共查询到20条相似文献,搜索用时 15 毫秒
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Pun E.Y.B. Wong K.K. Andonovic I. Laybourn P.J.R. de la Rue R.M. 《Electronics letters》1982,18(17):740-742
An efficient Bragg-deflection grating on x-cut LiNbO3, using proton exchange in benzoic acid through an aluminium grating mask, has been demonstrated. A deflection efficiency of 90% has been measured. 相似文献
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The principle and operation is reported of a novel coupler for optical LiNbO3 : Ti waveguides. As the coupling mechanism, the radiation of the energy of the semileaky TE-like mode into the substrate due to the crystal anisotropy is used. Efficient polarisation-dependent coupling can be obtained while retaining the planar configuration and without having to use any other materials or structures except for the LiNbO3 waveguide itself. 相似文献
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Integrated optical 4×4 star coupler on LiNbO3 总被引:1,自引:0,他引:1
A novel low-loss passive planar 4×4 star coupler consisting of four interconnected 3 dB couplers was fabricated on x-cut Ti: LiNbO3 using z-propagation. Almost even distribution was achieved for both TE and TM polarised light incident on any of the four inputs. Excess loss including fibre coupling was <4.2 dB. 相似文献
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Korotky S.K. Alferness R.C. Buhl L.L. Joyner C.H. Marcatili E.A.J. 《Electronics letters》1984,20(9):384-386
We report the generation of 47 ps (FWHM) optical pulses at a 5 Gbit/s repetition rate using a sinusoidally driven Ti-LiNbO3 directional coupler modulator with travelling-wave electrodes By selective DC bias of the switch, these pulses are obtained without overdriving and without velocity matching of the electrical and optical waves. 相似文献
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A multilevel grating coupler based on silicon-on-insulator (SOI) material structure is proposed to realize the coupling between waveguide and waveguide or waveguide and fiber. This coupler is compatible with the current fabrication facilities for complementary metal oxide semiconductor (CMOS) technology with vertical coupling. This structure can realize coupling when the beams with transverse electric (TE) polarization and transverse magnetic (TM) polarization are incident at the same time. The influences of the grating coupler parameters including wavelength, the thickness of waveguide layer, the thickness of SiO2 layer and the number of steps on the TE mode and TM mode coupling efficiencies are discussed. Theory researches and simulation results indicate that the wavelength range is from 1533 nm to 1580 nm when the TE mode and TM mode coupling efficiencies are both more than 40% as the grating period is 0.99 μm. The coupling efficiencies of the incident TE and TM modes are 49.9% and 49.5% at the wavelength of 1565 nm, respectively, and the difference between them is only 0.4%. 相似文献
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P. Cheben S. Janz D.-X. Xu B. Lamontagne A. Delage S. Tanev 《Photonics Technology Letters, IEEE》2006,18(1):13-15
A new diffractive device for light coupling between a planar optical waveguide and free space is proposed. The device utilizes a second-order waveguide grating to diffract the fundamental waveguide mode into two free propagating beams and a subwavelength grating (SWG) mirror to combine the two free propagating beams into a single beam. The finite-difference time-domain (FDTD) simulations show that the SWG mirror improves the coupling efficiency of the waveguide fundamental mode into the single out-coupled beam from about 30% to 92%. A high efficiency (>90%) is predicted for a broad wavelength range of 1520-1580nm. The proposed device is compact (/spl sim/80 /spl mu/m in length) and it eliminates the need for blazing the waveguide grating. 相似文献
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Shibata Y. Oku S. Kondo Y. Tamamura T. Naganuma M. 《Lightwave Technology, Journal of》1996,14(6):1027-1032
