In this paper, a compact, broadband, and CMOS compatible 2 × 2 optical switch based on hybrid plasmonic waveguides (HPWs) and curved directional coupler is presented. The proposed coupler consists of a combination of straight and curved hybrid plasmonic waveguides. By using the ability of HPWs for confining the light wave in a sub-wavelength scale and the curved structure to decrease the wavelength dependence of the directional coupler, a 3 dB power splitter with a 3 dB ± 0.5 bandwidth of about 410 nm and a footprint of 7.6 µ m × 2 µ m is achieved. By exploiting this optimal power splitter in a Mach–Zehnder interferometer structure, a 2 × 2 electro-optic switch with a broad bandwidth of 400 nm and a small footprint of 33 µ m × 2.5 µ m is realized, which denotes the widest bandwidth compared to the previously reported similar structures. The three-dimensional finite-difference time-domain simulation results show a switching speed of 0.15 THz for the proposed optical switch, while the extinction ratio, power consumption, and insertion loss are 20 dB, 95.2 fJ/bit, and 4 dB, respectively, at the central wavelength of 1550 nm.

In response to the increasing demands of the capacity enhancement of optical communication, a compact and high-performance silicon mode division multiplexer is proposed that multiplexes the fundamental and first-order transverse magnetic modes. The device structure is based on an asymmetric bent directional coupler with an ultrasmall coupling length of 3.67 µm. Utilizing single-layer silicon waveguides with the same heights allows the proposed device to be fabricated using a single-step CMOS-compatible fabrication process, which provides a cost-effective design in comparison with the previously reported structures. The three-dimensional finite-difference time-domain simulation results confirm that the device has a low loss of 0.87 dB, low crosstalk of − 21.8 d B , and high mode conversion efficiency of 98.3% at the communication wavelength of 1.55 µm. Furthermore, the device shows a broad bandwidth of about 110 nm, completely covering the C and L bands with crosstalk less than − 10 d B . Moreover, it is shown that the proposed mode (de)multiplexer is fabrication tolerant for the coupling gap variation of − 40 n m < Privacy Policy and Terms of Service apply.