This study investigates the photoresponse of few-layer black phosphorus (b-P) field-effect transistors (FETs) as a function of excitation wavelength, power, and frequency. b-P, a new 2D material with a direct bandgap that varies from 0.35 eV in bulk to 2.0 eV in single layers, is promising for tunable photodetection across the visible to infrared spectrum. The FETs exhibit ambipolar behavior in the dark state, with mobilities in the order of 100 cm²/Vs and current ON/OFF ratios exceeding 10³. Upon illumination, the b-P FETs show broadband and fast detection, responding to wavelengths from the visible to 940 nm with a rise time of about 1 ms. The responsivity reaches 4.8 mA/W, and it can be further enhanced by engineering a PN junction. These properties make few-layer black phosphorus a promising material for broadband and fast photodetectors.This study investigates the photoresponse of few-layer black phosphorus (b-P) field-effect transistors (FETs) as a function of excitation wavelength, power, and frequency. b-P, a new 2D material with a direct bandgap that varies from 0.35 eV in bulk to 2.0 eV in single layers, is promising for tunable photodetection across the visible to infrared spectrum. The FETs exhibit ambipolar behavior in the dark state, with mobilities in the order of 100 cm²/Vs and current ON/OFF ratios exceeding 10³. Upon illumination, the b-P FETs show broadband and fast detection, responding to wavelengths from the visible to 940 nm with a rise time of about 1 ms. The responsivity reaches 4.8 mA/W, and it can be further enhanced by engineering a PN junction. These properties make few-layer black phosphorus a promising material for broadband and fast photodetectors.