Is the Dyakonov-Shur plasma-wave instability observable in a real device?

In a gated 2D electron channel of length $L_{\mathrm{ch}}$ with fixed-voltage source and fixed-current drain, a drift velocity $v_{0}$ below the plasma-wave speed s makes plasma waves grow at a rate of order $v_{0}/L_{\mathrm{ch}}$, at fundamental frequency $f \sim s/(4L_{\mathrm{ch}})$, once growth exceeds viscous and momentum-relaxation damping. Does a real device (e.g. high-mobility graphene) show self-sustained emission at this frequency above the predicted threshold current? Answer yes or no.

Detection of narrowband emission near $s/(4 L_{\mathrm{ch}})$ that turns on at a threshold current and tunes with gate voltage as $s \sim n^{1/2}$, in a device whose damping is characterized independently.