Figure 1: Junction profile comparison.

(a) The lateral, vertical and interleaved junction profiles are illustrated for common depletion-mode modulators. The capacitance per unit length (C/L) is expressed below each junction profile. Frequency shifts based on equations (2), (3) and (6) are calculated as a function of applied potential for lateral, vertical and interleaved junction profiles, showing the large frequency shift of vertical junction profile. Calculations were performed at λ=1.55 μm and for a built-in potential of 0.7 V and a n- and p-type carrier concentration of 3 × 10¹⁸ cm⁻³. (b) The internal quality factors are plotted as a function of radius for an undoped microdisk and ridge resonators, showing high confinement and quality factor for the microdisk resonator. The TE radial mode profiles are overlaid with the resonator cross-sections. The thickness of the microdisk resonator was 220 nm. The ridge resonator had the crossection of the modulator in ref. 18.