Method and apparatus for wavelength-selective switches and modulators

• US 20070140618A1
• Filed: 10/06/2005
• Published: 06/21/2007
• Est. Priority Date: 10/06/2005
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Doerr, Christopher, Marom, Dan
• Granted Patent: US 7,376,311 B2
• Time in Patent Office: Days
• US Class Current: 385/37
• CPC Class Codes: G02B 6/12011 characterised by the arrayed waveguides, e.g. comprising a filled groove in the array section
• CPC Class Codes: G02B 6/12019 characterised by the optical interconnection to or from the AWG devices, e.g. integration or coupling with lasers or photodiodes coupling integrated waveguide to fibre G02B6/30, to optoelectronic element G02B6/42; monolithic integration of integrated waveguides with other optical elements G02B6/12004

Abstract

An apparatus and method are provided for manipulating light beams propagated through an optical apparatus that includes a planar lightwave circuit (PLC) and free-space optics unit. A multi-wave optical signal coupled to the PLC is propagated through a first and second waveguide array to generate a phased array output at an edge facet of the PLC. The phased array output at the edge facet is spatially Fourier transformed by the lens to generate a spectrally resolved image having a discrete light spot for each channel of the input optical signal, which is coupled to a pixelated optical receiving unit. When the optical receiving unit is a reflector, one or more of the discrete light spot are reflected to a desired waveguide array of a PLC to produce a desired output. When the optical receiving unit is a pixelated transmissive modulator, one or more of the discrete light spot are modulated as they pass through the modulator.

Claims

1. An optical apparatus for receiving a multi-wave input optical signal comprising:

a first planar lightwave circuit (PLC) including;

an input/output waveguide,

a first waveguide array having a first waveguide coupler, a second waveguide coupler and at least two waveguides optically connecting the first and second couplers, wherein the first coupler is directly coupled to the input/output wave guide, and

wherein said array exhibits a free-spectral range equal to the channel separation of the input optical signal, the first waveguide array introducing a first dispersion into the input optical signal,

a second waveguide array including an input waveguide coupler, wherein the input coupler is directly coupled to the second coupler of the first waveguide array, and

wherein the second waveguide array has a plurality of waveguides terminating at an edge facet of the PLC and exhibits a free-spectral range equal to all of the channels of the input optical signal and produces a second dispersion into the input optical signal which adds to the first dispersion;

a lens adjacent to the PLC; and

an optical receiving unit adjacent to the lens;

wherein the edge facet of the PLC and the optical receiving unit are respectively positioned at a front focal plane and a back focal plane of the lens such that an input optical signal is propagated through the PLC to generate a phased array output at the edge facet of the PLC, the phased array output is spatially Fourier transformed by the lens to generate a spectrally resolved image having a discrete or somewhat discrete light spot for each channel or band of channels of the input optical signal which is coupled to the optical receiving unit.

2. The apparatus of claim 1, wherein the optical receiving unit is a reflector device including a micromirror array for selectively reflecting one or more discrete light spots.

3. The apparatus of claim 1, wherein the optical receiving unit is a liquid crystal modulator array to modulate the reflection of selected one or more discrete light spots.

4. The apparatus of claim 1, wherein the optical output device is a pixelated modulator to modulate the transmission of selected one or more discrete light spots through the modulator.

5. The apparatus of claim 1, wherein the first waveguide array is a Mach-Zehnder interferometer.

6. The apparatus of claim 1, wherein the first waveguide array is a waveguide grating router.

7. The optical switching apparatus of claim 2, further comprising

at least one additional PLC arranged in a stacked configuration with the first PLC;

each additional PLC including an input/output waveguide and a first waveguide array coupled to the input/output waveguide, the first waveguide array having at least two waveguides and having a free-spectral range equal to the channel separation, the first waveguide array coupled to a second waveguide array having a plurality of waveguides terminating at an edge facet of the PLC and having a free-spectral range equal to the bandwidth of the multiple channels of the input optical signal and

wherein the reflector device is a tilting micromirror array for selecting reflecting one or more discrete light spots of the input optical signal to provide wavelength-selective switching of the input optical signal through the first PLC through one of the at least one additional PLC.

8. The optical switching apparatus of claim 1 further comprising

at least one additional PLC arranged in a side-by-side planar configuration with the first PLC;

each additional PLC including an input/output waveguide and a first waveguide array coupled to the input/output waveguide, the first waveguide array having at least two waveguides and having a free-spectral range equal to the channel separation, the first waveguide array coupled to a second waveguide array having a plurality of waveguides terminating at an edge facet of the PLC and having a free-spectral range to or greater than all of the channels of the input optical signal and

wherein the reflector device is a tilting micromirror array for selectively reflecting selected one or more discrete light spots of the input optical signal to provide wavelength-selective switching of the input optical signal through the first PLC through to one of the at least one additional PLC.

9. A method for optical switching comprising the steps of:

receiving a multi-wavelength light signal into an input/output waveguide of a wavelength selective switch;

coupling the light beam into a first waveguide array having a free-spectral range equal to the channel separation of the multi-wavelength light signal wherein said first waveguide array including a first waveguide coupler, a second waveguide coupler and at least two waveguides optically connecting the first coupler to the second coupler and introduces a first dispersion into the multi-wave light signal;

coupling the light beam output directly from the second coupler of the first waveguide array to an input waveguide coupler included in a second waveguide array having a free-spectral range equal to or greater than all of the channels of the multi-wave light signal and that introduces a second dispersion into the multi-wave light signal which periodically cancels the first dispersion, the second waveguide array terminates at an edge facet and generates a phased array output; and

spatially Fourier transforming the phased array output using one or more lenses to generate a spectrally resolved image having a discrete light spot for each channel of the multi-wave light signal.