Optical slow-wave resonant modulation in electro-optic GaAs/AlGaAs modulators.

The first decade of coupled resonator optical waveguides: bringing slow light to applications

“…Fig. 2 shows examples of CROWs made by ring resonators [58], microtoroids [59], microspheres [60], square microresonators [61], and pho-REVIEW ARTICLE 77 tonic crystal cavities [62]. More recently, Bragg-defined Fabry-Pérot cavities [22] have also been demonstrated.…”

“…(1) Because of multiple roundtrips inside the resonators, the effective phase shift φ eff experienced by the optical field propagating in the CROW is enhanced by a factor S with respect to the phase shift φ in a bare waveguide of the same length. This property makes CROWs of interest for the realization of phase-sensitive and phase-controlled devices as well as devices based on phase modulation [66,77].…”

“…Morichetti et al: First decade of coupled resonator optical waveguides a decade ago, pioneering works predicted [66] and experimentally demonstrated [77] the increase of the efficiency of electro-optic modulators assisted by slow-light propagation. In these applications, the reduction of the group velocity of the light has a twofold benefit: on the one hand, it provides an effective mechanism to match the velocity of the light to that of the microwave modulating signal, as required in lithium niobate wide-band traveling wave modulators [169]; on the other hand, owing to the increased dwelling time of the light in the structure, the strength of the electro-optic interaction scales up according to the slowdown factor S. A higher electro-optic efficiency can be exploited either to reduce the driving voltage of the modulator or to reduce the length of the electrodes, and hence to increase the bandwidth.…”

Transverse Bragg-Resonant Enhancement of Modulation and Switching

“…Improvements of such devices in terms of requisite modulation voltage or length of modulator, have been achieved either by using improved materials or by using slow-wave structures [4], [5]. While the aforementioned slow-wave structure "slows" light due to the weak coupling between two neighboring cavities [6], [7], in this letter, we analyze the transverse Bragg resonance (TBR) waveguide, in which the light is slowed due to the folded optical path, as shown in Fig.…”

“…In this case, we have and . Thus, the electrooptic effect in the TBR waveguide is enhanced by a factor (4) Intuitively, this is because the effective optical length (or length of interaction with the material) in a TBR waveguide is increased by a factor of , as illustrated by the "zigzag" line in Fig. 1.…”