All-Optical XOR Gate Based on a Saturable Cavity

F. T. Arecchi, Vittorio Degiorgio, A. Sona

변영태, 김재헌, Nam‐Gyu Park +2 more

Masahiko Jinno, Masafumi Koga, T. Matsumoto

Optical tristability, including spectral bistability, controlled either electrically or optically has been observed in a multielectrode DFB LD with a saturable absorber. A number of preliminary applications as optical logic gates (AND, OR, INVERT, NAND, NOR, and XOR) and optical memories are demonstrated experimentally.

Han Ye, Shen Ma, Zhongyuan Yu +2 more

We theoretically present a design for simultaneous all-optical OR and XOR logic gates based on single quantum dot (QD)-bimodal cavity system working in low-photon-number regime. The coupling between the QD and two degenerate cavity modes establishes new indirect excitation paths. Driven by single pulsed laser, both mode transmissions are observed. The delay between the peaks of the transmitted pulses is regarded as the extra transition interval (ETI) in the indirect path. When driven by two orthogonally polarized pulsed lasers with delay same as ETI, the coupling system suppresses the latter mode transmission due to the destructive interference effect. The OR and XOR logic gates based on presence of light are built and the function can be switched between two detectors by simply adjusting the driving pulse sequence. The results show that the proposed logic gates work well within a large range for coupling strength with comparable cavity decay rate. When taking two nonidealities (the detuning between two cavity modes and nonidentical coupling strengths) into consideration, the proposed system shows acceptable tolerances. Moreover, the robustness of the performance on parameters of the driving lasers, including pulse delay, width of pulse, absolute driving strength, and relative driving strength ratio, are demonstrated.

Stamatios V. Kartalopoulos

Cryptography in communications is of increasing importance and several sophisticated cryptographic algorithms have been developed. Quantum mechanical principles have been employed yielding cryptographic keys to generate ciphertext, especially applicable to optical communications, and which are believed to be unbreakable. In optical communications, the quantum ciphertext is the bit-by-bit exclusive-Or (XOR) operation of the quantum key and the text. Thus, an all-optical XOR gate is required at the transmitter, which for compactness and efficiency it should be simple and monolithically integrable. In this paper we review the quantum ciphertext generation, and we present a novel XOR gate that requires a single wavelength, in contrast to other solutions that require additional optical signals for control and synchronization. Simulation results support the viability of our novel all-optical XOR gate at data rates up to 40 Gbps.

Jeremy L. O’Brien, Geoff J. Pryde, AG White +2 more