Xian-Yin Wang

Design and analysis of a polymer Mach-Zehnder interferometer electro-optic switch over a wide spectrum of 110 nm

A dual-driving polymer Mach-Zehnder interferometer (MZI) electro-optic switch is designed and optimized, which consists of a phase-generating coupler (PGC) and a 3-dB directional coupler. Structural schematics and principles of the PGC and the switch are described. Novel formulas of the switching time are presented. Under the central operation wavelength of 1550 nm, simulation for the designed device shows that the push-pull switching voltage is 2.445 V, the switching time is 18.1 ps, and the cross talk is less than −30 dB. By optimizing the PGC structure, the phase error resulting from the wavelength shift can be compensated effectively, and a wide spectrum about 110 nm can be achieved. The proposed analytical technique on waveguides and electrodes proves to be accurate and computationally efficient when compared with the beam propagation method (BPM) and the experimental results.

Design of integrated 1×2, 1×4 low driving voltage polymer electro-optic switches based on Y-fed directional couplers

Two integrated 1 × 2 and 1 × 4 polymer electro-optic switches based on Y-fed directional couplers are designed and optimized in terms of the coupled mode theory, electro-optic modulation theory, conformal transforming method and image method. The principle of the 1 × 2 electro-optic switch is described. Parameters including the core size, buffer layer thickness, electrode thickness, electrode width and electrode gap are optimized. Simulation results show that the length of the designed 1 × 2 switch is about 3.126 mm, the driving voltages of the two branches are as low as 0.891 and −0.891 V, respectively, the crosstalk and insertion loss are less than −30 and 1.42 dB, respectively, within the operation wavelength from 1527 to 1574 nm. Under the same driving voltages, the 1 × 4 optical switch with a total length of less than 7 mm can be switched by altering the voltages applied on the electrodes of the three Y-fed directional couplers. Simulation results from the beam propagation method (BPM) indicate that the two designed devices exhibit favorable switching functions.

Analysis and optimum design of a polymer Y-fed coupler electro-optic switch using double-section reversed electrodes

A packaged polymer electro-optic switch using double-section reversed electrodes based on the Y-fed coupler structure is investigated in terms of the conformal transforming method, image method, coupled mode theory and electro-optic modulation theory. The structure and principle are described, and unique formulations are proposed for simulating the device, including the amplitude transfer matrix, propagation powers and output powers. Design and optimization are performed, and characteristics are analyzed. Under the central operation wavelength of 1550 nm, the coupling region length is 4391.5 µm, the driving voltages of the upper and lower branches are as low as +0.633 and −0.633 V, respectively; the insertion loss and crosstalk are less than 2.04 and −30 dB, respectively, within the relative large ranges of fabrication error and wavelength shift. The proposed analysis and formulations are proved to be sufficiently accurate by comparison with the beam propagation method (BPM). The designed switch with the above waveguide and electrode structure shows lower switching voltage compared to our previous reported switches.

Design of a polymer directional coupler electro-optic switch with rib waveguide structure

By using the conformal transformation, method of images, electro-optic modulation theory and coupled mode theory, an optimum design is performed, and the characteristics are analyzed for a polymer directional coupler electro-optic switch with a rib waveguide structure. The simulation results show that the coupling length is about 4420 µm, and the switching voltage is about 16.2 V for the operation wavelength 1550 nm. Under the operation voltages of 0 and 16.2 V, the insertion loss and the crosstalk of the coupling region are less than 0.30 and − 20 dB within the ranges of the wavelength from 1520 to 1580 nm and the coupling region length from 4130 to 4710 µm.

Transmission characteristics of microring resonator arrays

In terms of the coupled mode theory, novel formulas of the transfer functions are presented for a microring resonator array, which consists of multiple series-cascaded filter elements, and each of them contains double parallel-cascaded identical microrings. By using these formulas, we can analyze transmission characteristics for such a polymer device. Simulated results show that when some parameters are selected properly, the box-like spectral response can be formed, which is flat and steep, and the sidelobes and the cross talk can be dropped efficiently. The effects of manufacturing tolerances on the transmittance are discussed, which result in the shift of the transmission spectrum of the device.

Optimization design and manufacturing tolerance analysis of a polymer microring resonant wavelength multiplexer

Based on formulas presented, optimization design is performed and the effects of manufacturing tolerances on transmission characteristics are analyzed for a polymer microring resonant wavelength multiplexer around the central wavelength of 1.550918 µm with wavelength spacing 1.6 nm. Modeling results show that the insertion loss is less than 0.55 dB and crosstalk is less than –21 dB for each of eight vertical output channels of the designed device without tolerances. Some manufacturing tolerances result in a shift of the transmission spectrum and lead to increases of the inserted loss and crosstalk over the design case without tolerances

Analysis and optimization for a polymer cross-grid array of microring resonant wavelength multiplexers

Based on formulas presented for the amplitude coupling ratio and the transfer function, transmission characteristics are analyzed and parameters are optimized for a polymer cross-grid array of microring resonant wavelength multiplexers around the central wavelength of 1.550918 µm with wavelength spacing 1.6 nm. In the design of the device, by means of selecting a resonant order m=95 and introducing a resonant order increment of adjacent filter elements m=2, we increase the ring radius difference of adjacent filter elements R from 17 nm (for the case of m=0) to 337 nm. Calculated results show that the 3-dB bandwidth is about 0.2 nm, the ratio between the –1- and –10-dB bandwidths is about 0.22, the insertion loss is less than 0.5 dB, and crosstalk is below –39 dB for each of the eight horizontal output channels.

Characteristic Analysis of a Smooth Square Microring Resonant Wavelength Multiplexer

Novel formulas of amplitude coupling ratio and transmission functions are presented for a smooth square microring resonant (MRR) wavelength multiplexer. By using these formulas, transmission characteristics are analyzed and some parameters are optimized for such a 1 × 8 polymeric device around the central wavelength of 1550.92 nm with the wavelength spacing of 1.6 nm. In the design of the device, by using the smooth squares, a thicker coupling layer is obtained, and by resonating the light at different resonant orders in different filter elements, the ring radius increment is increased sufficiently, which is of benefit to the fabrication of the device. When the amplitude coupling ratio is 0.2, the 3-dB bandwidth of the spectral response is about 0.2 nm; the ratio between −1 dB and −10 dB bandwidths is about 0.2; the insertion loss is less than 1.33 dB; and the crosstalk is below −21 dB for every vertical output channel of the device.