Experimental Identification and Study of Coloured Conical Emission in Quadratic Nonlinear Media

We have explicitly identified coloured conical emission (CCE) and noncollinear optical parametric generation (OPG) by spectrum characterizations. With an experimental setup providing different pump pulse durations, CCE and noncollinear OPG are observed both alternatively and simultaneously. Comparisons between CCE and noncollinear OPG are studied. Accumulation behaviour of modulational instabilities is observed in our two-crystal cascaded configuration, which results in enhancement or depression of the CCE formation.