System for integrated photonic notch filter
A notch filter circuit includes a wavelength demultiplexer, a first pump rejection filter coupled to the wavelength demultiplexer, and a second pump rejection filter coupled to the wavelength demultiplexer. The notch filter circuit also includes a first notch filter arm coupled to the first pump rejection filter and including a first chain of asymmetric Mach-Zehnder interferometers (MZIs) and a second notch filter arm coupled to the second pump rejection filter and including a second chain of asymmetric MZIs.
1 . A notch filter circuit comprising:
a wavelength demultiplexer;
a first pump rejection filter coupled to the wavelength demultiplexer;
a second pump rejection filter coupled to the wavelength demultiplexer;
a first notch filter arm coupled to the first pump rejection filter and including a first chain of asymmetric Mach-Zehnder interferometers (MZIs); and
a second notch filter arm coupled to the second pump rejection filter and including a second chain of asymmetric MZIs.
2 . The notch filter circuit of claim 1 wherein the first pump rejection filter comprises:
a first spectral filter including a series of directional couplers; and
a second spectral filter optically coupled to the first spectral filter.
3 . The notch filter circuit of claim 2 wherein the first chain of asymmetric MZIs is optically coupled to the second spectral filter.
4 . The notch filter circuit of claim 2 wherein the series of directional couplers comprises a set of 1×2 directional couplers.
5 . The notch filter circuit of claim 4 wherein:
the first spectral filter includes two 1×2 directional couplers; and
the second spectral filter includes three 1×2 directional couplers.
6 . The notch filter circuit of claim 2 wherein the first notch filter arm further comprises a ring notch filter.
7 . The notch filter circuit of claim 1 wherein each of the asymmetric MZIs in the first chain of asymmetric MZIs is characterized by a free spectral range different from the free spectral range of others of the asymmetric MZIs in the first chain of asymmetric MZIs.
8 . The notch filter circuit of claim 7 wherein the free spectral range characterizing each of the asymmetric MZIs in the first chain of asymmetric MZIs decreases monotonically from a first asymmetric MZI of the asymmetric MZIs in the first chain of asymmetric MZIs to a last asymmetric MZI of the asymmetric MZIs in the first chain of asymmetric MZIs.
9 . The notch filter circuit of claim 1 wherein each of the asymmetric MZIs in the first chain of asymmetric MZIs is joined to adjacent asymmetric MZIs of the asymmetric MZIs in the first chain of asymmetric MZIs using a set of dispersive couplers.
10 . The notch filter circuit of claim 9 wherein a length of a first plurality of the set of dispersive couplers is equal to π/4Δβ and wherein a length of a second plurality of the set of dispersive couplers is equal to 5π/4Δβ, wherein Δβ is a waveguide dispersion of each of the dispersive couplers.
11 . The notch filter circuit of claim 1 wherein the second pump rejection filter comprises:
a first spectral filter including a series of directional couplers; and
a second spectral filter optically coupled to the first spectral filter.
12 . The notch filter circuit of claim 11 wherein the second chain of asymmetric MZIs is optically coupled to the second spectral filter.
13 . The notch filter circuit of claim 11 wherein the series of directional couplers comprises a set of 1×2 directional couplers.
14 . The notch filter circuit of claim 13 wherein:
the first spectral filter includes three 1×2 directional couplers; and
the second spectral filter includes three 1×2 directional couplers.
15 . The notch filter circuit of claim 11 wherein the second notch filter arm further comprises a ring notch filter.
16 . The notch filter circuit of claim 11 wherein each of the asymmetric MZIs in the second chain of asymmetric MZIs is characterized by a free spectral range different from the free spectral range of others of the asymmetric MZIs in the second chain of asymmetric MZIs.
17 . The notch filter circuit of claim 16 wherein the free spectral range characterizing each of the asymmetric MZIs in the second chain of asymmetric MZIs decreases monotonically from a first asymmetric MZI of the asymmetric MZIs in the second chain of asymmetric MZIs to a last asymmetric MZI of the asymmetric MZIs in the second chain of asymmetric MZIs.
18 . The notch filter circuit of claim 11 wherein each of the asymmetric MZIs in the second chain of asymmetric MZIs is joined to adjacent asymmetric MZIs of the asymmetric MZIs in the second chain of asymmetric MZIs using a set of dispersive couplers.
19 . The notch filter circuit of claim 18 wherein a length of a first plurality of the set of dispersive couplers is equal to π/4Δβ, wherein Δβ is a waveguide dispersion of the each of the dispersive couplers.
20 . The notch filter circuit of claim 19 wherein a length of a second plurality of the set of dispersive couplers is equal to 5π/4Δβ, wherein Δβ is a waveguide dispersion of each of the dispersive couplers.