Nonlinear chalcogenide microresonators and microspheres are an ideal platform to explore nonlinear optical effects in a compact footprint. Chalcogenide glasses are particularly attractive, with high nonlinearities and long wavelength transparency. Applications including, cascaded Brillouin generation, photosensitive control, sensing and frequency comb generation.

Cylindrical micro-resonators with normal dispersion are seen to support photonic snake states. These are a type of two-dimensional zig-zag solitonic wave arising via the control of the well-known snaking instability, discovered 50 years ago and ever since observed as an uncontrollable one in classical and quantum fluids, Bose-Einstein condensates, chemical reactions, and optics, amongst others. The spectrum of Photonic snakes is a two-dimensional continuous collection frequency combs featuring heterogeneity and intrinsic synchronization. The conditions for their existence, robustness, and deterministic excitation routes are identified. Applications such as spectroscopy, metrology, or communications may benefit by this new paradigm of micro-comb formation.

We present a terahertz-carrier frequency comb based on Kerr-Induced Synchronization (KIS) of an Optical Frequency Comb (OFC), wherein a commercially available C-band laser harnesses an OFC tooth and captures the repetition rate (frep) of the OFC. The linear relationship between the C-band laser modulation and the OFC frep modulation enables direct transfer of the C-band laser frequency to the OFC frep. In addition, the large KIS effect bandwidth facilitates frep tuning over a wide range of frequencies. This work addresses the THz gap by providing a direct path for millimeter wave generation, utilizing CMOS-compatible fabrication techniques and off-the-shelf components.

Recent works have demonstrated how silicon nitride integrated photonics can be endowed with photoinduced second-order nonlinearities for efficient frequency conversion. Here we will showcase how highly-efficient second-harmonic generation in a microresonator can be combined with self-injection locking to a DFB laser to create a standalone dual-wavelength displaying high output power, conversion efficiency and hertz-level coherence in an integrated fashion. We will also cover how the photoinduced nonlinearity can trigger cascaded effects, expanding the operation range and functionality of the microresonator, and discuss how silicon nitride microrings can be further mode engineered to provide combined high efficiency and wide tunability of the nonlinear processes.

Driven solitons are currently attracting a lot of attention both for their fundamental interest and potential applications in metrology and spectroscopy In this talk, I will discuss our recent results on novel driven solitons such as active solitons (in a laser cavity pumped below the lasing threshold), parametrically driven solitons (both quadratically and cubically driven) as well as soliton trapped in a phase modulation potential.

We show that in the Kerr-Induced Synchronization (KIS) regime, an external reference pump laser allows for the control of the opposite (in frequency) Dispersive Wave (DW) power and frequency, through self-balancing of the cavity soliton. We report an increase of more than 20~dB of the DW of an octave-spanning comb at 780 nm, with a reference pump in the telecom C-band, while tuning of the DW over three comb teeth. Our work paves the way for significant improvement of the carrier-envelope offset frequency detection of octave-spanning combs.

We demonstrate that a dissipative Kerr soliton comb tooth can be captured by another injected pump laser, resulting in Kerr induced synchronization. This regime is highly significant for metrology applications, where the soliton can passively lock onto a reference clock laser. The dynamics of the system also enable other forms of locking, where the comb tooth is captured at a fixed offset from the reference laser, entering the syntonization regime. Similar to breather entrainment, we establish that the syntonization frequency offset correlates with the soliton's repetition rate.

We demonstrate high frequency stability, low phase noise photonic oscillator based on optical self-injection locked laser pumping of silicon nitride integrated microresonator comb (microcomb), and frequency locking of comb teeth to temperature insensitive high finesse Fabry Perot cavity.

We demonstrate the versatility of dielectric metasurfaces as a compact, efficient and multifunctional platform to trap single atoms in a tweezer trap, and an ensemble of atoms in a magneto-optical-trap (MOT) for various AMO applications.

Nonlinear frequency generation is demonstrated in silicon nitride photonics using microring resonators with engineered dispersion through a Bragg grating perturbation. The processes by which these nonlinear effects occur introduces backscattered light, due to bidirectionally-propagating hybridized modes. Such backscattered light is often detrimental to the pump laser and imposes a limit on the power that can be delivered to the ring system, reducing the operating range of ring resonators for nonlinear light generation. We mitigate these effects with an on-chip passive optical isolator, which protects the pump laser from backscattered light, allowing for higher pump power operation regimes. Furthermore, we introduce a recycling channel that allows for power to be re-pumped into the mirroring resonator to enable controllable exploration into more interesting nonlinear optics phenomena.

Silicon carbide as a host material uniquely combines CMOS compatible photonics with high-quality optically interfaced qubits and strong optical nonlinearities. In this talk, I will discuss the use of silicon carbide microresonators to explore multimode correlations built through spontaneous pair generation via the optical nonlinearity as well as all-to-all coupling of quantum emitters. I will discuss opportunities to use inverse design and as well as classical cavity design methods for engineering these correlations.

We present a methodology to distinguish between absorptive and scattering losses in SiN optical waveguide resonators by measuring the thermo-optic redshift in resonant wavelength and deducing absorption losses using thermal properties determined through the differential 3ω method. This information offers researchers valuable insights for improving device performance and optimizing fabrication processes. We demonstrate results on the effect of a 650oC thermal anneal on R=120um whispering-gallery mode microring resonators fabricated using N-rich PECVD SiN with n=1.92 at 800nm, which reduced total losses from 1.4dB/cm to 0.64dB/cm at 780nm and yielded an intrinsic-Q of 1.1 million, due primarily to decreased absorption losses.

