An optical waveguide cantilever sensor is introduced, which is determined by monitoring the coupling efficiency between a waveguide cantilever and a waveguide receptor through the cantilever bending. A straightforward model is developed for an optical waveguide cantilever sensor, in which the coupling efficiency between the cantilever and receptor is calculated using the overlap integral. An effective index is introduced to analyze the thickness of input/output waveguides and cantilever for a maximum coupling with a fiber keeping the single-mode operation. The relationship of the optical waveguide sensor (cantilever, gap, and output waveguide) and the sensitivity is presented. As a consequence, we take an optical waveguide cantilever sensor structure of Si3N4/SiO2/Si as an example, and an optimized design is reported. Moreover, the analysis model is compared with a finite-difference beam propagation method. The result means that our model has a similar accuracy but is more simple, intuitive, and time-saving.
In this paper, we present a detailed analysis about the electro-optic (EO) polymer modulators using a full vectorial finite
difference (FVFD) mode solver for an optical waveguide and a finite-element method (FEM) for a microwave electrode.
A detailed discussion has been presented to describe a modulator about performance parameters: <i>V<sub>π</sub>L, ΔfL </i>with the design parameters, where <i>V<sub>π</sub>L</i> is the product of the half-wave voltage <i>V<sub>π</sub></i> and the electrode interaction length <i>L, </i>the parameter <i>ΔfL</i> is the product of the 3 dB optical bandwidth <i>Δf</i> and the electrode interaction length<i> L</i>.
Organic electro-optic polymer has low dielectric constant and high electro-optic coefficient, which is one of the perfect
materials for making modulators with low loss and high bandwidth. In this paper, we synthesized a novel chromophore
based on the 4-(diethylamino) salicylaldehyde electron donor and the rigid isolated benzyl group. Based on the
innovative chormophore, we designed low loss Mach-Zehnder interference modulators with 3dB bandwidth 50GHz
using tapered waveguides and coplanar waveguide electrodes as well as micro-strip electrodes. Performance parameters
of the modulators were detailed analyzed and two microwave driven electrodes were compared.
Base on the same two monomers, diphenolic acid (DPA) and isophthaloyl chloride (IPC), three chromophore-containing
nonlinear optical (NLO) polyarylate polymers were prepared. A tricyanofuran (TCF)-acceptor type chromophore group
was in main-chain (mPAR-chr1), side-chain (sPAR-chr1) and side-chain with a 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane (BPAPF) group (sPAR-F-chr1), respectively. The obtained polymers were characterized and evaluated by UV-Vis, <sup>1</sup>H NMR, DSC and TGA. All the polymers exhibited good electro-optic (EO) activity. The relationship between EO coefficients (r<sub>33</sub>) and the chromophore concentration of the three polymers were also characterized and discussed. There were no obvious differences found in EO activity between mPAR-chr1 and sPAR-chr1 polyarylates with the same chromophore. The fluorinated block polyarylate sPAR-F-chr1 has the largest r<sub>33</sub> value in these three polyarylates which is 52 pm/V at the wavelength of 1310 nm (which is almost twice the r<sub>33</sub> value of normal polymers contained the same chormophore at the same content), when the concentration of chromophore 1 is 18wt.%. 85% of the r<sub>33</sub> value was retained in the sPAR-F-chr1 after being heated at 85°C for 600 hours. The polymer sPAR-F-chr1, with good solubility, high T<sub>g</sub> (above 200 °C) and side functional group at the same time, may probably be a practical NLO material. These properties make the new polyarylates have potential applications in EO devices such as EO modulators and switches.
We present one theoretical analysis about the two resonators system. The model shows good agreement with other theoretical approaches. The properties of the system have been studied using the model. We also provide the analysis about the electromagnetically induced transparency (EIT) in the two resonators system,which shows, properly designed, the system exhibits a narrow high-quality-factor(Q) EIT-like resonant mode.
In this paper, we demonstrate a compact 8x8 λ-router using multimode-interference (MMI) crossing based on the
microring resonator. The 8x8 λ-router was designed and fabricated with a CMOS compatible silicon on insulator
technology. MMI is used to reduce the cross talk and the crossing losses of the device. Microrings with a nominal radius
of 2.5 μm and small variations of 10 nm of the nominal value allow respectively a free spectral range of 32 nm and
spacing between channels of 4 nm. The experimental results are in good agreement with the modeling. The basic add
drop filters of the devices exhibit losses of -2 dB and on/off contrast of the resonance of 20 dB. The total losses for one
channel are about -4 dB and the imbalance between the 8 channels is lower than 2 dB.
The doughnut beams with charges of 1 to 3 are generated by one and stacking two and three Liquid crystal(LC) spiral
phase plates with cell gaps of 7 μm respectively. Theoretically, any charge number can be obtained by the stacking
method. High efficiency and flexibility are the advantages of generating doughnut beams by stacking liquid crystal spiral
phase plates. The interference of doughnut beam generated by LC spiral phase plate and plane wave has been studied.
The numerical simulation results agree with the experiment.
An efficient shooting algorithm based on the simple-shooting method and the modified Newton-method for fiber Raman amplifier design is proposed. By introducing the Broyden's rank-one method, the time-consuming calculation of the Jacobian matrix is dramatically relieved. Numerical simulation results show that the simulation efficiency of the proposed method has been improved more than 70 percent compared with the conventional shooting method.
In this paper, a numerical method is presented to design a biconical waveguide. We use this method to calculate the transmitted and radiated power of the biconical waveguide in an integrated acousto-optic modulator, then we plot the normalized power loss curves versus the taper length and get the optimum design.
In this paper the parameters of a CW double-clad fiber laser are theoretically analyzed, which is of important references to designing the kindred double-clad fiber lasers. This paper also offers a personalizing design scheme of double-clad fiber lasers, with the influence of some important parameters on the output power clarified.
The overlap integral of guided acousto-optic interaction is investigated theoretically. The overlap integral of YZ-LiNbO3 (Y-cut crystal, Z-propagating surface acoustic wave) is discussed with different penetration depths for TE- and TM-polarized light. Some valuable results are obtained for the design of acousto-optic devices.
In an earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this
paper, we present a new approach based on the finite element - artificial transmitting boundary method and calculate the
2-D acoustical field on the substrate region.
In an earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element - artificial transmitting boundary method and calculate the 2-D acoustical field on the substrate region.