The Highland Technology PH200 is the first product in the 'PH' series of
extreme-performance photonic instruments. The PH200 Nanowatt Photoreceiver,
designed in collaboration with Phil Hobbs, is a free-space optical/electrical converter that
provides near shot noise performance in a rugged, compact package.
The unique photon feedback architecture delivers a bandwidth greater than 1 MHz,
with an unprecedented combination of linearity, bandwidth, and dynamic range
for 10nA to 100μA photodiode signals.

http://www.highlandtechnology.com/DSS/PH200DS.shtml