Synthesis of second-order nonlinearities in dielectric-semiconductor-dielectric metamaterials

Abstract

We demonstrate a large effective second-order nonlinear optical susceptibility in electronic optical metamaterials based on sputtered dielectric-semiconductor-dielectric multilayers of silicon dioxide/amorphous silicon (a-Si)/aluminum oxide. The interfacial fixed charges (Q f) with opposite signs on either side of dielectric-semiconductor interfaces result in a non-zero built-in electric field within the a-Si layer, which couples to the large third-order nonlinear susceptibility tensor of a-Si and induces an effective second-order nonlinear susceptibility tensor v eff (2). The value of the largest components of the effective v eff (2) tensor, i.e., v (2) zzz , is determined experimentally to be 2 pm/V for the as-fabricated metamaterials and increases to 8.5 pm/V after the post-thermal annealing process. The constituents and fabrication methods make these metamaterials CMOS compatible, enabling efficient nonlinear devices for chip-scale silicon photonic integrated circuits.

Electronic Metamaterials with Tunable Second-order Optical Nonlinearities

“…The deposition rate of each target and crystallization of films are characterized by means of small angle x-ray reflectivity (XRR) with a Bruker D8 Discover x-ray diffractometer. The XRR measurements, shown in the supplementary material of our previous work, confirm the fact that all sputtered films are amorphous 22.…”

“…The optical characterization is carried out via the Maker fringe setup that is used in our previous works. 22 The pump beam is generated using a Ti:Sapphire laser emitting 150 fs pulses with a 80 MHz repetition rate at a center wavelength of 800 nm. The polarization state of the pump is defined by a half-wave plate and a long pass filter with cut-off wavelength at 780 nm is set to filter out any signals from other sources in the range of interest.…”

“…14 Nevertheless due to shielding of the external field by a semiconductor, a sufficiently high internal electric field exists only within the first tens of nanometers from the semiconductor interfaces for both metal-oxide-semiconductor (MOS) and metal-semiconductor (MS) structures. [15][16][17] Current research in creating CMOS compatible materials exhibiting a high χ (2) coefficient mostly focuses on back-end processing 18 , composite metamaterials that utilize alternative physical mechanisms to synthesize non-zero χ (2) , 19,20 metallo-dielectric multilayers, 21 dielectric-semiconductor multilayers, 22 all-dielectric composite metamaterials, 8,23 and nonlinear processes enhanced by plasmonic metasurfaces and nanoatennas. 24,25 However these approaches do not allow for a good control over the exhibited nonlinearities.…”

On the observation of dispersion in tunable second-order nonlinearities of silicon-rich nitride thin films

“…1b. The revised Maker fringes analysis was then employed to carry out the tensorial analysis of the second-order nonlinearity [7,[11][12][13]. As is evident from the figure, the generated second-harmonic signal from the film with the highest silicon content (S3) is up to 20 times larger compared to that generated from the film with a stoichiometric composition (S1).…”

Development of Photonic Devices Based on the Strained Silicon Technology

“…(2) EF ISH of ∼40 pm/V. Following a similar approach, high frequency modulation was proposed by using layers of AlO 2 and SiN to achieve charges of opposite signs at the interfaces and, hence, inducing a χ (2) EF ISH 68 in those layers.…”