Relaxation Processes in Nonlinear Optical Polymers: A Comparative Study

Plasmonic IQ modulators with attojoule per bit electrical energy consumption

Coherent optical communications provides the largest data transmission capacity with the highest spectral efficiency and therefore has a remarkable potential to satisfy today’s ever-growing bandwidth demands. It relies on so-called in-phase/quadrature (IQ) electro-optic modulators that encode information on both the amplitude and the phase of light. Ideally, such IQ modulators should offer energy-efficient operation and a most compact footprint, which would allow high-density integration and high spatial parallelism. Here, we present compact IQ modulators with an active section occupying a footprint of 4 × 25 µm × 3 µm, fabricated on the silicon platform and operated with sub-1-V driving electronics. The devices exhibit low electrical energy consumptions of only 0.07 fJ bit⁻¹ at 50 Gbit s⁻¹, 0.3 fJ bit⁻¹ at 200 Gbit s⁻¹, and 2 fJ bit⁻¹ at 400 Gbit s⁻¹. Such IQ modulators may pave the way for application of IQ modulators in long-haul and short-haul communications alike.

Increasing bandwidth demands in optical communications requires components to be compact with energy-efficient operation. Here, the authors demonstrate plasmonic IQ modulators on a silicon photonics platform with phase shifters, operating with sub-1V electronics at 100 GBaud and low electrical energy consumption.

Role of temperature in controlling performance of photorefractive organic glasses

We present a detailed temperature-dependence study of dielectric, birefringent, conductive, and photorefractive (PR) properties of high-performance low-molecular weight organic glasses that contain 2-dicyanomethylene-3-cyano-2,5-dihydrofuran (DCDHF) derivatives. DCDHF organic glasses sensitized with C60 exhibit high two-beam coupling gain coefficients in the red-wavelength region. However, in the best performing DCDHF glasses at room temperature the PR dynamics are limited by slow molecular reorientation in the electric field. While orientational and, therefore, PR speed can be significantly improved by increasing the temperature above the glass-transition temperature of the material, the steady-state performance may worsen. Comprehensive study of the temperature dependence of various processes, which contribute to the PR effect in DCDHF glasses, clarifies the limiting factors and allows for optimization of the overall PR performance.