We report second-and third-harmonic generation in monolayer MoS 2 as a tool for imaging and accurately characterizing the material's nonlinear optical properties under 1560nm excitation. Using a surface nonlinear optics treatment, we derive expressions relating experimental measurements to second-and third-order nonlinear sheet susceptibility magnitudes, obtaining values of c = | | () s 2 ´-2.0 10 20 m 2 V-1 and, for the first time for monolayer MoS 2 , c = ´-| | () 1.7 10 s 3 28 m 3 V-2. These sheet susceptibilities correspond to effective bulk nonlinear susceptibility values of c = | | () 2.9 b 2-10 11 mV-1 and c = ´-| | () 2.4 10 b 3 19 m 2 V-2 , accounting for the sheet thickness. Experimental comparisons between MoS 2 and graphene are also performed, demonstrating ∼3.4 times stronger thirdorder sheet nonlinearity in monolayer MoS 2 , highlighting the material's potential for nonlinear photonics in the telecommunications C band.

We report the development of a high average power, picosecond-pulse, mid-infrared source based on difference-frequency generation (DFG) of two synchronous master oscillator power fiber amplifier systems. The generated idler can be tuned over the range 3.28–3.45 μm delivering greater than 3.4 W of average power, with a maximum pump to total DFG power conversion efficiency of 78%. The benefits of a synchronously pumped scheme, compared to CW seeding of DFG sources, are discussed.

We report the experimental observation of scalar and cross-phase modulation instabilities by pumping a highly birefringent photonic crystal fiber in the normal dispersion regime at 45° to its principal polarization axes. Five sideband pairs (two scalar and three vector ones) are observed simultaneously in the spontaneous regime, four of which have a large frequency shift from the pump, in the range 79-93 THz. These results are in excellent agreement with phase-matching arguments and numerical simulations.

We present results of high average power mid-infrared (mid-IR) generation employing synchronized nanosecond pulsed ytterbium and erbium fiber amplifier systems using periodically poled lithium niobate. We generate greater than 6 W of mid-IR radiation tunable in wavelength between 3.31–3.48 μm, at power conversion efficiencies exceeding 75%, with near diffraction limited beam quality (M² = 1.4). Numerical modeling is used to verify the experimental results in differing pump depletion regimes.

The efficient nonlinear conversion of Yb-doped fiber laser systems using a combination of stimulated Raman scattering and second-harmonic generation is an effective method for developing sources for biophotonic applications in the yellow–green spectral region. In this paper, we review recent progress in the development of these sources, compare the relative benefits of differing source architectures, and demonstrate stimulated emission depletion microscopy using an exemplar source.

We demonstrate a nanosecond 560 nm pulse source based on frequency-doubling the output of a combined Yb-Raman fiber amplifier, achieving a pulse energy of 2.0 µJ with a conversion efficiency of 32% from the 976 nm pump light. By introducing a continuous-wave 1120 nm signal before the cladding pumped amplifier of a pulsed Yb:fiber master oscillator power amplifier system operating at 1064 nm, efficient conversion to 1120 nm occurs within the fiber amplifier due to stimulated Raman scattering. The output of the combined Yb-Raman amplifier is frequency-doubled to 560 nm using a periodically poled lithium tantalate crystal with a conversion efficiency of 47%, resulting in an average power of 3.0 W at a repetition rate of 1.5 MHz. The 560 nm pulse duration of 1.7 ns and the near diffraction-limited beam quality (M²≤1.18) make this source ideally suited to biomedical imaging applications such as optical-resolution photoacoustic microscopy and stimulated emission depletion microscopy.