Determination of Orbital Angular Momentum Modes With Double Slit Experiments in W-band

We introduce a method for identifying Orbital Angular Momentum (OAM) modes in the millimeter wave range, especially in high-power environments where direct phase measurements are challenging. Instead of relying on phase measurements, the proposed method utilizes intensity measurements based on the asymmetric phase patterns of OAM beams. This approach involves using a Young's double slit interference setup to discern OAM modes, introducing the gyrotron-based OAM mode identification. We present simulation results and experimental results in low power, and compare with experimental result in high power.