Fig. 1. (a) The schematic of the polymer-loaded waveguide. (b) The waveguide loss of different optical modes vs. waveguide width w at 1550 nm. The inset illustrates the photonic potential distribution for the TM₀₀ mode at various waveguide widths. The blue background represents the TE continuum. (c) The electric field (|E_y|) profiles for TM₀₀ and TM₀₁ modes. (d) The electric field (|E_z|) profiles for TE₀₀ and TE₀₁ modes.

Fig. 2. (a) Schematic diagram of the polymer-loaded PCNBC. (b) The band diagram of the TE₀₀ modes for different filling factors: f = 0.3 (blue line) and f = 0.42 (red line). The inset shows the enlarged boxed region and the resonant frequency of the fundamental mode is marked with a red dot. (c) The mirror strength vs. filling factor. (d) The top views of the electric field (|E_z|) profile for the fundamental mode and second-order mode. The orientation of the PCNBC is along the x direction of the LN crystal. (e) Electric field (E_z) distribution profile of the magnified region in (d). The inset shows the electric profile at the y-z plane.

Fig. 3. (a) SEM image of the fabricated PCNBC. The bottom insets show the grating coupler (left) and the central region of the cavity (right), respectively. (b) Measured transmission spectrum of a cavity with f_c = 0.42, f_e = 0.3, N_t = 120, N_m = 100, and w = 2 μm. Inset: the detailed transmission spectrum of the fundamental mode is fitted with a Lorentzian line shape at around 1528.320 nm. (c) Measured Q factors of the fundamental mode vs. waveguide width w. (d) Measured transmission spectra of the fundamental mode for different N_t at N_m = 100. (e) Measured transmission spectra of the fundamental mode for different N_m at N_t = 120. The inset shows the Lorentzian fitting of the transmission spectrum at N_m = 200.

Fig. 4. (a) Measured transmission spectra of the PCNBC at different temperatures. The Q factor of the PCNBC is 0.8×10⁵. (b) Measured ΔT_π and the sensitivity of temperature for various devices with different Q factors.

Fig. 5. (a) The measured transmission spectra of a PCNBC (Q is 1.04×10⁵) at different input powers. The threshold power is 160 μW. (b) The measured threshold power for the devices with different transmissions and Q factors.

Fig. 6. (a) Optical micrograph of the tested PCNBC. The locations of the fibers are indicated by red dots. (b) The measured transmission spectra at different input fiber displacements. The device has a Q of 1.04×10⁵. (c) Devices with different Q factors are measured for Δφ.

Table 1. Comparison of various PCNBCs on LN substrate.