All-optical nano modulator on a silicon chip

Abstract

We present an all-optical modulator realized on a silicon chip. The proposed modulator has nano scale dimensions and a high extinction ratio. Its operation principle is based on a spatially non-uniform variation of the absorption of a miniaturized, silicon waveguide - based Mach-Zehnder interferometer (MZI). The absorption variation is obtained by illuminating the MZI with visible light. Our modulator may be used as an interfacing link between microelectronic processing circuits and optical information transmission links. We provide details on the fabrication and the experimental characterization of the suggested device. Since the operation principle is not based on a high Finesse resonator, the modulator is less sensitive to wavelength changes and its operation rate is not connected to the time required for the optical response to reach steady state but rather to material related effects.

Physics of Optical Modulation

“…Their absorption will release pairs of electrons and holes. This effect is commonly used in silicon in order to realize all-optical as well as electro-optical modulators and integrated devices [75,76]. The empirical relation is as follows: −3 ] (the change in the mobile holes concentration), n is the change in the refractive index, n e is the refractive index change due to electron concentration change, and n h is the refractive index change due to hole concentration.…”

Non-Conventional Modulation Schemes

“…Figure 5.14A shows at the top a schematic sketch of the fabricated device including the waveguides used in order to couple light into it from the tunable fiber laser, and at the bottom a device with visible light illuminated from above [66]. Although the device designed, fabricated and experimentally tested included an MZI with dimensions of less than 10 m 2 (about 9 microns by 1 micron), a more compact design based on the same concept having dimensions of less than 2 by 0.5 m (i.e.…”

“…In the future one may use ZnO nanorods for surface enhanced spectroscopies by coating their tips with metals as was done [60] with quantum dots and nanorods [61][62][63][64][65][66][67]. In order to also obtain vertical confinement of the guided light, the following fabrication procedure is proposed: first to coat a stripe of metallic layer on top of the chip.…”

Miniaturized Bragg modulator on a silicon chip

“…As an example such approaches include relatively long structures [2][3][4][5][6][7] based on changing the refractive index in a Mach-Zehnder interferometer, a ring resonator coupled to a waveguide [8,9] or multi mode interference configuration [10,11].…”