Here is python code as a wield.pytest that generates the Geontropic noise model from arXiv:2209.07543 [gr-qc, physics:hep-ph, physics:hep-th].

You'll need to install wield.utilities and wield.pytest to run. You can just drop  T_GQuEST_concept.py and GQuEST_models.py  in a folder and call pytest. The output is

Total power displacement 2.3306928419630585e-18
Effective_BW: 57.28 MHz  by c/L 0.954696717877494
Effective_BWsq: 14.68 MHz  by c/L 0.24468351704291535
Frequency of Max: 11.29MHz
3db_bandwidth: 12.70MHz
Total power displacement2 2.3306928419630585e-18
3db points:  [[ 5.49516136]
 [18.19782777]]
Effective_BW: 57.28 MHz  by c/L 0.954696717877494
Effective_BWsq: 14.68 MHz  by c/L 0.2446835170429154

GQuEST_model.pdf Shows the model with and without the IR cutoff. It also includes the integrated RMS. Note that the power spectrum falls off only as 1/F, so has a logarithmic divergence. We presume this logarithmic divergence gets cut of a c/w, for c the speed of light and w the beam radius. That's at about 100GHz for GQuEST's beam. That divergence is physically important, but not practically measurable.

GQuEST_model.pdf shows the same plot, but with overlayed axes to allow easy comparisons with the units of the Geontropic noise model paper. The code shows how to set up the plots for such fancy axes.

there are also plots showing the model in the Holometer.

Both of the plots also show that there is a reasonably close analytic formula for the noise. In python it is

Omega = 2*np.pi * F
Omega_SPEC = c_m_s/(2**0.5*L)
Canalytic = 2 * Cmax * Omega**2 * Omega_SPEC / (4 * Omega_SPEC**4 + Omega**4 - Omega**2 * Omega_SPEC**2)**0.5 / (Omega**2 + Omega_SPEC**2)**0.5

Which can be updated to be

\(\Omega = 2 \pi f\)

\(\newcommand{\obar}{\overline{\Omega}}\)\(\obar = \frac{c}{L}\)

\(S_L(f) \approx \frac{2 \Omega^2 \obar}{\sqrt{\Omega^4 - \frac{1}{2}\Omega^2 \obar^2 + \obar^4} \sqrt{2\Omega^2 + \obar^2}} S_L(f_{\text{pk}})\)

and Cmax is the maximum of the power spectrum. The above are in power, not amplitude, units.

I'll edit or add a comment with the Latex form once I have it.