Room-temperature MASERs (Microwave Amplification by Stimulated Emission of Radiation) are coherent sources that exploit stimulated emission to amplify electromagnetic waves at microwave frequencies. Here we report the first demonstration of an LED-pumped maser based on photo-excited triplet states of pentacene in p-terphenyl. The LED light is brightness enhanced and guided using a Cerium-doped Yttrium Aluminium Garnet luminescent crystal that uses light recycling to reach record luminance and power levels. We observe stable maser emission at 1.45 GHz using LED pumping at a much lower pump threshold power. This new maser is cost-effective, safe, and environmentally friendly, and hence ensures a wide variety of potential uses, including more sensitive magnetic resonance body scanners, quantum optical coherence tomography, advanced quantum computer components, portable atomic clocks, and better radio astronomy devices for deep space exploration.
The MASER, analogous to a laser but operating in the microwave range, amplifies electromagnetic waves through stimulated emission. Recent advancements in optically pumping Masers have reinvigorated the field, overcoming limitations such as high vacuum, strong magnetic fields, and extreme temperatures. This work presents a miniaturised hairpin cavity for microwave antenna design utilising optical Maser sources. The miniaturised cavity demonstrates its performance through simulations and experimentally by combining optical pumping with an optimised setup. The analysis reveals successful resonance at 1.45GHz, with high Q-factors and smaller volumes, facilitating the miniaturisation of Maser cavities. Furthermore, a novel toroidal resonator is investigated via simulation.
Non-invasive blood glucose measurement has long been desired since the invasive methods are not suitable to perform continuous monitoring. Near Infrared Spectroscopy is one of the most popular methods used in studies; however, despite more than 20 years of research, a practical and reliable noninvasive NIR glucose sensor is yet to be developed. In this study, we investigated the feasibility of NIRS towards the detection of glucose concentration. Although we can obtain adequate sensitivity, our measurements suffer from poor selectivity due to the fact that we can only detect the impurity level of water by NIRS due to strong water absorbance.
Sub-10 nanometer lithography is opening a new area for beyond-CMOS devices. Regarding to single nano-digit manufacturing we have established a new maskless patterning scheme by using field-emission, current controlled Scanning Probe Lithography (cc-SPL) in order to create optical nanodevices in thin silicon-on-insulator (SOI) substrates. This work aims to manufacture split ring resonators into calixarene resist by using SPL, while plasma etching at cryogenic temperatures is applied for an efficient pattern transfer into the underlying Si layer. Such electromagnetic resonators take the form of a ring with a narrow gap, whose 2D array was the first left-handed material tailored to demonstrate the so-called left-hand behavior of the wave propagation. It is shown that the resonance frequency can be tuned with the feature size of the resonator, and the resonance frequency can be shifted further into near infrared or even visible light regions.
Next-generation electronic and optical devices demand high-resolution patterning techniques and high-throughput fabrication. Thereby Field-Emission Scanning Probe Lithography (FE-SPL) is a direct writing method that provides high resolution, excellent overlay alignment accuracy and high fidelity nanopatterns. As a demonstration of the patterning technology, single-electron transistors as well as split ring electromagnetic resonators are fabricated through a combination of FE-SPL and plasma etching at cryogenic temperatures.
We propose a novel fiber sensor utilizing a thermomechanical MEMS element at the fiber tip. Owing to its
Parylene/Titanium bimaterial structure, the MEMS membrane exhibits an out-of plane displacement with changing
temperature. Together with the MEMS element, the embedded diffraction grating forms an in-line interferometer, from
which the displacement as well as the temperature can be deduced. The fabricated detector is placed at the single-mode
fiber output that is collimated via a graded index lens. This novel architecture allows for integrating MEMS detectors on
standard optical fibers, and easy substitution of the MEMS detector element to alter the measurement range and the
response time of the sensor.Temperature and time-constant measurements are provided and verified with reference
measurements, revealing better than 20 mK temperature sensitivity and 2.5 msec response time, using low-cost laser
source and photodetectors.
The thermal sensor system presented in this paper is based on the mechanical bending due to the incident IR radiation. A
diffraction grating is embedded under each pixel to facilitate optical readout. Typically the first diffraction order is used
to monitor the sub-micron mechanical displacement with sub-nanometer precision. In this work; two different optical
readout systems based on diffraction gratings are analyzed.
First setup employs a conventional 4f optical system. In this one-to-one imaging system, collimated light is propagated
through a lens, filtered with an aperture and then imaged onto a CCD by a second lens.
Second system is more compact to improve image quality and to reduce noise. This is achieved by using an off-axis
converging laser beam illumination that forms the Fourier plane near the imaging lens. This approach has important
advantages such as reducing number of optical components and minimizing the optical path. The system was optimized
considering parameters such as laser converging angle, laser beam size at MEMS chip, and magnification of the imaging
system.
This paper reports a novel uncooled infrared FPA whose performance is comparable to the cooled FPA's in terms of noise parameters. FPA consist of bimaterial microcantilever structures that are designed to convert IR radiation energy into mechanical energy. Induced deflection by mechanical energy is detected by means of optical methods that measures sub nanometer thermally induced deflections. Analytical solutions are developed for calculating the figure of merits for the FPA. FEM simulations and the analytical solution agree well. Calculations show that for an FPA, NETD of <5mK is achievable in the 8-12 μm band. The design and optimization for the detectors are presented. The mechanical structure of pixels is designed such that it can be possible to form large array size FPA's. Microfabrication of the devices, which can be improved to improve the performance further, employs low cost standard MEMS processes.
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