Optical filters based on ring resonators with integrated semiconductor optical amplifiers in GaInAsP-InP

Abstract

A key device in all-optical networks is the optical filter. A ring resonator filter with an integrated semiconductor optical amplifier (SOA) on the basis of GaInAsP-InP has been investigated and fabricated. A required passband shape of loss-compensated ring resonator filters can be custom-designed by the use of multiple coupled resonators. Results of single-, double-, and triple-ring resonators with integrated SOAs with free spectral ranges of 12.5, 25, and 50 GHz, respectively, are presented. A box-like filter response is obtained by the double- and triple-ring resonators using specific coupling coefficient

A GaInAsP-InP double-ring resonator coupled laser

“…A standard ridge waveguide laser structure was used for the SOA section, which required an additional epitaxial growth step [6]. The width of the SOA is 2.2 m. The bandgap wavelength of the quaternary material used for the passive waveguide is m. The waveguide ridge was deeply etched on the outer side of the ring to increase the light confinement and reduce the ring loss.…”

Fabrication-tolerant active-passive integration scheme for vertically coupled microring resonator

“…Both dielectric and semiconductor rings filters have been realized. In contrast to weakly-guided laterally coupled rings where a typical radius ranges from 300-700 µm [11], [16], vertically coupled architectures are capable of realizing smaller ring radii at the range of 10-20 µm due to the better optical confinement achievable, thus benefiting from a wider free spectral range for minimal signal crosstalk [12]- [14], [18]. Active switching of the optical signals with applied bias has also been achieved using laterally- [19] or vertically coupled [20] structures.…”

“…Further reduction in the ring laser's dimensions have, however, been hampered by processing difficulties such as sidewall-roughnessinduced scattering loss in the ridge ring waveguide, which restricts the bending radius. The circulating optical path can be used as either laterally-or vertically coupled high order filters [11]- [14], or WDM channel add-drop filters [15]- [18] with microrings cascaded in series or parallel. Both dielectric and semiconductor rings filters have been realized.…”

Ring-Resonator-Based Wavelength Filters

“…The distance between consecutive interference peaks is a measure for the FSR, while the exponential envelope of the interference peaks e. g. provides information on the coupling constants and the losses [17,50,55]. …”

“…This has been done mainly in relatively large racetrack structures, where enough coupling length is present to allow for thermo-optic tuning restricted to the coupling sections [50]. Furthermore, some more exotic methods have been demonstrated making use of MEMS (Micro Electro-Mechanical Systems) technology.…”