that IMS is general to various on-chip spectrometer architectures, other spatial modes, and technologies other than thermally driven Fourier transform spectrometers. Interferometric mode splitting shows promise as a general approach for robust and fundamentally broadband detection of orthogonal modes in guided-wave sensing. 

Chalcogenide phase-change materials exhibit large, reversible index shifts that promise nonvolatile, energy-efficient photonic technologies. Yet, current implementations either rely on ultrathin, lossy films integrated with passive Si/SiN waveguides, limiting index modulation, or exploit direct laser writing for localized switching, at the expense of strong optical confinement. Here we demonstrate an antimony trisulfide (Sb₂S₃) waveguide platform where the material itself forms the guiding core. The proposed architecture theoretically supports substantial modulation of both effective index and absorption, thereby providing a robust platform for the realization of reconfigurable and densely integrated photonic devices. 

This research leverages advanced monolithic silicon‐photonics integrated‐circuit manufacturing capabilities to realize system‐on‐chip photonic‐computing‐based linear‐algebra accelerators for a wide range of applications in artificial intelligence, machine learning, and multiple‐input multiple‐output wireless technology. With holistic codesign in both photonic and electronic domains, strategic electrical‐to‐optical signal conversion, a differential intensity‐modulation technique, and a dual rail‐to‐rail photodetection architecture, the monolithic photonic‐electronic test chip of a sign‐sign dot‐product accelerator achieves 8.92‐Gb/s/MAC computation throughput with 2.22‐pJ/b/MAC energy consumption for next‐generation large‐scale linear‐algebra computing hardware targeting higher than one TMAC/s/mm^2 computation density with only tens of fJ/MAC energy consumption. 

Abstract Phase‐sensitive integrated photonic devices are highly susceptible to minor manufacturing deviations, resulting in significant performance inconsistencies. This variability has limited the scalability and widespread adoption of these devices. Here, a major advancement is achieved through continuous‐wave (CW) visible light (405 and 520 nm) trimming of plasma‐enhanced chemical vapor deposition (PECVD) silicon‐rich nitride (SRN) waveguides. The demonstrated method achieves precise, bidirectional refractive index tuning with a single laser source in CMOS‐compatible SRN samples with refractive indices of 2.4 and 2.9 (measured at 1550 nm). By utilizing a cost‐effective setup for real‐time resonance tracking in micro‐ring resonators, the resonant wavelength shifts as fine as 10 pm are attained. Additionally, a record red shift of 49.1 nm and a substantial blue shift of 10.6 nm are demonstrated, corresponding to refractive index changes of approximately 0.11 and −2 × 10⁻². The blue and red shifts are both conclusively attributed to thermal annealing. These results highlight SRN's exceptional capability for permanent optical tuning, establishing a foundation for stable, precisely controlled performance in phase‐sensitive integrated photonic devices. 

An energy/area-efficient low-cost broadband linearity enhancement technique using the hybrid of notch-filter and bandpass-filter micro-ring modulators (Hybrid-MRMs) is proposed to achieve higher than 3.01-dB improvement in spurious-free-dynamic-ranges with intermodulation distortions (dSFDRIMD) and 17.9-dB improvement in integral nonlinearity (dINLPP) over a conventional notch-filter MRM (NF-MRM) across a 4.8-dB extinction-ratio full-scale range based on rapid silicon-photonics fabrication results for the emerging applications of various analog and digital optical communication systems. 

This study proposes a novel technique for a 2D beam steering system using hybrid plasmonic phase shifters with a cylindrical configuration in a 2D periodic array suitable for LIDAR applications. A nanoscale VCSEP design facilitates a sub-wavelength spacing between individual phase shifters, yielding an expanded field of view and side lobes suppression. The proposed design includes a highly doped sub-micron silicon pillar covered by a thin layer of nonlinear material and an additional conductive metal layer. Characterization of a single VCSEP demonstrated a Free Spectral Range (FSR) of 53.28 ± 2.5 nm and a transmission variation of 3 dB, with V_πL equal to 0.075 V-mm. 

The design, fabrication, and characterization of a 16-element optical phased array (OPA) using a high index ( n  = 3.1) silicon-rich silicon nitride (SRN) is demonstrated. We present one-dimensional beam steering with end-fire facet antennas over a wide steering range of >115° at a fixed wavelength of 1525 nm. A beam width of 6.3° has been measured at boresight, consistent with theory. We demonstrate SRN as a viable material choice for chip-scale OPA applications due to its high thermo-optic coefficient, high optical power handling capacity [negligible two-photon absorption (TPA)], wide transparency window, and CMOS compatibility. 

There is little literature characterizing the temperature-dependent thermo-optic coefficient (TOC) for low pressure chemical vapor deposition (LPCVD) silicon nitride or plasma enhanced chemical vapor deposition (PECVD) silicon dioxide at temperatures above 300 K. In this study, we characterize these material TOC’s from approximately 300-460 K, yielding values of (2.51 ± 0.08) · 10 −5 K −1 for silicon nitride and (5.67 ± 0.53) · 10 −6 K −1 for silicon oxide at room temperature (300 K). We use a simplified experimental setup and apply an analytical technique to account for thermal expansion during the extraction process. We also show that the waveguide geometry and method used to determine the resonant wavelength have a substantial impact on the precision of our results, a fact which can be used to improve the precision of numerous ring resonator index sensing experiments.