4.3.1 AND gate
The proposed plasmonic MMI trapezoid resonator cascaded with the teeth-shaped optical filter can need to design an all-optical AND logic gate. The optical values of the proposed plasmonic waveguide structure are:W1=88nm,W2=30nm,H1=450nm,H2=150nm,L=930nm.The transmission spectra of the proposed AND logic gate are shown in Figure.4.11(a)~(d). The signal port is always ON with the input intensity I0=1x106V2/m2. When the control ports A and B are both OFF,the output port is OFF. The magnetic field distribution is shown in Figure.4.12(a). The transmission efficiency at the wavelength 600nm is about 0% ,as shown in Figure.4.12 (b). When the control port A is OFF, and the control port B is ON,with the input light intensity I1=1x108 V2/m2, the output port is OFF. The magnetic field distribution is shown in Fig.4.13 (a) The transmission efficiency at the wavelength 600nm is about 0%, as shown in Fig. 4.13 (b). When the control port A is ON and the control port B is OFF, with the input light intensity I1=1x108 V2/m2, the output port is OFF. The magnetic field
distribution is shown in Figure. 4.14(a). The transmission efficiency at the wavelength 600nm is about 0% as shown in Figure .4.14 (b). When both the control ports A and B are ON with the input light intensity I1=1x108 V2/m2, the output port is ON. The magnetic field distribution is shown in Figure. 4.15(a). The transmission efficiency at the wavelength 600nm is about 98.2%, as shown in Figure.4.15 (b). The truth table and the transmission efficiency are shown in Tab. 4. 1.
4.3.2 OR gate
For the designing of the OR logic gate, the optical values of the proposed plasmonic waveguide structure are:W1=88nm,W2=30nm,H1=450nm,H2=150nm,L=930nm.The transmission spectra of the proposed OR logic gate are shown in Figure .4.16(a)~(d).In this structure, the signal port is always ON with the input intensity I0=1x106 V2/m2. When the control ports A and B are both OFF, the output port is OFF. The magnetic field distribution is shown in Figure .4.17(a). The transmission efficiency at the wavelength 600nm is about 0%, as shown in Figure. 4.17(b). When the control port A is OFF, with the input light intensity I1=2.0x108 V2/m2 and the control port R is ON, the output port is ON.
The magnetic field distribution is shown inFigure.4.18(a) .The transmission efficiency at the wavelength 600nm is about 92.1%, as shown in Figure. 4.18 (b). When the control port A is ON and the control port B is OFF, with the input light intensity I1=2.0x108 V2/m2, the output port is ON. The magnetic field distribution is shown in Figure. 4.19(a). The transmission efficiency at the wavelength 600nm is about 92.1% as shown in Figure. 4.19(b). When both the control ports A and B are ON with the input light intensity I1=2.0x108V2/m2, the output port is ON The magnetic field distribution is shown in Figure. 4.20(a). The transmission efficiency at the wavelength 600nm is about 0.008%, as shown in Figure .4.20 (b). The truth table and the transmission efficiency are shown in Tab. 4.2.
4.3.3 XOR gate
For the designing of the XOR logic gate, the optical values of the proposed plasmonic waveguide structure are: W1=88nm,W2=30nm,H1=450nm,H2=150nm,L=930nm.The transmission spectra of the proposed XOR logic gate are shown in Figure .4.21(a)~(d).The signal port is always ON with the input intensity I0=1x106V2/m2. When the control ports A and B are both OFF, the output port is OFF.
The magnetic field distribution is shown in Figure.4.22(a). The transmission efficiency at the wavelength 600nm is about 0% as shown in Figure 4.22(b). When the control port A is OFF, and the control port B is ON, with the input light intensity I1=2.2x108 V2/m2, the output port is ON. The magnetic field distribution is shown in Figure .4.23(a) .The transmission efficiency at the wavelength 600nm is about 92.1%, as shown in Fig. 4.23(b). When the control port A is ON and the control port B is OFF, with the input light intensity I1=2.2x108 V2/m2, the output port is ON. The magnetic field distribution is shown in Figure. 4.24(a). The transmission efficiency at the wavelength 600nm is about 92.1% as shown in Figure .4.24(b). When both the control ports A and B are ON with the input light intensity I1=2.2x108 V2/m2, the output port is OFF. The magnetic field distribution is shown in Figure. 4.25(a). The transmission efficiency at the wavelength 600nm is about 0.008%, as shown in Figure. 4.25(b). The truth table and the transmission efficiency are shown in Tab4.3.
