New Cascaded Architecture for Classical and Quantum Multiparameter Sensing

We present an innovative concept for quantum-enhanced multiparameter optical phase sensing that can be implemented in free space, optical fiber or on-chip. Our measurable phases are in series, or cascaded, enabling measurements as a function of position with only a single input and output. We have modeled up to 20 phases, and fitting shows near-linear scaling of the power requirements for additional phases. This novel approach represents a new paradigm in multiparameter quantum metrology, and can be applied to remote sensing, communications, and geophysics.Comment: 5 pages, 4 figures. Comments are welcom

High extinction ratio, low insertion loss, optical switch based on an electrowetting prism

An optical switch based on an electrowetting prism coupled to a multimode fiber has demonstrated a large extinction ratio with speeds up to 300 Hz. Electrowetting prisms provide a transmissive, low power, and compact alternative to conventional free-space optical switches, with no moving parts. The electrowetting prism performs beam steering of &plusmn;3&deg; with an extinction ratio of 47 dB between the ON and OFF states and has been experimentally demonstrated at scanning frequencies of 100&ndash;300 Hz. The optical design is modeled in Zemax to account for secondary rays created at each surface interface (without scattering). Simulations predict 50 dB of extinction, in good agreement with experiment.</p

Enhancement of third-order nonlinearity of thermally evaporated GeSbSe waveguides through annealing

Chalcogenides are a promising platform for infrared nonlinear optics but are susceptible to structural changes during fabrication that affect their linear and nonlinear optical properties. We analyze the structure and optical properties of thermally evaporated and annealed chalcogenide films. Thermally evaporated Ge Sb Se has an increased selenium content, bandgap, and concentration of heteropolar bonds. The concentration of heteropolar bonds can be reduced by annealing above the glass transition temperature, resulting in improved optical nonlinearity. We demonstrate a 4-fold enhancement of third-order nonlinearity in Ge Sb Se chalcogenide waveguides by thermal annealing and a decrease in propagation loss from 2.5 dB/cm to 1 dB/cm as an added benefit.</p

Realistic model of entanglement-enhanced sensing in optical fibers

Experimental limitations such as optical loss and noise have prevented entanglement-enhanced measurements from demonstrating a significant quantum advantage in sensitivity. Holland-Burnett entangled states can mitigate these limitations and still present a quantum advantage in sensitivity. Here we model a fiber-based Mach-Zehnder interferometer with internal loss, detector efficiency, and external phase noise and without pure entanglement. This model features a practical fiber source that transforms the two-mode squeezed vacuum (TMSV) into Holland-Burnett entangled states. We predict that a phase sensitivity 28% beyond the shot noise limit is feasible with current technology. Simultaneously, a TMSV source can provide about 25 times more photon flux than other entangled sources. This system will make fiber-based quantum-enhanced sensing accessible and practical for remote sensing and probing photosensitive materials. &nbsp;</p

Selective excitation of plasmon resonances with single V-point cylindrical vector beams

We use a rigorous group theoretical method to identify a class of cylindrical vector beams that can selectively excite the plasmon modes of axially symmetric plasmonic structures. Our choice of the single V-point cylindrical vector beams as the basis to decompose cylindrical beams dramatically simplifies the symmetry analysis in the group theory framework. With numerical simulations, we demonstrate that any plasmon eigenmodes, bright or dark, can be selectively excited individually or jointly. A straightforward protocol to get access to the desired plasmon mode using symmetry coupling is presented. &nbsp;</p

Orbital angular momentum-based dual-comb interferometer for ranging and rotation sensing

We present a dual-comb interferometer capable of measuring both the range to a target as well as the target&rsquo;s transverse rotation rate. Measurement of the transverse rotation of the target is achieved by preparing the probe comb with orbital angular momentum and measuring the resultant phase shift between interferograms, which arises from the rotational Doppler shift. The distance to the target is measured simultaneously by measuring the time-of-flight delay between the target and reference interferogram centerbursts. With 40 ms of averaging, we measure rotation rates up to 313 Hz with a precision reaching 1 Hz. Distances are measured with an ambiguity range of 75 cm and with a precision of 5.9 &micro;m for rotating targets and 400 nm for a static target. This is the first dual-comb ranging system capable of measuring transverse rotation of a target. This technique has many potential terrestrial and space-based applications for lidar and remote sensing systems. &nbsp;</p

Large extinction ratio optical electrowetting shutter.

