High speed optical telecommunication is enabled by wavelength division multiplexing, whereby hundreds of individually stabilized lasers encode the information within a single mode optical fiber. Higher bandwidths require higher a total optical power, but the power sent into the fiber is limited by optical non-linearities within the fiber and energy consumption of the light sources starts to become a significant cost factor [1]. Optical frequency combs have been suggested to remedy this problem by generating multiple laser lines within a monolithic device, their current stability and coherence lets them operate only in small parameter ranges [2][3][4]. Here we show that a broadband frequency comb realized through the electro-optic effect within a high quality whispering gallery mode resonator can operate at low microwave and optical powers. Contrary to the usual third order Kerr non-linear optical frequency combs we rely on the second order non-linear effect which is much more efficient. Our result uses a fixed microwave signal which is mixed with an optical pump signal to generate a coherent frequency comb with a precisely determined carrier separation. The resonant en- * harald.schwefel@otago.ac.nz hancement enables us to operate with microwave powers three orders of magnitude smaller than in commercially available devices. Such an implementation will be advantageous for next generation long distance telecommunication which relies on coherent emission and detection schemes to allow for operation with higher optical powers and at reduced cost [5].The data capacity of the internet is expected to grow by a factor of two every year [6], but current optical techniques are not able to meet the rising demand on the bandwidth of the undersea fibre network [7]. Techniques such as space division multiplexing [8], modedivision multiplexing [9] and wavelength division multiplexing (WDM) [5] in combination with time domain multiplexing (TDM) are being investigated to exploit the existing network to its full capacity. Current WDM systems employ an array of individually stabilized lasers, which are not phase locked to each other. For the next generation a major shift in the paradigm from multiple independent optical carriers to coherent optical frequency combs (OFCs) [7] combined with real time numerical calculation of the nonlinear pulse [5] will be necessary. The advantage of OFCs is that they can be generated from a single laser, potentially reducing the overall energy consumption of the system considerably. Furthermore, depending on the method of comb generation, OFCs can feature high phase and frequency stability, and may also arXiv:1808.10608v2 [physics.optics] 10 Jan 2019 2 a) top view WGM microwave antenna side pump laser OSA b) frequency detuning linewidth microwave frequency Ω Ω Ω 2Γ o Δ SFG SFG DFG Ω SFG DFG DFG Ω SFG DFG FIG. 1. Principles of χ (2) WGM-based frequency combs generation a) Schematic of the setup for the creation of electro-optic χ (2) -frequency combs.The interacting fields are resonantly enhanced by...

Cyclic voltammograms of pyrrole monomer and polypyrrole films prepared potentiostatically at 1.0 V versus an Ag/AgCl electrode have been examined. The insulating natural fibers, such as cotton, silk, and wool become electrically conducting when they are subjected to electrical treatment in the polymerizing solution of pyrrole in acetonitrile containing p-toluenesulfonic acid as a supporting electrolyte. The weight gain and the electrical conductivity of the fibers increase with the time of electrolysis and impressed current levels. The conductivities are in the range of 0.2 to 15 s/cm and dependent on the nature of the fibers.

SYNOPSISA study on the electrochemical grafting of polyaniline onto cotton, silk, and wool fibers was made. These insulating natural fibers became moderately conducting when they were subjected to electrical treatment in the polymerizing solution of aniline in aqueous HBF4 medium. The weight gain of the fibers increased linearly and electrical resistance decreased with the time of electrolysis. The multiple cycled voltammograms of the solution of aniline in the aqueous solution of HBF, at the tip of conducting silk and wool fibers, which functioned as a microelectrode, were successfully recorded. The deep green polyaniline film was deposited on the fiber microelectrodes during electrolysis at +0.85 V vs. an Ag/Ag+ electrode.The IR spectra suggest the coordination between the polyaniline and fibers. 0 1996 John Wiley & Sons, Inc.

No abstract