Optical multiplexer
The invention provides an optical multiplexing device comprising: a plurality of optical sources with integrated collimators ( 31 - 37 ) whose output beams are combined by mirrors ( 41 - 47 ) or other beam deflecting elements, which combine the beams into a single composite beam diverging from a common origin point ( 30 ). This is done by arranging the mirrors ( 41 - 47 ) staggered at different distances from the origin point, and at different angles to each other taking accourt of the dependence of the beam divergence in far field on the distance from the origin point.
1. A multiplexed optical source device comprising:
a plurality of n optical sources that output respective beams with asymmetric spatial distributions;
a plurality of n collimators arranged adjacent to respective ones of the optical sources so as to collimate their output beams; and
at least n-1 beam deflectors, each associated with one of the optical sources, and arranged so as to deflect the respective beams so that after deflection the deflected beams do not overlap and do not block deflected beams from other ones of the beam deflectors, and so that the beams are spatially multiplexed in the far field to form a single composite beam diverging from an imaginary common origin point thereby avoiding loss of power and spectral brightness during the beam combining.
2. The device of claim 1 , wherein the at least n- 1 beam deflectors are positioned at distance z from the origin point that are in farfield, far-field being defined as z>n ω 2 0 /λ, where 2ω 0 is the beam waist diameter and λ is the operating wavelength.
3. The device of claim 2 , wherein the at least n- 1 beam deflectors are arranged at an angle that takes account of the z dependence of the angle of beam divergence.
4. The device of claim 2 , wherein there are a plurality of beam deflectors, and the beam deflectors are arranged staggered at different distances z from the origin point, and at different angles to each other taking account of the z dependence of the angle of beam divergence.
5. The device of claim 1 , wherein the collimated output beams are at an angle to each other prior to deflection.
6. The device of claim 1 , wherein the collimators are single optical elements.
7. The device of claim 1 , wherein the collimators are cemented to their respective optical sources.
8. The device of claim 1 , wherein the collimators are arranged to achieve minimum beam divergence in far field.
9. The device of claim 1 , wherein the collimators are arranged so that their beam waists are formed on output facets of the optical sources, or within the optical sources.
10. The device of claim 1 , wherein the output beams have a fast axis and a slow axis, and the collimators are arranged to collimate the output beams along their fast axes.
11. The device of claim 1 , wherein the optical sources are lasers.
12. The device of claim 11 , wherein the lasers are diode lasers.
13. The device of claim 1 , wherein the beam deflectors are mirrors.
14. The device of claim 1 , wherein the beam deflectors are prisms.
15. The device of claim 1 , wherein n is in the range 2-10.
16. The device of claim 1 , wherein n is in the range 3-8.
17. The device of claim 1 , further comprising a focusing element arranged to focus the combined beam to a coupling region for coupling into an external component.
18. The device of claim 1 , further comprising a waveguide having an entrance aperture positioned to receive the combined beam.
19. The device of claim 18 , wherein the entrance aperture is arranged at the coupling region.
20. The device of claim 18 , wherein the waveguide is an optical fibre.
21. The device of claim 18 , wherein the waveguide is a planar waveguide.