For monitoring the power in a wavelength locker or for power stabilization of a laser diode Hamamatsu offers a number of InGaAs photodiodes mounted on ceramic substrates. When space is a premium the back thinned G9230-01 LD monitor is preferred because the photodiode is directly soldered to the substrate without any need for wire bonding. The diameter of the active area varies from 0.3 mm to 1 mm.