Abstract
We present a study on electrical and optical trade-offs of the doping map in a ring modulator. Here, we investigate the effects of the high-doped region distance to edge of the waveguide sidewall. Four groups of ring modulators with different rib-to-contact distances are fabricated and measured where the key parameters such as extinction ratio, insertion loss, transmission penalty, and bandwidth are compared quantitatively. Small-signal responses for the selected ring modulators are simulated where results are in agreement with measurement results. We show that, at 4dB extinction ratio, decreasing the high-doped region distance to rib from 800nm to 350nm will increase the bandwidth by 3.8 ×. However, we observed 8.4dB increase the insertion loss. We also show that the high-doped region location affects the trade-off between bandwidth and frequency response magnitude at low frequencies. At 350nm, this trade off is 2.5 × and 3.8× more efficient compared to 550nm and 800nm, respectively.
Highlights
Data traffic is increasing mostly due to consumer usage via high data-demanding applications such as video streaming and cloud computing
Performance of each of these ring modulators is compared according to the device bandwidth, extinction ratio (ER), and insertion loss (IL)
Ring modulators are fabricated on a Silicon on Insulator (SOI) wafer with a top Si layer of 220nm and 2μm thick buried oxide layer
Summary
Data traffic is increasing mostly due to consumer usage via high data-demanding applications such as video streaming and cloud computing. Too much reduction of d++ results in an increase in optical loss [11, 12] This is due to optical mode lateral extension to the highly doped region [5] as well as the dopant diffusion to the waveguide during the annealing process. The main goal in many of the above studies is to optimize Mach-Zehnder modulator (MZM) bandwidth and modulation efficiency, and the results may not be applicable to ring modulators This is due to the more complex nature of resonance in ring modulators which couples the optimization of optical and electrical parameters. The key performance parameters such as extinction ratio, modulator penalties, insertion loss, and ring modulator electrical and optical bandwidth are compared at various d++ values based on measurement and simulation results. Performance of each of these ring modulators is compared according to the device bandwidth, extinction ratio (ER), and insertion loss (IL)
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