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Large area silicon-air-silicon DBRs for infrared filter applications
摘要： This paper presents the design, fabrication, and optical characterization of silicon-based thin film Fabry-Pérot filters for spectroscopic sensing applications at short-wave infrared (SWIR: 1.5–2.5 μm) and mid-wave infrared (MWIR: 3–5 μm) wavelengths. Filter performance is enhanced using distributed Bragg reflectors composed of silicon and air-gap layers for enhanced refractive index contrast. A peak-to-peak surface variation of less than 20 nm in the fabricated micromachined structures was achieved across a large spatial area of 1 mm × 1 mm. Spectral measurements on released Fabry-Pérot filters show excellent agreement with optical simulations. The fabricated Fabry-Pérot filters demonstrate peak transmittance values greater than 50% across all spectral ranges, with measured full width at half maximum values in the range of 50 nm rendering them suitable for use in spectral sensing and imaging in the SWIR and MWIR wavelength ranges.
关键词： Silicon,Fabry-Perot interferometers,Spectroscopy,Optical device fabrication
更新于2025-09-23 15:22:29
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - N ovoFEL as Source of Powerful Ultramonochromatic Tunable Terahertz Radiation
摘要： Laser nature of a continuous pulse-periodical radiation of the Novosibirsk free-electron laser (NovoFEL) appears in a good coherency of its pulses and very narrow synchronized longitudinal modes. Filtration of one of the modes by a system of three resonance Fabry-Perot interferometers allows to create laser source with monochromaticity which is sufficient for typical high-resolution THz spectroscopy (δf/f ≤ 5·10-8, δf ≤ 0.1 MHz). Features of the source compared to other alternative devices are a wide tuning range (1.5-3 THz) and much more high output power (up to 50-100 mW).
关键词： high-resolution spectroscopy,Fabry-Perot interferometers,monochromaticity,NovoFEL,terahertz radiation
更新于2025-09-23 15:21:01
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An electro-tunable Fabry–Perot interferometer based on dual mirror-on-mirror nanoplasmonic metamaterials
摘要： Mirror-on-mirror nanoplasmonic metamaterials, formed on the basis of voltage-controlled reversible self-assembly of sub-wavelength-sized metallic nanoparticles (NPs) on thin metallic film electrodes, are promising candidates for novel electro-tunable optical devices. Here, we present a new design of electro-tunable Fabry–Perot interferometers (FPIs) in which two parallel mirrors – each composed of a monolayer of NPs self-assembled on a thin metallic electrode – form an optical cavity, which is filled with an aqueous solution. The reflectivity of the cavity mirrors can be electrically adjusted, simultaneously or separately, via a small variation of the electrode potentials, which would alter the inter-NP separation in the monolayers. To investigate optical transmittance from the proposed FPI device, we develop a nine-layer-stack theoretical model, based on our effective medium theory and multi-layer Fresnel reflection scheme, which produces excellent match when verified against full-wave simulations. We show that strong plasmonic coupling among silver NPs forming a monolayer on a thin silver-film substrate makes reflectivity of each cavity mirror highly sensitive to the inter-NP separation. Such a design allows the continuous tuning of the multiple narrow and intense transmission peaks emerging from an FPI cavity via electro-tuning the inter-NP separation in situ – reaping the benefits from both inexpensive bottom-up fabrication and energy-efficient tuning.
关键词： electro-tunable optical devices,voltage-controlled reversible self-assembly,self-assembled plasmonic nanoparticles,Fabry–Perot interferometers
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Long Length Fibre Fabry-Perot Interferometers and their Applications in Fibre Characterization and Temperature Sensing
摘要： Since the free spectral range (FSR) of a fibre Fabry-Perot (f-FP) is the reciprocal of the time delay inside the interferometer, it can be used for the precise measurement of fibre properties (chromatic dispersion when measured as a function of wavelength, birefringence, etc.) or for the measurement of environmental changes (such as temperature, pressure, stress, etc.) which alter the fibre’s parameters. Here we propose a method to precisely measure the FSR of long-length f-FP based on an incoherent optical source and RF beat signal analysis. We built a 7-m long f-FP made of a single mode fibre (SMF) and investigated the use of several algorithms to evaluate the FSR. When measuring over time, we achieved an excellent accuracy down to 2.4 Hz (corresponding to a relative error of 1.5× 10??). To demonstrate its use in sensing application, we varied the f-FP temperature and monitored the associated FSR. We achieved a sensitivity of 345 Hz/K, leading to an excellent temperature resolution below 10 mK. Additionally, the achieved high accuracy in the measured FSR can also be used to measure fibre’s properties very precisely (e.g., zero chromatic dispersion wavelength) or to determine their temperature dependence. The method requires no alignment and requires only a few off-the-shelf components and instruments.
