Spectrometer

1. A spectrometer comprising:

a substrate; and

a waveguide on the substrate, the waveguide having an elongate part and a tapered input for guiding electromagnetic radiation to the elongate part,

wherein the tapered input has an input end for receiving the electromagnetic radiation and an output end coupled to the elongate part, a width of the input end being greater than a width of the output end

wherein the width of the input end is between 1.5λ f and 2.5λ f , where λ f is a free space wavelength of the electromagnetic radiation which the waveguide is configured to receive.

2. The spectrometer of claim 1 , wherein the elongate part has substantially a same width as the width of the output end of the tapered input.

3. The spectrometer of claim 1 , wherein the elongate part and the tapered input are formed from a same material.

4. The spectrometer of claim 3 , wherein the elongate part and the tapered input are integrally formed.

5. The spectrometer of claim 1 , wherein the waveguide is configured to guide electromagnetic radiation of a plurality of wavelengths and the spectrometer comprises:

a plurality of resonators coupled to the elongate part of the waveguide, each resonator being configured to support a resonant mode at one of the plurality of wavelengths.

6. The spectrometer of claim 3 , wherein the elongate part has substantially a same width as the width of the output end of the tapered input.

7. The spectrometer of claim 6 , wherein the elongate part and the tapered input are formed from a same material.

8. The spectrometer of claim 7 , wherein the elongate part and the tapered input are integrally formed.

9. The spectrometer of claim 8 , wherein the waveguide is configured to guide electromagnetic radiation of a plurality of wavelengths and the spectrometer comprises:

a plurality of resonators coupled to the elongate part of the waveguide, each resonator being configured to support a resonant mode at one of the plurality of wavelengths.