Electronic control is graphene’s central attraction here. The first question is optical: how much power reaches each direction when the voltage changes?
83.6% relative is not 83.6% of the incoming power.
For propulsion, the denominator matters. A bright selected diffraction order may contain most of the reflected light while still carrying only a small fraction of incident power.
MEASURED OPTICAL RESULTS / HAN ET AL. 2025
Two reported operating states at 41.17 THz
Gate voltage
Outgoing angle
Absolute efficiency
Relative efficiency
10 V
−12°
7.8%
83.6%
−80 V
+45°
8.4%
76.5%
Absolute efficiency compares the selected order to incident optical power. Relative efficiency describes its share of reflected diffraction power under the paper’s definition. High relative efficiency does not mean most incoming power reaches the chosen order. The reported device was optically tested; force was not measured.
A measured precedent
Han and colleagues demonstrated a single-gate graphene hybrid in 2025. At 41.17 THz, the main reflected direction changed between −12° and +45°. The experiment establishes electrically controlled scattering in the mid-infrared; it did not measure a resulting propulsion force. The selector above shows those two reported optical states.
Count power with the right denominator
The selected orders had measured absolute efficiencies of 7.8% and 8.4%. Reported relative efficiencies were 83.6% and 76.5%, normalized to total reflected power over the measured angular space. We need the absolute fractions, all other orders and absorption to close the momentum and thermal budgets.
Optical switching is the first gate
Our proposed first milestone is a reproducible change in angular scattering at a stable incident power. Record reflection, transmission where applicable and the absorbed fraction for each electrical state. Use the measured distributions to predict a force change before analyzing the balance output. This prevents selecting an optical explanation after seeing a desired result.
Voltage introduces its own controls
Electrical switching can produce electrostatic attraction, leakage heating and cable forces. Use a mechanically and electrically comparable control sample, shield and characterize nearby conductors, and compare beam-on and beam-off sequences. A signal that follows voltage alone does not establish photon recoil. The optical change and measured mechanical change must agree.
QUESTIONS THAT MATTER
Can we assume 80% steering efficiency?
No. The 80% value in the earlier illustrative A1-EM calculation is an assumption. It is not a measured efficiency for our sample or the 2025 graphene prototype.
Would an infrared result prove solar-sail performance?
No. Sunlight spans wavelengths and polarization states. Broadband solar operation requires a separate optical and thermal assessment.
FOLLOW THE EVIDENCE
Go to the original work.
These are independent publications. They are not Metric Flight results or endorsements.