Figure 1

Schematic representation of the experimental set-up.
Two lasers, spectrally cleaned by Band Pass Filters (BPF) are combined in a beamsplitter (BS) and coupled to the sample. An optical micrograph of the sample is shown in the picture. The scale-bar refers to the sample only, the rest of the schematics is not in scale. A custom built Fabry Perot interferometer (FP filter) is used to achieve spectral resolution on the generated idler resonance. The FP filter position is controlled and stabilized using a reference laser in the telecom O-band and an active feedback loop. The output from the FP filter is fed to a spectrophotometer coupled to a CCD camera. PD stands for photodiode and SPF stands for Short Pass Filter.