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Chai J, Shi L, Guo N, Jin L, Li J, Bai M, Wei D, Huang W, Liu M, Zhu T. Long-period D-fiber grating based robust and efficient bidirectional coupler for whispering gallery mode excitation. OPTICS EXPRESS 2023; 31:227-234. [PMID: 36606962 DOI: 10.1364/oe.479223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
A robust and efficient bidirectional coupler for whispering gallery mode (WGM) excitation based on a long-period grating (LPG) inscribed in D-fiber is theoretically and experimentally demonstrated. The LPG coupling the fundamental core mode to the forward propagating cladding modes according to the phase-matching condition not only enhances the evanescent field of the fiber but also selectively excites the WGM in a wavelength band of interest. Experimental results show that a maximum resonance contrast as high as 10.5 dB and a quality factor (Q-factor) on the order of 104 can be achieved in an LPG coupled spherical silica WGM resonator with a diameter of 242 µm, where the LPG with a pitch of 680 µm is fabricated by arc-discharging in a side-polished D-fiber with a maximum polishing depth of 56 µm. In addition to high robustness and efficiency, such an LPG-based WGM coupler also demonstrates bidirectionality, i.e., it is independent of the injection direction of the input light, which provides a reliable and flexible fiber coupler for the WGM resonator based practical applications.
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Peng L, Riesen N, Li J, Han M, Nguyen LV, Ebendorff-Heidepriem H, Warren-Smith SC. Whispering gallery mode excitation using exposed-core fiber. OPTICS EXPRESS 2021; 29:23549-23557. [PMID: 34614619 DOI: 10.1364/oe.431544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/20/2021] [Indexed: 06/13/2023]
Abstract
Whispering gallery modes (WGMs) in micro-resonators are of interest due to their high Q-factors. Ultra-thin fiber tapers are widely deployed to couple light into micro-resonators but achieving stable and practical coupling for out-of-lab use remains challenging. Here, a new WGM coupling scheme using an exposed-core silica fiber (ECF) is proposed, which overcomes the challenge of using fragile fiber tapers. Microspheres are deposited onto the exposed channel for excitation via the evanescent field of the fiber's guided modes. The outer jacket of the ECF partially encapsulates the microspheres, protecting them from external physical disturbance. By varying the mode launching conditions in this few-mode ECF, in combination with a Fano resonance effect, we demonstrate a high degree of tunability in the reflection spectrum. Furthermore, we show multi-particle WGM excitation, which could be controlled to occur either simultaneously or separately through controlling the ECF mode launching conditions. This work can bring value towards applications such as optical switches and modulators, multiplexed/distributed biosensing, and multi-point lasing, integrated in a single optical fiber device that avoids fiber post-processing.
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Li A, Tian K, Yu J, Minz RA, Ward JM, Mondal S, Wang P, Nic Chormaic S. Packaged whispering gallery resonator device based on an optical nanoantenna coupler. OPTICS EXPRESS 2021; 29:16879-16886. [PMID: 34154240 DOI: 10.1364/oe.422830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/15/2021] [Indexed: 06/13/2023]
Abstract
In this work, we present a packaged whispering gallery mode (WGM) device based on an optical nanoantenna as the coupler and a glass microsphere as the resonator. The microspheres were fabricated from either SiO2 fiber or Er3+-doped fiber, the latter creating a WGM laser with a threshold of 93 µW at 1531 nm. The coupler-resonator WGM device was packaged in a glass capillary. The performance of the packaged microlaser was characterized, with lasing emission both excited in and collected from the WGM cavity via the nanoantenna. The packaged system provides isolation from environmental contamination, a small size, and unidirectional coupling while maintaining a high quality (Q-) factor (∼108).
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Li C, Zhu M, Ji P, Xiong C, Liao C. In-Fiber BaTiO 3 Microsphere Resonator for High-Sensitivity Temperature Measurement. MICROMACHINES 2021; 12:mi12030318. [PMID: 33803684 PMCID: PMC8002858 DOI: 10.3390/mi12030318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 11/23/2022]
Abstract
A fiber optic whispering gallery mode (WGM) resonator was proposed and realized by integrating an inline polymer waveguide with a microsphere mounted on it. The polymer waveguide with a diameter of 1 μm was printed with femtosecond laser-assisted multiphoton polymerization in a section of a grooved hollow-core fiber, which was sandwiched between two single-mode fibers. Two WGW resonators assembled with microspheres of different sizes were prepared. The transmission spectra of those stimulated WGMs were investigated both in simulation and experimentally. The temperature response of the resonators was particularly studied, and a linear sensitivity of −593 pm/°C was achieved from 20 °C to 100 °C.
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Affiliation(s)
- Chi Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (C.L.); (M.Z.); (P.J.); (C.X.)
- Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
| | - Meng Zhu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (C.L.); (M.Z.); (P.J.); (C.X.)
- Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
| | - Peng Ji
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (C.L.); (M.Z.); (P.J.); (C.X.)
- Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
| | - Cong Xiong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (C.L.); (M.Z.); (P.J.); (C.X.)
- Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
| | - Changrui Liao
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (C.L.); (M.Z.); (P.J.); (C.X.)
- Shenzhen Key Laboratory of Photonic Devices and Sensing Systems for Internet of Things, Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, Shenzhen University, Shenzhen 518060, China
- Correspondence:
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