Article
Optics
Sendy Phang
Summary: Artificial intelligence (AI) drives the creation of disruptive future technologies that change the way we live and work. A new computing platform based on the photonic reservoir computing architecture, exploiting the dynamics of stimulated Brillouin scattering, is reported here. This passive optical system is suitable for use with high performance optical techniques, enabling real-time AI.
Article
Optics
Hilel Hagai Diamandi, Gil Bashan, Yosef London, Kavita Sharma, Keren Shemer, Avi Zadok
Summary: The polarization attributes of forward stimulated Brillouin scattering in single-mode fibers are investigated in this study, where torsional-radial acoustic modes are stimulated by orthogonally polarized pump tones. This is the first report of such phenomenon in standard single-mode fibers. Analysis predicts that circular and orthogonal pump tones may stimulate acoustic vortex beams in the form of rotating torsional-radial modes, representing the transfer of angular momentum between the light field's polarization degree of freedom and the acoustic wave.
LASER & PHOTONICS REVIEWS
(2022)
Article
Multidisciplinary Sciences
Xin-Xin Hu, Zhu-Bo Wang, Pengfei Zhang, Guang-Jie Chen, Yan-Lei Zhang, Gang Li, Xu-Bo Zou, Tiancai Zhang, Hong X. Tang, Chun-Hua Dong, Guang-Can Guo, Chang-Ling Zou
Summary: The study demonstrates a method of magnetic-free non-reciprocity by optically-induced magnetization in an atom ensemble. Excellent isolation performance (with highest isolation ratio of 51.5 dB) is observed over a power dynamic range of 7 orders of magnitude, with noiseless property verified by quantum statistics measurements. This approach can be applied to other atoms and atom-like emitters, paving the way for future studies of integrated photonic non-reciprocal devices.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Kang Wang, Ming Cheng, Haotian Shi, Linfeng Yu, Yi Zhang, Li Kai, Junqiang Sun
Summary: In this study, a suspended silicon microring with racetrack and spiral structure is designed and fabricated to exploit the resonantly enhanced stimulated Brillouin scattering (SBS) effect. By introducing the silicon ridge waveguide as a line defect, the designed photonic-phononic waveguide provides independent control on the optical and acoustic modes. The efficient forward SBS in the microrings is demonstrated and the characteristic Brillouin parameters are extracted. Moreover, a stronger inhomogeneous broadening effect is observed in the spiral microring due to structural variations.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Giulia Zanini, Giuliano Scarcelli
Summary: Brillouin spectroscopy is a promising technique for noninvasively probing the mechanical properties of biologically relevant materials. In this study, the authors derive a signal localization theory and design an improved SBS spectrometer, which shows significant improvements in acquisition speed and spectral precision.
Article
Optics
Wenxi Pei, Hao Li, Wei Huang, Meng Wang, Zefeng Wang
Summary: A tunable gas Raman laser based on deuterium-filled hollow-core photonic crystal fibers (HC-PCFs) is reported here, showing Raman lasers ranging from 1643 nm to 1656 nm with a maximum output power of around 1.2 W and a Raman conversion efficiency of about 45.6% inside the cavity. This work provides an alternative choice for all-fiber lasers operating at 1.6-1.7 mu m band.
Article
Optics
Xinglin Zeng, Philip St. J. Russell, Yang Chen, Zheqi Wang, Gordon K. L. Wong, Paul Roth, Michael H. Frosz, Birgit Stiller
Summary: A stable oscillation of optical vortices and acoustic modes in a Brillouin laser is achieved using a chiral photonic crystal fiber (PCF), supporting helical Bloch modes (HBMs) that carry circularly polarized optical vortex and display circular birefringence. The implemented system enables the emission of 1st and 2nd-order vortex-carrying HBMs and precise measurement of the Brillouin gain peak with high resolution and accuracy.
