Reduced Equalization Needs of 100 GHz Bandwidth Plasmonic Modulators

As bit rates of optical interconnects increase, a large amount of complicated signal conditioning is needed to compensate for the insufficient bandwidth of current modulators. In this paper, we evaluate the reduced equalization requirements of high-bandwidth plasmonic modulators in short-reach transmission experiments. It is shown that transmission of 100 Gbit/s nonreturn-to-zero (NRZ) and 112 Gbit/s pulse-amplitude modulation4 over 1 km and 2 km distance is possible without any receiver equalization. At higher bit-rates, such as 120 Gbit/s NRZ, data transmission is demonstrated over 500 m with reduced receiver equalization requirements. Transmission up to 200 Gbit/s over 1 km is also shown with more complex receiver equalization. The reduced complexity of the receiver digital signal processing is attributed to a flat frequency response of at least 108 GHz of the plasmonic modulators. All single wavelength transmissions have been performed at 1540 nm in standard single mode fiber

Plasmonic Switches and Modulators for Optical Communications

With global data traffic growing continuously, a communication infrastructure capable of dealing with the ever-increasing bandwidth demands of the global society is required. A large amount of traffic arises inside the datacenters that house thousands of servers for computing and storing information. These servers are interconnected by communication links that more and more rely on optical rather than electrical technologies mainly due to the high bandwidth offered by optical interconnects. Recently, the field of plasmonics has attracted attention by the scientific community for applications in optical communications. The main feature of plasmonics is the ability to process optical signal at the nanometer scale. Device dimensions even below the wavelength of light are achieved, because plasmonic devices are not limited by diffraction unlike conventional optical approaches. Furthermore, plasmonic waveguides rely on metals and dielectrics only, which allows the metals to function as their own electrical contacts. The low resistances of the electrical contacts and the small capacitances given by the small device dimensions offer high-speed operation, since limiting RC time constants are minimized. The small dimensions further ensure sufficiently large electric fields to manipulate the signals, even at low drive voltages. The low drive voltages and small capacitances permit low-power operation. Additionally, the technology is suitable for cheap mass-production and may be processed together with electronic circuits on the same chip. In this thesis, two kinds of plasmonic devices are investigated: a modulator and a memristive switch. The modulator relies on phase modulation due to the linear electro-optic effect of an organic material that is integrated into a plasmonic waveguide. The plasmonic phase modulator is combined with a silicon photonic Mach-Zehnder interferometer to achieve efficient intensity modulation at highest speed. Furthermore, the modulator was demonstrated to function reliably in an optical interconnect, thus showing that plasmonics is indeed a viable proposition for future interconnect concepts. The plasmonic memristive switch is an electrically controlled plasmonic switch with a memory effect. The operation principle is based on the reversible formation of a conductive path in the dielectric layer. The device may find applications as a latching switch that maintains its state after activation and as a new kind of memory

Plasmonic Data Center Interconnects (DCIs)

Data centers require optical interconnect solutions that are highly scalable with respect to the channel count, the bit rates and the power consumption. Plasmonics offers smallest footprints, operates up to highest speed, requires little driver circuitry and thus meets many of the DCI requirements

500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics

Broadband electro-optic intensity modulators are essential to convert electrical signals to the optical domain. The growing interest in THz wireless applications demands modulators with frequency responses to the sub-THz range, high power handling and very low nonlinear distortions, simultaneously. However, a modulator with all those characteristics has not been demonstrated to date. Here we experimentally demonstrate that plasmonic modulators do not trade off any performance parameter, featuring – at the same time – a short length of 10s of micrometers, record-high flatfrequency response beyond 500 GHz, high power handling and high linearity, and we use them to create a sub-THz radio-over-fiber analog optical link. These devices have the potential to become a new tool in the general field of microwave photonics, making the sub-THz range accessible to e.g. 5G wireless communications, antenna remoting, IoT, sensing, and more