Nanowire network-based multifunctional all-optical logic gates

Abstract

All-optical nanoscale logic components are highly desired for various applications because light may enable logic functions to be performed extremely quickly without the generation of heat and cross-talk. All-optical computing at nanoscale is therefore a promising alternative but requires the development of a complete toolbox capable of various logic functionalities. We demonstrate nanoscale all-optical switches by exploiting the polarization-dependent light emission property of crossbar InP and AlGaAs nanowire networks. These networks can perform various logic operations, such as AND, OR, NAND, and NOR binary logic functions. Furthermore, on the basis of these logic operations, our networks successfully enable all-optical arithmetic binary calculations, such as n-bit addition, to be conducted. Our results underscore the promise of assembled semiconductor nanowire networks as a building block of on-chip all-optical logic components for future nanophotonics.

Fig. 1. Structural and optical properties of InP and AlGaAs crossbar NW networks.

(A) False-color scanning electron microscopy image of the crossbar InP and AlGaAs NW networks (illustrated with different colors); InP NWs are combed along the vertical direction and an AlGaAs NW along the horizontal direction to form six pairs of crossbar junctions. (B) PL spectra of the NWs measured at a single exemplary measurement spot. The polarization direction of the excitation lasers (at 532 and 730 nm) is labeled. arb. units, arbitrary units. (C) HRSTEM image of InP NWs. The inset shows the diffraction pattern demonstrating the ZB crystal structure and the formation of frequent twin planes along the NW growth axis. (D) EDX measurement results of AlGaAas NWs show the Al and Ga composition along the NW growth direction (that is, [111] crystal direction). The line scan location is shown in the inset (28).

Fig. 2. NW-based all-optical n-bit full adder.

(A) The optical image showing that, after a single combing, 10 AlGaAs and InP crossbar NW junctions exist in 30 μm × 30 μm area. The dashed white boxes highlight the locations where 10 parallel NAND and NOR logic gates can be constructed. (B) The truth tables of NOR and NAND logic gates using the polarization-dependent PL property of NWs. (C) The rules for obtaining the addition operation result from NAND and NOR logic gate outputs. (D) An example showing PL mapping of a single NW junction when the addition operation is performed [that is, 24 (11010₂) is added to 16 (01110₂)]. The addition operation result is obtained by following the rules shown in (C) (28).

Fig. 3. System-level demonstrated all-optical logic gate outputs.

All-optical logic gate outputs of our proof-of-principle system-level demonstration under different input configurations for NAND (A) and NOR (B) logic operations.