The spatial spectrum is obtained by using a lens to +3pfBE|
do Fourier transform and the far-field spectrum is recorded KhPDXY]!
by a CCD camera positioned in its focal plane. ?i\$U'2*z3
First, we summarize our results of on-axis excitation of a <^+&A7 Q-_
single 2D gap soliton in Fig. 1. Different from previous FC4hvO(/m
experimental observations in which either the probe beam ) LL.fPic
was launched off-axis to match the edge of the first BZ [6] 9S?b &]
or its input phase or spectrum was engineered [11], we aw3rTT(
demonstrate on-axis excitation of a 2D gap soliton without m~@Lt~LZs
a priori phase or spectral engineering. In fact, we show 0a+U >S#
