In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional cou...In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional coupler, which can divide the different waveguide eigenmodes into different optical paths. The results show a possibility to encode information onto different waveguide modes. We also experimentally demonstrate that the splitting ratio of this directional coupler structure can be tuned without changing its size.展开更多
Metasurfaces have found broad applicability in free-space optics,while its potential to tailor guided waves remains barely explored.By synergizing the Jones matrix model with generalized Snell’s law under the phase-m...Metasurfaces have found broad applicability in free-space optics,while its potential to tailor guided waves remains barely explored.By synergizing the Jones matrix model with generalized Snell’s law under the phase-matching condition,we propose a universal design strategy for versatile on-chip mode-selective coupling with polarization sensitivity,multiple working wavelengths,and high efficiency concurrently.The coupling direction,operation frequency,and excited mode type can be designed at will for arbitrary incident polarizations,outperforming previous technology that only works for specific polarizations and lacks versatile mode controllability.Here,using silicon-nanoantenna-patterned silicon-nitride photonic waveguides,we numerically demonstrate a set of chip-scale optical couplers around 1.55μm,including mode-selective directional couplers with high coupling efficiency over 57%and directivity about 23 d B.Polarization and wavelength demultiplexer scenarios are also proposed with 67%maximum efficiency and an extinction ratio of 20 d B.Moreover,a chip-integrated twisted light generator,coupling free-space linear polarization into an optical vortex carrying 1 h orbital angular momentum(OAM),is also reported to validate the mode-control flexibility.This comprehensive method may motivate compact wavelength/polarization(de)multiplexers,multifunctional mode converters,on-chip OAM generators for photonic integrated circuits,and high-speed optical telecommunications.展开更多
An ultrasensitive biosensor based on hybrid structure and composed of long-range surface plasmon polariton(LRSPP) and dielectric planar waveguide(PWG) modes is proposed. Both PWG and LRSPP modes have strong resonances...An ultrasensitive biosensor based on hybrid structure and composed of long-range surface plasmon polariton(LRSPP) and dielectric planar waveguide(PWG) modes is proposed. Both PWG and LRSPP modes have strong resonances to form strong coupling between the two modes, and the two modes can couple to enhance sensitivity of sensors. In the hybrid structure, PWG is composed of cytop–Si–cytop multilayers and the LRSPP configuration is composed of cytop–metal–sensing medium multilayer slabs. The highest imaging sensitivities of 2264 and3619 RIU-1were realized in the proposed sensors based on Au and Al-monolayer graphene, respectively, which are nearly 1.2 and 1.9 times larger than the 1910 RIU-1sensitivity of the conventional LRSPR sensor(LRSPP sensor). Moreover, it is demonstrated that the PWG-coupled LRSPP biosensor is applicable to the sensing medium,with refractive index in the vicinity of 1.34.展开更多
This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference fie...This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference field. A 442-nm laser was used to excite high-order waveguide modes in an asymmetric metal-cladding dielectric waveguide structure. The dispersion curve of the waveguide modes was theoretically analyzed, and the distribution of the interference field of high-order waveguide modes was numerically simulated using the finite-element method. The various dependences of the characteristics of hierarchical sub-wavelength photonic structures on the thickness and refractive index of the photoresist and the waveguide mode were investigated in detail. These hierarchical sub-wavelength photonic structures have various periods and numbers of layers and can be fabricated by a simple and low-cost method.展开更多
Optimization of the high power single-lateral-mode double-trench ridge waveguide semiconductor laser based on InGaAsP/InP quantum-well heterostructures with a separate confinement layer is reported. Two different wave...Optimization of the high power single-lateral-mode double-trench ridge waveguide semiconductor laser based on InGaAsP/InP quantum-well heterostructures with a separate confinement layer is reported. Two different waveguide structures of Fabry-Perot lasers emitting at a wavelength of 1.55 μm are fabricated. The influence of an effective lateral refractive index step on the maximum output power is investigated. A cw single mode output power of 165mW is obtained for a 1-mm-long uncoated laser.展开更多
In this paper, we first propose a metamaterial structure by etching the same two interdigital fingers on the upper ground of quarter mode substrate integrated waveguide（QMSIW）. The simulated results show that the pr...In this paper, we first propose a metamaterial structure by etching the same two interdigital fingers on the upper ground of quarter mode substrate integrated waveguide（QMSIW）. The simulated results show that the proposed QMSIWbased metamaterial has a continuous phase constant changing from negative to positive values within its passband. A periodic leaky-wave antenna（LWA）, which consists of 11 QMSIW-based metamaterial unit cells, is designed, fabricated,and measured. The measured results show that the fabricated antenna achieves a continuous beam scanning property from backward-43° to forward ＋32° over an operating frequencyrange of 8.9 GHz–11.8 GHz with return loss better than 10 d B.The measured antenna gain keeps consistent with the variation of less than 2 d B over the operating frequency range with a maximum gain of 12 d B. Besides, the measured and simulated results are in good agreement with each other, indicating the significance and effectiveness of this method.展开更多
SOI waveguides fabricated by wet-etching method are demonstrated.The single mode waveguide and 1×2 3dB MMI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of e...SOI waveguides fabricated by wet-etching method are demonstrated.The single mode waveguide and 1×2 3dB MMI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of effective index method and guided mode method.The devices are fabricated.Excellent performances,such as low propagation loss of -1.37dB/cm,low excess loss of -2.2dB,and good uniformity of 0.3dB,are achieved.展开更多
A wavelength filter with simple structure using multimode waveguide is proposed. The device uses mode conversion by a grating structure fabricated simultaneously with the multimode waveguide.
