Device Requirements for Optical Interconnects to Silicon Chips

Abstract

Abstract-We examine the current performance and future demands of interconnects to and on silicon chips. We compare electrical and optical interconnects and project the requirements for optoelectronic and optical devices if optics is to solve the major problems of interconnects to future high performance silicon chips. Optics has potential benefits in interconnect density, energy and timing. The necessity of low interconnect energy imposes low limits especially on the energy of the optical output devices, with a ~ 10 fJ/bit device energy target emerging. Some optical modulators and radical laser approaches may meet this requirement. Low (e.g., a few fF or less) photodetector capacitance is important. Very compact wavelength splitters are essential for connecting the information to fibers. Dense waveguides are necessary on-chip or on boards for guided wave optical approaches, especially if very high clock rates or dense WDM are to be avoided. Free space optics potentially can handle the necessary bandwidths even without fast clocks or WDM. With such technology, however, optics may enable the continued scaling of interconnect capacity required by future chips.

A strong electro-optically active lead-free ferroelectric integrated on silicon

“…However, the interest in this research field has mainly been motivated by the use of oxides in the electronic domain, such as memory applications 7 , gate dielectrics in field-effect transistors 8 or alloxide electronics 9 . Meanwhile, the steadily improving performance of complementary metal oxide semiconductor (CMOS) technology increases the difficulty to handle inter-or intra-chip data communication by means of electrical wiring 10 because of power constraints in combination with increased bandwidth demands. In this context, devices working in the optical domain have emerged as a mature field of research 11 , and building blocks required for a functional photonic network such as detectors 12 or modulators 13 have already been integrated on Si.…”

High-density waveguide superlattices with low crosstalk

“…Waveguide arrays are among the cornerstones of such systems. For example, waveguide arrays are widely used in emerging applications such as optical-phased arrays [18][19][20][21] , space-division multiplexing 22 and chip-scale optical interconnects 23,24 , and conventional applications such as wavelength-division multiplexers 25,26 . On the other hand, a waveguide array or a waveguide lattice can also be viewed 27 as fully analogous to a periodic chain of atoms, which lends itself to a broad spectrum of fascinating scientific possibilities ranging from Anderson localization of light 28,29 to parity-time symmetric effects 30 .…”

Routing and photodetection in subwavelength plasmonic slot waveguides

“…Performance agrees well with simulations, allowing such guides to be predictably designed. These guides could have various uses in subwavelength optoelectronic systems: they could allow deeply sub-micron sized photodetectors to be positioned extremely close to transistors for minimized receiver capacitance [8] by transporting light from other optical layers or from antennas or antenna arrays; they offer optical impedance matching of detectors for greater effi ciency [20] , and, when combined with light or plasmon sources, they could permit effi cient short-distance optical interconnects. The tight light concentration in such guides also suggests combining such guides with quantum-confi ned structures such as quantum dots and optically-active molecules.…”

“…Transposing some of these concepts to the near-IR wavelength region could lead to highly functional optoelectronic circuits [3][4][5][6][7] with a tremendous impact in many important areas of nanotechnology such as nanoscale sources and detectors for future optical interconnects [8] , heat-assisted magnetic recording (HAMR) for next generation hard drives [9] , DNA sequencing [10] , and many others where strong light matter interaction is required [11] . Such integrated optoelectronic circuits with nanoscale active components would require a fl exible waveguiding platform to confi ne and route optical signals.…”