An ultrafast reconfigurable nanophotonic switch using wavefront shaping of light in a nonlinear nanomaterial

Abstract

We demonstrate a new concept for reconfigurable nanophotonic devices exploiting ultrafast nonlinear control of shaped wavefronts in a multimode nanomaterial consisting of semiconductor nanowires. Femtosecond pulsed laser excitation of the nanowire mat is shown to provide an efficient nonlinear mechanism to control both destructive and constructive interference in a shaped wavefront. Modulations of up to 63% are induced by optical pumping, due to a combination of multimode dephasing and induced transient absorption. We show that part of the nonlinear phase dynamics can be inverted to provide a dynamical revival of the wavefront into an optimized spot with up to 18% increase of the peak to background ratio caused by pulsed laser excitation. The concepts of multimode nonlinear switching demonstrated here are generally extendable to other photonic and plasmonic systems and enable new avenues for ultrafast and reconfigurable nanophotonic devices. Light: Science & Applications (2014) 3, e207; doi:10.1038/lsa.2014.88; published online 26 September 2014Keywords: nanophotonics; nanowires; nonlinear optics; reconfigurable; ultrafast; wavefront shaping INTRODUCTION Many of the available photonic technologies are based on perfectly regular, ordered structures such as waveguides, photonic crystals and metamaterials. There is, however, an increasing interest to exploit the additional degrees of freedom offered by aperiodic or disordered designs. [1][2][3][4] One way of controlling the flow of coherent energy transfer in such a medium with high efficiency is through optimization of the specific arrangement of the scatterers. 5,6 Exciting new techniques have emerged based on shaping of the light field itself to match a given scattering configuration, either through time reversal 7,8 or iterative schemes. 9,10 The method of wavefront shaping is based on the general concept that the transmission through any medium can be described by a matrix which connects all ingoing and outgoing degrees of freedom. In principle, knowledge of the transmission matrix, 11,12 along with an ability to completely control the incident light, 10 would allow the selection of any desired output, turning an opaque medium into a versatile optical element. Next to the interest for biomedical imaging, 13-15 wavefront shaping shows promise for reconfigurable optical elements [16][17][18][19][20] and control of random lasers. 21 While initial work concentrated on monochromatic continuous-wave radiation, focusing through opaque scattering media has also been achieved using ultrashort pulses 22,23 and polychromatic light. 24 Here, we demonstrate both destructive and constructive switching of a shaped wavefront on ultrafast time scales through nonlinear optical excitation of the scattering medium. With the rapid development of applications exploiting wavefront shaping, active control of such shaped fields is of great interest. The principle is illustrated in Figure 1a. Wavefront shaping amounts to aligning the phasors resulting from independent light paths in th...

All-optical spatial light modulator for reconfigurable silicon photonic circuits

“…Wavefront shaping has been demonstrated as a powerful tool in both characterizing and controlling the optical modes in threedimensional complex media [17][18][19]. Translating these capabilities to an integrated platform opens up significant opportunities for freeform shaping of optical signals in integrated photonic circuits.…”

Perspectives: Nanofibers and nanowires for disordered photonics

“…46 Among possible enabled applications, the activation of nonlinearities is a tool to control destructive and constructive interference in shaped wavefronts by fs-laser excitation. 47 Enhanced absorption 42 is observed as well, even in nanocomposites 41 where nanowires are embedded within polymer matrices (Figs. 4(f) and 4(g)).…”

Поверхностные Волны На Границе Фоторефрактивного Кристалла И Среды С Положительной Керровской Нелинейностью

“…Возможность существования волн с осциллирующим затуханием при определенных условиях принципиально отличает контакт фоторефрактивного кристалла с фокусирующей керровской средой от контакта двух нелинейных керровских сред или контакта нелинейной и линейной сред. Данное обстоятельство имеет существенное значение для проектирования различных оптических устройств (переключателей, сенсоров), использующих волноводные свойства нелинейных поверхностных волн [25][26][27].…”