Coupled Peak Power Research Articles

Self-phase modulation in single CdTe nanowires.

We measure the transmission of near-infrared ps pulses through single CdTe nanowires. Benefitting from the strong light confinement and large effective nonlinearity of these nanowires, a significant spectral broadening of ∼ 5 nm and nonlinear phase shift of a few π due to self-phase modulation (SPM) is observed experimentally at coupled peak power of a dozen W with a propagating length down to several hundred µms. A nonlinear-index coefficient (n2) as high as (9.5 ± 1.4) × 10-17 m2/W at 1550 nm is extracted from transmission spectra, corresponding to a nonlinear parameter (γ) of ∼ 1050 W-1m-1. The simulations indicate a spectral broadening more than 1.5 µm in single nanowire when pumped by fs pulses in anomalous dispersion regime. The obtained results suggest that, CdTe nanowire is promising in developing ultracompact nonlinear optical devices for microphotonic circuits.

Coherent mid-infrared supercontinuum spectrum using a step-index tellurite fiber with all-normal dispersion

We demonstrate a coherent mid-infrared supercontinuum generation in a step-index tellurite fiber with an all-normal dispersion profile. A coherent supercontinuum spectrum spanning 1340–2840 nm in a 6.3-cm-long tellurite step-index fiber is obtained when the fiber is pumped with 200 fs laser pulses with a coupled peak power of 5.5 kW at 2000 nm. Such fiber-based coherent mid-infrared supercontinuum sources are highly required for the imaging of biological tissues in optical coherence tomography, pump–probe spectroscopy, pulse compression, and sensing.

Broadband incoherent four-wave mixing and 27 dB idler conversion efficiency using ultra-silicon rich nitride devices

The generation of broadband light within the telecommunication band has been instrumental to the design and characterization of advanced optical devices and systems. In this paper, stimulated degenerate four-wave mixing of an ultra-silicon rich nitride waveguide is investigated using a pulsed pump at 1.555 μm and incoherent broadband sources emitting in the 1.65 μm wavelength region as a signal. The waveguide possesses a large nonlinear parameter of 330 W−1/m as well as anomalous dispersion, required for phase matched parametric processes. The broadband idler ranging from 1.43 μm to 1.52 μm is generated using a coupled peak power of 4.6 W, spanning ∼100 nm at the −20 dB level, which is sufficient to cover parts of the E- and S-bands. The spectral span of the generated idler also agrees well with the calculation based on the phase-matching condition governing degenerate four-wave mixing. Cascaded incoherent four-wave mixing is also observed. Using a supercontinuum pump spanning from 1.1 to 1.7 μm with a coupled peak power of 26 W, an idler spanning from 1.2 to 1.4 μm is generated, equivalent to an idler on/off conversion efficiency of 27 dB.

Amorphous silicon nanowires combining high nonlinearity, FOM and optical stability

We demonstrate optically stable amorphous silicon nanowires with both high nonlinear figure of merit (FOM) of ~5 and high nonlinearity Re(γ) = 1200W(-1)m(-1). We observe no degradation in these parameters over the entire course of our experiments including systematic study under operation at 2 W coupled peak power (i.e. ~2GW/cm(2)) over timescales of at least an hour.

Mid-infrared to telecom-band supercontinuum generation in highly nonlinear silicon-on-insulator wire waveguides

We demonstrate the generation of a supercontinuum in a 2 cm long silicon wire by pumping the wire with mid-infrared picosecond pulses in the anomalous dispersion regime. The supercontinuum extends from 1535 nm up to 2525 nm for a coupled peak power of 12.7 W. It is shown that the supercontinuum originates primarily from the amplification of background noise. A detailed analysis of the spectral components which are generated through phase-matched processes is applied to extract the group velocity dispersion and fourth-order dispersion coefficient of the silicon wire waveguide.

Cavity enhanced stimulated Brillouin scattering in an optical chip for multiorder Stokes generation

We report the first demonstration of on-chip cascaded stimulated Brillouin scattering (SBS). Cascaded SBS is characterized in a 4 cm long chalcogenide (As₂S₃) rib waveguide where the end facet reflections provide a monolithic Fabry-Perot (FP) resonator. The presence of the FP cavity reduces the Brillouin gain threshold, which enables observation of cascaded SBS at reduced pump powers. We observe up to three orders of Stokes waves in the backscattered signal at a coupled peak power of 1.34 W. Anti-Stokes waves due to four-wave mixing between the pump and the Stokes wave were observed in the forward spectrum.

Er-diffused Ti:LiNbO3 waveguide laser of 1563 and 1576 nm emission wavelengths

The first continuous wave (cw) and pulsed mode operation of an Er-diffused Ti:LiNbO3 monomode waveguide laser at 1563 nm (E⊥ c) and 1576 nm (E∥ c) wavelengths is reported. A tunable Tl:KCl color center laser was used as a pump source. With π-polarized (Ep∥ c) pump radiation of 1479 nm wavelength an oscillation threshold of 13 mW coupled pump power was achieved for the 1576 nm emission line. Above 25 mW pump power additional lasing at 1563 nm wavelength was observed. σ-polarized (Ep⊥ c) pumping led to a single line emission at 1563 nm throughout with the highest cw output power of 3 mW and a slope efficiency of 3%. Time averaged emission linewidths of about 0.6 nm were measured for both wavelengths at about two times the threshold pump power level. With pulsed excitation of about 1 W coupled peak power output pulses of up to 200 mW peak power were measured.