Wavelength selective switch with a 2D arrangement of optical ports
View Patent ↗A wavelength cross connect is provided in which wavelength channels are individually switchable from one of a first set of ports to one of a second set of ports. Add and drop capability is provided on the sets of ports. Some embodiments feature a single row of ports, while others feature two dimensional arrays of ports. Some embodiments employ one dispersive element per port, and others employ one dispersive element per row of ports. Embodiments featuring transmissive and non-transmissive switching elements are provided.
1. A wavelength selective switch comprising:
a two dimensional array of N×N optical ports including an input port for launching a wavelength division multiplexed (WDM) signal with a plurality of wavelength channels;
a first bulk optical element having optical power and having a first focal plane and a second focal plane;
a second bulk optical element having optical power and having third focal plane and a fourth plane, the third focal plane being substantially coplanar with said second focal plane;
a dispersive element substantially in the fourth focal plane for dispersing the WDM signal in a dispersion plane; and
an array of switching elements substantially in the third focal plane, each switching element tiltable in both the dispersion plane and a plane perpendicular to the dispersion plane for selectively redirecting wavelength channels both in the dispersion plane and in planes perpendicular to the dispersion plane to alternate locations on the dispersive element;
wherein each wavelength of the WDM signal entering at one of said array of optical ports is individually switchable to any of the optical ports through appropriate control of the array of switching elements via the dispersive element.
2. A wavelength selective switch according to claim 1 wherein the switching elements are MEMS switching elements.
3. A wavelength selective switch according to claim 1 wherein the switching elements are transmissive.
4. A wavelength selective switch according to claim 1 wherein the first bulk optical element is selected from a group consisting of a lens, a curved mirror, an assembly of lenses and mirrors, and an assembly of lenses, mirrors and a curved mirror.
5. A wavelength selective switch according to claim 1 wherein the second bulk optical element is selected from a group consisting of a lens, a curved mirror, an assembly of lenses and mirrors, and an assembly of lenses, mirrors and a curved mirror.
6. A wavelength selective switch according to claim 1 , wherein the dispersive element is selected from a group consisting of: a reflective diffraction grating, a transmissive diffraction grating, and prisms.
7. An optical wavelength switch comprising:
a telescope arrangement comprising a coupling lens and a main lens, the main lens having a first focal plane substantially coinciding with a focal plane of the coupling lens;
a two dimensional array of optical ports optically coupled to the coupling lens, the two dimensional array of optical ports having a first port for launching an input optical signal and a plurality of second ports arranged in a square;
a dispersive element disposed substantially in a second focal plane of the main lens for dispersing the input optical signal in a dispersion plane; and
an array of switching elements disposed substantially in the first focal plane, each switching element tiltable in both the dispersion plane and a plane perpendicular to the dispersion plane;
wherein the ports, the telescope arrangement, the dispersive elements, and the switching elements being arranged such that:
a) a multi-wavelength signal entering at the first port propagates through the telescope arrangement to the dispersive element where the multi-wavelength signal is demultiplexed into a plurality of wavelength channels;
b) each wavelength channel after demultiplexing propagates through the main lens to a respective switching element of the plurality of switching elements; and
c) each switching element is individually controllable to reflect the wavelength channel to a selected one of the second ports via a path comprising in sequence the main lens, the dispersive element, the main lens, and the coupling lens.
8. The optical wavelength switch of claim 7 wherein the two dimensional array of optical ports, the coupling lens, the main lens, and the dispersive element are all disposed in a substantially co-axial manner.
9. The optical wavelength switch of claim 7 wherein the dispersive element is a reflective diffraction grating.
10. The optical wavelength switch of claim 7 wherein the array of switching elements is an array of MEMS switching elements.
11. The optical wavelength switch of claim 7 wherein the two dimensional array of ports is arranged in a square, and the first port is in the middle of the square.
12. The optical wavelength switch of claim 7 wherein the switch is further adapted to allow any wavelength channel to be switched back to the first port, the switch further comprising: a circulator external to the first port that allows the multi-wavelength signal to enter the first port, and also allows optical wavelength channels to be switched to the first port without interfering with the multi-wavelength signal.