Fig. 1. Correlated photon quantum efficiency calibration

Fig. 2. Signal light wavelength and idler light wavelength at different temperatures

Fig. 3. Quantum efficiency calibration experimental setup

Fig. 4. blackbody radiance measurement experiment

Fig. 5. Coincidence counts of 3 390 nm and 1 005 nm photon pairs with 775 nm laser fixed at 45 mW and varying 1 064 nm laser power in 30 s

Fig. 6. Front optical path optical path measurement

Fig. 7. Phase matching in the up-conversion

Fig. 8. Angle and field of view at the optical fiber coupling

Fig. 9. Measured blackbody radiance at 3 390 nm under different temperatures and pump power