Fig. 2
From: Room-temperature ultrasensitive photon-level detection in the subterahertz frequency regime

(a) Temporal waveforms of the frequency up-converted light (red) and pump light(gray). (b) Schematic diagram of up-converted light measurement.
From: Room-temperature ultrasensitive photon-level detection in the subterahertz frequency regime

(a) Temporal waveforms of the frequency up-converted light (red) and pump light(gray). (b) Schematic diagram of up-converted light measurement.