4.3.4 NAND gate
For the designing of the NAND logic gate, the optical values of the proposed plasmonic waveguide structure are: W1=88nm,W2=30nm,H1=480nm,H2=160nm,L=1410nm.The transmission spectra of the proposed NAND logic gate are shown in Figure .4.26(a)~(d).The signal port is always ON with the input intensity I0=1x106V2/m2. When the control ports Aand B are both OFF, the output port is ON. The magnetic field distribution is shown in Figure.4.27(a). The transmission efficiency at the wavelength 600nm is about 98.5% as shown in Figure. 4.27(b). When the control port A is OFF, and the control port B is ON, with the input light intensity I1=1x108V2/m2, the output port is ON. The magnetic field distribution is shown in Fig.4.28 (a) .The transmission efficiency at the wavelength 600nm is about 98.5%, as shown in Figure. 4.28 (b). When the control port A is ON and the control port B is OFF, with the input light intensity I1=1x108V2/m2 the output port is ON. The magnetic field distribution is shown in Figure. 4.29(a). The transmission efficiency at the wavelength 600nm is about 98.5% as shown in Figure. 4.29(b). When both the control ports A and B are ON with the input light intensity I1=1x108 V2/m2, the output port is OFF. The magnetic field distribution is shown in Figure. 4.30(a). The transmission efficiency at the wavelength 600nm is about 0.008%, as shown in Figure.4.30(b). The truth table and the transmission efficiency are shown in Tab.4.4.
4.3.5 NOR gate
For the designing of the NOR logic gate, the optical values of the proposed plasmonic waveguide structure are: W1=88nm,W2=30nm,H1=480nm,H2=160nm,L=1410nm.The transmission spectra of the proposed NOR logic gate are shown in Figure .4.31(a)~(d). the signal port is always ON with the input intensity I0=1x106V2/m2. When the control ports A and B are both OFF, the output port is ON.
The magnetic field distribution is shown in Figure .4.32(a). The transmission efficiency at the wavelength 600nm is about 98.2% as shown in Figure. 4.32(b) When the control port A is OFF, and the control port B is ON,with the input light intensity I1=2x108V2/m2, the output port is OFF. The magnetic field distribution is shown in Figure .4.33(a)The transmission efficiency at the wavelength 600nm is about 0.012%, as shown in Figure. 4.33 (b). When the control port A is ON and the control port B is OFF, with the input light intensity I1=2x108V2/m2 the output port is OFF. The magnetic field distribution is shown in Figure. 4.34(a). The transmission efficiency at the wavelength 600nm is about 0% as shown in Figure. 4.34(b). When both the control ports S and R are ON with the input light intensity I1=2x108V2/m2, the output port is OFF. The magnetic field distribution is shown in Fig.
4.35 (a). The transmission efficiency at the wavelength 600nm is about 0%, as shown in Fig.4.35 (b).
The truth table and the transmission efficiency are shown in Tab. 4.5.
4.4 Summary
The proposed plasmonic MMI trapezoid resonator cascaded with the teeth-shaped optical filter was used to design based on all-optical logic gates.
For the proposed OR logic gate,the normalized transmission efficiency of the high logic state is about 92.1% and the low logic state is 0%. For the proposed AND logic gate,the normalized transmission efficiency of the high logic state is about 98.2 % and the low logic state is 0%. For the proposed XOR logic gate the normalized transmission efficiency of the high logic state is about 92.1
% and the low logic state is 0%.For the proposed NAND logic gate the normalized transmission efficiency of the high logic state is about 98.5% and the low logic state is 0%.For the proposed NOR logic gate the normalized transmission efficiency of the high logic state is about 98.2% and the low logic state is 0%.
As the numerical results shown above, the proposed plasmonic MMI trapezoid resonator cascaded with the teeth-shaped optical filter could really function all-optical logic functions. They would be potential key components in the applications of all-optical signal processing systems.
Fig.4.1. Schematic structure of the trapezoid MMI plasmonic waveguide structure.
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