Sharp Bend Waveguide on 32 × 32 Photonic Bandgap Wavelength Switch
In this section, we design an 32×32 PBG wavelength switch based on SOI wafer which combines 1-D resonant PBG filter waveguide and 2-D PBG sharp bend waveguide. There are five regions on our designed integrated 32×32 PBG wavelength switch. The first and fifth regions are the input ports and output ports in our device, respectively. In both input and output ports, we set 32 ports single mode waveguide and the distance
between one port and another adjacent port is 128µm. Due to the distance between the two waveguides is enough length to use the technique of the fiber array to pack our designed 32 ports single mode waveguide filter. In 1-D resonant PBG filter waveguide, we use the technique of PBG, λ/4 phase shift and free-carrier plasma dispersion effect to design high transmittance, lower insertion loss and high quality factor resonant PBG filter waveguide. By adding various voltages to change carrier distribution, the index can be changed. We can filter the specific wavelength form the output port of waveguide. The various parameters exhibited among 1-D resonant PBG filter waveguide as shown in Table III.
The second and fourth regions are the transmission regions and connect 1-D resonant PBG filter waveguide and 32×32 wavelength switch.
In 2-D PBG sharp bend waveguide, we use the technique of photonic bandgap and line defect to control the direction of the light wave propagate in a waveguide. The light wave is confined in sharp bend waveguide successful in several shapes of air columns and propagates in the PBG defect line. That is, PBG sharp bend waveguide would make possible the realization of guiding the light wave in PBG defect line and reduce the volume of the optical communication device. The various parameters exhibited among 2-D PBG sharp bend waveguide with a square lattice as shown in Tables IV, V and VI. In center region is our designed 32×32 PBG wavelength switch and we focus on the new technology of router. The 32×
32 PBG wavelength switch combines PBG structure and MMI structure.
We implant the p-type boron and n-type phosphorus ions on the upper layer
of the PBG structure and add voltage to change the carrier concentration distribution. By changing carrier concentration distribution, the index can be changed. We can switch the specific wavelength form the output port of waveguide. The various parameter exhibited among 32 × 32 PBG wavelength switch with different refractive index change as shown in Table VII-XII.
Then we integrate the 1-D resonant PBG filter and 2-D PBG sharp bend waveguide into the 32×32 PBG wavelength switch as shown in Fig.
4-30. For example, we launch 32 ITU wavelengths of our designed 1-D resonant circular and hexagonal holes PBG filter waveguide at input ports.
By adding various voltages to change the refractive index and filter 32 different ITU wavelengths. The 32 ITU wavelengths of circular holes PBG filter waveguide are from 1532.2nm to 1544.6nm and the channel spacing is 0.4nm. The 32 ITU wavelengths of circular holes PBG filter waveguide are from 1530.1nm to 1545.2nm and the channel spacing is 0.4nm. The wavelength response at the output port of our resonant circular holes PBG filter waveguide is shown in Figs. 4-30. The uniformity over the 32 phase-shift wavelengths of circular and hexagonal holes PBG filter waveguide is 0.8368dB and 1.3343dB. The 32 ITU wavelengths propagate in the each channel of 32 ports 2-D PBG sharp bend waveguide individually. The structures in our designed 2-D PBG sharp bend waveguide are a square lattice of circular and hexagonal air columns. The propagation loss on each output port of 2-D PBG sharp bend waveguide with square lattice of circular and hexagonal air columns as shown in Table
VI. The 32 ITU wavelengths from 1532.2nm to 1544.6nm and 1530.1nm to 1542.5nm are filtered by 1-D resonant circular and hexagonal holes PBG filter waveguide, respectively. Then the 32 ITU wavelengths launch into the port 1 to port 32 of 2-D PBG sharp bend waveguide individually. The main application of 2-D sharp bend waveguide is used to connect optical communication device and optical fiber. The advantage of 2-D PBG sharp bend waveguide is reducing the size of optical device and providing high transmittance in optical communication. Then, the 32 ITU wavelengths from 1532.2nm to 1544.6nm and 1530.1nm to 1542.5nm pass through the 2-D PBG sharp bend waveguide with circular and hexagonal air columns air columns, respectively. Then the 32 ITU wavelengths propagate into the port 1to port 32 of 32×32 wavelength switch individually. We add voltage on the several electrode pads to change the carrier concentration distribution. By changing carrier concentration distribution, the index can be changed. We can switch the specific wavelength form the output port of waveguide. The 32 ITU wavelengths can be switched to different output port when they pass through the 32×32 wavelength switch. The various parameter exhibited among 32×32 PBG wavelength switch with different refractive index change as shown in Table IX and XII. Finally, the 32 ITU wavelengths pass through the next 2-D PBG sharp bend waveguide and 1-D resonant PBG filter waveguide. Then we use the technique of the fiber array to pack our designed 32 ports single mode waveguide filter. Fig. 4-31 shows the output power at individual 32 output ports with different refractive index change for 32 ITU wavelengths launching into the whole
integrated 32×32 PBG wavelength switch. The whole integrated 32×32 PBG wavelength switch is combined with 1-D resonant circular holes PBG filter waveguide and 2-D PBG sharp bend waveguide with circular air columns. Fig. 4-32 shows the output power at individual 32 output ports with different refractive index change for 32 ITU wavelengths launching into the whole integrated 32×32 PBG wavelength switch. The whole integrated 32×32 PBG wavelength switch is combined with 1-D resonant hexagonal holes PBG filter waveguide and 2-D PBG sharp bend waveguide with hexagonal air columns.