LASER & PHOTONICS REVIEWS
(2023)
Review
Crystallography
Jun Li, Hao Li, Zefeng Wang
Summary: The 1.7 mu m pulsed laser is crucial in bioimaging and gas detection, and FGRLs based on HC-PCFs offer an effective method for generating high-power lasers at this wavelength. Key factors for achieving high-power 1.7 mu m Raman output include gas pressure and pump peak power. The development direction of 1.7 mu m FGRLs is also discussed in this paper.
Article
Crystallography
Wenxi Pei, Hao Li, Wei Huang, Meng Wang, Zefeng Wang
Summary: The rotational stimulated Raman scattering of hydrogen molecules in an all-fiber cavity based on hollow-core photonic crystal fibers was reported. By using a homemade 1064 nm pulsed fiber amplifier, rotational SRS was induced in the gas cavity, leading to the generation of a 1135 nm Stokes wave. The output characteristics were explored by adjusting the pulse width and repetition frequency of the pump source, while a theoretical model was established for comparison with experimental results, facilitating the application of gas Raman laser based on HC-PCFs.
Article
Optics
Moshe Katzman, Dvir Munk, Maayan Priel, Etai Grunwald, Mirit Hen, Naor Inbar, Moshe Feldberg, Tali Sharabani, Roy Zektzer, Gil Bashan, Menachem Vofsi, Uriel Levy, Avi Zadok
Summary: This work presents the research on discrete-time integrated microwave photon filters on standard silicon, achieving long delays through surface acoustic waves and information recovery in the optical domain. These filters have high freedom in design and are immune to environmental phase drifts.
Article
Optics
Jianfan Yang, Luqi Yuan, Tian Qin, Fangxing Zhang, Yao Chen, Xiaoshun Jiang, Xianfeng Chen, Shanhui Fan, Wenjie Wan
Summary: Photonic gauge potentials play a crucial role in manipulating charge-neutral photons and enabling effects similar to Aharonov-Bohm in photonics. This study demonstrates anomalous gauge potentials induced by phonons with noninverted gauge phases, allowing for unique direction-dependent gauge phases in spatial-frequency space. Furthermore, photonic isolators have been constructed in the frequency domain, enabling nonreciprocal propagation of light along the frequency axis with coherent phase control for directional switching.
Article
Engineering, Electrical & Electronic
Jonas H. Osorio, Joao B. Rosolem, Fabio R. Bassan, Foued Amrani, Frederic Gerome, Fetah Benabid, Cristiano M. B. Cordeiro
Summary: Research achievements in hollow-core photonic crystal fibers technology have identified these fibers as excellent platforms for delivering high-power laser beams with minimal interaction with the fiber microstructure. Here, the utilization of a tubular-lattice hollow-core fiber as a promising platform for Power-over-Fiber systems is demonstrated, which expands the range of hollow-core fiber-based beam delivery applications. The experiments reported here identify hollow-core fibers as eligible candidates for next-generation Power-over-Fiber devices.
OPTICAL FIBER TECHNOLOGY
(2022)
Article
Crystallography
Hao Li, Wenxi Pei, Wei Huang, Meng Wang, Zefeng Wang
Summary: This study presents a high-power, highly efficient, wavelength-tunable nanosecond pulsed 1.7 mu m fiber laser based on hydrogen-filled hollow-core photonic crystal fibers (HC-PCFs) by rotational stimulated Raman scattering. Experimental results show a maximum average Stokes power of 3.3 W at 1705 nm with a slope efficiency of 84%, achieving the highest recorded value for 1.7 mu m pulsed fiber lasers.
Article
Physics, Multidisciplinary
Yao Yao, Tao Wang, Yi Liu, Bingjie Wang, Mingjiang Zhang
Summary: Silicon-core fibers, as a new type of semiconductor fiber, exhibit higher non-linear effects compared to traditional silica fibers. The study of forward-stimulated Brillouin scattering (FSBS) in silicon-core fibers helps to explore the potential of FSBS in fiber-optic sensing. This paper examines the FSBS effect in silicon-core fibers using the finite element method and determines the optimal coupling of different optical modes with the acoustic field modes.
