Chirp-induced modulation of broadband ultrafast semiconductor nonlinearities

Summary form only given. Broadband continuum nonlinearities, rather than narrowband exciton nonlinearities, are important for future ultrafast semiconductor devices operating on the 10-fs timescale. Recently, we have shown that frequency chirp is an additional control parameter of the semiconductor continuum nonlinearity in differential transmission (DT) experiments if pump and probe pulses have the same chirp (equal-chirp configuration). In this paper, we determine the effect of pulse chirp on the DT for different chirp configurations: chirped pump pulse/unchirped probe (pump-chirp), unchirped pump/chirped probe (probe-chirp), and equal-chirp. We will point out how optimal chirp-control of the spectrally integrated (SI) DT is achieved to improve ultrafast all-optical switching. Comprehensive DT measurements in the complete energy-time plane give a qualitative understanding of the SI DT.