A semiconductor monolithic wavelength selective router is proposed. An electrically tunable grating switch is monolithically integrated with a directional coupler. The effect of sidelobe on the demultiplexing characteristics of the router is investigated, and it is shown that the sidelobes degrade the wavelength crosstalk and introduce a power penalty for demultiplexing characteristics. A phase-synchronized sampled grating is introduced to suppress the sidelobes, and wavelength router switching is observed in this structure. The extinction ratio is over 10 dB at a current injection of 25 mA. Using this structure, power-penalty-free wavelength selective routing at a 2.5 Gb/s wavelength-division-multiplexed NRZ random pattern is demonstrated 相似文献
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A new circuit realization of X-band transmit-receive switch is proposed that is based on a PHEMT-controlled stub directional coupler. The operation of the switch is analyzed. The impedances of the stubs are optimized to yield a considerably larger bandwidth of the switch. It is shown that the circuit can serve as a building block for multithrow switches. 相似文献
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We report a broadly tunable (85 ?/V) wavelength-selective Ti: LiNbO3-waveguide directional coupler, with which we demonstrate ?=1.3 ?m/? = 1.55 ?m multiplexing while simultaneously modulating the long-wavelength channel. 相似文献
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Johnson G.A. Todd M.D. Althouse B.L. Chang C.C. 《Lightwave Technology, Journal of》2000,18(8):1101-1105
We present a new technique for fiber Bragg grating (FBG) sensor interrogation and multiplexing. The technique combines a scanning bandpass filter used to multiplex by wavelength multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fiber interferometer made with a 3×3 coupler to detect strain-induced wavelength shifts. A demonstration system interrogates four gratings in a single fiber at a sampling rate up to 20 kHz, with a noise floor measured at less than 10 nϵ/√(Hz) above 0.1 Hz 相似文献
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An accurate and stable narrow-band frequency discriminator may be obtained by using two standard dual monolithic crystal filters in parallel, asynchronously tuned. Low deviation from linearity and steep gradient are possible. Theory and experiment are compared for a 10.7 MHz discriminator. 相似文献
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Deri R.J. Sanada T. Yasuoka N. Makiuchi M. Kuramata A. Hamaguchi H. Wada O. Yamakoshi S. 《Photonics Technology Letters, IEEE》1990,2(8):581-584
Low-loss monolithic integration of a 3-dB waveguide coupler with twin photodetectors using large-mode size guides, mirror coupling, and low-capacitance lateral detectors is demonstrated. Waveguide-mirror integration introduces only ≈1 dB optical insertion loss at 1.54 μm wavelength, compared to top-illuminated detectors. Full balanced operation of the monolithic circuit with 33-dB local oscillator intensity noise suppression is demonstrated 相似文献
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采用参量振荡方法实现太赫兹辐射(THz-wave Parametric Oscillator,TPO),因只需一个固定波长的泵浦源和一块非线性晶体,且具有非线性转换效率高、调谐简单而倍受瞩目.以LiNbO3晶体为例,采用Q调制的Nd:YAG激光器(1.064μm)为泵浦源,角度匹配的非共线相位匹配方式,设计了太赫兹参量振荡器,实现了当入射角α从8.2°变化到14°,相位匹配角θ相应地从16.2°变化到54.75°,太赫兹波与泵浦光之间的夹角β从8.84°~67.88°,闲频光从1.068μm变化到1.079 6μm,太赫兹波从284~74μm(1~4 THz)的连续太赫兹波振荡. 相似文献
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D. Taillaert Harold Chong P.I. Borel L.H. Frandsen R.M. De La Rue R. Baets 《Photonics Technology Letters, IEEE》2003,15(9):1249-1251
We demonstrate a novel polarization splitter based on a two-dimensional grating etched in a silicon-on-insulator waveguide. The device couples orthogonal modes from a single-mode optical fiber into identical modes of two planar ridge waveguides. The extinction ratio is better than 18 dB in the wavelength range of 1530-1560 nm and the coupling efficiency is approximately 20%. The device is very compact and couples light only to transverse-electric modes of the planar waveguides. Therefore, it may be used in a polarization diversity configuration to implement a polarization insensitive photonic integrated circuit based on photonic crystal waveguides. 相似文献
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为了研究电场一定时,光束在非近轴条件下铌酸锂晶体的电光效应,采用折射率椭球张量的循环坐标变换方法,理论上推导了光轴正交截面上折射率分布的解析式,讨论了折射率、相位延迟以及透射率与光束入射方向之间的关系,并且进行了实验验证,取得了透过率随光束与光轴夹角α的实验数据。结果表明,y方向加电场时,入射光小角度偏转将引起x方向感应折射率以及光束透射率的明显变化,而y方向的感应折射率不变;光束与光轴的夹角α对铌酸锂晶体电光性能的影响远远大于光矢在x-y平面与x轴正半轴的夹角β对其的影响;x方向加电场时感应折射率同y方向加电场时类似,但此时相位延迟更小,在0°~0.4399°夹角范围内,前者的透过率变化较后者慢,并且在0.45°之后呈现出交替变化的规律,当夹角为0.5°,0.680°等位置时,它们具有相同的透过率。这一结果对利用角度调节以改善铌酸锂晶体的电光性能具有一定的指导意义。 相似文献