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Plasmonic-multimode-interference-based logic circuit with simple phase adjustment.

Ota M, Sumimura A, Fukuhara M, Ishii Y, Fukuda M - Sci Rep (2016)

Bottom Line: Also, simultaneous operations of XOR and AND gates are substantiated experimentally by combining 1 × 1 MMI based phase adjusters and 2 × 2 MMI based intensity modulators.An experimental on-off ratio of at least 4.3 dB is confirmed using scanning near-field optical microscopy.The proposed structure will contribute to high-density plasmonic circuits, fabricated by complementary MOS-compatible process or printing techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi-shi, Aichi 441-8580, Japan.

ABSTRACT
All-optical logic circuits using surface plasmon polaritons have a potential for high-speed information processing with high-density integration beyond the diffraction limit of propagating light. However, a number of logic gates that can be cascaded is limited by complicated signal phase adjustment. In this study, we demonstrate a half-adder operation with simple phase adjustment using plasmonic multimode interference (MMI) devices, composed of dielectric stripes on a metal film, which can be fabricated by a complementary metal-oxide semiconductor (MOS)-compatible process. Also, simultaneous operations of XOR and AND gates are substantiated experimentally by combining 1 × 1 MMI based phase adjusters and 2 × 2 MMI based intensity modulators. An experimental on-off ratio of at least 4.3 dB is confirmed using scanning near-field optical microscopy. The proposed structure will contribute to high-density plasmonic circuits, fabricated by complementary MOS-compatible process or printing techniques.

No MeSH data available.


Experimental results of the fabricated devices.(a) Scanning electron micrographs of the proposed device, which was fabricated using focused ion beam etching. (b–e) Observed near-field optical images and output characteristics of the half adder using the MMI structure. Upper parts of panels (b–e) are the output characteristics averaged over the 1 μm and normalized with respect to the maximum value of the AND “11” output.
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f3: Experimental results of the fabricated devices.(a) Scanning electron micrographs of the proposed device, which was fabricated using focused ion beam etching. (b–e) Observed near-field optical images and output characteristics of the half adder using the MMI structure. Upper parts of panels (b–e) are the output characteristics averaged over the 1 μm and normalized with respect to the maximum value of the AND “11” output.

Mentions: Scanning electron micrographs are shown in Fig. 3a of the devices fabricated based on the FDTD simulations. The devices were composed of 500-nm-thick SiO2 patterns on a 550-nm-thick Au film, which was deposited on a SiO2 substrate and formed by focused ion beam etching. Here, the width of the fabricated single-mode waveguide, phase adjuster, and MMI intensity modulator were 380 nm, 890 nm and 2800 nm, respectively. The length of the fabricated phase adjuster and MMI intensity modulator were 3060 nm and 6490 nm. SPPs were generated via the gratings using the manner similar to that reported in ref. 23, and the number of input SPPs was determined by comparing the results with and without the grating. In Fig. 3b–e, we show the distribution of the near-field optical intensity in the plasmonic MMI structure, which was observed with a scanning near-field optical microscope. The near-field optical patterns corresponding to the input, reference, and output waveguides were clearly observed with an on-off ratio of at least 4.3 dB, as shown in Table 2 and the upper parts of panels (b–e) in Fig. 3. When compared with the simulated results, the experimental on-off ratios were lower owing to the imprecise fabrication process and positioning accuracy of the grating. This lower on/off ratio can be improved by improving fabrication accuracy or connecting the outputs of the device to a plasmonic equalizer which use plasmonic amplification28. The results confirm the feasibility of logic operations in simple plasmonic MMI structures.


Plasmonic-multimode-interference-based logic circuit with simple phase adjustment.

Ota M, Sumimura A, Fukuhara M, Ishii Y, Fukuda M - Sci Rep (2016)

Experimental results of the fabricated devices.(a) Scanning electron micrographs of the proposed device, which was fabricated using focused ion beam etching. (b–e) Observed near-field optical images and output characteristics of the half adder using the MMI structure. Upper parts of panels (b–e) are the output characteristics averaged over the 1 μm and normalized with respect to the maximum value of the AND “11” output.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834483&req=5

f3: Experimental results of the fabricated devices.(a) Scanning electron micrographs of the proposed device, which was fabricated using focused ion beam etching. (b–e) Observed near-field optical images and output characteristics of the half adder using the MMI structure. Upper parts of panels (b–e) are the output characteristics averaged over the 1 μm and normalized with respect to the maximum value of the AND “11” output.
Mentions: Scanning electron micrographs are shown in Fig. 3a of the devices fabricated based on the FDTD simulations. The devices were composed of 500-nm-thick SiO2 patterns on a 550-nm-thick Au film, which was deposited on a SiO2 substrate and formed by focused ion beam etching. Here, the width of the fabricated single-mode waveguide, phase adjuster, and MMI intensity modulator were 380 nm, 890 nm and 2800 nm, respectively. The length of the fabricated phase adjuster and MMI intensity modulator were 3060 nm and 6490 nm. SPPs were generated via the gratings using the manner similar to that reported in ref. 23, and the number of input SPPs was determined by comparing the results with and without the grating. In Fig. 3b–e, we show the distribution of the near-field optical intensity in the plasmonic MMI structure, which was observed with a scanning near-field optical microscope. The near-field optical patterns corresponding to the input, reference, and output waveguides were clearly observed with an on-off ratio of at least 4.3 dB, as shown in Table 2 and the upper parts of panels (b–e) in Fig. 3. When compared with the simulated results, the experimental on-off ratios were lower owing to the imprecise fabrication process and positioning accuracy of the grating. This lower on/off ratio can be improved by improving fabrication accuracy or connecting the outputs of the device to a plasmonic equalizer which use plasmonic amplification28. The results confirm the feasibility of logic operations in simple plasmonic MMI structures.

Bottom Line: Also, simultaneous operations of XOR and AND gates are substantiated experimentally by combining 1 × 1 MMI based phase adjusters and 2 × 2 MMI based intensity modulators.An experimental on-off ratio of at least 4.3 dB is confirmed using scanning near-field optical microscopy.The proposed structure will contribute to high-density plasmonic circuits, fabricated by complementary MOS-compatible process or printing techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi-shi, Aichi 441-8580, Japan.

ABSTRACT
All-optical logic circuits using surface plasmon polaritons have a potential for high-speed information processing with high-density integration beyond the diffraction limit of propagating light. However, a number of logic gates that can be cascaded is limited by complicated signal phase adjustment. In this study, we demonstrate a half-adder operation with simple phase adjustment using plasmonic multimode interference (MMI) devices, composed of dielectric stripes on a metal film, which can be fabricated by a complementary metal-oxide semiconductor (MOS)-compatible process. Also, simultaneous operations of XOR and AND gates are substantiated experimentally by combining 1 × 1 MMI based phase adjusters and 2 × 2 MMI based intensity modulators. An experimental on-off ratio of at least 4.3 dB is confirmed using scanning near-field optical microscopy. The proposed structure will contribute to high-density plasmonic circuits, fabricated by complementary MOS-compatible process or printing techniques.

No MeSH data available.