Explore the vast range of titles available.

We demonstrate a new scheme for infrared spectroscopy with visible light sources and detectors. The technique relies on the nonlinear interference of correlated photons, produced via spontaneous parametric down conversion in a nonlinear crystal. Visible and infrared photons are split into two paths and the infrared photons interact with the sample under study. The photons are reflected back to the crystal, resembling a conventional Michelson interferometer. Interference of the visible photons is observed and it is dependent on the phases of all three interacting photons: pump, visible and infrared. The transmission coefficient and the refractive index of the sample in the infrared range can be inferred from the interference pattern of visible photons. The method does not require the use of potentially expensive and inefficient infrared detectors and sources, it can be applied to a broad variety of samples, and it does not require a priori knowledge of sample properties in the visible range.

We investigated the propagation of femtosecond laser pulses through a metamaterial that has a negative index of refraction for wavelengths around 1.5 micrometers. From the interference fringes of a Michelson interferometer with and without the sample, we directly inferred the phase time delay. From the pulse-envelope shift, we determined the group time delay. In a spectral region, phase and group velocity are negative simultaneously. This means that both the carrier wave and the pulse envelope peak of the output pulse appear at the rear side of the sample before their input pulse counterparts have entered the front side of the sample.

We report on the characterisation of one of two broadband squeezed light sources (SLSs) developed for the quantum enhanced space-time (QUEST) experiment, using balanced homodyne detection. QUEST consists of a pair of co-located, table-top, power-recycled Michelson interferometers designed to probe stationary space-time fluctuations. The interferometers are designed to be shot-noise limited in the frequency range from 1 to 200 MHz, and squeezed light will be employed with the goal to reduce the shot noise by 6 dB at frequencies inside the linewidth of the optical parametric amplifier (OPA). We directly observed up to 6.8 dB of squeezing and maintained at least 3 dB of squeezing across the full 100 MHz measurement bandwidth. After accounting for the dark noise contribution, the inferred squeezing level increased to 8.6 dB. Our SLS is based on a hemilithic OPA with a 43.6 mm round-trip optical length and a linewidth of 138(2) MHz, making it the broadest-linewidth device to date among those suitable for long-term integration with interferometers operating at a wavelength of 1064 nm.

We put forward two methods for phase stabilization in the all-fiber Michelson interferometer. To perform passive phase stabilization, we use a heat bath for all fibers and electro-optical components, and put the interferometer in a hermetic case. To perform active phase stabilization, we monitor output power of the interferometer and develop an electronic feedback control. The phase stabilization methods enable stable interference pattern for several minutes, and can be helpful for the development of the optimal quantum receiver for coherent signals.

Self-stabilizing the quantum key distribution (QKD) system is essential to evaluate eavesdroppers’ information accurately. We develop and verify a polarization-insensitive time-bin decoder chip for QKD with the hybrid asymmetric Faraday-Michelson interferometer (AFMI) based on the planar lightwave circuit (PLC). Compared with existing chip-based QKD works, the scheme can intrinsically compensate for the polarization perturbation to quantum signals and thus work at arbitrary temperatures. We experimentally verify the chips in a time-bin QKD system at the clocking rate of 1.25 GHz and obtain an average secure key rate (SKR) of 1.34 Mbps over a 50 km fiber channel with an optimized analysis model. The steady variations of the quantum bit error and SKR with random polarization disturbance demonstrate that PLC-based AFMIs are available for developing self-stable QKD systems.

This paper presents the method and experimental results of the fabrication of holographic grating. The holographic grating was fabricated by using an alternative setting of Michelson Interferometer. In general, the interference pattern produces by Michelson interferometer is a circle fringe pattern. By an alternative setting of the interferometer, we could obtain a fringe pattern that has a linear shape. The angles between the two arms of Michelson interferometer, cross-beam angle, were adjusted until a linear interference pattern occurs. The interference pattern was projected onto a screen where a photoresist film is located. The photoresist film functional as a collective material of an interference pattern, i.e., a holographic grating. The film is developed and then fixed by a chemical process. By the chemical process, the holographic grating is permanence recorded on the film. After the fabrication process, we analyzed the physical properties of the holographic grating. We also measured the grating space by Scanning Electron Microscope (SEM). Relationships between cross-beam angles and grating space are shown and discussed. Experimental results show that we could apply the proposed method to fabricate a holographic grating.

In this article, we present an application of the optomechanical cavities for absolute rotation detection. Two optomechanical cavities, one in each arm, are placed in a Michelson interferometer. The interferometer is placed on a rotating table and is moved with a uniform velocity of y ¯ ˙ with respect to the rotating table. The Coriolis force acting on the interferometer changes the length of the optomechanical cavity in one arm, while the length of the optomechanical cavity in the other arm is not changed. The phase shift corresponding to the change in the optomechanical cavity length is measured at the interferometer output to estimate the angular velocity of the absolute rotation. An analytic expression for the minimum detectable rotation rate corresponding to the standard quantum limit of measurable Coriolis force in the interferometer is derived. Squeezing technique is discussed to improve the rotation detection sensitivity by a factor of γ m / m at 0 K temperature, where γ m and m are the damping rate and angular frequency of the mechanical oscillator. The temperature dependence of the rotation detection sensitivity is studied.

Pure Ag thin films with a thickness of 10 nm were deposited on glass substrates using a thermal evaporator system. Nanoparticles were then induced in the films by a Michelson interferometer dewetting process. The particle size was found to decrease with an increasing laser power and exposure time. The minimum particle size was 150 nm for a laser power of 4 W and exposure time of 60 s. However, a smaller particle size of 110 nm was obtained by adopting a two-step exposure process with a rotation angle of 30° and an exposure time of 55 s. The absorption peak wavelength of the dewetted films increased with an increasing rotation angle. By contrast, a blue shift in the absorption spectrum occurred as the laser power increased. The half-height widths of the absorption peaks of the films dewetted using different rotation angles were wider than those of the films dewetted without rotation, indicating that the two-step rotation process resulted in a wider particle size distribution. Overall, the results show that the optical properties of the laser-dewetted Ag films are highly dependent on the interference parameters.

The paper describes the use of a color camera for spatial phase shift shearography according to the carrier frequency method, whereby the focus is on measurement stability and practical usability. The basics are derived from the simple and extremely robust Michelson interferometer setup with spatial aperture and quality criteria are formulated according to the achievable result quality. The state of research of Multi-Wavelengths application is shown in general as well as in a publication, which serves as a further basis for comparison. The use of three laser sources and a Bayer-Matrix RGB color camera is considered to be the most effective method for the following development. For this purpose, the 3 out-of-plane illumination arrangement is used, which provides the three separate results in the spatial directions in only one measurement (for shear direction in x). The conditions and the special features of the spatial phase shift with a color camera are discussed and theoretical comparisons to the classical application with a black and white camera are made. On an experimental test, the high-resolution quality and usability of the presented method (3 Out-of-Plane Multi-Wavelengths RGB Camera spatial phase shift shearography) is demonstrated and validated. Prospective considerations are the extension to dual-shear applications (shear direction in x and in y simultaneously).

The article considers the possibility of controlling the quality of a conducting surface using a Michelson interferometer, in which the information carrier is surface plasmon-polaritons (a type of surface electromagnetic waves) of the terahertz range. It is shown that using such an interferometer, it is possible both to control the uniformity of the dielectric coating on the surface of a metal product, and to detect inhomogeneities on the controlled surface, as well as to evaluate their geometric and optical characteristics.