Conditions for highly efficient anti-Stokes conversion in gas-filled hollow core waveguides.

Using a four-mode theoretical analysis we show that highly efficient anti-Stokes conversion in waveguides is more challenging to realize in practice than previously thought. By including the dynamics of conversion to 2(nd) Stokes via stimulated Raman scattering and four-wave mixing, models predict only narrow, unstable regions of highly efficient anti-Stokes conversion. Experimental results of single-pass Raman conversion in confined capillary waveguides validate these predictions.

Demonstrations of analog-to-digital conversion using a frequency domain stretched processor.

The first proof-of-concept demonstrations are presented for a broadband photonic-assisted analog-to-digital converter (ADC) based on spatial spectral holography (SSH). The SSH-ADC acts as a frequency-domain stretch processor converting high bandwidth input signals to low bandwidth output signals, allowing the system to take advantage of high performance, low bandwidth electronic ADCs. Demonstrations with 50 MHz effective bandwidth are shown to highlight basic performance with approximately 5 effective bits of vertical resolution.