A direct current and a modulation signal are simultaneously applied to contact pads on a device under test, such as a laser diode, with a probe that reduces signal distortion and power dissipation by transmitting a modulated signal through an impedance matching resistor and transmitting of a direct current...http://www.google.com.hk/patents/US7453276?utm_source=gb-gplus-share專利 US7453276 - Probe for combined signals
