Bidirectional Four-wave Mixing Research Articles

Simultaneous full set of three-input canonical logic units in a single nonlinear device for an all-optical programmable logic array

All-optical canonical logic units-based programmable logic array (CLUs-PLA) is an important combinational logic device owing to its flexibility and user-defined feature. However, the limited number of three-input CLUs generated in a single nonlinear device hinders their practical application. In this study, we overcome this limitation and experimentally demonstrate the simultaneous generation of a full set of three-input CLUs in only one nonlinear device. By performing bidirectional four-wave mixing (FWM) and wavelength spacing optimization, the all-optical three-input PLA with a full set of CLUs enables arbitrary functions. We experimentally demonstrate the implementation of a series of combinational logic functions including, user-defined logic functions, full adder, and full subtractor, exhibiting error-free performances for all logic operations at 40 Gb/s. The scheme can reduce the number of nonlinear devices in CLUs-PLA, which simplifies the computing system and reduces power consumption. Therefore, the scheme has great potential for future high-speed optical computing systems.

Circulator-free on-chip bidirectional four-wave mixing.

On-chip bidirectional four-wave mixing (FWM), which may meet the rapidly increasing demands on integration level and system versatility, has never been implemented for the lack of competent on-chip optical circulators that are indispensable for separating the bidirectional channels. In this scenario, we first propose and demonstrate a circulator-free scheme that fully utilizes the inherent clockwise and counter-clockwise transmission natural of an add-drop microring resonator to implement on-chip bidirectional FWM. It should be noted that the proposed scheme additionally provides a universal solution for multichannel nonlinear operations and the related applications, with the advantages of compact structure and low crosstalk. The implementation for multimode channels is investigated for demonstration, as the mode division multiplexing technique is of particular interest in integrated optoelectronics and the resonance-enhanced nonlinear structure with superior dimension compared to straight waveguides has never been implemented for a multimode case. The experimental results exhibit that the FWM efficiencies of the two-mode channels are -26.78 and -28.69 dB, respectively, and the crosstalk is lower than -35 dB.

Investigation on Expanding the Computing Capacity of Optical Programmable Logic Array Based on Canonical Logic Units

A general structure of an all-optical canonical logic based programmable logic array (CLUs-PLA) based on three methods to expand its computing capacity is presented. These methods include introducing bidirectional structure for nonlinear devices, utilizing wavelength multicast of four-wave mixing (FWM), and exploiting different nonlinear effects simultaneously, which fully utilize the parallelism of optical signals. Aiming at this general structure, we quantitatively analyze its computing capacity in detail, which is obviously enlarged comparing with the standard CLUs-PLA. To demonstrate our proposal, an experiment of CLUs’ simultaneous generation in nine parallel wavelength channels using bidirectional FWM is carried out. Comparing with the standard CLUs-PLA, the computing capacity of the expanded one is enlarged to 7.5 times.

Canonical logic units using bidirectional four-wave mixing in highly nonlinear fiber

All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing (FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones. The numerical simulations are made to analyze the relationship between the FWM efficiency and the position of two interactional signals.

Investigation of a simultaneous multifunctional photonic logic gate based on bidirectional FWM

We demonstrate a multi-functional photonic logic gate for RZ-PolSK signals based on four wave mixing (FWM) in highly nonlinear fiber (HNLF). Bidirectional operation with one spool of HNLF is implemented numerically at 40Gb/s. The basic logic arithmetics, such as XOR, AB¯,A¯B, XNOR, AND, NOR, and complex logic functions such as half-subtracter, half-adder, comparator and decoder are simultaneously realized by adjusting the polarization controllers. This novel structure is low-cost and rather flexible. Proper logic results, clear waveforms and high Q factors of eye diagrams are presented. Simulation analysis shows that bit error-free operation for the logic gate can be obtained when the wavelength separation is from −7 to 6nm for two input signals. The impact of the input power on the Q factor is also investigated. Due to the femoto-second response time of Kerr-effect in HNLF we used in the scheme, the logic gate has great potential in future ultra-high speed optical transmission systems.

Polarization- and interval-independent wavelength conversion at 2.5 Gb/s by means of bidirectional four-wave mixing in semiconductor optical amplifiers

We report interval-polarization-independent wavelength conversion at 2.5 Gb/s using four-wave mixing in a single semiconductor optical amplifier. These results have been obtained with a dual-pump configuration in a bidirectional geometry. Bit-error-rate (BER) curves are reported for a conversion shifts of -1 and +1 THz. The signal polarization was automatically scrambled during the BER measurement. The penalty with respect to the back-to-back line is 2.4 and 1.6 dB, respectively.

All-optical OTDM-to-WDM signal-format translationandOTDM add-drop functionality using bidirectional fourwave mixing in semiconductor optical amplifier

The authors report simultaneous demultiplexing and wavelength conversion of two 10 Gbit/s channels from a 40 Gbit/s OTDM signal using bidirectional four wave mixing in a single semiconductor optical amplifier. Simultaneous demultiplexing and clearing of a 10 Gbit/s channel from the 40 Gbit/s OTDM data stream is also reported. The BER penalty induced by bi-FWM is < 1 dB.

Bidirectional four-wave mixing in semiconductor optical amplifiers: theory and experiment

Bidirectional four wave mixing (FWM) is investigated in a bulk semiconductor optical amplifier (SOA) for dispersion compensation and for the clear/drop functionality in optical time division multiplexed (OTDM) systems. Good performance for bidirectional midspan spectral inversion (MSSI) is theoretically predicted for bit rates of 10, 20, and 40 Gb/s and is shown to be in agreement with measurements performed at 10 and 20 Gb/s. Measurements of the clear/drop functionality using the bidirectional technique show excellent performance for a 4/spl times/10 Gb/s signal and is again in good agreement with simulations. The clear/drop functionality is also simulated for 4/spl times/20 Gb/s and 4/spl times/40 Gb/s signals.