Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNonlinear carrier dynamics in silicon nano-waveguides
102
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Carrier recombination dynamics in strip silicon nano-waveguides is analyzed through time-resolved pump-and-probe experiments, revealing a complex recombination dynamics at densities ranging from ${10^{14}}$ to ${10^{17}},$cm$^{{-3}}$. Our results show that the carrier lifetime varies as recombination evolves, with faster decay rates at the initial stages (with lifetime of ${sim 800},$ps), and much slower lifetimes at later stages (up to ${sim 300},$ns). We also observe experimentally the effect of trapping, manifesting as a decay curve highly dependent on the initial carrier density. We further demonstrate that operating at high carrier density can lead to faster recombination rates. Finally, we present a theoretical discussion based on trap-assisted recombination statistics applied to nano-waveguides. Our results can impact the dynamics of several nonlinear nanophotonic devices in which free-carriers play a critical role, and open further opportunities to enhance the performance of all-optical silicon-based devices based on carrier recombination engineering.
rate research
Read More
Nanophotonic waveguides with sub-wavelength mode confinement and engineered dispersion profiles are an excellent platform for application-tailored nonlinear optical interactions at low pulse energies. Here, we present fully air clad suspended-silicon waveguides for infrared frequency comb generation with optical bandwidth limited only by the silicon transparency. The achieved spectra are lithographically tailored to span 2.1 octaves in the mid-infrared (2.0-8.5 um or 1170--5000 cm-1) when pumped at 3.10 um with 100 pJ pulses. Novel fork-shaped couplers provide efficient input coupling with only 1.5 dB loss. The coherence, brightness, and the stability of the generated light are highlighted in a dual frequency comb setup in which individual comb-lines are resolved with 30 dB extinction ratio and 100 MHz spacing in the wavelength range of 4.8-8.5 um (2100-1170 cm-1). These sources are used for broadband gas- and liquid-phase dual-comb spectroscopy with 100 MHz comb-line resolution. We achieve a peak spectral signal-to-noise ratio of 10 Hz^0.5 across a simultaneous bandwidth containing 112,200 comb-lines. These results provide a pathway to further integration with the developing high repetition rate frequency comb lasers for compact sensors with applications in chip-based chemical analysis and spectroscopy.
We demonstrate a wide range of novel functions in integrated, CMOS compatible, devices. This platform has promise for telecommunications and on-chip WDM optical interconnects for computing.
Silicon is an ideal material for on-chip applications, however its poor acoustic properties limit its performance for important optoacoustic applications, particularly for Stimulated Brillouin Scattering (SBS). We theoretically show that silicon inverse opals exhibit a strongly improved acoustic performance that enhances the bulk SBS gain coefficient by more than two orders of magnitude. We also design a waveguide that incorporates silicon inverse opals and which has SBS gain values that are comparable with chalcogenide glass waveguides. This research opens new directions for opto-acoustic applications in on-chip material systems.
The third-order optical nonlinearity in optical waveguides has found applications in optical switching, optical wavelength conversion, optical frequency comb generation, and ultrafast optical signal processing. The development of an integrated waveguide platform with a high nonlinearity is therefore important for nonlinear integrated photonics. Here, we report the observation of an enhancement in the nonlinearity of an air-cladding silicon pedestal waveguide. We observe enhanced nonlinear spectral broadening compared to a conventional silicon-on-insulator waveguide. At the center wavelength of 1555 nm, the nonlinear-index coefficient of air-cladding silicon pedestal waveguide is measured to be about 5% larger than that of a conventional silicon-on-insulator waveguide. We observe enhanced spectral broadening from self-phase modulation of an optical pulse in the pedestal waveguide. The interaction of light with the confined acoustic phonons in the pedestal structure gives rise to a larger nonlinear-index coefficient. The experimental results agree well with the theoretical models.
We designed, fabricated and tested gallium phosphide (GaP) nano-waveguides for second harmonic generation (SHG). We demonstrate SHG in the visible range around 655 nm using low power continuous-wave pump in the optical communication O-band. Our structures utilize modal phase matching, such that lower order eigenmodes of the pump are phase matched to higher order eigenmodes of the second harmonic. We observe phase matched SHG for different combinations of interacting modes by varying the widths of the waveguides and tuning the wavelength of the pump. The presented results contribute to the development of integrated photonic platforms with efficient nonlinear wave-mixing processes for classical and quantum applications.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