We numerically investigate the trade-offs between the dispersion properties,coupling efficiency,and geometrical constraints in dual-wire （twin-lead） terahertz （THz） waveguides.In particular,we show that their inhe...We numerically investigate the trade-offs between the dispersion properties,coupling efficiency,and geometrical constraints in dual-wire （twin-lead） terahertz （THz） waveguides.In particular,we show that their inherent linearly polarized quasi-transverse electromagnetic （TEM） modes exist for waveguide transverse dimensions comparable with the wavelength,enabling significant end-fire coupling （10%） for numericalaperture limited Gaussian beams while supporting a relatively low-dispersion propagation of below 0.5 ps 2 /m,as desired for short-pulse time-domain spectroscopy applications.Starting from the dual-wire structure,we also demonstrate that low-dispersion tapers can be designed to improve coupling efficiency.展开更多
The normal mode interference characteristic in shallow water waveguide is a valu- able topic in the fields of underwater acoustic. A method for extracting the interference components of normal modes from broadband aco...The normal mode interference characteristic in shallow water waveguide is a valu- able topic in the fields of underwater acoustic. A method for extracting the interference components of normal modes from broadband acoustic propagation data recorded by a single hy- drophone without any prior information is present in this paper. First, a Hermitian matrix is formed by the power spectral density. Second, a singular value decomposition （SVD） is performed on the Hermitian matrix to obtain the orthonormal eigenvectors, which are proportional to the interference components of normal modes. The fundamental equations of the new extracting method are derived based on normal mode and waveguide invariant theory. And the validity of the present method is verified by the numerical simulation and experimental results. In addition, the extracted results of normal-mode interference components are intended to be used for passive ranging of broadband sources.展开更多
We propose to generate a sub-nanometer-confined optical field in a nanoslit waveguiding mode in a coupled nanowire pair(CNP).We show that,when a conventional waveguide mode with a proper polarization is evanescently c...We propose to generate a sub-nanometer-confined optical field in a nanoslit waveguiding mode in a coupled nanowire pair(CNP).We show that,when a conventional waveguide mode with a proper polarization is evanescently coupled into a properly designed CNP with a central nanoslit,it can be efficiently channeled into a high-purity nanoslit mode within a waveguiding length<10μm.The CNP can be either freestanding or on-chip by using a tapered fiber or planar waveguide for input-coupling,with a coupling efficiency up to 95%.Within the slit region,the output diffraction-limited nanoslit mode offers an extremely confined optical field(∼0.3 nm×3.3 nm)with a peak-to-background ratio higher than 25 dB and can be operated within a 200-nm bandwidth.The group velocity dispersion of the nanoslit mode for ultrafast pulsed operation is also briefly investigated.Compared with the previous lasing configuration,the waveguiding scheme demonstrated here is not only simple and straightforward in structural design but is also much flexible and versatile in operation.Therefore,the waveguiding scheme we show here may offer an efficient and flexible platform for exploring light–matter interactions beyond the nanometer scale,and developing optical technologies ranging from superresolution nanoscopy and atom/molecule manipulation to ultra-sensitivity detection.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00200 and 2011CB921200the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant No XDB01030200+2 种基金the National Natural Science Foundation of China under Grant No 11374289the Fundamental Research Funds for the Central Universities under Grant No K2470000012the Program for New Century Excellent Talents in University
文摘In photonie integrated circuits, information is usually encoded in the optical path. In this work, based on the multi-mode dielectric-loaded surface plasmon polariton waveguide, we numerically design a directional coupler, which can divide the different waveguide eigenmodes into different optical paths. The results show a possibility to encode information onto different waveguide modes. We also experimentally demonstrate that the splitting ratio of this directional coupler structure can be tuned without changing its size.
