Abstract

The development of efficient low-loss electro-optic and nonlinear components based on silicon or its related compounds, such as nitrides and oxides, is expected to dramatically enhance silicon photonics by eliminating the need for non-CMOS-compatible materials. While bulk Si is centrosymmetric and thus displays no second-order (χ(2)) effects, a body of experimental evidence accumulated in the last decade demonstrates that when a strain gradient is present, a significant χ(2) and Pockels coefficient can be observed. In this work we connect a strain-gradient-induced χ(2) with another strain-gradient-induced phenomenon, the flexoelectric effect. We show that even in the presence of an extremely strong strain gradient, the degree by which a nonpolar material like Si can be altered cannot possibly explain the order of magnitude of observed χ(2) phenomena. At the same time, in a polar material like SiN, each bond has a large nonlinear polarizability, so when the inversion symmetry is broken by a strain gradient, a small (few degrees) reorientation of bonds can engender χ(2) of the magnitude observed experimentally. It is our view therefore that the origin of the nonlinear and electro-optic effects in strained Si structures lies not in the Si itself but in the material providing the strain: the silicon nitride cladding.

© 2015 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Pockels effect based fully integrated, strained silicon electro-optic modulator

Bartos Chmielak, Michael Waldow, Christopher Matheisen, Christian Ripperda, Jens Bolten, Thorsten Wahlbrink, Michael Nagel, Florian Merget, and Heinrich Kurz
Opt. Express 19(18) 17212-17219 (2011)

Wavelength dependence of Pockels effect in strained silicon waveguides

Pedro Damas, Xavier Le Roux, David Le Bourdais, Eric Cassan, Delphine Marris-Morini, Nicolas Izard, Thomas Maroutian, Philippe Lecoeur, and Laurent Vivien
Opt. Express 22(18) 22095-22100 (2014)

Observation of second-harmonic generation in silicon nitride waveguides through bulk nonlinearities

Matthew W. Puckett, Rajat Sharma, Hung-Hsi Lin, Mu-han Yang, Felipe Vallini, and Yeshaiahu Fainman
Opt. Express 24(15) 16923-16933 (2016)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (2)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (11)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription