In this work, we explore the ferroelectric properties of zirconium dioxide ($\text{ZrO}_{2}$) thin films for application in electrooptic (Pockels) modulation. $\text{ZrO}_{2}$ is a compatible material already in use in CMOS foundries as high K oxide. The $\text{ZrO}_{2}$ films were grown via pulsed laser deposition (PLD), and their compatibility and integration with the silicon photonics platform were investigated.

Quantum networks enhance quantum communication schemes and link multiple users over large areas. Harnessing high dimensional quantum states - qu-d-its - allows for a denser transfer of information with increased robustness to noise compared to qubits. Frequency encoded qu-d-its can be manipulated at telecom wavelengths with off-the-shelf fibered devices. We use a low free spectral range silicon microresonator to propose, assess and optimize a reconfigurable entanglement-based quantum key distribution network with frequency-bin encoded Bell states of dimension d = 2 and d = 3, using a single fibered hardware. We achieve secure key rates of 1374 bit/s with qutrits (d = 3), and estimate the communication range to 295 km with qubits (d = 2) across 21 parallel two-user quantum channels. This multi-dimensional versatile demonstration is stable beyond 21 h and lays the groundwork for larger dimensionality implementations deployed on metropolitan fiber links.

Brillouin scattering enables efficient and coherent conversion between optical photons and gigahertz-frequency phonons. Implementing this interaction in silicon photonics provides a pathway toward scalable and cost-effective devices, leveraging mature fabrication processes. However, achieving strong overlap and tight confinement of optical and mechanical modes in silicon nanophotonic waveguides remains a significant challenge. Here, we propose and demonstrate a novel strategy that enables independent control of optical and mechanical modes in periodically segmented silicon waveguides. Our approach combines two distinct periodic lattices: one with a period shorter than half of the optical wavelength, providing light guiding by metamaterial-induced index contrast, and another that creates a complete phononic bandgap confining acoustic modes. This dual-lattice strategy opens new degrees of freedom to optimize optomechanical confinement and coupling simultaneously. Based on this approach, we experimentally demonstrate remarkably high Brillouin gain of , resulting in a three-tone Stokes gain of 3 and anti-Stokes loss of 4 with 6.4 MHz mechanical linewidth. These results illustrate the potential of subwavelength silicon metamaterials for engineering on-chip optomechanical interactions.

Stimulated Brillouin scattering in integrated photonic waveguides enables coherent coupling between optical photons and gigahertz acoustic phonons, providing a powerful mechanism for on-chip microwave photonics and opto-acoustic signal processing. Despite theoretical predictions of ultra-strong Brillouin interactions arising from enhanced light-sound coupling at device boundaries, most state-of-the-art integrated demonstrations remain governed by bulk photoelastic effects. This limitation stems from trade-offs between optical loss, interaction with waveguide boundaries and accessible phonon frequencies associated with the use of transverse-electric optical modes coupled to horizontally breathing mechanical modes. Here we demonstrate a new approach based on transverse-magnetic optical modes coupled to vertically breathing mechanical modes in suspended silicon membranes engineered with subwavelength metamaterial claddings. In this geometry, the interaction is dominated by the moving-boundary effect occurring at smooth top and bottom interfaces, while the phonon frequency is set primarily by the membrane thickness rather than its width. We observe forward Brillouin interactions at a record frequency of 12 GHz with a gain of 7200 W^-1 m^-1 and a mechanical quality factor of 620, yielding the highest Brillouin gain-to-quality-factor ratio reported in silicon waveguides. The devices exhibit net Brillouin amplification in millimeter-scale waveguides with pump powers below 15 mW, establishing a scalable platform for high-frequency integrated opto-acoustic signal processing.

Accurate knowledge of the uneven free spectral range of an optical microresonator, which provides direct insight into group velocity dispersion, is essential for understanding and controlling Kerr frequency comb dynamics. In this work, we present a simple and highly precise method for measuring the free spectral range over a 5 THz bandwidth in silicon nitride microresonators, leveraging a wavemeter with 0.4 MHz resolution. Our fully fibered plug-and-play experimental setup enables accurate extraction of resonance frequencies. By carefully analyzing the spectral position of each resonance, we measure both second- and third-order free spectral range expansion coefficients. This approach offers a robust and accessible tool for dispersion characterization in integrated photonic circuits, paving the way for next generation of Kerr comb sources and quantum photonic technologies.