FRONTIERS IN PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Di Wang, Xindong Zhang, Xueqing Zhao, Zhangyi Yang, Wei Dong
Summary: We propose and theoretically demonstrate a photonic-assisted frequency measurement system based on stimulated Brillouin scattering (SBS) with high accuracy, high resolution, and the capability of multiple frequencies estimation. The system achieves great performance by optimizing the gain spectrum and loss spectrum. It can obtain the frequency information of multiple unknown signals.
OPTICAL FIBER TECHNOLOGY
(2022)
Article
Physics, Applied
Taichi Muratsubaki, Takeshi Fujisawa, Yusuke Sawada, Takanori Sato, Kunimasa Saitoh
Summary: The novel direct-binary-search algorithm proposed enhances the device performance under diameter variation by considering structures based on holes with different diameters. Through the design of a fabrication-tolerant four-mode waveguide crossing in the 2μm waveband, the proposed method shows improved transmission of TE3 mode and good insertion losses and crosstalks despite diameter variations.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Yusuke Sawada, Takeshi Fujisawa, Takanori Sato, Kunimasa Saitoh
Summary: This paper proposes a novel wavefront-matching algorithm for the design of silicon waveguides, addressing the instability issue of conventional methods in high-index contrast. The effectiveness of the proposed method is demonstrated through detailed design examples, achieving high conversion efficiency for mode converters.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Yusuke Sawada, Takeshi Fujisawa, Takanori Sato, Kunimasa Saitoh
Summary: This article investigates the necessity of a full-vector propagation analysis for the design of high-refractive index difference waveguides using a wavefront matching method. It demonstrates that a full-vector WFM method is superior for designing waveguide lenses with a high Delta. Furthermore, experimental results show that a full-vector WFM method outperforms a scalar WFM method in terms of insertion loss.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Optics
Kodai Nakamura, Takeshi Fujisawa, Kunimasa Saitoh
Summary: A novel hybrid algorithm combining GWO and DBS is proposed for designing mosaic-based devices, resulting in improved average and best performances by 0.5 and 1.6 points compared to designs using DBS alone.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2022)
Article
Optics
Yizhou Wang, Takeshi Fujisawa, Kunimasa Saitoh
Summary: The paper presents an analytical expression for the mode-coupling coefficient between non-identical step-index cores, allowing for quick estimation of crosstalk in heterogeneous SI multi-core fibers. The analytical results are validated through numerical simulations using FEM and show good agreement. The feasibility of designing Hetero-SI-MCFs within standard cladding diameter is discussed, highlighting potential applications in SDM systems.
OPTICS COMMUNICATIONS
(2022)
Article
Optics
Aichi Muratsubaki, Takeshi Fujisawa, Takanori Sato, Kunimasa Saitoh
Summary: Two types of mosaic-based 2 x 2 3-dB couplers for wavelengths around 2.1 μm are proposed, with different loss and imbalance characteristics, and high fabrication tolerance.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2022)
Article
Optics
Takeshi Fujisawa, Kunimasa Saitoh
Summary: By introducing air-holes around the core of a ring-core fiber, arbitrary higher-order spatial states generation can be achieved, including orbital angular momentum states. This mechanism, not relying on phase matching, exhibits very low wavelength dependence, providing a novel and efficient approach for manipulating the spatial state of light.
