Optical neuromorphic computing marks a breakthrough over traditional digital computing by offering energy-efficient, fast, and parallel processing solutions while challenges remain in incorporating nonlinearity efficiently. Leveraging nonlinear wave dynamics in optical fibers as a computational resource may provide a solution. Our research demonstrates how femtosecond pulse propagation in optical fibers can emulate neural network inference, utilizing the high phase sensitivity of broadband light for creating nonlinear input-output mappings akin to Extreme Learning Machines (ELMs). Experimental results show high classification accuracies and low RMS errors in function regression, all at pico-joule pulse energy. This indicates our method's potential to lower energy consumption for inference tasks, complementing existing spatial-mode systems. We also investigated femtosecond pulses' nonlinear broadening effects – self-phase modulation and coherent soliton fission – demonstrating their distinct impacts on classification tasks and showcasing broadband frequency generation as a powerful, energy-efficient tool for next-generation computing.
The precise control over optical pulse parameters in fiber systems is crucial in many applications. Our research focuses on optimizing optical femtosecond pulses for nonlinear optics, addressing challenges in fiber-based systems with dispersion and nonlinearity. Utilizing spectral phase control and optimization algorithms like particle swarm and simulated annealing, we fine-tune a complex phase mask for desired pulse shapes. Our method involves custom phase-profile optimization via spectral-domain phase modulation to compensate for nonlinear effects in pulse delivery. Using a chirped femtosecond source and a fiber amplifier, our implemented optimization scheme produces near-transform-limited pulses after propagation in polarization-maintaining fiber. This approach accommodates diverse pulse durations, showcasing the effectiveness of off-the-shelf programmable components with optimization algorithms in nonlinear optics and optical signal processing applications.
Our latest work in softphotonics features the seamless integration of liquid-core fibers into standard fiber systems, achieving unprecedented advancements in nonlinear optics and signal processing. Utilizing liquids like CS2 and halocarbonates, we have developed a reliable splicing technique with standard fibers, enabling low-loss all-fiber interconnectivity. This breakthrough provides insights into intra-fiber thermodynamics and enables robust, long-term applications in optical signal processing in the near-infrared. Our method opens new avenues for exploring negative pressures and facilitating multi-laser excitation for cross-phase modulation, showcasing the potential of liquid-filled fibers in future optical technologies.
Our research in neuromorphic computing leverages nonlinear optical dynamics to emulate neural network functionalities. In our experiments, we explore supercontinuum generation and other complex wave dynamics for information processing in the optical domain. Utilizing spectral-domain phase modulation and nonlinear femtosecond pulse broadening in multiple nonlinear fibers, we demonstrate effective data encoding and processing followed by a read-out layer training, akin to Extreme Learning Machines. Our benchmarks on diverse datasets showcase the scalability and inference capabilities of our system, and the distinct performance differences of two nonlinear domains, i.e. self-phase modulation and soliton fission. This work opens new avenues in quantifying physics-based analog computing platforms, suggesting implications for green computing, Big Data communications, and intelligent diagnostics.
Time-entanglement is a promising resource for the implementation of quantum communications over standard fiber networks. In particular, photonic qudits can enhance the performance of quantum communication, including quantum key distribution, in terms of noise robustness, quantum information content, distance reach, as well as security and secret key rates. However, time-entangled photonic qudits are not ready yet to be fully exploited for quantum communications in fiber networks that are fully compatible with standard telecommunication architecture. Here, we demonstrate the implementation of telecommunication-compatible quantum communications based on picosecond-spaced time-entangled qudits. To this end, we make use of an integrated photonic chip comprising a cascade of programmable interferometers and a spiral waveguide. We use entangled qudits to implement high-speed quantum key distribution, chip-to-chip entanglement distribution, and quantum state propagation over 60 km of standard fiber. Our results show the potential of time-entangled qudits for high-speed quantum communications in telecommunication-compatible architecture.
Quantum technologies harness nonclassical features of particles, here, photons, to develop novel, efficient, and precise devices for information processing applications. Superposition, entanglement, as well as the coherent manipulation of quantum states are at the heart of the second quantum revolution (quantum 2.0) which targets the development of secure cryptographic systems, complex computation protocols, and more. Emerging quantum architectures rely on the realistic implementation of photonic schemes which are scalable, resource-efficient, and compatible with CMOS technologies as well as fiber networks. This work demonstrates current schemes utilized for time-/frequency-bin entanglement generation and processing by leveraging existing telecommunications and integrated photonics infrastructures.
We review our work on implementing integrated QFC sources based on microring resonators for on-chip generation of two- and multi-photon time-bin entangled states, d-level frequency-entangled photon pairs, and multipartite d-level cluster states. We also present our recent progress on telecom-compatible, scalable, time-entangled two-photon qubits using on-chip Mach-Zehnder interferometers (MZI) in combination with spiral waveguides. Both approaches are highly cost-effective, efficient, and practical, since we coherently manipulate the time and frequency modes through standard fiber-linked components that are compatible with off-the-shelf telecommunications infrastructures. Our work paves the way for robust sources and processors of complex photon states for future quantum technologies.
In this contribution we report on a novel approach for pump and stokes pulse generation in extremely compact all-fiber
systems using parametric frequency conversion (four-wave-mixing) in photonic-crystal fibers. Representing a
completely alignment-free approach, the all-fiber ytterbium-based short-pulse laser system provides intrinsically
synchronized tunable two-color picosecond pulses emitted from a single fiber end. The system was designed to address
important CH-stretch vibrational resonances. Strong CARS signals are generated and proved by spectroscopic
experiments, tuning the laser over the resonance of toluene at 3050cm-1. Furthermore the whole laser setup with a
footprint of only 30x30cm2 is mounted on a home-built laser-scanning-microscope and CARS imaging capabilities are
verified. The compact turn-key system represents a significant advance for CARS microscopy to enter real-world, in
particular bio-medical, applications.
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