Reciprocal Phase Transition Electro-Optic Modulation

Electro-optic (EO) modulation is a well-known and essential topic in the field of communications and sensing, while ultrahigh modulation efficiency is unprecedentedly desired in the current green and data era. However, dramatically increasing the modulation efficiency is difficult in conventional mechanisms, being intrinsically limited by the monotonic mapping relationship between the electrical driving signal and modulated optical signal. To break this bottleneck, a new mechanism termed phase-transition EO modulation is revealed from the reciprocal transition between two distinct phase planes arising from the Hopf bifurcation, being driven by a transient electrical signal to cross the critical point. A monolithically integrated mode-locked laser is implemented as a prototype, strikingly achieving an ultrahigh modulation energy efficiency of 3.06 fJ bit⁻¹ improved by about four orders of magnitude and a contrast ratio exceeding 50 dB. The prototype is experimentally implemented for radio-over-fiber communication and acoustic sensing. This work indicates a significant advance on the state-of-the-art EO modulation technology and opens a new avenue for green communication and ubiquitous sensing applications.