Ultra-sensitive all-optical sampling at 1.5 μm using waveguide two-photon absorption

Ultra-sensitive all-optical sampling at 1.5 /spl mu/m using two-photon-absorption in a commercial 1.3 /spl mu/m quantum-well semiconductor laser has been demonstrated. Using only direct detection of the unamplified two photon absorption photocurrent, a temporal resolution of /spl sim/2 ps and a sensitivity of less than 2 mW/sup 2/ have been achieved.