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1.
Semi-vectorial analysis of a compact wavelength demultiplexer based on the tapered multimode interference coupler
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Based on a parabolically tapered multimode interference (MMI) coupler
with a deep-etched SiO2/SiON rib waveguide, a compact wavelength
demultiplexer operating at 1.30 and 1.55\mum wavelengths is
proposed and analysed by using three-dimensional semi-vectorial
finite-difference beam propagation method (3D-SV-FD-BPM). The results
show that a MMI section of 330.0\mum in length, which is only
76% length of a straight MMI coupler, is achieved with the
contrasts of 42.3 and 39.2dB in quasi-TE mode, and 38.4 and 37.8dB in
quasi-TM mode at wavelengths 1.30 and 1.55\mum, respectively, and
the insertion losses below 0.2dB at both wavelengths and in both
polarization states. The alternating direction implicit algorithm
with the Crank--Nicholson scheme is applied to the discretization of
the 3D-SV-FD-BPM formulation along the longitudinal direction.
Moreover, a modified FD scheme is constructed to approximate the
resulting equations along the transverse directions, in which the
discontinuities of the derivatives of magnetic field components
Hy and Hx along the vertical and horizontal interfaces,
respectively, are involved. 相似文献
2.
Compact In0.67Ga0.33As0.6P0.4/In0.71Ga0.29As0.74P0.26 on InP single ring resonators incorporating 2 × 2 multimode interference (MMI) turning-mirror couplers with cross coupling factor of 0.15 have been demonstrated. The form of race tracks is a 15-degree arc of 260 μm radius joined with a 60-degree arc of 110 μm radius, and finished with another 15-degree arc of 260 μm radius. The MMI turning-mirror coupler of 128 μm in length is used in the single ring resonators, which correspond to free spectral ranges of 82 GHz. A contrast of 4 dB, a finesse of nearly 3 and full-width at half-maximum (FWHM) of 0.24 nm for the drop port have been achieved in this single ring resonator. From the experimental value Tmax/Tmin of 21 dB, the experiment coupling factor coincides with the simulation. 相似文献
3.
An improved 1 × 4 coupler based on all solid multi-core photonic crystal fiber is proposed and analyzed. The expressions to calculate the coupling length and the coupling efficiency are deduced based on the coupled-mode equations firstly. Then a full-vector finite element method (FEM) is used to calculate the coupling length and the coupling efficiency. Next, the propagation characteristics and the performances of the coupler are analyzed through using a full vector beam propagation method (BPM). Research shows that the results derived by FEM agree with that by BPM. The coupling length of the coupler is 4.1 mm at λ = 1.55 μm. A maximum coupling efficiency of 24.96% can be obtained. The coupling ratio is more than 22.5% over a wavelength range of 100 nm. The polarization-dependent loss at λ = 1.55 μm is equal to 0.73 dB. Finally, the influences of the micro-variation of structure parameters and the material refractive index on the working performances of the coupler are investigated. 相似文献
4.
A 1310 and 1550 nm coarse wavelength multi/demultiplexer based on benzocyclobutene (BCB 4024-40) polymer is demonstrated for the first time. The device is designed based on a combination of general interference and paired interference mechanisms of multimode interference (MMI). It is fabricated on BK7 glass substrate with a thin layer of SiO2 as cover. A cost effective chemical etching technique is used in the fabrication process to take advantage of the photosensitive nature of the polymer. The device length was significantly reduced by adopting the restricted multimode interference scheme, lower beat length ratio and cascaded MMI couplers. The measured crosstalk at 1310 nm was 14.4 dB and at 1550 nm was 20.6 dB. The measured insertion loss is around 3.2-3.5 dB for both ports. 相似文献
5.
In this paper, we systematically study a designed structure of a bending dual-core photonic crystal fiber (PCF). We propose the controllable wavelength-selective coupling PCF. This coupler allows highly accurate control of the filtering wavelength. The different wavelengths can be selected by controlling the bending radius of the fiber. Coupling characteristics of novel bending wavelength-selective coupling PCF are evaluated by using a vector finite element method and their application to a multiplexer demultiplexer (MUX–DEMUX) based on the novel coupler is investigated. When the fiber length is 4168 μm, the bending radius of PCF couplers for 1.48/1.55 μm, 1.3/1.55 μm, 0.98/1.55 μm, and 0.85/1.55 μm is calculated, respectively, and the beam propagation analysis is performed. Different from the traditional wavelength-selective coupling PCF, the dual-core PCF is bent and it can realize the separation of multiple wavelengths. 相似文献
6.