关键词： fibre characterization,temperature sensing,RF beat signal analysis,free spectral range,fibre Fabry-Perot interferometers
更新于2025-09-12 10:27:22
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Femtosecond Laser Micromachining of Fabry-Pérot Interferometers for Magnetic Field Sensing
摘要： Fs-laser micromachining is a high precision fabrication technique that can be used to write novel three-dimensional structures, depending on the nature of light-matter interaction. In fused silica, the material modification can lead to (i) an increase of the refractive index around the focal volume, resulting in the formation of optical circuits, or (ii) an enhancement of the etch rate of the laser-affected zones relative to the pristine material, leading to a selective and anisotropic etching reaction that enables fabrication of microfluidic systems. Here, both effects are combined to fabricate a Fabry-Pérot interferometer, where optical waveguides and microfluidic channels are integrated monolithically in a fused silica chip. By filling the channel with a magnetic fluid whose refractive index changes with an external magnetic field, the device can be used as a magnetic field sensor. A linear sensitivity of -0.12 nm/mT is obtained in the 5.0±0.5 to 33.0±0.5 mT range, with the field being applied parallel to the light propagation direction.
关键词： Magnetic Field Sensing,Optofluidic Sensor,Femtosecond Laser Micromachining,Ferrofluids,Fabry-Pérot Interferometers
更新于2025-09-11 14:15:04
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Bimodal Resonance Phenomena—Part III: High-Contrast Grating Reflectors
摘要： The extraordinary broadband high-reflectivity features of high-contrast gratings (HCGs) are stimulating great interest in many optoelectronic applications. In view of obtaining a simple simulation framework, the analogy of HCG reflectors with bimodal Fabry–Pérot interferometers is proposed. The closed-form expressions of the interferometer reflectivity, obtained starting from a novel parametrization of the scattering matrices characterizing the bar–air interface, allow a complete exploration of the device parameter space, explaining and predicting the phenomenon of ultra-broadband quasi-100% reflectivity. In this paper, an optimized and numerically efficient design procedure is described and compared with the standard rigorous coupled wave analysis, both for the classical bar-in-air configuration and for a more robust and practical one, with bars lying on a dielectric support. It is shown that the model can be applied also in the more realistic case of lossy gratings.
关键词： Gratings,Fabry-Pérot interferometers
更新于2025-09-09 09:28:46
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Simultaneous measurements of temperature and pressure with a dual-cavity Fabry-Perot sensor
摘要： A fiber-optic dual-cavity Fabry-Perot interferometric sensor for the simultaneous measurement of temperature and pressure is proposed and experimentally demonstrated. The sensor cascades a fiber-optic intrinsic Fabry–Perot interferometer (IFPI) and an extrinsic Fabry–Perot interferometer (EFPI). The IFPI is used as the temperature sensor and the EFPI is used as the pressure sensor. The pressure sensor is based on a diaphragm-free structure, and can work stably at high temperature. Two optical path differences are interrogated simultaneously by using the fast Fourier transform-based white-light interferometry and the peak-to-peak method. Experimental results show that the proposed sensor exhibits a temperature sensitivity of 29.63 nm/°C within the temperature range of 40-1100 °C, and a pressure sensitivity of 1465.8 nm/MPa within the pressure range of 0-10 MPa at the room temperature.
关键词： pressure measurement,femtosecond laser micromachining,fiber optics sensors,Fabry-Perot interferometers,temperature measurement
更新于2025-09-04 15:30:14
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Investigation on the Thermo-Optic Coefficient of Silica Fiber Within a Wide Temperature Range
摘要： In this paper, the thermo-optic coef?cient of silica ?ber is analyzed and measured within a wide temperature range of 0–1200 °C for the ?rst time. To obtain the thermo-optic coef?cient, experiments were carried out by using ?ber optic extrinsic Fabry–Perot interferometers (EFPIs) embedded in silica ?ber. The optical cavity lengths of the EFPIs were measured with white-light interferometry. The experimental results show that the ?rst and second orders of the thermo-optic coef?cient are 1.090 × 10?5/°C and 1.611 × 10?9/°C2, respectively. The quadratic model for the temperature dependence of the basic optical parameter, the refractive index, is rigorous within a wide temperature range. Furthermore, this paper also provides a temperature calibration method for extrinsic Fabry–Perot interferometric temperature sensors. The temperatures measured by the sensors are in excellent agreement with those measured by the reference thermocouple. Hence, this calibration method is promising for temperature sensors with a wide working temperature range.
关键词： thermo-optic coef?cient,Fabry-Perot interferometers,silica ?ber
更新于2025-09-04 15:30:14