Ring resonator adopting multimode waveguide turning mirrors

The characteristic response of In
_0.532
Ga
_0.468
As/In
_0.528
Ga
_0.257
Al
_0.215
As on InP single ring resonators in the form of race tracks with a radius of 260(15
⁰
), 110(60
⁰
) and 260(15
⁰
) mum are presented. The used 2times2 multimode interference (MMI) couplers with coupling factor 0.85 are as short as 128 mum. Deep etching vertical mirror was used in the middle of MMI crossing. The free spectral ranges of 83 GHz and the through output (max)-drop (min) ratio of 21 dB have been achieved for the single ring resonator.