Described here is a concept for a variable-altitude aerobot mission to Venus developed as part of the 2020 NASA Planetary Science Summer School in collaboration with NASA Jet Propulsion Laboratory. The Venus Air and Land Expedition: a Novel Trailblazer for in situ Exploration (VALENTInE) is a long-duration New Frontiers–class mission to Venus in alignment with the goals recommended by the 2013 Planetary Science Decadal Survey. VALENTInE would have five science objectives: (1) determine the driving force of atmospheric superrotation, (2) determine the source of D/H and noble gas inventory, (3) determine the properties that govern how light is reflected within the lower cloud later, (4) determine whether the tesserae are felsic, and (5) determine whether there is evidence of a recent dynamo preserved in the rock record. The proposed mission concept has a total duration of 15 Earth days and would float at an altitude of 55 km, along with five dips to a lower altitude of 45 km to study Venus’s lower atmosphere. The instrument payload allows for measurements of the atmosphere, surface, and interior of Venus and includes six instruments: an atmospheric weather suite, a mass spectrometer, a multispectral imager, a near-infrared spectrometer, light detection and ranging, and a magnetometer. Principle challenges included a limitation caused by battery lifetime and low technology readiness levels for aerobots that can survive the harsh conditions of Venus’s atmosphere. This preliminary mission was designed to fit within an assumed New Frontiers 5 (based on inflated New Frontiers 4) cost cap.

The past decade has seen significant growth in the field of thin film lithium niobate electro-optic modulators, which promise reduced voltage requirements and higher modulation bandwidths on a potentially integrated platform. This article discusses the state-of-the-art in thin film modulator technology and presents a simplified simulation technique for quickly optimizing a hybrid silicon- or silicon nitride-lithium niobate modulator. Also discussed are the feasibility of creating a 1 V half-wave voltage, 100 GHz bandwidth modulator, and the design specifications for a single hybrid silicon-lithium niobate platform optimized to operate across all telecommunication bands (between 1260 and 1675 nm wavelengths).

Direct time-domain sampling oscilloscopic capture of ultra-high bandwidth (32-102 GHz) modulated optical waveforms at 1550 nm is demonstrated at optical power levels below -100 dBm. To detect fast optical waveforms directly at power levels far below what traditional optical oscilloscope methods can measure, we use a time-correlated single-photon counting (TCSPC) sampling acquisition method, recently developed integrated electro-optic devices with >100 GHz electro-optic bandwidth, and single photon detectors with <; 5 ps jitter. We show the reconstruction of the time domain signals by collecting histograms of time-binned single photons captured using TCSPC and characterize the spectral components in the frequency domain. The ability to acquire ultra-weak eye diagrams and identify high-frequency spectral components from a relatively small ensemble of single-photon measurements may lead to significant advances in optical waveform capture technology.

A low-power, passive integrated photonic heterodyne interferometer with one meter of on-chip delay is demonstrated for laser frequency stabilization applications with 30 parts-per-billion accuracy. This technology can be integrated with future space-borne optical metrology systems.

ymmetric forward and backward transmission through photonic structures can be achieved via optical nonlinearities, but existing systems have typically used slow thermo-optic effects. A new resonator design has now enabled low-loss, non-reciprocal pulse routing based on the Kerr nonlinearity in integrated silicon waveguides.

Mach-Zehnder electro-optic modulators (EOM) based on thin-film lithium niobate bonded to a silicon photonic waveguide circuit have been shown to achieve very high modulation bandwidths. Open eye-diagram measurements made in the time domain of beyond-small-signal modulation are used to support the modulation-sideband measurements in showing that such EOM’s can support high-frequency modulations well beyond 100 GHz.

Time-domain sampling oscilloscopic capture of ultra-high bandwidth modulated optical waveforms at 1550 nm is demonstrated at ultra-low power levels below -100dBm, with eye SNR varying from 13dB at 30 GHz to 6dB at 100 GHz.

Lithium Niobate (LN) was the dominant material platform for integrated optics for several decades, based on its superior electro-optical and nonlinear (NL) optical properties. However, silicon photonics, despite its less favorable intrinsic properties, has been rapidly adopted by industry to support a smaller device footprint; higher component density; lower energy consumption; and compatibility with high-volume, low-cost silicon microelectronics manufacturing processes. However, the performance of LN integrated optics remains unsurpassed by silicon photonics. By adopting a thin-film technology and hybrid waveguide designs, LN and silicon photonics could both be integrated as optoelectronics layers in future 3D integrated microsystems. We discuss the multilayer device architecture vision and recently reported enabling research progress in thin-film LN technology and its integration into the silicon photonics system.

