Nonlinear optical properties of push–pull polyenes for electro-optics

Improved nonlinear organic chromophores of varying conjugation length with either thiobarbituric acid or 3-dicyanomethylene-2,3-dihydrobenzothiophene-1,1-dioxide (FORON® Blue) acceptors have been synthesized and investigated for their nonlinear optical properties. Very large quadratic hyperpolarizabilities β(−2ω; ω, ω) have been found, up to 25,700×10^(−48) esu at λ=1.91 μm. In a guest–host polymer very high electro-optic (EO) coefficients, of up to 55 pm/V, have been determined at λ=1.31 μm with 20-wt % chromophore loading. We find good agreement between molecular parameters evaluated by electric-field-induced second-harmonic generation (EFISH) and the measurements of guest–host solid–solid solutions. The latter method is well suited to the determination of the product of dipole moment μ and hyperpolarizability β quickly and reliably at the wavelength of interest for EO applications without the complications associated with EFISH measurements

Quantum key distribution and 1 Gbit/s data encryption over a single fibre

We perform quantum key distribution (QKD) in the presence of 4 classical channels in a C-band dense wavelength division multiplexing (DWDM) configuration using a commercial QKD system. The classical channels are used for key distillation and 1 Gbps encrypted communication, rendering the entire system independent from any other communication channel than a single dedicated fibre. We successfully distil secret keys over fibre spans of up to 50 km. The separation between quantum channel and nearest classical channel is only 200 GHz, while the classical channels are all separated by 100 GHz. In addition to that we discuss possible improvements and alternative configurations, for instance whether it is advantageous to choose the quantum channel at 1310 nm or to opt for a pure C-band configuration.Comment: 9 pages, 7 figure

From [(11)C]CO2 to [(11)C]amides:a rapid one-pot synthesis via the Mitsunobu reaction

Radiosynthesis of [11C]amides via the Mitsunobu reaction.</p

Fast tunable parallel optical delay line

A new tunable optical delay line for OTDM applications can achieve sub-nanosecond tuning time across three time slots spaced 100ps apart. Using parallel fiber delays, the delay line requires only one modulator operating below the baseband data rate. A simple control algorithm based on a latency diagram can further reduce the average latency beyond that of the straightforward hardware implementation by 50%. Using the demonstrated delay line, 10 GHz electronics has the potential to access a throughput of 160Gb/s optical data

TOAD having enhanced extinction ratio of the switching window

A Terahertz Optical Asymmetric Demultiplexer (TOAD) having preferably two non-linear elements (NLES) in which the extinction ratio is enhanced by saturating both NLEs when closing a switching window. A data signal input on one port of the TOAD is split onto two optical paths, each including one NLE. The optical paths converge at an output port. To start a switching window, a first control signal is input on an optical path that includes only one of the two NLEs. To close a switching window, one or more control signals are input such that both NLEs receive a control signal at a predetermined time after the first control signal is received by one of the NLEs. Only data signals passing through the first NLE during the switching window are output on the output port. Since both NLEs receive a second control signal at the same time, they decay together and thus avoid creation of unintended switching windows. Additionally, in certain embodiments of the present invention, the second control signal can be input on the data port or the output port, eliminating the need for a separate port for the second control signal as required by certain known TOADs

Practical all-optical sampling technique for high bandwidth, low energy optical communication signals

An extremely simple, real-time measurement technique for characterizing high-speed, low energy optical communication signals using an ultrafast SOA-based optical switch and low bandwidth electronics is presented. The technique successfully resolves pulses with an energy of 1.5 fJ in a 160 GHz pulse stream using a 10-GHz repetition rate optical control with pulse energy of only 20 fJ

Perfectly synchronized bit-parallel WDM data transmission over a single optical fiber

We demonstrate a bit-level synchronization technique by conducting a bit-parallel wavelength-division-multiplexed (WDM) data transmission over 27.5 km of optical fiber. Multiple WDM channels, which may represent individual bits in a byte or a word in parallel computer input-output, are transmitted in the optical fiber in non-return-to-zero format. These bits experience time skew due to group velocity dispersion. By sampling with an all-optical switch in the range where all these bits overlap, we obtained perfectly synchronized WDM signals. The synchronized WDM channels are demultiplexed with an array waveguide grating. Bit error rates below 10-10 are measured for each channel. The spectral range of the experimental demonstration covers about 24 nm with the smallest wavelength separation of 1.4 nm, enough to pack 16 bits into the span. More bits are available if smaller channel-separation and wider spectral span are employed

Novel optical pulse width management device

A novel optical pulse width management device is proposed and demonstrated. The device requires very slow switching energy, on the order of a few tens of femto-joules. It can perform stretching of a RZ to a much broader pulse, and conversion of RZ data streams to NRZ format for bit rates greater than 20 Gbit/s

Novel M-ary architecture for optical CDMA using pulse position modulation

In this paper, a novel en/decoder architecture for implementation of M-ary modulation using pulse position modulation (PPM). The PPM scheme allows a practical, scalable mean to achieve the merits of M-ary modulation while maintaining the asynchronous operation of the entire network