Free-space/arrayed-waveguide router

• US 6,263,127 B1
• Filed: 05/13/1999
• Issued: 07/17/2001
• Est. Priority Date: 05/13/1999
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Dragone, Corrado Pietro, Ford, Joseph Earl
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/311,544
• Time in Patent Office: 796 Days
• Field of Search: 385/24, 385/15, 385/37, 385/16, 385/17, 385/27, 385/33, 385/36, 385/46, 385/14, 385/11, 385/34
• US Class Current: 385/24
• 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
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/29313 characterised by means for controlling the position or direction of light incident to or leaving the diffractive element, e.g. for varying the wavelength response switching G02B6/35
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0022 using fibre gratings
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: H04Q 2011/0032 using static wavelength routers (e.g. arrayed waveguide grating router [AWGR] )

Abstract

A router combines free-space and guided wave optics to drastically increase the number of channels used in WDM transmission systems. The two-stage router uses the partial demultiplexing characteristic of an arrayed waveguide router (AWR) combined with a free-space optical router to fully demultiplex an input WDM signal. The two-stage router can be used to obtain output wavelength signals in either one- or two-dimensional arrays.

Claims

1. An optical apparatus comprising

an optical arrayed waveguide router (AWR) for receiving at an input wavelength division multiplexed (WDM) signal having M wavelength channels, M>

1, and a one dimensional array of N outputs, 1<

N<

M, for outputting the WDM signal within the free spectral range (FSR) of the AWR, each output n, where 1≦

n≦

N, including a partially demultiplexed signal having a plurity of wavelength channels n, n +N, n+2N, . . . n+{M/N−

1}N of the WDM signal, and

a free-space optical wavelength channel demultiplexer for receiving each of the partially demultiplexed signal channels and for producing therefrom M wavelength channels, each of the M wavelength channels being outputted at a different one of M outputs.

2. The apparatus of claim 1 wherein the free-space optical wavelength channel demultiplexer includes

a first lens for collimating the partially demultiplexed signal channels from the one-dimensional array of N outputs onto a grating;

said grating being a transmissive grating for demultiplexing each of the one-dimensional array of partially demultiplexed signals into individual wavelength channels so as to form a two-dimensional array of wavelength channels;

a second lens for focusing the two-dimensional array of wavelength channels onto a two-dimensional array of elements.

3. The apparatus of claim 2 wherein the two-dimensional array of elements is a two-dimensional array of mirror elements, one or more mirror elements being individually controlled to reflect one of the two-dimensional array of wavelength channels back through the second lens, the transmissive grating, the first lens to said AWR when a first control signal is applied to said one or more mirror elements.

4. The apparatus of claim 3 wherein when a second control signal is applied to a mirror element that mirror element reflects its wavelength channels back through

a third lens for focusing the reflected wavelength channel onto a second grating;

said second grating being a transmissive grating for multiplexing together into a combined signal each reflected wavelength channel which originated from the same partially demultiplexed signal;

a fourth lens for focusing the combined signal onto a second AWR.

5. The apparatus of claim 4 further including

a first circulator for coupling signals to and from the AWR and

a second circulator for coupling signals to and from the second AWR.

6. The apparatus of claim 5 wherein the AWR and the second AWR each include

an input waveguide for receiving the WDM signal, a first free space region connected to both the input waveguide and to a first end of a set of chirped waveguides, a second free space region connected to both a second end of the chirped waveguides and to a set of N output waveguides which terminate in a one-dimensional array of N outputs.

7. The apparatus of claim 5 where the one-dimensional array of elements includes a one-dimensional array of optical fibers.

8. The apparatus of claim 5 where the one-dimensional array of elements is a one-dimensional waveguide array formed together with the AWR on a waveguide unit.

9. The apparatus of claim 3 further including

a first circulator for coupling signals to and from the AWR.

10. The apparatus of claim 1 wherein the free-space optical wavelength channel demultiplexer includes

a first lens for focusing the partially demultiplexed signal channels from the one-dimensional array of N outputs onto a grating;

said grating being a reflective grating for demultiplexing each of the one-dimensional array of partially demultiplexed signals into individual wavelength channels so as to form a one-dimensional array of wavelength channels;

said lens focusing the one-dimensional array of wavelength channels onto a one-dimensional array of elements.

11. The apparatus of claim 1 wherein the M outputs are arranged in a one-dimensional array.

12. The apparatus of claim 1 wherein the M outputs are arranged in a two-dimensional array.

13. An optical apparatus comprising

a planar optical arrayed waveguide router (AWR) for receiving an input wavelength division multiplexed (WDM) signal having M wavelength channels, M>

1, and an output,

a lens for collimating a signal from the AWR output onto a free-space optical wavelength channel demultiplexer, and

the free-space optical wavelength channel demultiplexer being oriented in a different plane than the AWR, for receiving the collimated output from the lens and for producing therefrom M wavelength channels, each of the M wavelength channels being outputted at a different one of M outputs.

14. The optical apparatus of claim 13 wherein the AWR includes

an input waveguide for receiving the WDM signal,

a first free space region connected to both the input waveguide and to a first end of a set of chirped waveguides,

a first side of a second free space region connected to a second end of the chirped waveguides, and

a second side of the second free space region being formed having a straight line edge to serve as the output of the AWR.