We present the design of a harmonic resonant filter that can be used with a Fourier transform spectrometer (FTS) for simultaneous measurement of a series of lines in the CO rotational ladder. To enable studies of both broad CO absorptions in Venus and modestly red-shifted CO emission from external galaxies, relatively broad (approximately 10-30-GHz FWHM) transmission passbands are desirable. Be...

We demonstrate a novel wavelength-comb-swept laser based on two intra-cavity filters: an acousto-optic tunable filter (AOTF) and a Fabry-Pérot etalon filter. The AOTF is used for the tunable selection of the output wavelength with time and the etalon filter for the narrowing of the spectral linewidth to extend the coherence length. Compared to the conventional wavelength-swept laser, the acoust...

This paper presents the design and analysis of a liquid refractive index sensor that utilizes a unique physical mechanism of resonant optical tunneling effect (ROTE). The sensor consists of two hemicylindrical prisms, two air gaps, and a microfluidic channel. All parts can be microfabricated using an optical resin NOA81. Theoretical study shows that this ROTE sensor has extremely sharp transmis...

In terahertz (THz) and far-infrared (FIR) spectroscopic measurements, weak absorption spectral features due to small quantities of test sample can be masked by undesirable etalon fringe artifacts caused by multiple reflections within a pellet or a rigid sample holder. A double-layered nitrocellulose (NC) membrane structure is proposed in this paper as an alternative holder for small quantities ...

Abstract Palladium is the most prominent material in both scientific and industrial research on gas storage, purification, detection, catalysis due to its unique properties as a catalyst hydrogen absorber. Advancing dynamic optical phenomena of palladium reacting with hydrogen, transduction gas-matter reaction into light-matter interaction attempted visualize surface chemistry behaviors. The si...

This paper describes a fiber-optic temperature sensor that uses a spectrum-modulating Sic etalon. The spectral output of this type of sensor may be analyzed to obtain a tem.+ perature measurement which is largely independent of the transmission properties of the m sensor's fiber-optic link. A highly precise laboratory-type spectrometer is described in detail, and this instrument is used to stud...

We present the hysteresis of the response of the poly(N-isopropylacrylamide)-co-acrylic acid microgel-based etalons to solution temperature and pH changes. We find that the optical hysteresis of the etalon can be controlled using various solution ionic strengths and/or counterions, as well as by varying the microgel's acrylic acid concentration.

A Fabry-Perot etalon is used in the image plane as a means of selecting arbitrary directions of propagation in the angular spectrum of an object. This provides a simple widely tunable spatial filter that could be useful in a number of image processing and pattern recognition applications.