Absorbant saturable à base de nanotubes de carbone et de puits quantiques pour la régénération tout-optique du signal télécom à très haut débit

RENNES-INSA (352382210) / SudocSudocFranceF

Highlighting excitonic optical properties of bundled carbon nanotubes to tailor novel saturable absorbers

International audienceWe present the ability of bundled carbon nanotubes to replace classical III-V semiconductor quantum-wells in nanomaterials-based devices, such as efficient saturable absorbers. Preliminary study of bundled carbon nanotubes films is presented using scanning electronic microscopy and Raman spectroscopy. Then, performing time-resolved pump-probe experiments, we show that excitonic nonlinear optical properties of bundled carbon nanotubes are simultaneously marked by ultrafast subpicosecond absorption recovery time, relative great contrast ratio and total recovery of absorption, in direct comparison with quantum-wells nanostructures. This first direct comparison attributes strong potential to bundled carbon nanotubes for all-optical switching devices, as lower-cost nanomaterials solution

Ultrafast nonlinear optical properties of bundles of carbon nanotubes

International audienceThe optical properties of bundled nanotubes were examined for high-bit-rate telecommunication applications. The diameters of the nanotubes in the bundles were determined to be from 0.6783 to 1.5147 nm, and their chiralities were also determined using resonant vibration modes. Their crystallographic quality was examined using atomic-scale resolution microscopy. Then, we highlight this vicinity performing calculations to determine the intertube equilibrium distance. These simulations integrate van der Waals interactions between nanotubes. Ultrafast and efficient nonlinear absorption properties of bundled nanotube films produced using a simple process were demonstrated and compared with semiconducting quantum-wells

Bundles of Carbon Nanotubes : a combined spectroscopic and theoretical study-influence of the weak mutual interactions on the optical properties

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Ultrafast optical switch based on bundled carbon nanotubes

International audienc

A direct comparison of single-walled carbon nanotubes and quantum-wells based subpicosecond saturable absorbers for all optical signal regeneration at 1.55 µm

Topic: Lasers, Optics and OptoelectronicsInternational audienceSubpicosecond optical transmission experiments are used to compare saturable absorber (SA) based on bundled single-walled carbon nanotubes (SWNT) and iron-doped InGaAs/InP epitaxial multiple quantum wells (MQW) at 1.55 μm telecom wavelength. The SA key parameters (contrast ratio, saturation fluence, and recovery time) relevant for high speed all optical signal regeneration (AOSR) are extracted from the normalized differential transmission (NDT). Although both SA exhibit good contrast ratios, SWNT show a full signal recovery as well as a much faster response time than MQW. This original work on SA shows that SWNT are excellent candidates for future low cost AOSR

Ultrafast response of harmonic modelocked THz lasers

International audienceThe use of fundamental modelocking to generate short terahertz (THz) pulses and THz frequency combs from semiconductor lasers has become a routine affair, using quantum cascade lasers (QCLs) as a gain medium. However, unlike classic laser diodes, no demonstrations of harmonic modelocking, active or passive, have been shown in THz QCLs, where multiple pulses per round trip are generated when the laser is modulated at the harmonics of the cavity's fundamental round-trip frequency. Here, using time-resolved THz techniques, we show for the first time harmonic injection and mode-locking in which THz QCLs are modulated at the harmonics of the round-trip frequency. We demonstrate the generation of the harmonic electrical beatnote within a QCL, its injection locking to an active modulation and its direct translation to harmonic pulse generation using the unique ultrafast nature of our approach. Finally, we show indications of self-starting harmonic emission, i.e., without external modulation, where the QCL operates exclusively on a harmonic (up to its 15th harmonic) of the round-trip frequency. This behaviour is supported by time-resolved simulations of induced gain and loss in the system and shows the importance of the electronic, as well as photonic, nature of QCLs. These results open up the prospect of passive harmonic modelocking and THz pulse generation, as well as the generation of low-noise microwave generation in the hundreds of GHz region

Exploring optical properties of carbon nanotubes in bundles for high-bit-rate telecommunication applications

International audienc