基金National Natural Science Foundation of China(61675114,61875103,61935013,61975133,U1701661)Natural Science Foundation of Beijing Municipality(501100004826)+1 种基金Tsinghua University Initiative Scientific Research Program(20151080709)Beijing Young Talents Support Project(2017000020124G044)。
文摘Metasurfaces have found broad applicability in free-space optics,while its potential to tailor guided waves remains barely explored.By synergizing the Jones matrix model with generalized Snell’s law under the phase-matching condition,we propose a universal design strategy for versatile on-chip mode-selective coupling with polarization sensitivity,multiple working wavelengths,and high efficiency concurrently.The coupling direction,operation frequency,and excited mode type can be designed at will for arbitrary incident polarizations,outperforming previous technology that only works for specific polarizations and lacks versatile mode controllability.Here,using silicon-nanoantenna-patterned silicon-nitride photonic waveguides,we numerically demonstrate a set of chip-scale optical couplers around 1.55μm,including mode-selective directional couplers with high coupling efficiency over 57%and directivity about 23 d B.Polarization and wavelength demultiplexer scenarios are also proposed with 67%maximum efficiency and an extinction ratio of 20 d B.Moreover,a chip-integrated twisted light generator,coupling free-space linear polarization into an optical vortex carrying 1 h orbital angular momentum(OAM),is also reported to validate the mode-control flexibility.This comprehensive method may motivate compact wavelength/polarization(de)multiplexers,multifunctional mode converters,on-chip OAM generators for photonic integrated circuits,and high-speed optical telecommunications.
基金National Natural Science Foundation of China(NSFC)(61505111)Guandong Natural Science Foundation(2015A030313549)+2 种基金Science and Technology Planning Project of Guangdong Province(2016B050501005)Science and Technology Project of Shenzhen(JCYJ20140828163633996,JCYJ20150324141711667)Natural Science Foundation of SZU(201452,201517,827-000051,827-000052,827-000059)
文摘An ultrasensitive biosensor based on hybrid structure and composed of long-range surface plasmon polariton(LRSPP) and dielectric planar waveguide(PWG) modes is proposed. Both PWG and LRSPP modes have strong resonances to form strong coupling between the two modes, and the two modes can couple to enhance sensitivity of sensors. In the hybrid structure, PWG is composed of cytop–Si–cytop multilayers and the LRSPP configuration is composed of cytop–metal–sensing medium multilayer slabs. The highest imaging sensitivities of 2264 and3619 RIU-1were realized in the proposed sensors based on Au and Al-monolayer graphene, respectively, which are nearly 1.2 and 1.9 times larger than the 1910 RIU-1sensitivity of the conventional LRSPR sensor(LRSPP sensor). Moreover, it is demonstrated that the PWG-coupled LRSPP biosensor is applicable to the sensing medium,with refractive index in the vicinity of 1.34.
基金Project supported by the National Natural Science Foundation of China(Grant No.61505074)the National Key Basic Research Program of China(Grant No.2013CBA01703)the Hong Liu Young Teachers Training Program Funded Projects of Lanzhou University of Technology(Grant No.Q201509)
文摘This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference field. A 442-nm laser was used to excite high-order waveguide modes in an asymmetric metal-cladding dielectric waveguide structure. The dispersion curve of the waveguide modes was theoretically analyzed, and the distribution of the interference field of high-order waveguide modes was numerically simulated using the finite-element method. The various dependences of the characteristics of hierarchical sub-wavelength photonic structures on the thickness and refractive index of the photoresist and the waveguide mode were investigated in detail. These hierarchical sub-wavelength photonic structures have various periods and numbers of layers and can be fabricated by a simple and low-cost method.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61274046 and 61474111the National Basic Research Program of China under Grant No 2013AA014202
文摘Optimization of the high power single-lateral-mode double-trench ridge waveguide semiconductor laser based on InGaAsP/InP quantum-well heterostructures with a separate confinement layer is reported. Two different waveguide structures of Fabry-Perot lasers emitting at a wavelength of 1.55 μm are fabricated. The influence of an effective lateral refractive index step on the maximum output power is investigated. A cw single mode output power of 165mW is obtained for a 1-mm-long uncoated laser.
