21. For example, at optical frequencies , plasmons can couple with a photon to create another quasiparticle called a plasmon polariton. 22. One undesirable effect of angle tuning is that the optical frequencies involved do not propagate collinearly with each other. 23. Such systems also have the important advantage of very narrow channel spacing in optical frequency -division multiplexing ( OFDM ) systems. 24. However, since energy detection is inherently " square-law " detection, it intrinsically mixes any optical frequencies present on the detector. 25. For example, in " Fall ", a single perpendiculars curve is repeated to create a field of varying optical frequencies . 26. Optical frequency multipliers are very common in high-power lasers, notably those used for inertial confinement fusion ( ICF ) experiments.27. Surface plasmons occur at optical frequencies , but at microwave frequencies, they are the normal currents that occur on any electrical conductor. 28. We have not even begun to tap the applications at microwave frequencies, let alone what may lie ahead at optical frequencies , 29. Below optical frequencies ( that is, at microwave and radio frequencies ), the spectrum analyzer is a closely related electronic device. 30. Kinetic inductance is therefore only significant at optical frequencies and in superconductors, where { \ tau \ rightarrow \ infty }.
