Fig. 4: Experimental observation of nonreciprocal transverse localization.
From: Observation of nonreciprocal transverse localization of light
a–d The obtained intensity patterns of moiré coupling field superposed of two honeycomb substructures with different twist angles of 0, 16.4°, 27.8° and 54.0°. The green circles indicate the incident position of the probe beam. e–h The corresponding output patterns of the forward probe beam. i–k The transmission of the backward probe beam with Δc′ increased from −32 MHz to 60 MHz at Δc = 68 MHz and twist angle θ = 27.8°. Since the backward output is too weak to observe, the gain g of the camera CCD2 was set as 15 dB for larger Δc′. To avoid the saturation of the CCD2 at smaller Δc′, g was then adjusted to 3 dB. In the forward case, g = 0 means no gain on CCD1. wb/wf represents the nonreciprocity between the backward and forward output beam sizes. l The dependence of the isolation ratio 10log10(Tf/Tb) on the input power P when both probe beams with the same parameters are present simultaneously but without backward coupling field (experimental measurements – circles). The curve is a guide to the eye.
