Patent US4933649A successfully refreshed from Google Patents.
US4933649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coherent aperture filling of an array of lasers
Assignee: Massachusetts Institute of Technology
•
Filing: 1986-10-17
•
Granted: 1990-06-12
•
Expires: 2006-10-17
Abstract
Abstract A technique for coherent aperture filling by amplitude phase exchange is described which suppresses the far field side lobes of an array of lasers. The power contained in these side lobes is transferred to the central lobe so that it contains greater than 90% of the total array power. This is achieved by a field transformation which generates from the uniform phase and varying amplitude distribution of the input array a varying phase modulation with nearly uniform, i.e., aperture filled, amplitude distribution in the output beam. Far-field grating lobes from the nonuniformity in phase are then suppressed by an additional phase correcting element matched to compensate the phase modulation. In a preferred embodiment, the field transformation element, including a single step binary phase shifter flanked by a pair of lenses in an a focal imaging configuration, is followed by a binary phase grating for phase compensation.
Inventors
- 👤 Gary J. Swanson
- 👤 James R. Leger
- 👤 Michael K. O. Holz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:06
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/42; G02B6/4201; G02B6/4249; G02B6/425; G02B27/00; G02B27/58; H; H01; H01S; H01S5/00; H01S5/40; H01S5/4025; H01S5/4031; H01S5/4062; H01S5/4081
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
76 words
Apparatus for suppressing the far-field side lobes of an array of lasers comprising: field transformation means for phase modulating light from the array of lasers to produce an aperture filled amplitude distribution; and phase grating means matched to the phase of the light emanating from the field transformation means to compensate for the phase modulation to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
Claim 2
Dependent Claim
76 words
Apparatus for suppressing the far-field side lobes of an array of lasers comprising: field transformation means for phase modulating light from the array of lasers to produce an aperture filled amplitude distribution; and phase grating means matched to the phase of the light emanating from the field transformation means to compensate for the phase modulation to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
Claim 3
Dependent Claim
35 words
The apparatus of claim 1 wherein the array of lasers are used as an array of gain elements to form an external cavity, the cavity being a single, multiple-arm, cavity with one common output mirror.
Claim 4
Dependent Claim
33 words
The apparatus of claim 1 wherein the array of lasers form an external cavity, the cavity configured as two, multiple-arm, cavities with individual intermediate output mirrors followed by a second common feedback mirror.
Claim 5
Dependent Claim
26 words
The apparatus of claim 1 wherein the field transformation means phase shifts the central diffraction lobe (DC component) of the light from the array of lasers.
Claim 6
Dependent Claim
17 words
The apparatus of claim 1 wherein the field transformation means includes a single step binary phase shifter.
Claim 7
Dependent Claim
25 words
The apparatus of claim 5 wherein the transverse step size of the binary phase shifter is less than the size of the central diffraction lobe.
Claim 8
Dependent Claim
23 words
The apparatus of claim 5 wherein the step size of the phase shifter is approximately one-half the size of the central diffraction lobe.
Claim 9
Dependent Claim
15 words
The apparatus of claim 1 wherein the field transformation means includes a non-binary phase shifter.
Claim 10
Dependent Claim
21 words
The apparatus of claim 5 or 8 further including a pair of lenses flanking the phase shifter in an afocal configuration.
Claim 11
Dependent Claim
14 words
The apparatus of claim 1 wherein the compensating means is a binary phase grating.
Claim 12
Dependent Claim
14 words
The apparatus of claim 1 wherein the compensating means is a non-binary phase grating.
Claim 13
Independent Claim
30 words
The apparatus of claims 1, or 2, or 3 wherein the field transformation means and the means for the phase modulation are either transmissive or reflective or any combination thereof.
Claim 14
Dependent Claim
18 words
The apparatus of claim 1 wherein the array of lasers has a fill factor greater than twenty-five percent.
Claim 15
Dependent Claim
26 words
The apparatus of claim 1 wherein the fill factor of the array of lasers is greater than ten percent and further including a second transformation stage.
Claim 16
Dependent Claim
20 words
The apparatus of claim 1 including a preprocessing stage consisting of a lens array system for collimating the array output.
Claim 17
Dependent Claim
39 words
The apparatus of claim 4 wherein the means of phase shifting the DC central lobe is restricted to an area less than the size of the central lobe to modify the light distribution in the resultant far-field central field.
Claim 18
Dependent Claim
85 words
Apparatus for suppressing the far-field side lobes of a coupled array of lasers comprising: a single step binary phase shifter flanked by pair of lenses in an afocal configuration for DC phase shifting light from the coupled array of lasers; and a binary phase grating for receiving light from the phase shifter matched to the phase of light emanating from the phase shifter thereby to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
Claim 19
Dependent Claim
85 words
Apparatus for suppressing the far-field side lobes of a coupled array of lasers comprising: a single step binary phase shifter flanked by pair of lenses in an afocal configuration for DC phase shifting light from the coupled array of lasers; and a binary phase grating for receiving light from the phase shifter matched to the phase of light emanating from the phase shifter thereby to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
Claim 20
Dependent Claim
15 words
The apparatus of claim 1 wherein the array of lasers generates light having uniform phase.
Claim 21
Dependent Claim
15 words
The apparatus of claim 1 wherein the lasers in the array of lasers are coupled.
Claim 22
Dependent Claim
13 words
The apparatus of claim 1 wherein the compensating means is a continuous grating.
Claim 23
Dependent Claim
17 words
The apparatus of claim 1 wherein the compensating means is a multi-step approximation to a continuous grating.
Claim 24
Dependent Claim
20 words
The apparatus of claim 1 wherein the array of lasers is a phased laser array having an angularly steerable beam.
Claim 25
Dependent Claim
80 words
Apparatus for suppressing the far-field side lobes of an array of lasers comprising repeatedly applied stages, each stage including: field transformation means for phase modulating light from a preceding stage to produce an aperture filled amplitude distribution; and phase grating means matched to the phase of light emanating from the field transformation means to compensate for the phase modulation to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
Claim 26
Dependent Claim
80 words
Apparatus for suppressing the far-field side lobes of an array of lasers comprising repeatedly applied stages, each stage including: field transformation means for phase modulating light from a preceding stage to produce an aperture filled amplitude distribution; and phase grating means matched to the phase of light emanating from the field transformation means to compensate for the phase modulation to suppress the side lobes thereby to concentrate substantially all the light from the array of lasers into a central lobe.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |