Energy-efficient electro-optic modulators are at the heart of short-reach optical interconnects, and silicon photonics is considered the leading technology for realizing such devices. However, the performance of all-silicon devices is limited by intrinsic material properties. In particular, the absence of linear electro-optic effects in silicon renders the integration of energy-efficient photonic-electronic interfaces challenging. Silicon-organic hybrid (SOH) integration can overcome these limitations by combining nanophotonic silicon waveguides with organic cladding materials, thereby offering the prospect of designing optical properties by molecular engineering. In this paper, we demonstrate an SOH Mach-Zehnder modulator with unprecedented efficiency: the 1-mm-long device consumes only 0.7 fJ bit 21 to generate a 12.5 Gbit s 21 data stream with a bit-error ratio below the threshold for hard-decision forward-error correction. This power consumption represents the lowest value demonstrated for a non-resonant Mach-Zehnder modulator in any material system. It is enabled by a novel class of organic electro-optic materials that are designed for high chromophore density and enhanced molecular orientation. The device features an electro-optic coefficient of r 33 <180 pm V 21 and can be operated at data rates of up to 40 Gbit s Keywords: electro-optic materials; electro-optic modulation; nonlinear organic materials; silicon-organic hybrid INTRODUCTIONOptical interconnects are the most promising option to overcome transmission bottlenecks in data centres and high-performance computers, and energy consumption is one of the most important parameters of the associated photonic-electronic interfaces. Targeted figures are tens of femtojoule per bit for transmitters in off-chip connections, and a few femtojoule per bit for on-chip links.1 Key requirements are low drive voltages that can be provided by standard CMOS (complementary metal oxide semiconductor) circuitry without further amplification. Apart from energy efficiency, modulators need to provide fast electro-optic (EO) response along with large optical operation bandwidth to ensure high-speed transmission and flexibility in wavelength-division multiplexing systems. Moreover, dense integration is essential, calling for a small device footprint.Silicon photonics is currently the most promising technology to realize such devices, leveraging mature high-yield CMOS processing and offering the potential of photonic-electronic co-integration on large-area silicon wafers. However, second-order nonlinearities are absent in bulk silicon due to inversion symmetry of the crystal lattice.

Abstract-We report on the hybrid integration of silicon-oninsulator slot waveguides with organic electro-optic materials. We investigate and compare a polymer composite, a dendron-based material, and a binary-chromophore organic glass (BCOG). A record-high in-device electro-optic coefficient of 230 pm/V is found for the BCOG approach resulting in silicon-organic hybrid MachZehnder modulators that feature low U π L-products of down to 0.52 Vmm and support data rates of up to 40 Gbit/s.

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, neither silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonicorganic hybrid (POH) integration, which combine silicon-oninsulator (SOI) waveguides and plasmonic nanostructures with organic electro-optic cladding materials.

Abstract:We demonstrate frequency comb sources based on siliconorganic hybrid (SOH) electro-optic modulators. Frequency combs with line spacings of 25 GHz and 40 GHz are generated, featuring flat-top spectra with less than 2 dB power variations over up to 7 lines. The combs are used for WDM data transmission at terabit/s data rates and distances of up to 300 km. References and links1. I. Coddington, W. C. Swann, L. Nenadovic, and N. R. Newbury, "Rapid and precise absolute distance measurements at long range," Nat. Photonics 3(6), 351-356 (2009). 2. S. T. Cundiff and A. M. Weiner, "Optical arbitrary waveform generation," Nat. Photonics 4(11), 760-766 (2010

We present an all-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers integrated into a microfluidic chip. The chip is entirely made from polymers, enabling the use of the devices as low-cost disposables. The microgoblet cavities feature quality factors exceeding 10(5) and are fabricated from poly(methyl methacrylate) (PMMA) using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow. In contrast to silica-based microtoroid resonators, this approach replaces technically demanding vacuum-based dry etching and serial laser-based reflow techniques by solution-based processing and parallel thermal reflow. This enables scaling to large-area substrates, and hence significantly reduces device costs. Moreover, the resonators can be fabricated on arbitrary substrate materials, e.g., on transparent and flexible polymer foils. Doping the microgoblets with the organic dye pyrromethene 597 transforms the passive resonators into lasers. Devices have lasing thresholds below 0.6 nJ per pulse and can be efficiently pumped via free-space optics using a compact and low-cost green laser diode. We demonstrate that arrays of microgoblet lasers can be readily integrated into a state-of-the-art microfluidic chip replicated via injection moulding. In a proof-of-principle experiment, we show the viability of the lab-on-a-chip via refractometric sensing, demonstrating a bulk refractive index sensitivity (BRIS) of 10.56 nm per refractive index unit.