Multifunctional photonic integrated circuit for diverse microwave signal generation, transmission and processing

Microwave photonics (MWP) studies the interaction between microwave and optical waves for the generation, transmission and processing of microwave signals (i.e., three key domains), taking advantages of broad bandwidth and low loss offered by modern photonics. Integrated MWP using photonic integrated circuits (PICs) can reach a compact, reliable and green implementation. Most PICs, however, are recently developed to perform one or more functions restricted inside a single domain. In this paper, as highly desired, a multifunctional PIC is proposed to cover the three key domains. The PIC is fabricated on InP platform by monolithically integrating four laser diodes and two modulators. Using the multifunctional PIC, seven fundamental functions across microwave signal generation, transmission and processing are demonstrated experimentally. Outdoor field trials for electromagnetic environment surveillance along an in-service high-speed railway are also performed. The success to such a PIC marks a key step forward for practical and massive MWP implementations.Comment: 17 page

Cost-effective photonic super-resolution millimeter-wave joint radar-communication system using self-coherent detection

A cost-effective millimeter-wave (MMW) joint radar-communication (JRC) system with super resolution is proposed and experimentally demonstrated, using optical heterodyne up-conversion and self-coherent detection down-conversion techniques. The point lies in the designed coherent dual-band constant envelope linear frequency modulation-orthogonal frequency division multiplexing (LFM-OFDM) signal with opposite phase modulation indexes for the JRC system. Then the self-coherent detection, as a simple and low-cost means, is accordingly facilitated for both de-chirping of MMW radar and frequency down-conversion reception of MMW communication, which circumvents the costly high-speed mixers along with MMW local oscillators and more significantly achieves the real-time decomposition of radar and communication information. Furthermore, a super resolution radar range profile is realized through the coherent fusion processing of dual-band JRC signal. In experiments, a dual-band LFM-OFDM JRC signal centered at 54-GHz and 61-GHz is generated. The dual bands are featured with an identical instantaneous bandwidth of 2 GHz and carry an OFDM signal of 1 GBaud, which help to achieve a 6-Gbit/s data rate for communication and a 1.76-cm range resolution for radar

Angled fiber-based Fabry–Perot interferometer

Herein, we propose and experimentally demonstrate a novel, to the best of our knowledge, all-fiber Fabry–Perot (FP) interferometer that is formed by a simple angled fiber that can function as a beam splitter. According to the principle of the angled fiber, we verify the influence of an oblique angle on the light propagation path and light intensity ratio. Subsequently, angled fiber-based FP interferometers are experimentally demonstrated, and the influence of the oblique angle on the visibility of interference fringes and temperature characteristics is investigated. Finally, the temperature characteristics of this proposed FP interferometer are investigated experimentally, and the temperature sensitivity is 12.62 and 10.89 pm/°C for 42° and 40° angled fiber-based fiber FP interferometers, respectively. This proposed FP interferometer is fabricated by using a simple angled fiber, which has the advantages of ease of fabrication and all-fiber characteristics and hence can meet the requirements of mass production and high stability in various practical application areas

Temperature-insensitive curvature sensor based on Bragg gratings written in strongly coupled multicore fiber

[EN] A novel temperature-insensitive optical curvature sensor has been proposed and demonstrated. The sensor is fabricated by inscribing fiber Bragg gratings with short lengths into a piece of strongly coupled multicore fiber (SCMCF) and spliced to the conventional single-mode fiber. Due to the two supermodes being supported by the SCMCF, two resonance peaks, along with a deep notch between them, were observed in the reflection spectrum. The experimental results show that the depth of the notch changes with the curvature with a sensitivity up to 15.9dB/m-1 in a lower curvature range. Besides, thanks to the unique property of the proposed sensor, the notch depth barely changes with temperature. Based on the intensity demodulation of the notch depth, the temperature-insensitive curvature sensor is achieved with the cross sensitivity between the temperature, and the curvature is as low as 0.001m-1/¿C.National Natural Science Foundation of China (62071395); the 111 Project (B18045); Sichuan Province Science and Technology Support Program (2020YJ0329); Universitat Politècnica de València (PAID-01-18); Ministerio de Economía y Competitividad (PGC2018-101997-B-I00, TEC2017-88029-R).Liu, Z.; Zheng, D.; Madrigal-Madrigal, J.; Villatoro, J.; Antonio-Lopez, JE.; Schülzgen, A.; Amezcua-Correa, R.... (2021). Temperature-insensitive curvature sensor based on Bragg gratings written in strongly coupled multicore fiber. Optics Letters. 46(16):3933-3936. https://doi.org/10.1364/OL.432889S39333936461

