Wavelength selective optical switch
A wavelength selective optical switch includes an incidence/emergence unit that includes an input port at which signal light made up of light of numerous wavelengths is incident and an output port at which light signals of selected wavelengths are emergent, a wavelength dispersion element that spatially disperses signal light according to a wavelength of the signal light, and synthesizes reflected light, a condenser element that condenses light dispersed by the wavelength dispersion element on a two-dimensional plane, a space phase modulator arranged so as to receive incident light deployed on an xy plane made up of an x-axis direction deployed according to wavelength and a y-axis direction orthogonal to the x-axis direction, and having numerous pixels arranged in a lattice on the xy plane, and a space phase modulator drive unit.
1. A wavelength selective optical switch comprising:
an incidence/emergence unit that includes an input port at which signal light made up of light of numerous wavelengths is incident and an output port at which light signals of selected wavelengths are emergent;
a wavelength dispersion element that spatially disperses signal light according to a wavelength of the signal light, and synthesizes reflected light;
a condenser element that condenses light dispersed by the wavelength dispersion element on a two-dimensional plane;
a space phase modulator arranged so as to receive incident light deployed on an xy plane made up of an x-axis direction deployed according to wavelength and a y-axis direction orthogonal to the x-axis direction, and having numerous pixels arranged in a lattice on the xy plane, and uses a multi-level optical phased array that periodically changes a phase shift quantity in the y-axis direction for the pixels on the x-axis in a saw tooth waveform; and
a space phase modulator drive unit that drives electrodes of the pixels arrayed in the xy axial directions of the space phase modulator, and reflects light of each wavelength respectively in a plurality of directions,
wherein the incidence/emergence unit includes a plurality of input ports and output ports, and when one output port is arranged at a position at which light entering from one input port and reflected from the space phase modulator is incident, other input ports and output ports are arranged at positions that do not correspond to high-order diffracted light thereof.
2. The wavelength selective optical switch according to claim 1 , wherein
when a 0-order diffracted light obtained by spectral reflection of light incident on the space phase modulator from one of the input ports is taken as a reference, if an angle of reflection at which the light is incident on one of the output ports is taken as θ N , then an angle of reflection θ M at which the light is incident on all the other output ports is arranged at a position such that
p·θ N +Δθ<θ M <( p+ 1)θ N −Δθ,
where p is an integer, and, if a focal length of a condenser lens is taken as f and a beam diameter of a light beam at a position of incidence on the output ports is taken as φ, Δθ is φ/2f or less.
3. The wavelength selective optical switch according to claim 2 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
4. The wavelength selective optical switch according to claim 2 , wherein
the space phase modulator is a liquid crystal element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
5. The wavelength selective optical switch according to claim 1 , wherein
when a 0-order diffracted light obtained by spectral reflection of light incident on the space phase modulator from one of the input ports is taken as a reference, if an angle of reflection at which the light is incident on one of the output ports is taken as θ N , then an angle of reflection θ M at which the light is incident on that output port from all the other input ports is arranged at a position such that
p·θ N +Δθθ M <( p+ 1)θ N −Δθ,
where p is an integer, and, if a focal length of the condenser lens is taken as f and a beam diameter of a light beam at a position of incidence on the output ports is taken as φ, Δθ is φ/2f or less.
6. The wavelength selective optical switch according to claim 5 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
7. The wavelength selective optical switch according to claim 5 , wherein
the space phase modulator is a liquid crystal element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
8. The wavelength selective optical switch according to claim 1 , wherein
when a 0-order diffracted light obtained by spectral reflection of light incident on the space phase modulator from one of the input ports is taken as a reference, if an angle of reflection at which the light is incident on one certain output port is taken as θ N , and an angle of incident light is taken as θ 0 with 0-order diffracted light as a reference, then reflected light is received whose angle of reflection at which the light is incident on all the other output ports is in a range of θ 0 /2<θ N <θ 0 .
9. The wavelength selective optical switch according to claim 8 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
10. The wavelength selective optical switch according to claim 8 , wherein
the space phase modulator is a liquid crystal element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
11. The wavelength selective optical switch according to claim 1 , wherein
when a 0-order diffracted light obtained by spectral reflection of light incident on the space phase modulator from one of the input ports is taken as a reference, if an angle of reflection at one of the output ports is taken as θ N , and an angle of incident light is taken as θ 0 with 0-order diffracted light as a reference, then reflected light is received whose angle of reflection at which the light is incident on that output port from all the other input ports is in the range of θ 0 /2<θ N <θ 0 .
12. The wavelength selective optical switch according to claim 11 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
13. The wavelength selective optical switch according to claim 1 , wherein a bidirectional spacing d between the optical fiber and a microlens is 125 μm or less.
14. The wavelength selective optical switch according to claim 1 , wherein the input ports and output ports serve as a planar lightwave circuit.
15. The wavelength selective optical switch according to claim 1 , wherein
the input ports have a plurality of microlenses and optical fibers positioned on a central axis of the respective microlenses, and
when the effective diameter of the microlenses is taken as φ and spacing of adjacent microlenses is taken as d, a lens array is arranged such that φ<d.
16. The wavelength selective optical switch according to claim 1 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
17. The wavelength selective optical switch according to claim 1 , wherein
the space phase modulator is an LCOS element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
18. The wavelength selective optical switch according to claim 1 , wherein
the space phase modulator is a liquid crystal element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.
19. The wavelength selective optical switch according to claim 1 , wherein
the space phase modulator is a liquid crystal element having numerous pixels arrayed in two dimensions, and
the space phase modulator drive unit controls the voltage applied to each pixel according to wavelength selection characteristics.