Optical devices based on optically coupled optical whispering gallery-mode resonators formed on a rod
Devices having whispering-gallery-mode (WGM) resonators configured to meet requirements of various applications and facilitate fabrication of such devices.
1. An optical device having an optical whispering gallery mode resonator, comprising:
an optical resonator that is shaped to include an optical path and supports whispering gallery modes propagating in the optical path and including a selected whispering gallery mode that has a zero electric field at a selected location in the optical path at which electric fields of other whispering gallery modes are not zero; and
an optically absorptive structure formed at the selected location in the optical path of the optical resonator and structured to absorb light of the other whispering gallery modes at the selected location without absorbing light in the selected whispering gallery mode so as to sustain the light in the selected whispering gallery mode as a single optical mode in the optical resonator while suppressing the other whispering gallery modes.
2. The device as in claim 1 , wherein the optically absorptive structure formed at the selected location includes one or more quantum dots.
3. The device as in claim 1 , wherein the optical resonator is made of a crystalline material.
4. The device as in claim 1 , comprising an optical coupler coupled to the optical resonator to evanescently couple light into the optical resonator in the selected whispering gallery mode.
5. A method for maintaining a single optical mode in an optical resonator, comprising:
providing an optical resonator that is shaped to include an optical path and supports whispering gallery modes propagating in the optical path and including a selected whispering gallery mode that has a zero electric field at a selected location in the optical path at which electric fields of other whispering gallery modes are not zero; and
attenuating light at the selected location in the optical path of the optical resonator to suppress light of the other whispering gallery modes at the selected location without attenuating light in the selected whispering gallery mode so as render the selected whispering gallery mode to be a single optical mode present in the optical resonator.
6. The method as in claim 5 , wherein the attenuating light at the selected location in the optical path of the optical resonator includes forming an optically absorptive structure at the selected location in the optical resonator to absorb light at the selected location inside the optical resonator.
7. The method as in claim 5 , wherein the attenuating light at the selected location in the optical path of the optical resonator includes using one or more optically irradiative elements at the selected location to be in evanescent coupling with the optical resonator to cause attention of light at the selected location inside the optical resonator.
8. The method as in claim 7 , wherein the one or more optically irradiative elements include an optical waveguide, located outside the optical resonator and near the selected location in the optical resonator, to evanescently couple to a whispering gallery mode of the optical resonator that has a non-zero amplitude at the selected location to cause attention of the whispering gallery mode.
9. An optical device having an optical whispering gallery mode resonator, comprising:
an optical resonator that is shaped to include a circular optical path and supports whispering gallery modes propagating in an optical path and including a selected whispering gallery mode that has a zero electric field at a selected location in the optical path at which electric fields of other whispering gallery modes are not zero; and
an optical coupler located outside the optical resonator near the selected location in the optical path of the optical resonator to be in evanescently coupling with whispering gallery modes at the selected location to suppress electric fields of other whispering gallery modes at the selected location to render the selected whispering gallery mode to be a single optical mode present in the optical resonator.
10. The device as in claim 9 , wherein the optical coupler includes an optical waveguide.
11. The device as in claim 9 , wherein the resonator is made of a crystalline material.