The use of near-zero index (NZI) materials for controlling radiative energy in thermal energy management has gained significant attention. However, conventional metal oxides suffer from notable changes in their optical properties at high temperatures, limiting their practicality in the near-infrared (NIR) range. This research investigates the potential of Lanthanum-doped Barium Stannate (LBSO) as a refractory NZI material suitable for high-temperature environments. By employing LBSO in a metal-insulator-metal (MIM) nano-cavity structure alongside Barium Titanate (BTO), a wavelength-selective thermal emitter was developed. The emitter exhibited impressive performance, with approximately 97% absorption at 2.2 µm, coinciding with the peak emission wavelength at 1000 ℃. Notably, the LBSO-based device demonstrated outstanding stability even under harsh high-temperature conditions.
BaTiO3 (BTO) has emerged as an electro-optic (EO) material in integrated photonics, offering advantages over traditional materials such as LiNbO3 due to larger Pockels coefficients. BTO thin films on oxide substrates have been extensively studied for on-chip EO modulators that manipulate light properties in waveguides. One application is in compact laser systems for atomic gravity sensors, where BTO-based single-sideband (SSB) modulators reduce cost and power consumption by suppressing sidebands. This research presents the fabrication of an SSB modulator using BTO film on MgO substrate, operating at 780 and 1560 nm wavelengths. The modulator uses a Mach-Zehnder interferometer to convert a 1560 nm light source into a 6.8 GHz optical signal. This work advances integrated photonics by exploring the potential of BTO in compact laser systems for atomic gravity sensors.
A Brillouin optical correlation domain analysis (BOCDA) system using time-domain data processing for concurrently interrogating a plurality of sensing positions is proposed, where the time-domain data processing combined with differential measurement effectively enhances the measurement range and measurement time as much as the spatial resolution of the BOCDA system. In the experiment, the distribution of the Brillouin gain spectra (BGS) along a 10.15 km test fiber is successfully obtained with a spatial resolution less than 5 cm by concurrently interrogating 980 correlation peaks.
An all-fiber type, CW, linearly polarized thulium-doped fiber laser is reported. Highly linear polarization was achieved by a special management of fiber Bragg gratings, which performs as the laser cavity reflectors. The laser generated 28 W signal output at 1949 nm with a slope efficiency of 47.3%. The polarization extinction ratio of the laser was measured to be around 20 dB. The beam quality of the laser was near diffraction-limited, with M2 of 1.1. The laser’s output features make it to be a potential light source for some important applications such as for pumping holmium-doped solid state lasers.
Huge enlargement of the sensing range of Brillouin optical correlation domain analysis (BOCDA) is achieved by simultaneously applying double modulation and optical time gate on the basis of differential measurement scheme. The BOCDA system with a spatial resolution less than 1 cm and a sensing range over 10 km is experimentally demonstrated, which corresponds to distributed measurement with more than 1 million effective sensing points.
We measured the Brillouin frequency in fiber taper and identified the shift of the Brillouin frequency when strain and temperature changed. As taper diameter decreases, strain coefficient for Brillouin frequency decreases down to 0.0488 MHz/με while temperature coefficient is maintained.
In this study, we successfully generated the large bandwidth of supercontinuum spectra through hollow fibers filled with DNA. Also, by observing that spectra bandwidth was the widest in the order of the hollow core fiber filled with DNA modified by copper ion, the hollow core fiber with only DNA, and the bulk hollow core fiber, we demonstrated that DNA material modified with copper ions can further enhance the spectral bandwidth of supercontinuum. As a result, we anticipate that the SCG as a broadband light source can be used in analytical methods to demonstrate a wide range of biological and environmental questions.
We demonstrate a self Q-switched Bismuth-doped germanosilicate fiber laser operating at 1463 nm. It is experimentally shown that stable Q-switched pulses with a temporal width of ~ 1.8 μs can be obtained from a simple, all-fiberized Fabry-Perot type cavity without using a saturable absorber at a repetition rate of ~65 kHz with a pump power of ~260 mW. The tuning capability of the temporal characteristics of the output pulses is also investigated. The possible physical mechanism is discussed.
We demonstrate a high-performance single-ended correlation-domain Brillouin sensor based on a phase modulation of Brillouin pump and a differential measurement scheme. Large DC noise induced by direct reflection of Brillouin pump was successfully removed by the phase modulation-based differential measurement as well as additional 4-fold enhancement in the spatial resolution. By applying an intentional loss to the end of a sensing fiber one of two correlation peaks within the fiber is suppressed, leading to double enlargement of the measurement range compared to former in-line reflector based systems. In the experimental confirmation a distributed strain measurement with a range of 100 m and a spatial resolution of 5 cm is presented.
We newly propose and experimentally demonstrate a differential lock-in detection scheme for the enhancement of
Brillouin optical correlation domain analysis (BOCDA), where additional phase modulation is applied to the Brillouin
pump wave and the on-off control on which is used for data acquisition. The theoretical model and the experimental
results show that at least three-fold improvement is obtained in the spatial resolution of the distributed measurements and
the Brillouin gain spectrum (BGS) with much narrower 3dB bandwidth than that of conventional BOCDA systems is
acquired by the differential lock-in detection.
We propose a novel technique for expansion of spatial measurement range in a Brillouin optical
correlation domain analysis (BOCDA) sensor system. Unlike conventional BOCDA, which has only a
single correlation peak within the sensing fiber, the proposed scheme has multiple correlation peaks
within the sensing section, and enables us to obtain selectively the physical information at a position
corresponding to each correlation peak since the fiber under test consists of different kinds of fibers
with different Brillouin frequency shifts. Using the proposed technique, we have successfully
expanded a measurement range while maintaining the spatial resolution.
We demonstrate a novel kind of tunable optical delays based on dynamic grating generated
by Brillouin scattering in an optical fiber. An axial strain gradient is applied to a 15 m section
of a polarization-maintaining fiber, and the Brillouin reflection grating is generated positionselectively
by controlling the optical frequencies of Brillouin pump waves. Tunable time
delays of up to 132 ns are achieved with an 82 ns Gaussian pulse.
We present a novel and simple atom trap in a pyramidal and a conical hollow mirror cavity and its application to atom optics. Using a conical axicon mirror trap, we also have produced a pulsed cold atomic beam extracted from the trapped atoms. We point out several novel features of our cold atomic beams.
The quality of a plastic product is determined by the material used, the mold design, and the processing conditions. The objectives of a mold design consist of a mold cooling system, a runner system, and associated gate locations with their types and sizes, and cavity design. Meanwhile, the most important processing conditions during the fill phase are the mold temperature, the melt temperature, and the filling time. In this paper, we use genetic algorithm to optimize molding conditions, which consist of the mold temperature, the melt temperature, and the filling time, based upon the results from flow simulation.
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