Tzong-Yow Tsai Zhi-Cheng Lee Yen-Cheng Fang Ming-Hong Cha 《Optics Communications》2006,263(2):197-200
A novel compact wavelength-division multiplexer using highly dispersive waveguide-to-waveguide coupling is designed, simulated and analyzed. The device consists of two very close single-moded waveguides that are periodically connected to form a mode-dependent dispersive grating. It is demonstrated that the wavelengths over the edges of the photonic band gap contributed by the grating can be separated in a very short propagation distance. Using the finite-difference time-domain method, the result shows that the wavelengths of 1570 and 1530 nm are separated by the grating in a coupler length of 57 μm which is much shorter than the required length of about 340 μm without grating assistance. The channel contrast of 20 dB and the insertion loss about 2 dB are achieved. 相似文献
7.
用多模干涉原理分析和设计了光通信波长(1.30μm~1.55μm)的Si1-xGex/Si滤波器,并用模的传播分析方法对其传输特性进行了研究。结果发现,在Ge含量x=0.04时,干涉区的脊高和宽度分别为6.35μm和8μm。如果多模干涉区长度LM=2302.5μm,可滤1.30μm而通1.55μm的波长。且具有31dB的对比度和0.01dB的插入损耗;如果多模干涉区长度LM=2512.5μm,可滤1.55μm而通1.30μm的波长。具有16dB的对比度和0.09dB的插入损耗。 相似文献
8.
An ultra small size 4-channel wavelength division demultiplexer based on 2D photonic crystal modified Y-Branch, suitable for integration, is proposed in this paper. The output wavelengths of designed structure can be tuned for communication applications (around 1550 nm) by choosing suitable defect parameters in the corner of each resonance cavity and output waveguides. The cross section of the structure is 313.28 μm2 (17.8 μm × 17.6 μm) and desirable for integration based on popular planar technology. The bandwidth of each channel is near to 1 nm and the channel spacing is approximately 3.5 nm and wavelengths of demultiplexer channels are 1548.8 nm, 1551.9 nm, 1555.4 nm and 1559.3 nm respectively. Also, the crosstalk is between −33.1855 dB and −10.4947 dB. Furthermore, the mean values of the crosstalk and quality factor are −22.54 dB and 1496.7 respectively. 相似文献
9.
The objective of this paper is to investigate the implementation of a hybrid photonic crystal (PhC) 1.31/1.55 μm wavelength division multiplexer (WDM) and wavelength channel interleaver with channel spacing of roughly 0.8 nm between the operating wavelengths of 1.54-1.56 μm. It is based on 1-D photonic crystal (PhC) structure connected with an output 2-D PhC structure. The power transfer efficiency of the hybrid PhC WDM at 1.31 μm and 1.55 μm were computed by eigen-mode expansion (EME) method to be about 88% at both the wavelengths. The extinction ratios obtained for the 1.31 μm and 1.55 μm wavelengths are − 25.8 dB and − 22.9 dB respectively. 相似文献
10.
We investigate characteristics of gold metal strip waveguides based on long range surface plasmon polaritons (LRSPPs) along thin metal strips embedded in a polymer for practical applications at the telecommunication wavelengths of 1.31 and 1.55 μm. Guiding properties of the gold strip waveguides are theoretically and experimentally evaluated with the limited thickness and width up to ∼20 nm and ∼10 μm, respectively. The lowest propagation loss of ∼1.4 dB/cm is obtained with a 14.5-nm-thick and 2-μm-wide gold strip at 1.55 μm. With a single-mode fiber, the lowest coupling loss of ∼0.4 dB/facet is achieved with a 14.5-nm-thick and 5-μm-wide gold strip at 1.55 μm. The lowest insertion losses are obtained 8-9 dB with 1.5 cm-long gold strips of a limited thickness and width at both the wavelengths. We demonstrate a 10 Gbps optical signal transmission via the LRSPP waveguide with a 14 nm-thick, 2.5 μm-wide, and 4 cm-long gold strip. These LRSPP waveguides have potential applications for optical interconnects and communications. 相似文献
11.
