Electro-optic effect in silicon nitride

On the origin of the second-order nonlinearity in strained Si–SiN structures

“…It was further shown in [53] that the nonlinearity can be activated by the formation of Si-Br bonds during an HBr dry etching process, and we predict a similar effect for SiN bonds. Finally, the fact that χ (2) has been observed in SiN waveguides that are naturally strained [19][20][21][22][23] also serves to confirm our explication.…”

“…a relatively small degree of "tetragon poling", the values of SGI-χ (2) reported in the literature will result. Note that one of the possible mechanisms for a non-zero second order susceptibility in SiN invoked in the literature [21][22][23] has been the re-orientation of Si clusters with broken inversion symmetry [51], but no quantitative estimate of the effect had been given. Since each Si-N bond (or tetragon) already carries a large nonlinear polarizability that leads to a large χ (2) with a strain-gradient induced alignment, , it appears to us that it is entirely unnecessary to invoke Si clusters whose nonlinear polarizability is inherently small (since the bonds inside are homopolar).…”

“…The four bonds comprising each tetragon do produce a large nonlinear polarizability, but, since silicon nitride is an amorphous, or, rather, a ceramic material, the tetragons are randomly oriented and these polarizabilities cancel. It is our hypothesis that a strain gradient can "orient" these tetragons in a preferential direction, resulting in a nonzero χ (2) .This hypothesis is based on well-known recent results that show silicon nitride films are known to possess both  (2) and a Pockels coefficient [19][20][21][22][23] whose origin has not yet been fully understood. We also make clear the connection between the strain-gradient induced χ (2) (SGI-χ (2) ) and flexo-electric effect [24][25], in support of our hypothesis.…”

3D design and analysis of an electro-optically tunable athermal and polarization-insensitive ring resonator-based add-drop filter for DWDM systems

“…This material system is CMOS-compatible, thus, the device can be integrated on a Si-photonics platform, enabling low-power dense wave division multiplexing (DWDM) solutions. An additional interesting feature of this material system is the higher electro-optic coefficient of compared to silicon which leads to the demonstration of electro-optical effects [41] enhanced by placing a thin-layer of lithium niobate as mentioned in Subsection 3.4 . For fabrication considerations, a process was investigated and suggested for this model.…”

Não-linearidade X(2) e X(3) em micro-ressoadores fotônicos baseados em silício com oscilação paramétrica do visível ao infravermelho

“…, aumentando a magnitude da susceptibilidade χ(2) em uma ordem de grandeza[67].Além disso, a simetria do material também pode ser perturbada aplicando uma pressão mecânica (gradiente de pressão) sobre o meio. O efeito foi observado em um guia de onda de silício, devido à tensão causada pela deposição de nitreto de silício sobre o guia de onda[68].…”