Effects Of Waveguide Width Research Articles

Improving the performance of ring resonator refractive index sensor through structural modifications

In this work, different types of whispering gallery mode ring resonator structures such as strip, slotted, hybrid plasmonic mode, and subwavelength grating ring resonators are simulated using the finite difference time domain method (FDTD). The proposed devices are modeled to be used as refractive index sensor. The comparative analysis of strip, slotted, hybrid plasmonic mode, and subwavelength grating ring resonators is done in terms of sensitivity, Q factor, and figure of merit (FOM) to find out the most suitable device according to the requirement. Additionally, the effect of waveguide width on sensitivity and Q factor is analyzed. The analysis shows that, compared to other simulated whispering gallery mode ring resonator sensor designs, the subwavelength grating ring resonator produces the best sensitivity of 1012 nm/RIU, and the slotted ring resonator produces the best FOM of 1610.

Integrated-optic wavelength demultiplexer on lithium niobate by double proton exchange

An integrated-optic wavelength demultiplexer produced by double proton exchange on z-cut lithium niobate is demonstrated. The mode sorting effect and waveguide dispersion characteristics are utilized to demultiplex the optical fields at the wavelengths 980 nm and 1550 nm. The opposite waveguide dispersion in the two output waveguides can be obtained by designing the aspect ratio of the waveguide structure and the refractive index profile of the waveguide. The design parameters include the waveguide width, the proton-exchange time, the annealing time, and the depth of the second proton-exchanged layer. The semivectorial finite difference method is utilized to calculate the effective index of the guided mode in the output waveguide in order to obtain the required waveguide dispersion for wavelength demultiplexing. In the experiment, the effects of waveguide width, branching angle, and depth of the second proton-exchanged layer on the device performance are discussed.

Integrated-optic biosensor by electro-optically modulated surface plasmon resonance

We present a new integrated-optic surface plasmon resonance (SPR) biosensor based on electro-optical modulation. The SPR characteristics for the analyte concentration detection can be electro-optically modulated by applying the voltage on the electrodes of the biosensor fabricated on lithium niobate, which is an excellent electro-optic material. Two measurement methods, electro-optically modulated SPR spectral measurement and electro-optically modulated SPR intensity measurement, are demonstrated and their measurands are the SPR wavelength and the output optical intensity, respectively. Human serum albumin is coated on the gold film surface of the proposed biosensor to detect the concentration of beta-blocker, which is a remedy for heart disease. As the applied voltage increases such that the effective index of guided mode rises, the SPR wavelength shifts toward the long wavelength side and the output optical intensity at the wavelength of 632.8 nm diminishes. The linear regression slope of the relation between the measurand and the applied voltage is dependent on the analyte concentration and can be used to determine the concentration variation. Experimental results measured by the electro-optically modulated SPR methods are compared with those measured by the conventional spectral and intensity methods, and the effects of waveguide width on the biosensor performance are discussed.

Finite-width waveguide and waveguide intersections for self-collimated beams in photonic crystals

The effect of waveguide width on the propagation of self-collimated beams in photonic crystals is studied using the finite-difference time-domain method. It is shown that, to obtain good transmission, it would be better to keep the waveguide width above a minimum value. It is also shown that waveguide intersections based on the effect of self-collimated beams can provide high throughput and low cross talk simultaneously within a relatively wide bandwidth.

Fabrication tolerance study of a compact passive polarization rotator

In this paper, the expected performance of a compact low-loss passive polarization rotator is reported by using rigorous numerical approaches. The effects of waveguide width, slant angle, etch depth, and refractive index variations during its fabrication on the overall polarization conversion and polarization crosstalk are reported. It is also expected that over the 1.53to 1.61-/spl mu/m wavelength range, polarization conversion would be more than 99% and polarization crosstalk would be better than -20 dB.

Silicon-on-insulator optical rib waveguides: loss, mode characteristics, bends and y-junctions

Optical rib waveguides with widths from 2.73 to 7.73 microns have been formed in SIMOX-based silicon-on-insulator (SOI) structures consisting of a 4.32 micron thick surface-silicon layer and a 0.398 micron buried-oxide layer. The effect of waveguide width, bend radius, y-junction splitting and interface roughness on loss and mode characteristics have been studied at wavelengths of 1.15 and 1.523 microns. The experimental results support the hypothesis that certain rib dimensions can lead to single-mode waveguides even though planar SOI waveguides of similar multimicron dimension are multimode. The propagation losses of waveguides 3.72 microns wide were found to be nominally 0.0 dB/cm and 0.4 dB/cm for the TE and TM modes, respectively, when measured at 1.523 microns, where the measurement error was ±0.5 dB/cm. This means that the loss is experimentally indistinguishable from pure bulk silicon. These results are thought to be the lowest loss measurements for silicon integrated optical waveguides reported to date.