A large extinction ratio optical shutter has been demonstrated using electrowetting liquids. The device is based on switching between a liquid-liquid interface curvature that produces total internal reflection and one that does not. The interface radius of curvature can be tuned continuously from 9 mm at 0 V to -45 mm at 26 V. Extinction ratios from 55.8 to 66.5 dB were measured. The device shows promise for ultracold chip-scale atomic clocks

Third order nonlinearities in Ge-As-Se-based glasses for telecommunications applications

We have studied the third order optical nonlinearities of Ge-As-Se-based glasses. The glasses have high melting and glass transition temperatures that offer the potential for integration with traditional compound oxide glasses into highly nonlinear, high-index-contrast fibers. We used z-scan and femtosecond pump-probe techniques to measure the nonlinear refractive index and two-photon absorption coefficient of the glasses at telecommunication wavelengths. Nonlinearities as high as ϳ900ϫ that of silica were measured at 1540 nm in High capacity optical systems require devices such as cross connects, add-drop filters, repeaters, and wavelength converters. While some of these functions are currently being performed electronically, it is expected that they may eventually be replaced with optical devices in which nonlinear materials will play an important role. A key property of such materials is the optical Kerr effect that produces a change in the index of refraction proportional to the optical intensity I and the nonlinear index coefficient n 2 , ⌬n = n 2 I. The Kerr effect has an ultrafast time response and could be the basis for ultrafast optical switches with low switching energy. Two-photon absorption also occurs when the photon energy is above half-gap in the material and limits the maximum phase shift achievable. A figure of merit n 2 / ␤, 1 where n 2 is the nonlinear refractive index and ␤ the two-photon absorption coefficient, can be defined to assess the material properties relevant for efficient optical switching. To achieve a nonlinear optical phase shift of , necessary for a MachZender optical switch, with a nonlinear transmission loss of 20%, a figure of merit of ϳ2 is required. 2 Chalcogenide glasses have large values of nonlinearity at 1.55 m, several orders of magnitude larger than the value for conventional silica glass. 2 Many such glasses have been previously studied. 3-5 Among these, the Ge-As-Se system is of interest due to high nonlinearity, high refractive index (2.4-2.65), suitable optical transmission at 1.55 m and a relatively broad glass formation region. In this paper, we focus on glasses with particular promise for fabrication into high-index-contrast highly nonlinear fiber for 1.55 m applications. Glasses from Ge-As-Se family have glass transition temperatures in the range of 150-390°C making them suitable for integration with low refractive index compoundoxide glasses into high-index-contrast solid-core fiber. Highly nonlinear fiber can be used for applications including supercontinuum generation, 6 frequency metrology, 7 and wavelength conversion. 11 However, the chalcogenide glasses used in the fiber core must have a glass transition and softening temperature compatible with that of lower index glasses used for the cladding. We have investigated several chalcogenide glasses with glass transition temperatures from 292 to 380°C: Ge 33 As 12 Se 55 (commercially available as AMTIR-1, from Amorphous Materials), Ge 35 As 15 Se 50 , Ge 25 As 10 Se 65 , and Ge 22 As 20 Se 58 (commercially available as GASIR1, from Umicore). The glasses are found to have nonlinearities between 200ϫ −900ϫ that of silica, and figures of merit n 2 / ␤ as high as 3.2. The samples of Ge 33 As 12 Se 55 , Ge 35 As 15 Se 50 , and Ge 25 As 10 Se 65 were prepared as follows. For each glass composition, 5N (99.999%) purity amorphous selenium shot, 7.5N (99.999995%) purity crystalline lump arsenic, and 6N (99.9999%) purity single crystal germanium were batched into a fused quartz looped tube along with a magnesium metal strip (4N purity). The tube was placed into a two-level furnace, with the looped portion of the tube, in the hotter furnace zone. Over ϳ12 h, the As and Se components melted and were distilled from the loop into the lower part of the tube containing the Ge. After distillation, the lower portion of the tube was sealed, creating the melt vessel, and the loop containing impurities was discarded. 12 The melt vessel was placed into a rocking furnace at 900°C for 12 h, homogenizing the glass melt. The melt was then placed into a second furnace at the expected glass transition temperature. This furnace was switched off, allowing the glass to cool slowly to room temperature. The glass boules were cut into flat disks of about 3 mm thickness and the facets were ground parallel and polished to optical quality. Samples of Ge 33 As 12 Se 55 prepared in this manner were found to have similar n 2 , ␤, and bandgap energy to commercial samples a) Electroni