Arbitrary spectral synthesis and waveform generation with HiBi fiber loop mirrors

An arbitrary spectral synthesis scheme with parallel-connecting high-birefringence fiber loop mirrors (HiBi-FLMs) based on Fourier synthesis theory has been proposed and demonstrated. Three typical spectra of triangle, rectangle and sawtooth shape have been synthesized by implementing only four HiBi-FLMs. The experimental results are in good agreement with theoretical simulations with a goodness of fit of 0.9565. Furthermore, higher precise optical spectrum with narrower bandwidth can be obtained by adopting longer polarization- maintaining fiber and more sections of HiBi-FLMs. Besides, a typical application of arbitrary waveform generation has been implemented. By incorporating with frequency-to- time mapping, triangle- and sawtooth-shaped electrical pulses with repetition rate of 1 GHz and pulse width of ~860 ps have been generate

Temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating

[EN] This Letter presents a simple temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating (ECFBG). By partly inserting an ECFBG into a ceramic ferrule, the reflection spectrum of the ECFBG splits into two peaks as a result of the applied tilt angle. The magnitude and direction of inclination in one dimension can be determined by monitoring the wavelength separation between both peaks, which is inherently insensitive to temperature. The proposed tilt sensor has a good linear response within a wide dynamic range of +/- 45 degrees, with a sensitivity of 0.012 nm/degrees, with a resolution of 0.83 degrees, and with an accuracy of 0.41 degrees. Being free from any inherent mechanical joint/friction, along with the advantages of a compact structure, good repeatability, and low cost, the proposed sensor is highly suitable for practical engineering applications. (C) 2019 Optical Society of AmericaNational Natural Science Foundation of China (61405166, 61775185); Sichuan Province Science and Technology Support Program (2018HH0002); Higher Education Discipline Innovation Project (B18045); Ministerio de Economia y Competitividad (DIMENSION TEC2017 88029-R); Horizon 2020 Framework Programme (722509).Zheng, D.; Cai, Z.; Floris, I.; Madrigal-Madrigal, J.; Pan, W.; Zou, X.; Sales Maicas, S. (2019). Temperature-insensitive optical tilt sensor based on a single eccentric-core fiber Bragg grating. Optics Letters. 44(22):5570-5573. https://doi.org/10.1364/OL.44.005570S557055734422Lin, C. H., & Kuo, S. M. (2008). Micro-impedance inclinometer with wide-angle measuring capability and no damping effect. Sensors and Actuators A: Physical, 143(1), 113-119. doi:10.1016/j.sna.2007.08.021Qiang Zhang, Tao Zhu, Fengyang Yin, & Kin Seng Chiang. (2014). Temperature-Insensitive Real-Time Inclinometer Based on an Etched Fiber Bragg Grating. IEEE Photonics Technology Letters, 26(10), 1049-1052. doi:10.1109/lpt.2014.2313334Zhuang, Y., Chen, Y., Zhu, C., Gerald, R. E., & Huang, J. (2018). Probing changes in tilt angle with 20 nanoradian resolution using an extrinsic Fabry-Perot interferometer-based optical fiber inclinometer. Optics Express, 26(3), 2546. doi:10.1364/oe.26.002546Guan, B.-O., Tam, H.-Y., & Liu, S.-Y. (2004). Temperature-Independent Fiber Bragg Grating Tilt Sensor. IEEE Photonics Technology Letters, 16(1), 224-226. doi:10.1109/lpt.2003.820101Bao, H., Dong, X., Zhao, C., Shao, L.-Y., Chan, C. C., & Shum, P. (2010). Temperature-insensitive FBG tilt sensor with a large measurement range. Optics Communications, 283(6), 968-970. doi:10.1016/j.optcom.2009.11.014Xinyong Dong, Zhan, C., Kun Hu, Ping Shum, & Chi Chiu Chan. (2005). Temperature-insensitive tilt sensor with strain-chirped fiber Bragg gratings. IEEE Photonics Technology Letters, 17(11), 2394-2396. doi:10.1109/lpt.2005.857978Yang, R., Bao, H., Zhang, S., Ni, K., Zheng, Y., & Dong, X. (2015). Simultaneous Measurement of Tilt Angle and Temperature With Pendulum-Based Fiber Bragg Grating Sensor. IEEE Sensors Journal, 15(11), 6381-6384. doi:10.1109/jsen.2015.2458894Chen, H.-J., Wang, L., & Liu, W. F. (2008). Temperature-insensitive fiber Bragg grating tilt sensor. Applied Optics, 47(4), 556. doi:10.1364/ao.47.000556MacPherson, W. N., Flockhart, G. M. H., Maier, R. R. J., Barton, J. S., Jones, J. D. C., Zhao, D., … Bennion, I. (2004). Pitch and roll sensing using fibre Bragg gratings in multicore fibre. Measurement Science and Technology, 15(8), 1642-1646. doi:10.1088/0957-0233/15/8/036Zheng, D., Madrigal, J., Chen, H., Barrera, D., & Sales, S. (2017). Multicore fiber-Bragg-grating-based directional curvature sensor interrogated by a broadband source with a sinusoidal spectrum. Optics Letters, 42(18), 3710. doi:10.1364/ol.42.003710Zheng, D., Madrigal, J., Barrera, D., Sales, S., & Capmany, J. (2017). Microwave Photonic Filtering for Interrogating FBG-Based Multicore Fiber Curvature Sensor. IEEE Photonics Technology Letters, 29(20), 1707-1710. doi:10.1109/lpt.2017.2742579Kong, J., Ouyang, X., Zhou, A., Yu, H., & Yuan, L. (2016). Pure Directional Bending Measurement With a Fiber Bragg Grating at the Connection Joint of Eccentric-Core and Single-Mode Fibers. Journal of Lightwave Technology, 34(14), 3288-3292. doi:10.1109/jlt.2016.256554