基金Project supported by the National Natural Science Foundation of China(Grant No.61372034)
文摘In this paper, we first propose a metamaterial structure by etching the same two interdigital fingers on the upper ground of quarter mode substrate integrated waveguide（QMSIW）. The simulated results show that the proposed QMSIWbased metamaterial has a continuous phase constant changing from negative to positive values within its passband. A periodic leaky-wave antenna（LWA）, which consists of 11 QMSIW-based metamaterial unit cells, is designed, fabricated,and measured. The measured results show that the fabricated antenna achieves a continuous beam scanning property from backward-43° to forward ＋32° over an operating frequencyrange of 8.9 GHz–11.8 GHz with return loss better than 10 d B.The measured antenna gain keeps consistent with the variation of less than 2 d B over the operating frequency range with a maximum gain of 12 d B. Besides, the measured and simulated results are in good agreement with each other, indicating the significance and effectiveness of this method.
文摘SOI waveguides fabricated by wet-etching method are demonstrated.The single mode waveguide and 1×2 3dB MMI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of effective index method and guided mode method.The devices are fabricated.Excellent performances,such as low propagation loss of -1.37dB/cm,low excess loss of -2.2dB,and good uniformity of 0.3dB,are achieved.
文摘A wavelength filter with simple structure using multimode waveguide is proposed. The device uses mode conversion by a grating structure fabricated simultaneously with the multimode waveguide.
基金supported by the FQRNT (Le Fonds Qubcois de la Recherche sur la Nature et les Technologies)the Natural Sciences and Engineering Research Council of Canada (NSERC)+1 种基金the NSERC Strategic Projectsthe INRS. M. P. wishes to acknowledge a Marie Curie Outgoing International Fellowship (No. PIOF-GA-2008-221262)
文摘We numerically investigate the trade-offs between the dispersion properties,coupling efficiency,and geometrical constraints in dual-wire （twin-lead） terahertz （THz） waveguides.In particular,we show that their inherent linearly polarized quasi-transverse electromagnetic （TEM） modes exist for waveguide transverse dimensions comparable with the wavelength,enabling significant end-fire coupling （10%） for numericalaperture limited Gaussian beams while supporting a relatively low-dispersion propagation of below 0.5 ps 2 /m,as desired for short-pulse time-domain spectroscopy applications.Starting from the dual-wire structure,we also demonstrate that low-dispersion tapers can be designed to improve coupling efficiency.
文摘The normal mode interference characteristic in shallow water waveguide is a valu- able topic in the fields of underwater acoustic. A method for extracting the interference components of normal modes from broadband acoustic propagation data recorded by a single hy- drophone without any prior information is present in this paper. First, a Hermitian matrix is formed by the power spectral density. Second, a singular value decomposition （SVD） is performed on the Hermitian matrix to obtain the orthonormal eigenvectors, which are proportional to the interference components of normal modes. The fundamental equations of the new extracting method are derived based on normal mode and waveguide invariant theory. And the validity of the present method is verified by the numerical simulation and experimental results. In addition, the extracted results of normal-mode interference components are intended to be used for passive ranging of broadband sources.
基金This work was sup-ported by the National Key Research and Development Program of China(2018YFB2200404)the New Cornerstone Science Foundation,the National Natural Science Foundation of China(92150302 and 62175213)+1 种基金the Natural Science Foundation of Zhejiang Province(LR21F050002)the Fundamental Research Funds for the Central Universities.
文摘We propose to generate a sub-nanometer-confined optical field in a nanoslit waveguiding mode in a coupled nanowire pair(CNP).We show that,when a conventional waveguide mode with a proper polarization is evanescently coupled into a properly designed CNP with a central nanoslit,it can be efficiently channeled into a high-purity nanoslit mode within a waveguiding length<10μm.The CNP can be either freestanding or on-chip by using a tapered fiber or planar waveguide for input-coupling,with a coupling efficiency up to 95%.Within the slit region,the output diffraction-limited nanoslit mode offers an extremely confined optical field(∼0.3 nm×3.3 nm)with a peak-to-background ratio higher than 25 dB and can be operated within a 200-nm bandwidth.The group velocity dispersion of the nanoslit mode for ultrafast pulsed operation is also briefly investigated.Compared with the previous lasing configuration,the waveguiding scheme demonstrated here is not only simple and straightforward in structural design but is also much flexible and versatile in operation.Therefore,the waveguiding scheme we show here may offer an efficient and flexible platform for exploring light–matter interactions beyond the nanometer scale,and developing optical technologies ranging from superresolution nanoscopy and atom/molecule manipulation to ultra-sensitivity detection.
