A silicon cross-slot waveguide filled with electro-optic polymer is proposed to release the polarization-dependent issue
of the electro-optic modulator. There are two slots in both the horizontal direction and vertical direction, so this
waveguide structure can confine both the TE and TM modes. The four silicon regions can be lightly doped as the
electrodes. There is slanted electric field in the slot region when the voltages are applied on the electrodes. The electric
field component act at principal optical axis whose electric-optic (EO) coefficient is r<sub>33</sub> or r<sub>13</sub> can be adjusted by
changing the voltages on the four electrodes. With optimal voltages, the effective refractive index of the TE and TM
modes can be changed equally. The Mach-Zehnder modulator based on cross-slot waveguide can achieve polarizationinsensitive.
As a key nonreciprocal device, the optical circulator builds optical links to several terminals in a circulating manner. The waveguide-type circulator with port count more than four has not been discussed, mainly due to the strict phase matching and adjustment. In this paper, a six-port optical circulator is proposed by introducing the nonreciprocal phase shifts (NPS) into a 3×3 multimode interference coupler. The structure with Ce:YIG material bonded to SOI waveguide is employed to illustrate the implementation and do the device simulation. There is no complex phase matching in the whole design. Good performance can be expected with the present fabrication techniques. This design scheme can also be easily generalized to the circulators with even more terminals.
This paper presents a novel micro-ring-resonator-assisted structure as an optical switch. This device couples two outputs
of a 1x2 power splitter into a micro-ring resonator (MRR). The double-beam interference will occur in the MRR. If the
phase difference between the beams and the coupling coefficients of MRR are set properly, the device can switch the
light by applying phase shift on MRR. High extinction ratio or low crosstalk can be achieved, even if the modulation
additional loss is large.
By using overlapping-imaging characteristic of the multimode interference (MMI) and the area modulation method, this paper presents a three-wavelength 3×3 rearrangeable switch, which consists of the two cascaded building blocks: a 2×2 tunable splitter and a full shuffle 1×3 switch with only one compound modulation region. Its operation characteristics are analyzed by utilizing 2-D BPM simulation. The simulated extinction ratio is higher than 30dB for all operating wavelengths 1545 nm, 1550 nm and 1555 nm. Good 3-D performances can be expected after optimization and improved fabrication.