Fig. 1. Schematic diagram of multidimensional-multiplexing and RI sensing integrated device, and simulation results of subwavelength fiber transmission performance. (a) 3D structure of device; normalized electric field intensity of (b) x-polarized modes and (c) y-polarized modes for fiber at 0.25 THz (arrows represent electric vectors)

Fig. 2. Simulation results of subwavelength fiber transmission performance. (a) Effective RI and birefringence, (b) fractional power in core, (c) loss, and (d) GVD values of x-polarized and y-polarized states with and without foam cladding for fiber as functions of frequency

Fig. 3. Schematics of four types of bent fibers. (a) x-bent 90° fiber; (b) x-bent S-shaped fiber; (c) y-bent 90° fiber; (d) y-bent S-shaped fiber

Fig. 4. Transmission varying with bend radius and frequency for 90° and S-shaped bending fibers. Transmission of (a) 90° and (b) S-shaped bending fibers at 0.25 THz as a function of bending radius; transmission of (c) 90° and (d) S-shaped bending fibers with bending radius of 10 mm as a function of frequency

Fig. 5. Structure diagram of Y-splitter and simulation results of beam splitting performance. (a) Schematic of 50/50 Y-splitter. Input port is P1, while two outputs are P2 and P3; (b) simulated power distribution of x-polarized state for the Y-splitter at 0.25 THz; (c) transmission of Y-splitter at P2 and P3 ports as a function of frequency; (d) simulated power distribution of y-polarized state for Y-splitter at 0.25 THz

Fig. 6. Schematic of directional coupler and power distributions of two orthogonal polarization modes. (a) Schematic of directional coupler placed along x-axis (arrow lines indicate propagation paths of both x-polarized and y-polarized states for directional coupler, x-axis represents placement direction for subwavelength fibers); (b) simulated power distributions of directional coupler for x-polarized and y-polarized states at 0.25 THz

Fig. 7. Schematics of four types of directional couplers. (a) x-placed x-bent directional coupler; (b) y-placed x-bent directional coupler; (c) x-placed y-bent directional coupler; (d) y-placed y-bent directional coupler

Fig. 8. Transmissions and ER values for four directional couplers as functions of coupling length at operating frequency of 0.25 THz. (a) x-placed x-bent directional coupler; (b) y-placed x-bent directional coupler; (c) x-placed y-bent directional coupler; (d) y-placed y-bent directional coupler

Fig. 9. Transmission and ER values for four directional couplers as functions of frequency. (a) x-placed x-bent directional coupler; (b) y-placed x-bent directional coupler; (c) x-placed y-bent directional coupler; (d) y-placed y-bent directional coupler

Fig. 10. Power distributions on xz-plane of x-polarized and y-polarized states at 0.25 THz for x-placed x-bent directional coupler. (a) x-polarized state; (b) y-polarized state

Fig. 11. Schematics of directional couplers consisting of S-shaped bending fibers. (a) x-placed x-bent directional coupler; (b) x-placed y-bent directional coupler

Fig. 12. Transmission and ER values of two directional couplers as functions of frequency. (a) x-placed x-bent directional coupler; (b) x-placed y-bent directional coupler

Fig. 13. Simulated power distributions at 0.27 THz for x-placed y-bent directional coupler. (a) x-polarized state; (b) y-polarized state

Fig. 14. Structure and simulation results of dispersion compensator. (a) Schematic of dispersion compensator; (b) single grating unit cross-sections in xz-plane and yz-plane; (c) transmission and GVD values of dispersion compensator as functions of frequency

Fig. 15. Structure and simulation results of π-shifted grating. (a) Schematic of π-shifted grating; (b) single grating unit cross-sections in xz-plane and yz-plane; (c) transmission for y-polarized state of π-shifted grating as a function of frequency

Fig. 16. Simulated power distribution for modes propagating along multidimensional-multiplexing and sensing integrated device

Fig. 17. Transmission and ER values for signals with different polarizations as functions of frequency. (a) Transmission and ER values of x-polarized and y-polarized narrowband signals with a central frequency of 0.25 THz at drop port and through port for integrated device as functions of frequency; (b) transmission of x-polarized narrowband signal with central frequency of 0.27 THz at through port for integrated device as a function of frequency

Fig. 18. Transmission spectra of phase-shifted grating under different refractive indices and center frequency varying with RI. (a) Transmission spectra of phase-shifted grating; (b) central frequency of transmission spectrum as a function of RI