arXiv subjects

Marc Jankowski

Publications and source records attributed to Marc Jankowski.

26 records · Page 2Linked to original sources

arXiv2021

Dispersion-engineered $χ^{(2)}$ nanophotonics: a flexible tool for nonclassical light

This article reviews recent progress in quasi-phasematched $χ^{(2)}$ nonlinear nanophotonics, with a particular focus on dispersion-engineered nonlinear interactions. Throughout this article, we establish design rules for the bandwidth and interaction lengths of various nonlinear processes, and provide examples for how these processes can be engineered in nanophotonic devices. In particular, we apply these rules towards the design of sources of non-classical light and show that dispersion-engineered devices can outperform their conventional counterparts. Examples include ultra-broadband optical parametric amplification as a resource for measurement-based quantum computation, dispersion-engineered spontaneous parametric downconversion as a source of separable biphotons, and synchronously pumped nonlinear resonators as a potential route towards single-photon nonlinearities.

physics.optics↗

arXiv2021

Mid-infrared nonlinear optics in thin-film lithium niobate on sapphire

Periodically poled thin-film lithium niobate (TFLN) waveguides have emerged as a leading platform for highly efficient frequency conversion in the near-infrared. However, the commonly used silica bottom-cladding results in high absorption loss at wavelengths beyond 2.5 $μ$m. In this work, we demonstrate efficient frequency conversion in a TFLN-on-sapphire platform, which features high transparency up to 4.5 $μ$m. In particular, we report generating mid-infrared light up to 3.66 $μ$m via difference-frequency generation of a fixed 1-$μ$m source and a tunable telecom source, with normalized efficiencies up to 200%/W-cm$^2$. These results show TFLN-on-sapphire to be a promising platform for integrated nonlinear nanophotonics in the mid-infrared.

physics.optics↗

arXiv2021

Ultra-low-power second-order nonlinear optics on a chip

Second-order nonlinear optical processes are used to convert light from one wavelength to another and to generate quantum entanglement. Creating chip-scale devices to more efficiently realize and control these interactions greatly increases the reach of photonics. Optical crystals and guided wave devices made from lithium niobate and potassium titanyl phosphate are typically used to realize second-order processes but face significant drawbacks in scalability, power, and tailorability when compared to emerging integrated photonic systems. Silicon or silicon nitride integrated photonic circuits enhance and control the third-order optical nonlinearity by confining light in dispersion-engineered waveguides and resonators. An analogous platform for second-order nonlinear optics remains an outstanding challenge in photonics. It would enable stronger interactions at lower power and reduce the number of competing nonlinear processes that emerge. Here we demonstrate efficient frequency doubling and parametric oscillation in a thin-film lithium niobate photonic circuit. Our device combines recent progress on periodically poled thin-film lithium niobate waveguidesand low-loss microresonators. Here we realize efficient >10% second-harmonic generation and parametric oscillation with microwatts of optical power using a periodically-poled thin-film lithium niobate microresonator. The operating regimes of this system are controlled using the relative detuning of the intracavity resonances. During nondegenerate oscillation, the emission wavelength is tuned over terahertz by varying the pump frequency by 100's of megahertz. We observe highly-enhanced effective third-order nonlinearities caused by cascaded second-order processes resulting in parametric oscillation. These resonant second-order nonlinear circuits will form a crucial part of the emerging nonlinear and quantum photonics platforms.

physics.optics↗

arXiv2019

Ultrabroadband Nonlinear Optics in Nanophotonic Periodically Poled Lithium Niobate Waveguides

Quasi-phasematched interactions in waveguides with quadratic nonlinearities enable highly efficient nonlinear frequency conversion. In this article, we demonstrate the first generation of devices that combine the dispersion-engineering available in nanophotonic waveguides with quasi-phasematched nonlinear interactions available in periodically poled lithium niobate (PPLN). This combination enables quasi-static interactions of femtosecond pulses, reducing the pulse energy requirements by several orders of magnitude, from picojoules to femtojoules. We experimentally demonstrate two effects associated with second harmonic generation. First, we observe efficient quasi-phasematched second harmonic generation with <100 fJ of pulse energy. Second, in the limit of strong phase-mismatch, we observe spectral broadening of both harmonics with as little as 2-pJ of pulse energy. These results lay a foundation for a new class of nonlinear devices, in which co-engineering of dispersion with quasi-phasematching enables efficient nonlinear optics at the femtojoule level.

