Sub-nanosecond light-pulse generation with waveguide-coupled carbon nanotube transducers

Abstract

Carbon nanotubes (CNTs) have recently been integrated into optical waveguides and operated as electrically-driven light emitters under constant electrical bias. Such devices are of interest for the conversion of fast electrical signals into optical ones within a nanophotonic circuit. Here, we demonstrate that waveguide-integrated single-walled CNTs are promising high-speed transducers for light-pulse generation in the gigahertz range. Using a scalable fabrication approach we realize hybrid CNT-based nanophotonic devices, which generate optical pulse trains in the range from 200 kHz to 2 GHz with decay times below 80 ps. Our results illustrate the potential of CNTs for hybrid optoelectronic systems and nanoscale on-chip light sources.

High-speed electroluminescence from semiconducting carbon nanotube films

“…The emission intensity increases exponentially with increasing Vds. When the thermal excitation is ignored, the excitation rate P(Vds) by the impact exciton mechanism is given by the following equation: 3,10,13,52 𝑃(𝑉 ds ) = 𝑃 0 exp (− 𝐸 th 𝑒𝜆 OP 𝛼𝑉 ds )…”

“…Nanocarbon materials, such as carbon nanotubes (CNTs), are promising candidates for optoelectronic light sources on silicon chips, because they can be easily formed on silicon substrate. Two types of light emitters, blackbody emitters based on Joule heating [1][2][3][4] and electroluminescence (EL) emitters based on electron-hole recombination in semiconducting single-walled carbon nanotubes (SWNTs) [5][6][7][8][9][10][11][12][13][14] , have been previously reported as nanocarbon-based emitters on silicon chips. Although these emitters demonstrated the steady-state light emission under DC bias voltage in most studies, high-speed light modulation is required for optical communications.…”

“…Recently, high-speed modulation at ~ 1 GHz has been demonstrated for an individual-CNT 15 and CNT-film blackbody emitters. 2,3 On the other hand, for EL emitters, only slow modulation at ~ 100 Hz has been demonstrated 14 , and there are no reports on high-speed EL emission.…”

“…17 In addition, as chirality-enriched SWNTs are commercially available, semiconducting SWNTs can be easily formed on silicon wafers by a drop-casting or spin-coating process. 3,14,15,[18][19][20][21] Furthermore, EL emitters are promising candidates for integrated light sources on silicon chips for optical communications with optical fibers and silicon photonic devices, because the EL spectra lie in the near-infrared (NIR) region, which includes telecommunication wavelengths. 15,22,23 However, the high brightness and high-speed EL emitters with stable performance have not been demonstrated to date.…”

Nanoscale Patterning of Carbon Nanotubes: Techniques, Applications, and Future

“…The group demonstrated further examples of waveguide‐coupled SWCNT devices assembled through DEP patterning achieving light pulse generation up to 2 GHz and <80 ps decay times (Figure 20d). [ 395 ] Single SWCNTs can also be grown directly over microcavities from patterned CNT growth catalyst. [ 393a ] Single SWCNT devices with ultrashort channels of 10 nm were recently assembled via DEP and demonstrated stable emission at telecom wavelengths (Figure 20e–g), [ 396 ] showing the potential of SWCNT photonic devices to be implemented in ULSI nanoscale photonic circuitry.…”