Wavelength dispersing device

Patent metadata

Field	Value
Publication number	US-10061083-B2
Application number	US-201615167459-A
Country	US
Kind code	B2
Filing date	May 27, 2016
Priority date	May 2, 2008
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A compact wavelength dispersing device and a wavelength selective optical switch based on the wavelength dispersing device is described. The wavelength dispersing device has a folding mirror that folds the optical path at least three times. A focal length of a focusing coupler of the device is reduced and the NA is increased, while the increased optical aberrations are mitigated by using an optional coma-compensating wedge. A double-pass arrangement for a transmission diffraction grating allows further focal length and overall size reduction due to increased angular dispersion.

First claim

What is claimed is:

1. A wavelength dispersing device comprising:
an input for inputting a light beam;
an aberration correction element for receiving the light beam and performing pre-correction for aberration;
a mirror for receiving the pre-corrected light beam and reflecting the pre-corrected light beam at a first point in time;
a diffraction grating for producing narrowband sub-beams; and
a reflector for receiving the narrowband sub-beams;
the narrowband sub-beams being reflected by the mirror at a second point in time,
the aberration correction element receiving the reflected narrowband sub-beams, performing aberration correction on the reflected narrowband sub-beams, and transmitting the aberration-corrected, reflected narrowband sub-beams to a line of dispersion, and
the aberration correction element having a wedge angle to apply coma compensation to the light beam and the reflected narrowband sub-beams to compensate for coma caused, at least in part, by the reflection of the pre-corrected light beam by the mirror.

2. The wavelength dispersing device of claim 1 , where the reflector and the diffraction grating produce an angular dispersion of the narrowband sub-beams.

3. The wavelength dispersing device of claim 1 , where
each narrowband sub-beam, of the narrowband sub-beams, is associated with a focal spot, and
each focal spot is located on the line of dispersion.

4. The wavelength dispersing device of claim 1 , where the mirror is a concave mirror.

5. The wavelength dispersing device of claim 1 , where the aberration correction element is a wedge.

6. The wavelength dispersing device of claim 5 , where the wedge is oriented at a minimum deviation angle for the narrowband sub-beams.

7. The wavelength dispersing device of claim 1 , where the coma is further caused by off-axis reflections of the pre-corrected light beam.

8. The wavelength dispersing device of claim 1 , where the coma is further caused by off-axis reflections of the pre-corrected light beam and the narrowband sub-beams from the mirror.

9. The wavelength dispersing device of claim 1 , where an array of directors are disposed along the line of dispersion.

10. A method comprising:
inputting, at an input, a light beam;
performing, by an aberration correction element, pre-correction for aberration on the light beam;
receiving, by a mirror, the pre-corrected light beam and reflecting the pre-corrected light beam at a first point in time;
producing, by a diffraction grating and based on received the reflected light beam, narrowband sub-beams;
the narrowband sub-beams being reflected by the mirror at a second point in time;

receiving, by the aberration correction element, the reflected narrowband sub-beams;
performing, by the aberration correction element, aberration correction on the reflected narrowband sub-beams,
the aberration correction element having a wedge angle to apply coma compensation to the light beam and the reflected narrowband sub-beams to compensate for coma caused, at least in part, by the reflection of the pre-corrected light beam by the mirror; and

transmitting, by the aberration correction element, the aberration-corrected, reflected narrowband sub-beams to a line of dispersion.

11. The method of claim 10 , further comprising:
producing, by a reflector and the diffraction grating, an angular dispersion of the narrowband sub-beams.

12. The method of claim 10 , where
each narrowband sub-beam, of the narrowband sub-beams, is associated with a focal spot, and
each focal spot is located on the line of dispersion.

13. The method of claim 10 , where the mirror is a concave mirror.

14. The method of claim 10 , where the aberration correction element is a wedge.

15. The method of claim 14 , where the wedge is oriented at a minimum deviation angle for the narrowband sub-beams.

16. The method of claim 10 , where the coma is further caused by off-axis reflections of the pre-corrected light beam.

17. The method of claim 10 , where the coma is further caused by off-axis reflections of the pre-corrected light beam and the narrowband sub-beams from the mirror.

18. The method of claim 10 , where an array of directors are disposed along the line of dispersion.

Assignees

• Lumentum Operations Llc

Inventors

• Mclaughlin Sheldon

Classifications

• G01J3/22

  Littrow mirror spectrometers · CPC title

• G01J3/0291

  Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements · CPC title

• G02B6/354

  Switching arrangements, i.e. number of input/output ports and interconnection types · CPC title

• G01J3/021

  using plane or convex mirrors, parallel phase plates, or particular reflectors · CPC title

• G02B17/0856

  comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors · CPC title