Device for integrating demultiplexing and optical channel monitoring
A method for integrating power monitoring capabilities with passive demultiplexing operations, utilizing the high-order diffraction from an optical diffraction grating. The technique helps avoid insertion loss and polarization dependent loss penalties, and device size penalties, typically incurred with optical taps and multiple diffraction gratings. The technique can also be modified slightly to provide information on channel wavelength and optical signal-to-noise-ratio, as well as channel power.
1. A device for integrating demultiplexing and optical channel monitoring, comprising:
a diffraction grating;
an input waveguide providing an optical input to said diffraction grating; a first set of output waveguides providing optical outputs to said diffraction grating at a predetermined order of diffraction;
a second set of output waveguides providing monitor outputs to said diffraction grating at another order of diffraction different from said predetermined order of diffraction; and
a third set of output waveguides at a further order of diffraction different from said predetermined order of diffraction and said another order of diffraction, said third set of outputs providing monitor outputs to said diffraction grating;
wherein said second set of output waveguides are positioned at channel locations, and said third set of output waveguides are positioned at between-channel locations to provide information on inter-channel noise.
2. A device as claimed in claim 1 , wherein said another order of diffraction is higher than said predetermined order of diffraction.
3. A device as claimed in claim 1 wherein said farther order of diffraction is lower than said predetermined order of diffraction.
4. A device as claimed in claim 3 , wherein said predetermined order of diffraction is order n, said another order of diffraction is order n+1, and said farther order of diffraction is order n−1.
5. A device as claimed in claim 1 , farther comprising a detector array coupled to said second set of waveguides.
6. A device as claimed in claim 5 , wherein said diffraction grating is an echelle grating.
7. A device as claimed in claim 6 , which is in the form of an integrated optical device.
8. A method of performing demultiplexing and optical channel monitoring, comprising the steps of:
directing an optical input signal containing multiple channels to a diffraction grating;
receiving reflected and diffracted signals at a first set of output waveguides providing optical outputs at a predetermined order of diffraction; and
receiving reflected and diffracted signals at a second set of output waveguides providing monitor outputs at another order of diffraction different from said predetermined order of diffraction;
wherein reflected and diffracted signals are received at a third set of output waveguides at a further order of diffraction different from said predetermined order of diffraction and said another order of diffraction, said third set of output waveguides providing monitor outputs to said diffraction grating; and
wherein said second set of output waveguides are positioned at channel locations, and said third set of output waveguides are positioned at between-channel locations to provide information on inter-channel noise.
9. A method as claimed in claim 8 , wherein said another order of diffraction is higher than said predetermined order of diffraction.
10. A method as claimed in claim 8 , wherein said further order of diffraction is lower than said predetermined order of diffraction.
11. A method as claimed in claim 10 , wherein said predetermined order of diffraction is order n, said another order of diffraction is order n+1, and said further order of diffraction is order n−1.