Article
Engineering, Electrical & Electronic
Yuto Sagae, Takashi Matsui, Takayoshi Mori, Taiji Sakamoto, Taro Iwaya, Takanori Sato, Kunimasa Saitoh, Kazuhide Nakajima
Summary: We propose a design concept for a 3-mode 4-core fiber with a common depressed layer and numerically investigate its performance compared to other types of weakly coupled homogeneous 3-mode 4-core fibers. We find that the fiber with the common depressed layer effectively suppresses optical confinement loss while maintaining feasible inter-core crosstalk. We confirm the feasibility of the proposed design through evaluating the fabricated fiber's optical characteristics and further optimize the design to achieve lower loss.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
Zheyu Zhao, Takanori Sato, Takeshi Fujisawa, Taro Iwaya, Yuto Sagae, Taiji Sakamoto, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: This paper investigates the design of C-band double-cladding 2LP mode multicore fiber (2LP-MCF) with 125-mu m cladding diameter by numerical simulation. The results show that using a two-ring layout can improve crosstalk and critical bend radius, leading to significantly reduced crosstalk levels in 8-core and 10-core 2LP-MCFs compared to heterogeneous 2LP-MCFs without a double-cladding layer.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2023)
Article
Optics
Takeshi Fujisawa, Takuya Mitarai, Takuya Okimoto, Naoya Kono, Naoki Fujiwara, Takanori Sato, Hideki Yagi, Kunimasa Saitoh
Summary: This paper investigates ultracompact mode multiplexers based on a mosaic structure for various wavelength bands. The Bayesian technique is used for the design, showing its superiority in the search for the best structure. The fabricated devices on the Si-waveguide platform demonstrate the potential of mosaic-based devices for future compact optical transceivers.
Article
Optics
Takanori Sato, Takeshi Fujisawa, Masaki Wada, Takayoshi Mori, Taiji Sakamoto, Ryota Imada, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: We propose a silica-based LP11 mode rotator with multiple tapered trenches, which is a basic and indispensable optical component for space division multiplexing. Compared with the conventional interference-based LP11 mode rotator with a simple L-shape waveguide, our proposed rotator has advantages in mode conversion efficiency, insertion loss, and fabrication tolerance due to the adiabatic mode conversion principle. By using a shortcut to adiabaticity approach, we effectively miniaturize the device compared to standard tapered structures. Among silica-based mode multi/demultiplexers, our proposed LP11 mode rotator shows considerable promise.
Article
Optics
Zheyu Zhao, Yizhou Wang, Takanori Sato, Takeshi Fujisawa, Kunimasa Saitoh
Summary: The numerical results of 6-core and 8-core step-index 2LP-mode multi-core fibers with 125-μm cladding diameter and two-ring layout for C-band show that the crosstalk less than -51 and -35 dB/km can be obtained respectively. It is found that the two-ring layout is beneficial for improving the crosstalk and critical bending radius, and it is effective for both few-mode and single-mode multi-core fibers.
Proceedings Paper
Optics
Takayoshi Mori, Takeshi Fujisawa, Junji Sakamoto, Yoko Yamashita, Taiji Sakamoto, Ryota Imada, Ryoto Ima, Takanori Sato, Kei Watanabe, Ryoichi Kasahara, Toshikazu Hashimoto, Kunimasa Saitoh, Kazuhide Nakajima
Summary: This study presents a low loss silica PLC based mode dependent loss equalizer with a variable range of 2.5 dB. It demonstrates a variable differential modal gain equalization in a two-LP-mode EDFA over the entire C-band for the first time.
2022 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)
(2022)
Proceedings Paper
Optics
Yuto Sagae, Takashi Matsui, Taiji Sakamoto, Taro Iwaya, Takayoshi Mori, Takanori Sato, Kunimasa Saitoh, Kazuhide Nakajima
Summary: A higher relative core multiplicity factor of beyond 12 is achieved in a 125-mu m cladding diameter uncoupled multi-core fibre by using a common depressed layer design. Feasible inter-core crosstalk below -40 dB/km and effective area over 80 mu m(2) in C-L band are successfully obtained simultaneously.
2022 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Takeshi Fujisawa, Takayoshi Mori, Junji Sakamoto, Yoko Yamashita, Taiji Sakamoto, Ryota Imada, Ryoto Ima, Takanori Sato, Kei Watanabe, Ryoichi Kasahara, Toshikazu Hashimoto, Kazuhide Nakajima, Kunimasa Saitoh
Summary: A mode-dependent-loss (MDL) equalizer based on silica-PLC is proposed and experimentally demonstrated for the first time in three-mode transmission. By selectively attenuating specific modes, 1.5-dB MDL equalization is achieved for systems with large mode loss.
2022 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)
(2022)
