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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) - SiC-SiO <sub/>2</sub> MEMS-DBR Based Widely Tunable Optical Filters Around 1550 nm with Narrow FWHM
摘要： Ever growing optical data transmission networks and miniaturization of spectroscopic equipment demand for small, energy efficient and mass-produced optical components. Here we present distributed Bragg reflector (DBR) mirror based widely tunable optical Fabry-Perot filters comprising a novel material combination namely, silicon carbide (SiC) and silicon dioxide (SiO2) layers with refractive indices of 2.46 and 1.45, respectively. The resulting refractive index step of 1, provides high reflectivities (>99.5 %) with wide stopbands of more than 300 nm. Hence, large wavelength tuning range and a narrow full width at half maximum (FWHM) filtered signals can be produced. Structuring the dielectric layers by surface micromachining creates a free standing movable mirror supported by four beams. Due to inherent stress created during low-temperature plasma enhanced chemical vapor depositions (PECVD) we obtain a tunable stable plane concave resonator. In the end the cross section of a filter shows a fixed bottom DBR deposited on a silicon substrate, a tunable airgap and an electrothermally actuated top MEMS DBR with a gold electrode for heating current IMEMS. On the substrate backside where the filtered signal is exiting an anti-reflection coating is deposited.
关键词： tunable optical filters,SiC-SiO2 MEMS-DBR,PECVD,Fabry-Perot filters,surface micromachining
更新于2025-09-11 14:15:04
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Sensitivity-enhanced Fabry-Perot filled with PDMS temperature sensor based on Vernier effect
摘要： Temperature characteristics of Sensitivity- enhanced Fabry-Perot filled with PDMS temperature sensor based on Vernier effect consisting of two Fabry–Perot interferometers (FPI), one of the FPI’s cavity is internally filled with PDMS, are observed experimentally. Results show that temperature sensitivity of the Sensitivity-enhanced Fabry-Perot sensors is 1.808 nm/℃. It is Vernier effect lead to a double improvement of the temperature sensitivity compar- ed with the sensor with single FPI, of which the cavity is internally populated with PDMS but no Vernier effect. Moreover, the improvement can be enlarged by optimizing the free spectra range of these two FPIs.
关键词： modified temperature sensor,PDMS,Vernier effect,Fabry–Perot interferometer
更新于2025-09-11 14:15:04
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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) - Gas Detection using a MEMS-Based Swept Laser Source
摘要： Swept Laser Sources (SLS) provide wide wavelength tuning range and high tuning speed making them attractive sources for sensing, biomedical and industrial imaging applications. MEMS based swept lasers have recently gained more attention with their potential low cost, high tuning speeds, high output power and possibility of integration with other devices. The adaptation of MEMS based swept lasers in gas sensing would allow the detection of multiple gases at high speed and sensitivity with a single device which is a major benefit over many of the available commercial devices. In this work, we present practical sensing of carbon dioxide gas using a MEMS based swept laser. The SLS under study consists of a ring fiber cavity of length 20 m, a semiconductor optical amplifier (SOA) as a gain medium, an isolator to allow a uni-directional laser operation, a fiber polarization controller, an intracavity in-plane MEMS optical tunable filter and a tapping fiber-coupler to couple some power out of the loop. The MEMS filter is a Fabry-Perot filter, based on deeply etched 80-μm height silicon/air Bragg mirrors. One of the mirrors is movable using an electrostatic comb-drive actuator. By applying a voltage across the comb-drive, an attractive force is developed which pulls the movable mirror towards the fixed one, thus the resonant wavelength of the filter is tuned, and the lasing wavelength as well.
关键词： MEMS,swept laser source,carbon dioxide,Fabry-Perot filter,gas detection
更新于2025-09-11 14:15:04
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[IEEE 2019 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2019.6.3-2019.6.7)] 2019 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Electronic Retuning of Acousto-Optic Laser Mode Locker. Experimental study
摘要： The effect of electronic retuning of acoustic resonances in an acousto-optic laser mode locker is investigated theoretically and experimentally. In the approximation of plane acoustic waves, the problem of excitation of the Fabry–Perot acoustic resonator by a plate piezoelectric transducer is solved with taking into account real parameters of a RF generator and matching elements. The resonances were retuned by changing reactive matching elements (inductance coil and capacitor) connected between the generator and the transducer. In the experiment, an acousto-optic cell made of crystalline quartz with a two-sectional lithium niobate transducer was used.
