Fig. 1. (a) Three-dimensional schematic diagram of the proposed filter incorporating waveguides and electrodes. (b) Top view of the waveguide layout of the proposed filter. (c) Cross-sectional view of the LNOI waveguides used in this work.

Fig. 2. (a) Calculated transmission spectra assuming r = 259 µm, Δl = 1634 µm, l₁ = 39 µm, l₂ = 18 µm, and l₃ = 18 µm. Calculated transmission spectra while maintaining the above parameters but tuning (b) k₁, (c) k₂, and (d) the refractive index of Arm2.

Fig. 3. (a) A photograph of the chip including S5 and (b) a microscope image of the tuning electrodes of S5. SEM images of (c) the waveguides and (d) the TMI of S2.

Fig. 4. Transmission spectra of (a) S1, (b) S2, (c) S3, (d) S4, and (e) S5 within the 1542–1558 nm wavelength range. (f) Transmission spectra of S5 across the 1530–1600 nm wavelength range.

Fig. 5. Transmission spectra with different ambient temperatures measured at (a), (c) through port and (b), (d) drop port. Variation of the dip wavelengths with the ambient temperature of (e) S4 and (f) S5; a linear fit is used to obtain the slope.

Fig. 6. Transmission spectra of (a) S5 and the spectra at different tuning powers when tuning (b) TMI₁, (c), (d) TMI₂, and (e), (f) TMI₃. (g) Variation of bandwidth ratio with the applied tuning power.

Fig. 7. (a) Transmission spectra of S5. (b) The type A and (c) the type B transmission spectra of S5 at different TO tuning powers applied to Arm2. (d) The type B transmission spectra of S5 at different EO tuning voltages applied to Arm2. (e) Bandwidth ratio and (f) dip wavelength change with the applied TO power. (g) The type B spectral bandwidth and (h) dip wavelength at the drop port at different tuning voltages.

Fig. 8. (a) Transmission spectra of S5 when TO tuning Arm1 with different powers. (b) Dependence of the dip wavelength on the tuning power.