摘要 :
The excellent optical and unique material properties of lithium niobate have long established it as a prevailing photonic material, especially for the long-haul telecom modulator and wavelength-converter applications. However, con...
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The excellent optical and unique material properties of lithium niobate have long established it as a prevailing photonic material, especially for the long-haul telecom modulator and wavelength-converter applications. However, conventional lithium niobate optical waveguides are bulky, hence large-scale photonic circuit implementations are impeded and high power requirements are imposed. To address these shortcomings, thin-film lithium niobate technology has been a topic of intense research in the last few years and a plethora of ultracompact devices with significantly superior performances than the conventional counterparts have been demonstrated. These efforts have rejuvenated lithium niobate for novel electro-, nonlinear-, and quantum-optic applications. Herein, the most recent advancements of this booming field are summarized and a perspective for future directions is given.
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摘要 :
Photonics on thin-film lithium niobate (TFLN) has emerged as one of the most pursued disciplines within integrated optics. Ultracompact and low-loss optical waveguides and related devices on this modern material platform have reju...
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Photonics on thin-film lithium niobate (TFLN) has emerged as one of the most pursued disciplines within integrated optics. Ultracompact and low-loss optical waveguides and related devices on this modern material platform have rejuvenated the traditional and commercial applications of lithium niobate for optical modulators based on the electro-optic effect, as well as optical wavelength converters based on secondorder nonlinear effects, e.g., second-harmonic, sum-, and difference-frequency generations. TFLN has also created vast opportunities for applications and integrated solutions for optical parametric amplification and oscillation, cascaded nonlinear effects, such as low-harmonic generation; third-order nonlinear effects, such as supercontinuum generation; optical frequency comb generation and stabilization; and nonclassical nonlinear effects, such as spontaneous parametric downconversion for quantum optics. Recent progress in nonlinear integrated photonics on TFLN for all these applications, their current trends, and future opportunities and challenges are reviewed.
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摘要 :
Spatially-variant photonic crystals (SVPCs), in which the orientation of the unit cell changes as a function of position, are shown to be capable of abruptly controlling light beams using just low index materials and can be made t...
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Spatially-variant photonic crystals (SVPCs), in which the orientation of the unit cell changes as a function of position, are shown to be capable of abruptly controlling light beams using just low index materials and can be made to have high polarization selectivity. Multi-photon direct laser writing in the photo-polymer SU-8 was used to fabricate three-dimensional SVPCs that direct the flow of light around a 90 degree bend. The lattice spacing and fill factor were maintained nearly constant throughout the structure. The SVPCs were characterized at a wavelength of 2.94 μm by scanning the faces with optical fibers and the results were compared to electromagnetic simulations. The lattices were shown to direct infrared light of one polarization through sharp bends while the other polarization propagated straight through the SVPC. This work introduces a new scheme for controlling light that should be useful for integrated photonics.
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摘要 :
We generate quantum-correlated photon pairs using cascaded χ(2):χ(2)?(2):?(2)\mathrm {\chi ^{(2)}:\chi ^{(2)}} traveling-wave interactions for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC) in...
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We generate quantum-correlated photon pairs using cascaded χ(2):χ(2)?(2):?(2)\mathrm {\chi ^{(2)}:\chi ^{(2)}} traveling-wave interactions for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC) in a single periodically-poled thin-film lithium-niobate (TFLN) waveguide. When pulse-pumped at 50MHz, a 4-mm-long poled region with nearly 300%/Wcm2 SHG peak efficiency yields a generated photon-pair probability of 7±0.2×10?4 with corresponding coincidence-to-accidental ratio (CAR) of 13.6±0.7. The CAR is found to be limited by Stokes/anti-Stokes Raman-scattering noise generated primarily in the waveguide. A Raman peak of photon counts at 250?cm?1 Stokes shift from the fundamental-pump wavenumber suggests most of the noise that limits the CAR originates within the lithium niobate material of the waveguide.
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摘要 :
We propose, simulate and experimentally demonstrate a method for realizing spatially-mapped birefringence onto integrated photonic devices and circuits. The fabrication method is based on applying a damascene-like process to diele...
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We propose, simulate and experimentally demonstrate a method for realizing spatially-mapped birefringence onto integrated photonic devices and circuits. The fabrication method is based on applying a damascene-like process to dielectric film stacks to form anisotropic optical waveguides. An integrated polarizing beam-splitter (PBS) is realized with unprecedented performance: a record 0.52 octaves of fractional bandwidth (116 THz), maximum on-chip insertion loss of 1.4 ± 0.8 dB, and a minimum extinction ratio of 16 ± 3 dB, pushing it into the realm of wideband spectroscopy and imaging applications. Additionally, photonic structures such as polarization-selective beam-taps and polarization-selective microring resonators are demonstrated.
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摘要 :
Chip-scale implementations of second-order nonlinear optics benefit from increased optical confinement that can lead to nonlinear interaction strengths that are orders of magnitude higher than bulk free-space configurations. Here,...