Strongly coupled multicore fiber with FBGs for multipoint and multiparameter sensing

[EN] A compact optical fiber sensor by embedding fiber Bragg gratings (FBGs) in strongly coupled multicore fiber (SCMCF) is proposed for multipoint and multiparameter sensing. To build the device, two FBGs with different peak wavelengths were inscribed in a segment of SCMCF. Then one end of the SCMCF was fusion spliced to a single-mode fiber (SMF) and the other end of the SCMCF was cleaved. In the SMF-SCMCF structure, two supermodes are excited, as a result, the reflection spectrum exhibits a sinusoidal pattern with two sharp peaks. The wavelength position of the FBGs and the supermode coupler can be extracted simultaneously. Two distinct FBGs inscribed in different positions of the SCMCF were used to demonstrate quasi-distributed multipoint sensing in the proposed structure. To the best of our knowledge, this is the first demonstration of an optical fiber sensor that combines FBGs with SCMCF. The sensor here proposed has the advantage of compact size, low-cost, good mechanical strength and ease of interrogation.This work was supported in part by National Key Research and Development Program of China (2019YFB2203204), National Natural Science Foundation of China (61922069, 61775185), the "111" Plan (B18045), Sichuan Science and Technology Program (2020YJ0329), and the Spanish Ministry of Economy and Competitiveness under the project DIMENSION TEC2017 88029-R. J.V. acknowledges funding from the Fondo Europeo de Desarrollo Regional (FEDER) and the Ministerio de Economia y Competitividad (Spain) under project PGC2018-101997-B-I00. DocumentLiu, Z.; Zheng, D.; Madrigal-Madrigal, J.; Villatoro, J.; Antonio-Lopez, E.; Schuelzgen, A.; Amezcua-Correa, R.... (2020). Strongly coupled multicore fiber with FBGs for multipoint and multiparameter sensing. Optical Fiber Technology. 58:1-7. https://doi.org/10.1016/j.yofte.2020.102315S175

Visualization2.mp4

A video describing the principle and advantages of the proposed optical frequency comb generation schem