Gain-assisted electroabsorption modulators
View Patent ↗A light modulator having a waveguide and a resonator is disclosed. The waveguide routes light of wavelength λ past the resonator. The resonator is coupled to the waveguide such that a portion of the light is input to the resonator, the resonator having a resonance at λ. The resonator includes a gain region in which light of wavelength λ is amplified and an absorption region in which light of wavelength λ is absorbed, the absorption region having first and second states, the first state absorbing less light of wavelength λ than the second state, the state of the absorption region is determined by an electrical signal coupled to the absorption region. The gain region provides a gain that compensates for the light absorption in the first state. In one embodiment, the waveguide and resonator are critically coupled when the absorption region is in the second state.
1. A light modulator comprising;
a waveguide routing light of wavelength λ; and
a resonator coupled to said waveguide such that a portion of said light is input to said resonator, said resonator having a resonance at λ and comprising a gain region in which light of wavelength λ is amplified and an absorption region in which light of wavelength λ is absorbed, said absorption region having first and second states, said first state absorbing less light of wavelength λ than said second state, said state of said absorption region being determined by an electrical signal coupled to said absorption region.
2. The light modulator of claim 1 wherein said gain region provides a gain that compensates for said light absorption in said first state.
3. The light modulator of claim 1 wherein said waveguide and resonator are critically coupled when said absorption region is in said second state.
4. The light modulator of claim 1 wherein said resonator is a microdisk resonator.
5. The light modulator of claim 1 wherein said resonator is a micro-ring resonator.
6. The light modulator of claim 1 wherein said resonator is a folded cavity resonator.
7. The light modulator of claim 1 wherein said resonator comprises a layered structure having a quantum well layer, said quantum well layer having different bandgap energies in said gain and absorption regions.
8. A light modulator comprising;
a waveguide routing light of wavelength λ; and
a resonator coupled to said waveguide such that a portion of said light is input to said resonator, said resonator having a resonance at λ and comprising a gain region in which light of wavelength λ is amplified and an absorption region in which light of wavelength λ is absorbed, said absorption region having first and second states, said first state absorbing less light of wavelength λ than said second state, said state of said absorption region being determined by an electrical signal coupled to said absorption region;
wherein said resonator comprises a layered structure having a quantum well layer, said quantum well layer having different bandgap energies in said gain and absorption regions;
wherein said waveguide comprises a waveguide region in said layered structure, said waveguide region being different from said gain and absorption regions in said layered structure and wherein said quantum well layer in said waveguide region and said gain region has different bandgap energies.
9. A light modulator comprising;
a waveguide routing light of wavelength λ; and
a resonator coupled to said waveguide such that a portion of said light is input to said resonator, said resonator having a resonance at λ and comprising a gain region in which light of wavelength λ is amplified and an absorption region in which light of wavelength λ is absorbed, said absorption region having first and second states, said first state absorbing less light of wavelength λ than said second state, said state of said absorption region being determined by an electrical signal coupled to said absorption region;
wherein said resonator is vertically coupled to said waveguide.
10. A method for modulating a light signal of wavelength λ traveling in a waveguide, said method comprising:
coupling a portion of said light into a resonator having a resonance at λ;
attenuating said light in said resonator by either a first or second attenuation factor; and
amplifying light traveling in said resonator by an amount that is less than or equal to said first attenuation factor.
11. The method of claim 10 wherein said attenuation factor is determined by applying an electrical signal to said resonator.
12. The method of claim 10 wherein said resonator is a microdisk resonator.
13. The method of claim 10 wherein said resonator is a micro-ring resonator.
14. The method of claim 10 wherein said resonator is a folded cavity resonator.