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Chip-scale implementations of second-order nonlinear optics benefit from increased optical confinement that can lead to nonlinear interaction strengths that are orders of magnitude higher than bulk free-space configurations. Here, we present thin-film-based ultraefficient periodically-poled lithium niobate nonlinear waveguides, leveraging actively-monitored ferroelectric domain reversal engineering and nanophotonic confinement. The devices exhibit up to 4600?%W?1cm?2 conversion efficiency for second-harmonic generation, pumped around 1540 nm. In addition, we measure broadband sum-frequency generation across multiple telecom bands, from 1460 to 1620 nm. As an immediate application of the devices, we use pulses of picojoule-level energy to demonstrate second-harmonic generation with over 10% conversion in a 0.6-mm-long waveguide. Our ultracompact and highly efficient devices address growing demands in integrated-photonic frequency conversion, frequency metrology, atomic physics, and quantum optics, while offering a coherent link between the telecom and visible bands.
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An efficient source of quantum-correlated photon-pairs that is integrable with existing silicon-electronics fabrication techniques is desirable for use in quantum photonic integrated circuits. Here we demonstrate signal-idler phot...
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An efficient source of quantum-correlated photon-pairs that is integrable with existing silicon-electronics fabrication techniques is desirable for use in quantum photonic integrated circuits. Here we demonstrate signal-idler photon pairs with high coincidence-to-accidental count ratios of over 103 on a coarse wavelength-division-multiplexing grid that spans 140nm by using a 300-μm-long poled region in a thin-film periodically-poled lithium-niobate ridge waveguide bonded to silicon. The pairs are generated via spontaneous parametric downconversion pumped by a continuous-wave tunable laser source. The small mode area of the waveguide allows for efficient interaction in a short length of the waveguide and, as a result, permits photon-pair generation over a broad range of signal-idler wavelengths.
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摘要 :
The technology for compact thin-film lithium niobate electrooptic modulators has made significant advances recently. With achieving high levels of maturity for such platforms, a model is now required in order to accurately design ...
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The technology for compact thin-film lithium niobate electrooptic modulators has made significant advances recently. With achieving high levels of maturity for such platforms, a model is now required in order to accurately design the devices and reliably predict their performance limits. In this paper, a general transmission-line model is developed for predicting the frequency-dependent response of the compact modulators. The main radio frequency (RF) parameters of the modulators, such as characteristic impedance, effective index, and attenuation constant are calculated as a function of the coplanar waveguide dimensions, and validated by using numerical simulations. The accuracy of the model in predicting the 3-dB modulation bandwidth of the devices is verified by comparison with experimental results. Finally, guidelines for device design with significant improvement in the attainable modulation bandwidth are also presented by optimization of RF and optical parameters, predicting
$>$
100 GHz modulation bandwidth. The presented model is not limited to emerging thin-film lithium niobate devices, and is applicable to any type of ultracompact electrooptic modulator.
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This paper presents the case for the silicon Raman laser as a potential source for the technologically important midwave infrared (MWIR) region of the optical spectrum. The mid-IR application space is summarized, and the current p...
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This paper presents the case for the silicon Raman laser as a potential source for the technologically important midwave infrared (MWIR) region of the optical spectrum. The mid-IR application space is summarized, and the current practice based on the optical parametric oscillators and solid state Raman lasers is discussed. Relevant properties of silicon are compared with popular Raman crystals, and linear and nonlinear transmission measurements of silicon in the mid-IR are presented. It is shown that the absence of the nonlinear losses, which severely limit the performance of the recently demonstrated silicon lasers in the near IR, combined with unsurpassed crystal quality, high thermal conductivity and excellent optical damage threshold render silicon a very attractive Raman medium, even when compared to the very best Raman crystals. In addition, silicon photonic technology, offering integrated low-loss waveguides and microcavities, offers additional advantages over today's bulk crystal Raman laser technology. Using photonic crystal structures or microring resonators, the integrated cascaded microcavities can be employed to realize higher order Stokes emission, and hence to extend the wavelength coverage of the existing pump lasers. Exploiting these facts, the proposed technology can extend the utility of silicon photonics beyond data communication and into equally important applications in biochemical sensing and laser medicine
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摘要 :
This paper presents the recent progress on integrated second-order
nonlinear waveguides on silicon substrates for second-harmonic generation.
In particular, demonstrations of thin-film lithium niobate, III–V
compound semicondu...
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This paper presents the recent progress on integrated second-order
nonlinear waveguides on silicon substrates for second-harmonic generation.
In particular, demonstrations of thin-film lithium niobate, III–V
compound semiconductor and dielectric waveguides integrated on silicon
substrates are reviewed. For completeness, the fundamentals of the
nonlinear optical processes involved are briefly introduced. Methods
demonstrated for phase matching, e.g., periodic poling and mode-shape
modulation, in the compact integrated devices are discussed. Finally, an
outlook for how integrated photonics may benefit from the progress in
this field is provided.
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