A design of a highly efficient second-harmonic generation hybrid silicon carbide (SiC)-thin-film LiNbO3 optical device is presented with a normalized nonlinear conversion efficiency as high as 1280%/(W-cm(2)). It is shown that low-loss bends and tapers in the SiC rib can be used to fold the device into any desirable aspect ratio to meet design requirements or fabrication limitations. Direct numerical integration of the coupled-wave equations is used to simulate the generated second-harmonic output power under a variety of fabrication tolerance considerations. (c) 2018 Optical Society of America.

We demonstrate an ultra-high-bandwidth Mach-Zehnder electro-optic modulator (EOM), based on foundry-fabricated silicon (Si) photonics, made using conventional lithography and wafer-scale fabrication, oxide-bonded at 200C to a lithium niobate (LN) thin film. Our design integrates silicon photonics light input/output and optical components, such as directional couplers and low-radius bends. No etching or patterning of the thin film LN is required. This hybrid Si-LN MZM achieves beyond 106 GHz 3-dB electrical modulation bandwidth, the highest of any silicon photonic or lithium niobate (phase) modulator.

A foundry-compatible hybrid silicon-lithium niobate electro-optic modulator with an optical bandwidth greater than 6 GHz is presented. Wafer-scale photolithography processing is used to fabricate silicon features before bonding to a 600 nm lithium niobate film.

We design a nonlinear waveguide for 2f-to-3f optical frequency conversion based on silicon nitride-lithium niobate and calculate high nonlinear conversion efficiencies of 898, 623, and 3169 %-W-1-cm(-2) for the processes discussed.

The bonding of silicon-on-insulator (SOI) to lithium niobate-on-insulator (LNOI) is becoming important for a new category of linear and nonlinear micro-photonic optical devices. In studying the bonding of SOI to LNOI through benzocyclobutene (BCB), a popular interlayer bonding dielectric used in hybrid silicon photonic devices, we use thermal stress calculations to suggest that BCB thickness does not affect thermal stress in this type of structure, and instead, thermal stress can be mitigated satisfactorily by matching the handles of the SOI and LNOI. We bond LNOI with a silicon handle to a silicon chip, remove the handle on the LNOI side, and thermally cycle the bonded stack repeatedly from room temperature up to 300 degrees C and back down without incurring thermal stress cracks, which do appear when using LNOI with a lithium niobate handle, regardless of the BCB thickness. We show that this process can be used to create many hybrid silicon-lithium niobate waveguiding structures on a single patterned SOI chip bonded to a large-area (16 mm x 4.2 mm) lithium niobate film. (C) 2017 The Authors. Published by Elsevier B.V.

Bonded silicon-on-insulator and lithium niobate-on-insulator dies are shown to be thermally stable up to 300° over a 67.2 mm 2 bonded area. Optical propagation through a waveguide on this bonded hybrid silicon-lithium niobate platform is performed.

A set of optical components for the hybrid silicon-lithium niobate platform is designed and tabulated as robust parameterized-cells. Eye diagrams of an IQ electro-optic modulator are simulated at 25 and 50 Gbps.

We demonstrate a photonic waveguide technology based on a two-material core, in which light is controllably and repeatedly transferred back and forth between sub-micron thickness crystalline layers of Si and LN bonded to one another, where the former is patterned and the latter is not. In this way, the foundry-based wafer-scale fabrication technology for silicon photonics can be leveraged to form lithium-niobate based integrated optical devices. Using two different guided modes and an adiabatic mode transition between them, we demonstrate a set of building blocks such as waveguides, bends, and couplers which can be used to route light underneath an unpatterned slab of LN, as well as outside the LN-bonded region, thus enabling complex and compact lightwave circuits in LN alongside Si photonics with fabrication ease and low cost.

Integrated optics devices for nonlinear optics may be made by using unpatterned thin films of a nonlinear crystal such as lithium niobate in conjunction with (for example, bonded to) an easily-patterned material such as silicon or silicon nitride which is commonly used in a silicon photonics platform. We propose and analyze a device for difference-frequency generation in a hybrid waveguide which uses the strongest nonlinear tensor coefficient without ion-exchanging, etching, or periodically-poling lithium niobate, which can considerably simplify the fabrication process.

We describe the design and operation of a silicon-photonic device for monitoring power variations of individual channels in a multi-wavelength DWDM network. Amplitude variations of ~20 dB, for channels spaced by 100 GHz, are measured.

A compact silicon photonic channelized optical spectrum monitor is designed and realized, which can replace a large rack-mounted OSA's channel power monitoring functionality, and the signal processing algorithm underlying its operation is described.