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Register a new userAll-optical switching in dye-doped DNA nanofibers
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Authors
Adam Szukalski
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All-optical switches are introduced which are based on deoxyribonucleic acid (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline derivative. Optical birefringence is found in the organic nanofibers, with fully reversible switching controlled through continuous-wave laser irradiation. The photoinduced signal is remarkably large, with birefringence highlighted by optically-driven refractive index anisotropy approaching 0.001. Sub-millisecond characteristic switching times are found. Integrating dye-intercalated DNA complex systems in organic nanofibers, as convenient and efficient approach to template molecular organization and controlling it by external stimuli, might open new routes for realizing optical logic gates, reconfigurable photonic networks and sensors through physically-transient biopolymer components.
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Since the first experimental observation of all-optical switching phenomena, intensive research has been focused on finding suitable magnetic systems that can be integrated as storage elements within spintronic devices and whose magnetization can be controlled through ultra-short single laser pulses. We report here atomistic spin simulations of all-optical switching in multilayered structures alternating n monolayers of Tb and m monolayers of Co. By using a two temperature model, we numerically calculate the thermal variation of the magnetization of each sublattice as well as the magnetization dynamics of [Tbn/Com] multilayers upon incidence of a single laser pulse. In particular, the condition to observe thermally-induced magnetization switching is investigated upon varying systematically both the composition of the sample (n,m) and the laser fluence. The samples with one monolayer of Tb as [Tb1/Co2] and [Tb1/Co3] are showing thermally induced magnetization switching above a fluence threshold. The reversal mechanism is mediated by the residual magnetization of the Tb lattice while the Co is fully demagnetized in agreement with the models developed for ferrimagnetic alloys. The switching is however not fully deterministic but the error rate can be tuned by the damping parameter. Increasing the number of monolayers the switching becomes completely stochastic. The intermixing at the Tb/Co interfaces appears to be a promising way to reduce the stochasticity. These results predict for the first time the possibility of TIMS in [Tb/Co] multilayers and suggest the occurrence of sub-picosecond magnetization reversal using single laser pulses.
Optically induced ultrafast switching of single photons is demonstrated by rotating the photon polarization via the Kerr effect in a commercially available single mode fiber. A switching efficiency of 97% is achieved with a $sim1.7$,ps switching time, and signal-to-noise ratio of $sim800$. Preservation of the quantum state is confirmed by measuring no significant increase in the second-order autocorrelation function $g^{(2)}(0)$. These values are attained with only nanojoule level pump energies that are produced by a laser oscillator with 80,MHz repetition rate. The results highlight a simple switching device capable of both high-bandwidth operations and preservation of single-photon properties for applications in photonic quantum processing and ultrafast time-gating or switching.
Electro-optic modulators within Mach--Zehnder interferometers are a common construction for optical switches in integrated photonics. A challenge faced when operating at high switching speeds is that noise from the electronic drive signals will effect switching performance. Inspired by the Mach--Zehnder lattice switching devices of Van Campenhout et al. [Opt. Express, 17, 23793 (2009)] and techniques from the field of Nuclear Magnetic Resonance known as composite pulses, we present switches which offer protection against drive-noise in both the on and off state of the switch for both the phase and intensity information encoded in the switched optical mode.
All-optical switching (AOS) of magnetic domains by femtosecond laser pulses was first observed in the transition metal-rare earth (TM-RE) alloy GdFeCo1-5; this phenomenon demonstrated the potential for optical control of magnetism for the development of ever faster future magnetic recording technologies. The technological potential of AOS has recently increased due to the discovery of the same effect in other materials, including RE-free magnetic multilayers6,7. However, to be technologically meaningful, AOS must compete with the bit densities of conventional storage devices, restricting optically-switched magnetic areas to sizes well below the diffraction limit. Here, we demonstrate reproducible and robust all-optical switching of magnetic domains of 53 nm size in a ferrimagnetic TbFeCo alloy using gold plasmonic antenna structures. The confined nanoscale magnetic reversal is imaged around and beneath plasmonic antennas using x-ray resonant holographic imaging. Our results demonstrate the potential of future AOS-based magnetic recording technologies.
Networks inside current data centers comprise a hierarchy of power-hungry electronic packet switches interconnected via optical fibers and transceivers. As the scaling of such electrically-switched networks approaches a plateau, a power-efficient solution is to implement a flat network with optical circuit switching (OCS), without electronic switches and a reduced number of transceivers due to direct links among servers. One of the promising ways of implementing OCS is by using tunable lasers and arrayed waveguide grating routers. Such an OCS-network can offer high bandwidth and low network latency, and the possibility of photonic integration results in an energy-efficient, compact, and scalable photonic data center network. To support dynamic data center workloads efficiently, it is critical to switch between wavelengths in sub nanoseconds (ns). Here we demonstrate ultrafast photonic circuit switching based on a microcomb. Using a photonic integrated Si3N4 microcomb in conjunction with semiconductor optical amplifiers (SOAs), sub ns (< 500 ps) switching of more than 20 carriers is achieved. Moreover, the 25-Gbps non-return to zero (NRZ) and 50-Gbps four-level pulse amplitude modulation (PAM-4) burst mode transmission systems are shown. Further, on-chip Indium phosphide (InP) based SOAs and arrayed waveguide grating (AWG) are used to show sub-ns switching along with 25-Gbps NRZ burst mode transmission providing a path toward a more scalable and energy-efficient wavelength-switched network for future data centers.
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