An endlessly single mode highly polarization maintaining nonlinear microstructure fiber at telecommunication window is reported via full-vector finite element method. By taking three ring hexagonal PCF with suitable fiber parameter such as air hole diameter in cladding region d = 0.8 μm, pitch 2.3 μm and introducing four symmetrical large air holes near core region d′ = 2 μm, single mode (Veff ≤ π), small effective mode area 2.7 μm2, nonlinear co-efficient 44.39 W−1 km−1, high phase birefringence of the order of 10−3 and group birefringence of the order of 10−4 with beat length 0.3 μm at wavelength 1.55 μm are achieved. 相似文献
12.
P.P. Sahu 《Optics Communications》2007,277(2):295-301
In this paper, a novel MMI coupler, based on general interference, with tapered waveguide geometry has been proposed for reduction of coupling length. The coupling characteristics and power imbalance of the proposed structure are compared with conventional MMI structures by using a mathematical model based on sinusoidal modes. It is seen that the beat length for tapered MMI coupler with angle of taper ∼1.05° is reduced by ∼24% of that of conventional MMI coupler and the coupling characteristics obtained with the mathematical model, match well with those obtained by more sophisticated BPM computer aided design software. The power imbalance for tapered 3 dB MMI coupler is more sensitive to the wavelength than that for conventional 3 dB MMI coupler and variation of power imbalance with fabrication tolerance for both the MMI coupler is almost same. 相似文献
13.
A new two dimensional photonic crystal demultiplexer of wavelength (WDM) is designed by exploiting two Fabry–Pérot reflectors at the end of the bus waveguides. The results show that the light with different wavelengths can be successfully filtered to different ports by setting different radius of the center defect rods in the drop waveguides and high drop efficiency can be achieved by means of reflection feedbacks. The proposed filter has a cross section equal to 9.7 μm × 5.8 μm. In the designed filter, an improvement of the number of channels has been achieved. The normalized transmission spectra of this component have been studied using finite difference time domain (FDTD) method. The important parameters consider for this studies are radius of rods used in Fabry–Pérot reflectors, and radius of center defect rods in the drop waveguides. The demultiplexer we designed can easily separate the light with seven different wavelengths simultaneously. The scope of this paper lies on demultiplexer for communication systems around 1.55-μm wavelength. 相似文献
14.
A soft glass dual core polarization splitter based on highly birefringent photonic crystal fiber (PCF) is proposed and the full vector finite element method (FEM) is employed to analyze the impacts of structural parameters on birefringence and the coupling length, and simulation results show that high birefringence on the order of 10−2 can be obtained at 1.55 μm, moreover, hole size, hole pitch and elliptic ratio all affect birefringence and the coupling length. Based on these results, the PCF's structure is optimized to realize a polarization splitter of 282 μm whose largest extinction ratio is around −45.42 dB at 1.55 μm. Meanwhile, the bandwidth at the extinction ratio of −10 dB is about 90 nm, and around 32 nm at −20 dB. 相似文献
15.
Jiasheng Xu 《Journal of Physics and Chemistry of Solids》2006,67(7):1427-1431
Uniform hexagonal pencil-like BaCO3 whiskers have been successfully synthesized by the chemical reaction of barium chloride and urea via a facile hydrothermal route. Most whiskers have well-defined crystallographic facets and a regular prismatic hexagon with the length up to 50 μm and diameter around 5 μm. The straight pencil-like BaCO3 whisker is grown along the c-axial direction, the six faces of whiskers are consisted of both {0 1 0} and {1 1 0} planes. The present hydrothermal synthetic system tends to provide an appropriate chemical microenvironment for the formation of hexagonal pencil-like BaCO3 whiskers, due to the fact that the homogeneous decomposition of urea plays an essential role in the whole process. 相似文献
16.