关键词： acoustic Fabry–Perot resonator,piezoelectric transducer,acousto-optic modulator,acousto-optic interaction,laser mode locking
更新于2025-09-11 14:15:04
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A Refractive Index Sensor Based on a Fabry–Perot Interferometer Manufactured by NIR Laser Microdrilling and Electric Arc Fusion
摘要： In-line Fabry–Perot cavities manufactured by a new technique using electric arc fusion of NIR laser microdrilled optical fiber flat tips were studied herein for refractive index sensing. Sensors were produced by creating an initial hole on the tip of a standard single-mode telecommunication optical fiber using a Q-switched Nd:YAG laser. Laser ablation and plasma formation processes created 5 to 10 micron cavities. Then, a standard splicing machine was used to fuse the microdrilled fiber with another one, thus creating cavities with lengths around 100 micrometers. This length has been proven to be necessary to obtain an interferometric signal with good fringe visibility when illuminating it in the C-band. Then, the sensing tip of the fiber, with the resulting air cavity, was submitted to several cleaves to enhance the signal and, therefore, its response as a sensor, with final lengths between tens of centimeters for the longest and hundreds of microns for the shortest. The experimental results were analyzed via two signal analysis techniques, fringe visibility and fast Fourier transform, for comparison purposes. In absolute values, the obtained sensitivities varied between 0.31 nm?1/RIU and about 8 nm?1/RIU using the latter method and between about 34 dB/RIU and 54 dB/RIU when analyzing the fringe visibility.
关键词： fiber sensors,glass ablation,Fabry–Perot interferometer,microdrilling,Nd:YAG laser manufacturing
更新于2025-09-11 14:15:04
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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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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Giant Dual-Mode Graphene-Based THz Modulator
摘要： We report a high-performance terahertz (THz) modulator with dual-operation mode. For the pulse operation mode, the proposed THz modulator has the advantage of high modulation depth (MD) and can operate in a broadband frequency range. We have experimentally achieved a MD larger than 90% for the fifth-order pulse THz echo at 0.8 THz and the MD stays larger than 75% in a broadband frequency range larger than 1 THz. While, for the coherent operation mode, the Fabry-Perot (F-P) interference effect has been taken into consideration and a MD larger than 75% at 0.76 THz has also been realized.
关键词： dual-operation mode,terahertz modulator,modulation depth,Fabry-Perot interference,graphene
更新于2025-09-11 14:15:04
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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) - The Photonic Guitar Pickup: A High-Sensitivity, High-Bandwidth Fiber Strain Sensor
摘要： The photonic guitar pickup: a high-sensitivity, high-bandwidth fiber strain sensor. Fiber-strain sensors have found numerous applications from structural health monitoring for vibrations, to pressure and temperature sensing. Many of these sensors exploit the strain-sensitivity of the reflection wavelength of fiber-bragg gratings, (cid:83)-shifted gratings or other waveguide devices. The strain is typically inferred from a change of reflected or transmitted light intensity. Light intensity measurements are not very robust and have an inherently limited accuracy. We propose that a frequency-based strain measurements using fiber Fabry-Perot (FFP) cavities provide not only superior sensitivity but also retain a very high measurement bandwidth. Here, we present a fiber optic vibration sensor based on an FFP cavity, which consists of a matched pair of 23 dB fiber Bragg gratings coupled to a custom-built signal processing circuit. The wavelength of a laser diode is locked to one of the many cavity resonances using the Pound–Drever–Hall scheme. We demonstrate that such a strain sensor has an ultrawide dynamic sensing range, from less than 1 Hz to clinical ultrasound frequencies near 6 MHz. Its linear sensitivity range extends from below 1 n(cid:72) to 2 (cid:80)(cid:72), and its dynamic response limit is as high as 12 m(cid:72)/s. To demonstrate the high fidelity of the strain measurements we attached the FFP cavity sensor to the top plate of an acoustic guitar and recorded several melodies. As expected the sensor system was largely