physics.optics↗

arXiv2018

Ultrahigh-efficiency second-harmonic generation in nanophotonic PPLN waveguides

Periodically poled lithium niobate (PPLN) waveguide is a powerful platform for efficient wavelength conversion. Conventional PPLN converters however typically require long device lengths and high pump powers due to the limited nonlinear interaction strength. Here we use a nanostructured PPLN waveguides to demonstrate an ultrahigh normalized efficiency of 2600%/W-cm$^2$ for second-harmonic generation of 1.5-$μ$m radiation, more than 20 times higher than that in state-of-the-art diffused waveguides. This is achieved by a combination of sub-wavelength optical confinement and high-fidelity periodic poling at a first-order poling period of 4 $μ$m. Our highly integrated PPLN waveguides are promising for future chip-scale integration of classical and quantum photonic systems.

physics.app-ph↗

arXiv2017

Temporal Simultons in Optical Parametric Oscillators

We identify and demonstrate a regime of operation in optical parametric oscillators (OPOs) in which the formation of temporal simultons produces stable half-harmonic pulses. Simultons are simultanous bright-dark solitons of a signal field at frequency $ω$ and the pump field at $2ω$ which form in a quadratic nonlinear medium. The formation of simultons in an OPO is evidenced by sech$^2$ spectra with broad instantaneous bandwidths which increase with pump power, and large slope efficiencies. In contrast to conventional synchronously pumped OPOs, operation in this regime is achieved by using relatively large parametric gains, and a low finesse resonator detuned to a slightly longer roundtrip time than the pump repetition period. In the experiment we achieve sub-50 fs sech$^2$ pulses with a slope efficiency of 570%, and a conversion efficiency of 55% as a result of formation of simultons in an OPO. We verify the distinct features of OPO operation in the simulton regime analytically and numerically. These results represent a fundamental shift in the understanding and design of OPOs, in which the nonlinear dynamics that arise during asynchronous operation can be used to efficiently generate few-cycle long-wavelength frequency combs.

physics.optics↗

arXiv2016

Reduced models and design principles for half-harmonic generation in synchronously-pumped optical parametric oscillators

We develop reduced models that describe half-harmonic generation in a synchronously-pumped optical parametric oscillator above threshold, where nonlinearity, dispersion, and group-velocity mismatch are all relevant. These models are based on (1) an eigenmode expansion for low pump powers, (2) a simulton-like sech-pulse ansatz for intermediate powers, and (3) dispersionless box-shaped pulses for high powers. Analytic formulas for pulse compression, degenerate vs. nondegenerate operation, and stability are derived and compared to numerical and experimental results.

physics.optics↗

arXiv2015

Cascaded half-harmonic generation of femtosecond frequency combs in mid-IR

For the growing demand of frequency combs in mid-infrared (mid-IR), known as the "molecular fingerprint" region of the spectrum [1], down conversion of near-IR frequency combs through half- harmonic generation offers numerous benefits including high conversion efficiency and intrinsic phase and frequency locking to the near-IR pump [2]. Hence cascaded half-harmonic generation promises a simple path towards extending the wavelength coverage of stable frequency combs. Here, we report a two-octave down-conversion of a frequency comb around 1 μm through cascaded half-harmonic generation with ~64% efficiency in the first stage, and ~18% in the second stage. We obtain broadband intrinsically-frequency-locked frequency combs with ~50-fs pulses at ~2 μm and ~110-fs pulses at ~4 μm. These results indicate the effectiveness of half-harmonic generation as a universal tool for efficient phase- and frequency-locked down-conversion, which can be beneficial for numerous applications requiring long-wavelength coherent sources.

physics.optics↗