A novel mid-infrared (MIR) biochemistry sensor using two suspended GaAs waveguides based on an asymmetric Mach-Zender Interferometer (MZI) is proposed. The propagation properties and refractive index (RI) sensing performances of MZI are investigated by the finite element method (FEM). The simulation results show that the maximum waveguide sensitivities (S wg ) of the TE and TM modes in the suspended GaAs waveguide are ∼ 1.2 and ∼ 1.0. This design of the GaAs waveguide using the suspension structure is to enhance the interaction between the vanishing field and measured material. The RI sensitivity of the asymmetric MZI structure increases with the length of the sensing arm, which can reach 854.5 nm/RIU with a Q of 208.2 after parameter optimization. The two arms of the MZI are designed as width-asymmetric structures to make the sensor more sensitive to the measured material. The asymmetric MZI sensing structure has high RI sensitivity and compact structure, which provides a feasible scheme for biochemical sensing.
We present an ultra-compact modular division (de)multiplexer [(de)MUX] based on the lithium niobate waveguide, an asymmetric directional coupler (ADC) composed of silica-lithium niobate waveguide (SLNW) and lithium niobate waveguide (LNW) for the modular division multiplexer. The TE0 and TE1 modes were optimized by using the finite element method (FEM). By rationally designing the size of SLNW and LNW, TE0 mode light is injected into the In1 port of LNW, and TE0 mode light is converted to TE1 mode in the coupling zone and transmitted in the SLNW, output from the Out2 port. It is shown that the coupling length of this MUX is only 6 µm. At a working wavelength of 1.55 µm, when TE0 enters the coupling area from port In1, the mode is coupled and converted to TE1; the TE1 mode is output from Out2; the value of IL is 0.87 dB; and the value of MCE is 99.5%. When TE0 enters from port In2, the TE0 mode is output from Out2, with 0.1 dB for IL, 99.7% for MCE, and −25 dB for CT.
A polarization beam splitter (PBS) based on a lithium niobate film
asymmetric directional coupler is proposed. The PBS is located on a
lithium niobate platform on an insulator consisting of a silicon
nitride–lithium niobate waveguide (SLW) and a lithium niobate
waveguide (LNW). By rationally designing the SLW and LNW sizes, TE
polarization satisfies the phase matching condition and TM
polarization phase mismatch. The numerical simulation results show
that the extinction ratio (ER) and insertion loss (IL) of PBS for TE
mode are 30.57 and 0.66 dB, respectively, and the ER and IL of
PBS for TM mode are 28.15 and 0.11 dB, respectively, at an
operating wavelength of 1.55 µm.
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