P.P. Sahu 《Optics Communications》2008,281(4):573-579
In this paper, a thermally tunable EDFA gain equalizer filter based on point symmetric cascaded Mach-Zehnder (CMZ) filter based two mode interference (TMI) coupler is presented with its mathematical model. Transmission characteristics of these CMZ couplers are analyzed and compared with Y symmetric CMZ couplers by using this model. For EDFA gain equalizer, point symmetric CMZ circuit is chosen due to its higher wavelength flattening width than Y symmetric CMZ circuit. The ripples of equalized EDFA gain spectrum are formulated and estimated from the equalized gain spectrum of point symmetric CMZ filters. It is found that 2 stage point symmetric CMZ coupler with binomial coupler distribution (2PB CMZ) using Δn = 5% provides gain equalized width of 35 nm with ripple of 0.4-0.6 dB and bending loss of 0.24 dB and device length is ∼15 times lower than that of the existing EDFA gain equalizer based CMZ filter. It is also seen that if during the fabrication process, waveguide core width w is increased or decreased by 0.1 μm (in percentage ∼±6.6%), the power imbalance of TMI based 2PB CMZ filter is slightly increased by ∼8% in comparison to that based on directional coupler (DC) by 40%. Low power thermooptic structure of varying gap between two waveguide cores with silicon trench just below the heater is used and it requires ∼1.5 times less heating power than the conventional structure for thermal tuning of EDFA gain equalization. 相似文献
17.
An efficient electrode scheme is developed to enhance the inline detector performance of a 1.55 μm, InP–InGaAsP, Traveling Wave-Semiconductor Optical Amplifier (TW-SOA). A traveling wave approach is used to determine the voltage developed along the length of the TWSOA, accurately. A single electrode along the entire length of the device and a single, short length electrode kept at certain distance from the front facet are investigated, for input optical power levels ranging from −25 dBm to +5 dBm. Efficient position of the single electrode along the cavity length is determined for maximum detected voltage. Under this scheme, the inline detector with an electrode length of 100 μm positioned at 200 μm from the front facet, is found to provide a improvement of 6 dB and 8 dB in detected voltage for 40 mA and 50 mA bias respectively, at −10 dBm input, when compared with the maximum detected voltage reported in the literature. 相似文献
18.
Licheng Wang 《Solid State Communications》2006,138(2):72-75
A convenient hydrothermal process was applied to prepare the cube-like MnSe2 microcrystallines through the reaction of MnSO4·H2O with Se and NaH2PO2·H2O in aqueous solution at 160 °C for 12 h. Powder X-ray diffraction (XRD) analysis confirmed that the product was the cubic phase of MnSe2 with cell parameter a=6.440 Å. The chemical composition of the MnSe2 was determined by XPS. The Raman spectrum of MnSe2 presented the peaks of the Se-Se stretching mode at 232.44 and 266.58 cm−1. The images of scanning electron microscope (SEM) and transmission electron microscope (TEM) showed the cube-like morphology of the product with the edge length ranging from 20 to 30 μm. The formation mechanism of the MnSe2 microcrystallines was discussed as well. 相似文献
19.
Ram Prakash Dwivedi 《Optics Communications》2011,284(5):1418-1423
We report, for the first time, on the design of a plasmonic modulator working on the principle of the elasto-optic effects in a directional coupling structure, utilizing three parallel metal-dielectric-metal waveguides. We propose to achieve the active switching of the power propagation using the elasto-optic effect and optimize the extinction ratio of the optical modulation. The device is characterized and numerically analyzed using the finite-element-method at the wavelengths of 1.55 μm. For the modulator length of 2.33 μm, the extinction ratio of the modulation is nearly 14 dB, and the calculated attenuation loss is 4.5 dB. The calculated driving voltage is 4.8 V for the given modulator. The effect of the applied voltage on the modulation is also analyzed. 相似文献
20.
In this paper, we present and explore a new hybrid cladding design for improved birefringence and highly nonlinear photonic crystal fibers (PCFs) in a broad range of wavelength bands. The birefringence of the fundamental mode in such a PCF is numerically analyzed using the finite element method (FEM). It is demonstrated that it is possible to design a simple highly nonlinear hybrid PCF (HyPCF) with a nonlinear coefficient of the about 46 W−1 km−1 at a 1.55 μm wavelength. According to simulation, the highest modal birefringence and lowest confinement loss of our proposed structure at the excitation wavelength of λ = 1.55 μm can be achieved at a magnitude of 1.77 × 10−2 and of the order less than 102 dB/km with only five rings of air-holes in the fiber cladding. 相似文献