Longitudinal to transversal conversion of mode-locked states in an empty optical resonator

A longitudinal mode-locked state can be converted to a transverse mode-locked state by exploiting the spectral and spatial filtering of an empty optical resonator. Carrier and amplitude modulation sidebands were simultaneously transmitted by the conversion resonator, yielding phase-locked superpositions of up to five transverse modes. Equivalently, an amplitude-modulated beam was converted into a beam that periodically moved across the transverse plane. Precise control over the spatial beam shape during oscillation was gained by independently altering the set of transverse modes and their respective powers, which demonstrated an increased level of control in the generation of transverse mode-locked states.