Commonly, the spectra of high Q-factor microresonators are fixed or only weakly tunable, which limits their versatility. To address this limitation, we demonstrate continuous tunability of the axial Free Spectral Range (FSR) of parabolic microresonators created by bending a 125 μm radius optical fiber segment. By controlling the bent fiber profile with linear stages affixed to its ends, we vary its FSR between 1.9 pm and 2.7 pm for more than 65 equally spaced eigenmodes. We show that the FSR tunability can be achieved with precision better than 0.2 pm. The demonstrated tunability, together with the inherently small FSR of our parabolic microresonators, unlock their potential applications including optical frequency comb generation and frequency conversion.

Optical photons are excellent quantum information carriers, but weak optical nonlinearity poses significant challenges to the scalability and computational capabilities of these systems. Currently, only probabilistic methods can achieve nonlinear quantum operations crucial for universality and fault tolerance, restricting the clock speed and making it challenging to scale due to significant resource overhead. Ultrafast quantum nanophotonics with second-order optical nonlinearity presents a potential solution to overcome these challenges. In this talk, we will discuss recent experimental advances, including the on-chip generation and measurement of ultra-broadband squeezed states, all-optical realizations of switching and nonlinear functions for ultrafast feedforward operations, and widely tunable optical parametric oscillators in an emergent thin-film lithium niobate on insulator platform. We further delve into how the enhanced optical nonlinearity can enable novel functionalities such as photon-number-resolving measurements and deterministic quantum state engineering, offering a practical path to scalable, fault-tolerant quantum information processors room-temperature.

We present a comprehensive investigation of the period chirp, a detrimental effect originating from the lithographic step in the fabrication of holographic gratings. Starting from the origin of the period chirp we discuss its measurement, its effects on the compressed pulses when chirped gratings are used in pulse compressors, and finally, we show possible ways to eliminate the period chirp directly in the fabrication.

In this report, we demonstrate two novel fundamental notions in the counter-propagating nonlinear interaction scheme, namely mode rejection and all-optical gratings. We consider a probe Forward Signal (FS) and a counter-propagating Backward Control Beam (BCB) that are launched at the opposite ends of a multimode and multicore fibre. When both the FS and the CB are in a strong nonlinear regime, a FS with arbitrary modal state undergoes the suppression of a specific spatial mode that is fixed by the CB, which we name mode rejection. When the FS and the CB are respectively in a weak and a strong nonlinear regime, the CB plays the role of an all-optical grating for the FS. This dynamic is exploited to achieve key-all optical operations for the multimode platform, including tunable power splitting, power combining, and power switching.

Laser-based secondary sources of radiation in the soft X-ray and EUV range have the potential for imaging at the smallest spatial and temporal scales, given their wavelength range and ultrashort duration (fs or under). Recently novel degrees of freedom of light beam manipulation have been extended into the high intensity regime, to enhance their emissivity or expand their capability. We have used these pulse shaping techniques to generate coherent EUV sources, where High Harmonics from laser-gas interaction are seen to reproduce IR wavefront shaping and can generate light tubes with Orbital Angular Momentum using EUV optics. At close to relativistic intensities, we have performed simulations that show that structured laser pulses can also improve the performance of incoherent plasma-based x-ray sources. The outcomes of these simulations, as well as optimization strategies and applications, will be presented.

Beam shaping has gained increasing importance in laser-based processing, offering enhanced efficiency, quality, and precision across various applications. This paper discusses the challenges of characterizing and defining criteria for evaluating shaped beams in laser material processing. It highlights the essential role of beam shaping in Continuous Wave (CW) processes like high-quality welding for e-mobility and pulsed applications like surface texturing. Various beam shaping technologies are explored, and criteria such as efficiency, uniformity, sharpness, robustness, and depth of field are proposed for evaluating beam performance. Proper characterization and evaluation of shaped beams are crucial to optimize laser performance, ensuring reliable and repeatable outcomes in laser-based processes.

We show, both theoretically and experimentally, that it is possible to determine a nonuniform temperature distribution along a SNAP microresonator from a single measurement of its spectrum. In our experiment, we use a silica microcapillary containing a SNAP microresonator. The microcapillary is filled with water and locally heated with a moving heating source (light-pumped microfiber) introducing the temperature distribution parameterized as T(z)=T_0 exp(-|z-z_Q+iw|/L), where z is the coordinate along the microcapillary axis, z_Q is the heating source position, and w≪L is the width of the source. At each heating source position z_Q, we restore the parameters of this distribution from the SNAP microresonator spectrum. Our theoretical calculations are in a good agreement with the experimental data.

Due to the local nature of the interactions in nonlinear photonic topological insulators, attempts to describe their topology using traditional band structure approaches are not suitable. Here, we develop a general framework for classifying the topology of nonlinear materials. Using the so-called spectral localizer to define local topological markers, we provide a quantitative definition of topologically non-trivial nonlinear modes that are distinguished by the appearance of a topological interface surrounding the mode. Moreover, we show how the spectral localizer can be used to probe the time-evolution of nonlinearly induced topological domains within a system.

We report a high power Yb:YAG thin disk laser with cylindrical vector polarization incorporating an intracavity S-waveplate. By adjusting the angle of the S-waveplate in the resonator, we could select a cylindrical vector polarization state of the laser output, radial or azimuthal polarization, in the Yb:YAG thin disk laser resonator. The laser yielded ⪆10 W of both radial or azimuthal polarized output for incident pump power of 131 W in continuous-wave mode of operation, corresponding to the slope efficiency of ⪆18%. Output characteristics will be discussed in detail.