Figure 1: Experimental layout.

The NSE is simulated using a continuous-wave laser centred at 532 nm, which is passed through an attenuator (Att., λ/2-waveplate+polarizer) then through an azimuthal phase mask. The phase mask imprints a vortex phase structure creating a series of diffracted orders. The first order (with ) is isolated with an iris in the far field of an f=1 m lens and collected with an f=250 mm lens forming a telescope with a 4:1 de-magnification factor. The vortex beam is centred onto the input facet of a lead-doped glass slab (height D=5 mm, length 400 mm and width 40 mm). The near and far fields of the output facet of the glass slab are imaged separately with two lenses onto a camera so as to monitor the real-space intensity distribution and the spatial-frequency spectrum of the simulated boson star. The inset graph shows the heat-induced refractive index change (Δn, normalized to one) in the glass sample as predicted by the full numerical solution to equation (4) (blue dashed line), by the distributed loss model (red line, σ=D/2) and the experimentally measured Δn (thick black line).