BMC Optical Modulator used in scanning photocurrent microscopy (SPCM)

Ajou University in Korea has recently reported on femtosecond scanning photocurrent microscopy using our Optical Modulator devices. In this application Ti:Sapphire lasers were divided into pump and probe beams, then focused on the samples using an objective lens, while a pair of two-axis steering mirrors were used to manipulate the positions of both focused laser spots. Our optical modulator was then used to modulate the probe pulse at 20 kHz to capture the photocurrent generated by the probe pulse signals and filter out the photocurrents generated directly by the pump pulse. It is noted in their paper that “this modulator is advantageous over the acousto-optic types because it is free from the dispersion effects and delivers better spatial resolution for the focused laser”. Figure 1 shows the setup of the experiment.

Figure 1. Schematic of experiments. (a) Schematic diagram of ultrafast carrier dynamics in a semiconductor nanowire device. (b) Schematic diagram of the experimental setup (CM, chirped mirrors; DM, optical modulator).

For the results on combining scanning photocurrent microscopy and ultrafast pump probe techniques, head to ACS Nano to read the full paper.