Silicon-Organic Hybrid (SOH) Devices for Nonlinear Optical Signal Processing

Silicon-on-insulator (SOI) is a promising material system for dense on-chip integration of both silicon photonic and electronic devices. The high refractive index of silicon enables strong light confinement and compact lowloss devices at telecommunication wavelengths. In addition, on-chip nonlinear optical signal processing becomes feasible, because the third-order nonlinear susceptibility χ
⁽³⁾
of silicon is about 200 times that of glass, and because the tight light confinement enhances the nonlinear response. However, for many applications it would be desirable to have even stronger nonlinearities, and to exploit second-order χ
⁽²⁾
-nonlinearities which are negligibly small in mono-crystalline silicon. On the other hand, many organic materials are highly nonlinear, but have only a low refractive index. Silicon-organic hybrid (SOH) systems combine the strengths of both materials resulting in extremely large effective nonlinearities. We report on the design of a 100 Gbit/s / 1 V modulator based on an 80 μm long slow-light SOI photonic crystal slot waveguide filled with a χ
⁽²⁾
-nonlinear organic material. Further, we demonstrate demultiplexing of a 120 Gbit/s signal to 10 Gbit/s with four-wave mixing in a 6 mm long SOI slot waveguide, on which an organic highly χ
⁽³⁾
-nonlinear material was deposited with a molecular beam.