Multilayer photonic platforms enable large-scale photonic integrated circuits with compact, sophisticated routing and densely integrated components, but their fabrication requires the deposition of high-quality cladding layers and flat intermediate surfaces. Contact planarization using hydrogen silsesquioxane (HSQ) offers a low-cost solution, yet prior demonstrations have been limited to etch depths below 150 nm and minimum feature sizes of 100 nm, well short of the requirements of standard silicon photonic processes. In this work, we present a bilayer HSQ deposition process that achieves effective planarization over a substantially broader dimensional range, covering trench widths from 75 nm to 1 μm and inter-structure spacings from 50 nm to 3 μm, for silicon etch depths of both 220 nm and 300 nm. Residual thickness variations of approximately 1 nm are obtained for narrow features with spacings between 50 nm and 500 nm, rising to approximately 7 nm for large 3 μm trenches. Inter-layer optical transitions between silicon and silicon nitride single-mode waveguides exhibit insertion losses as low as 0.3 dB per interface, confirming the optical quality of the planarized layers. These results establish bilayer HSQ contact planarization as a practical, high-performance approach for silicon-silicon nitride multilayer photonic platforms.

We demonstrate supercontinuum generation expanding over 2.27 octaves from 1.55 µ m to 7.5 µ m wavelength in suspended silicon waveguides, harnessing metamaterial cladding to tailor dispersive waves position.

In this paper, we present the development of a multilayer silicon-silicon nitride platform for dense optical phased arrays. We demonstrate the viability of this platform achieving low propagation losses of 1.3 dB/cm and 2.55 dB/com for single mode waveguides realized in the silicon and silicon nitride layers, respectively.

Suspended silicon waveguides with metamaterial cladding are used to implement a spatial heterodyne Fourier transform (SHFT) spectrometer operating near 5.5 μ$m$ wavelength. This device offers a resolution of 13 cm -1 and bandwidth of 100 cm -1.

Integrated optomechanics finds increasingly broadening applications. Here, we propose and demonstrate a novel approach to simultaneously confine optical and mechanical modes in non-suspended silicon resonators using subwavelength structuration. A record acoustic quality factor of up to 1280 is achieved under ambient conditions and room temperature.

Photonic integration in a silicon nitride (SiN) platform enables low propagation losses and a wide transparency range, making it ideal for quantum applications. However, polarization control in SiN is challenging because of its low birefringence. This work demonstrates polarization beam splitters using asymmetric directional couplers in SiN, designed for 950 nm and 1300 nm wavelengths. These devices exhibit low insertion losses (<1 dB) and high polarization extinction ratios (20 dB-30 dB).

We demonstrated a supercontinuum generation with multiple dispersive waves introduced by quasi-phase-matching through dispersion modulation in a Si3N4 waveguide when the pump is in the normal dispersion region.

Nonlinear frequency conversion is crucial for reaching new optical frequencies and creating light sources that are essential for research and industrial applications. Among the various strategies to generate a multispectral source, supercontinuum generation (SCG), which is the extreme spectral broadening from a pulsed laser source, is suitable for various applications in metrology, imaging, spectroscopy, and optical communications. While initially developed based on optical fibers, tremendous advancements in photonic integrated waveguides have been performed to benefit precise dispersion control, high nonlinearity, and compact size. The fast development of integrated platforms enables new nonlinear processes that go beyond classical SCG, pushing on-chip SCG toward practical applications. This review will begin with the SCG principle in the cubic χ (3) nonlinear process. Then we analyze recent advances in silicon nitride (SiN) for advanced dispersion, high-nonlinearity III–V platform for efficient SCG and lithium niobate (LN), which exploits both χ (2) and χ (3) nonlinearities. Finally, we present a comprehensive discussion of targeted applications, detailing their specific requirements for SCG performance. This analysis provides a forward-looking perspective on the future capabilities of on-chip SCG.

In this work, we demonstrate a substantial enhancement in photoluminescence from semiconducting single-walled carbon nanotubes through integration with a small-mode-volume silicon photonic crystal nanobeam cavity. Our design approach enables precise control of the cavity resonance over a wavelength range exceeding 30 nm, effectively covering the emission spectrum of semiconducting single-walled carbon nanotubes while maintaining stable optical performance. The fabricated nanobeam cavities, embedded with polymer-sorted semiconducting single-walled carbon nanotubes, exhibit low modal volumes of V = 0.07(λ/n)3, facilitating strong light-matter interaction characterized by high coupling efficiency and a Purcell factor on the order of 10000(λ/n)3 at a wavelength of 1570 nm. This hybrid integration exploits the robust light-matter interaction properties of the cavity, leading to a pronounced increase in emission intensity from the carbon nanotubes.

Optical antennas are key components of an optical phased array system, enabling light coupling between the chip and the free space. In such systems, surface gratings are commonly used as antenna elements, which however suffer from a strong polarization sensitivity of their scattering angle and efficiency. Here, we propose a versatile approach to realize micro antennas based on surface gratings with a polarization insensitive behavior exploiting a subwavelength metamaterial in the silicon-on-insulator platform. In the experimental demonstration, the antenna successfully achieves the same diffraction angle of 10° for both TE and TM polarizations and an estimated scattering efficiency of -4 dB despite a very compact footprint of 6.4 $$\mu m$$ x 2.9 $$\mu m$$ . The difference in diffraction efficiency between the two polarizations remains smaller than 1 dB over a bandwidth of 31 nm.