immune to noise arising from optical intensity fluctuations. We made distortion-free audio recordings of musical pieces from infrasound (~8 Hz) to 30 kHz with a 50 dB dynamic range in acoustic power. The remaining noise in our measurements arises from electronic sources and not optical sources, giving hope that future developments may be able to further increase the dynamic range of the measurements, if needed. In separate experiments the same sensor was affixed to the rim of a wineglass and to the side of a steel cantilever to monitor the (photo-)acoustic response of these mechanical resonators to periodic photo-excitation. We found, for example, that the limit of detection for orthophosphate through the photoacoustic excitation of the respective molybdenum-blue complex was below 2 ppm. Finally, the sensor was embedded in tissue phantoms to validate that it accurately responds to low frequencies (heart beat) and high frequencies (ultrasound pulse). In its most recent version the laser driver and the PDH circuit are addressed through a Raspberry-Pi microcontroller, making the sensor system very compact and relatively inexpensive. We propose that sensor systems based on PDH-interrogated FFP-sensor heads are robust and versatile for a large variety of monitoring applications.
关键词： Fabry-Perot cavity,vibration sensor,dynamic range,Pound–Drever–Hall scheme,fiber strain sensor
更新于2025-09-11 14:15:04
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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) - Integrated Semiconductor Quantum Photonics
摘要： For fundamental tests of quantum physics as well as for quantum communications, non-classical states of light are an important tool. In this talk, we will present our work on developing nonlinear AlGaAs waveguides into a platform for quantum photonics in semiconductors. Most III-V semiconductors exhibit a large second-order optical nonlinearity, but phase-matching the nonlinear interaction is notoriously difficult. As a solution Bragg-reflection waveguides allow efficient creation of photon pairs through spontaneous parametric down-conversion. They have the potential to be homogeneously integrated with a pump laser and passive and active components on the chip. In our waveguides, we can create high-fidelity polarization [1] and time-bin entangled [2] photon pairs, which cover a large frequency band in the low-loss telecommunication window, suitable for serving multiple users through wavelength division multiplexing. For all our applications, it is important that we can design the desired linear and nonlinear properties, which in turn makes precise characterization necessary. For this purpose, we have developed a Fourier-transform Fabry-Perot spectroscopy technique [3], which yields the relevant device parameters with superior accuracy. We will further present our results on devices that integrate electrically injected lasers and the nonlinear conversion. A layer of quaternary quantum dots acts as the gain medium in a Fabry-Perot waveguide laser, which lases at room temperature in the Bragg mode, i.e. the pump mode for creating photon pairs. We will close with an outlook on further device integration towards a complete semiconductor quantum photonics platform.
关键词： AlGaAs waveguides,photon pairs,Bragg-reflection waveguides,quantum photonics,Fourier-transform Fabry-Perot spectroscopy,spontaneous parametric down-conversion
更新于2025-09-11 14:15:04
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Signal Processing Criteria Based on Electro-Optic Filters for Fiber Optic Access Transceiver Systems
摘要： The study outlines the different types of electro-optic filters that are used in fiber optic access transceiver systems. These filters are classified into the electrical filter in the receiver side and optical filters are located between fiber optic and transmitter. The optical filters are, namely, Fabry Perot, Gaussian, and Bessel filters. While electrical filters that are namely low pass Bessel, low pass Gaussian, and low pass squared raised cosine roll-off filters. The study emphasizes the important criteria in the employment of electro-optic filters in this system for signal fast processing. The Fabry Perot optical filters in addition to low pass squared raised cosine roll-off filters are clarified the best-obtained results in the comparison with other proposed filters.
关键词： Fabry Perot filter,signal processing,low pass cosine roll-off filter,transceiver systems
更新于2025-09-11 14:15:04