Controllable Self-Steepening of Ultrashort Pulses in Quadratic Nonlinear Media

By analyzing ultrashort optical pulse propagation in quadratic nonlinear media beyond the slowly varying envelope approximation, we find that the sign and magnitude of self-steepening can be controlled through the wave vector mismatch. As an example of this phenomenon’s impact on ultrashort pulse propagation, we show that it may be used to cancel the propagation effects of group-velocity mismatch. We obtain quantitative agreement between theory, simulations, and experiments.

Figure 1

An illustration of CSS: (a) positive self-steepening $\Delta k=+|\Delta k_0|$), and (b) negative self-steepening $\Delta k=-|\Delta k_0|$). The spectral bandwidths correspond to a transform-limited 2-cycle pulse. The curves are generated by numerically integrating (3, 4), neglecting both linear dispersion and GVM.

Figure 2

SEWA- vs SVEA-model calculations of total coefficients to the $|a_1{|}^2{\partial }_{\tau }{a}_1$ term (8b), for ${\lambda }_0=1360\mathrm{nm}$ (light lines) and ${\lambda }_0=1480\mathrm{nm}$ (heavy lines), in BBO.

Figure 3

SVEA- and SEWA-model simulations (first and second rows), and corresponding experimental results (third row). $\Delta k$ values are listed in the top left corners. Initial spectrum is dotted; output is solid.