Suppression of back reflection in a waveguide
A structure for guiding electromagnetic radiation, including: a substrate; a waveguide provided on the substrate and having a first end for receiving electromagnetic radiation and a second end; and an anti-reflection region provided at the second end of the waveguide on the substrate, the length and the width of the anti-reflection region being optimized to suppress back reflection of radiation that reaches the second end.
1. A structure for guiding electromagnetic radiation of a select wavelength, comprising: a substrate; a waveguide provided on the substrate and having a first end for receiving electromagnetic radiation of a select wavelength and a second end; and an anti-reflection region provided at the second end of the waveguide on the substrate, a length and a width of the anti-reflection region being selected to suppress back reflection of the electromagnetic radiation at the second end during operation, wherein the width of the anti-reflection region is substantially larger than the wavelength of the electromagnetic radiation in the anti-reflection region, and the length of the anti-reflection region is substantially longer than the wavelength of the electromagnetic radiation in the anti-reflection region, such that the anti-reflection region is configured to absorb the electromagnetic radiation and cause the electromagnetic radiation to diverge.
2. A structure according to claim 1 , wherein the anti-reflection region has a width (Wa) substantially wider than a width (Wb) of the waveguide.
3. A structure according to claim 1 , wherein the anti-reflection region has a width at least 3 times wider than the wavelength of the electromagnetic radiation which will reach the anti-reflection region.
4. A structure according to claim 1 , wherein the anti-reflection region has a length at least 5 times the wavelength of the electromagnetic radiation which will reach the anti-reflection region.
5. A structure according to claim 1 , wherein the waveguide and the anti-reflection region are formed from a same material.
6. A structure according to claim 1 , comprising:
one or more layers forming the waveguide and the anti-reflection region.
7. A structure according to claim 6 , wherein the one or more layers comprise:
a quantum well.
8. A structure according to claim 1 , wherein the structure comprises:
semiconductor material.
9. A structure according to claim 1 , wherein the structure is included in a photonic component.
10. A structure according to claim 1 , wherein the structure is included in a chip.
11. A structure according to claim 1 , wherein the structure is included in a spectrometer.
12. A structure according to claim 11 , comprising:
a plurality of resonators provided on the substrate and being coupled to the waveguide, each of the resonators being resonant at a predetermined wavelength of the electromagnetic radiation.
13. A structure according to claim 12 , wherein the plurality of resonators are disk resonators.
14. A structure according to claim 3 , wherein the waveguide and the anti-reflection region are formed from a same material.
15. A structure according to claim 14 , comprising:
one or more layers forming the waveguide and the anti-reflection region.
16. A structure according to claim 15 , wherein the one or more layers comprise:
a quantum well.
17. A structure according to claim 4 , wherein the waveguide and the anti-reflection region are formed from a same material.
18. A structure according to claim 17 , comprising:
one or more layers forming the waveguide and the anti-reflection region.
19. A structure according to claim 1 , wherein the waveguide is configured to receive electromagnetic radiation in a predetermined range of wavelengths, and the select wavelength is a mean wavelength of the predetermined range.
20. A structure according to claim 1 , wherein the electromagnetic radiation diverges beyond a width of the waveguide.