Our<10 GHz photodetectors contain a PIN photodiode that uses the photovoltaic effect to convert optical power into electrical current. When terminated into a 50 Ω resistor on an oscilloscope, the pulse width of a laser can be measured. When terminated into a 50 Ω resistor on a spectrum analyzer, the frequency response of a laser can be measured. EOT's <10 GHz photodetectors have their own internal bias supply consisting of a long life lithium battery. Plugging a coaxial cable into the photodetector's BNC output connector and terminating with 50 Ω on an oscilloscope or spectrum analyzer is all that is required for operation.