Optical fiber poling by induction

Abstract

Conventional thermal poling methods require direct physical contact to internal fiber electrodes. Here, we report an indirect electrostatic induction technique using electrically floating wires inside the fiber combined with external electric fields that can allow for facile poling of complex microstructured fibers (MOFs) of arbitrarily long lengths. In combination with our unique ability to use liquid gallium electrodes, inducing second-order nonlinearities inside otherwise difficult to access multi-core or multi-hole MOFs now becomes entirely feasible and practical. The formation of a permanent second-order nonlinearity is unequivocally demonstrated by realizing quasi-phase-matched frequency doublers using periodic UV erasure methods in the induction-poled fibers. The second-order susceptibility created inside the fiber is driven by the potential difference established between the floating electrodes, which we calculate via numerical simulations.

Optical fiber poling by induction: analysis by 2D numerical modeling

“…While this the experiment al field applied b ould, by definitio thus complete more, the model H3O + ion injectio ng times, does n conditions, giv ry reaches a val remains constan e variable floati dependent char modify the fiel mbination at th he salient featur an allow us draw d the modified 2 ics of the secon n it is both close wn in Fig. 1 al, (b) Na + and (c the inductor (po olution of the s tude of the electr diameter, NA = 0 [7].…”

“…The method for "charging" optical fibers has been recently further developed by De Lucia et al [7], who discovered that it is possible to create a space charge region using electrostatic induction between an external inductor and the floating electrodes embedded inside a fused silica twin-hole fiber. As this novel technique avoids any physical contact to the internally embedded electrodes, it automatically lifts a number of restrictions on the use of microstructured optical fibers for poling where the multiple contacting of individual electrodes becomes a prohibitive challenge.…”

“…As this novel technique avoids any physical contact to the internally embedded electrodes, it automatically lifts a number of restrictions on the use of microstructured optical fibers for poling where the multiple contacting of individual electrodes becomes a prohibitive challenge. Thus the induction poling technique, together with the use of embedded liquid electrodes such as Gallium [7], could, for example, allow for the poling of complex photonic crystal fibers (PCF), with the aim of realizing devices that fully exploit the inherently desirable PCF properties of strong optical mode confinement, dispersion, effective group index engineering, etc for highly efficient nonlinear functionality. In order to systematically implement these advanced device concepts, it is first necessary to develop comprehensive numerical models of the induction poling mechanism itself.…”

“…The early issues mainly related to the high risk of breakdown between the two electrodes (typically separated by a few tens of microns) were addressed by Margulis et al [6], who demonstrated that it is possible to induce a value of ( ) higher than the one obtained in the conventional case [5] by means of a poling configuration in which the two embedded electrodes are both connected to the same positive potential of the anode. The method for "charging" optical fibers has been recently further developed by De Lucia et al [7], who discovered that it is possible to create a space charge region using electrostatic induction between an external inductor and the floating electrodes embedded inside a fused silica twin-hole fiber. As this novel technique avoids any physical contact to the internally embedded electrodes, it automatically lifts a number of restrictions on the use of microstructured optical fibers for poling where the multiple contacting of individual electrodes becomes a prohibitive challenge.…”

“…However, our recent experimental demonstration of electrostatic induction poling suggests that substantial modifications to the boundary conditions of these current 2D models are required in order to fully elucidate this novel poling mechanism. In the first instance, this arises due to the inherent assumption [8] ex i represents on s and i = 2 for th s accounts for drift in the ele the diffusivity, z nt, V the electric e. The electric fie g duration are d ic regime, from w nlinearity spatial mentation of th nsions identical d in ref [7] (i.e. enclosed by a v ced adjacent to charges up the f y distributed N ion of 1 ppm a pm of H3O + ions e fiber at t = 0 s vely charged, no s at ground pote n considering t al.…”