EP0136871A2
Expired / Lapsed
EP
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Fiber optic amplifier
Assignee: Leland Stanford Junior University
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Filing: 1984-09-20
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Granted: —
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Expires: 2004-09-20
Abstract
Abstract @ A pair of small diameter optical fibers (12, 14) are arranged in a side-by-side configuration, the first fiber (12) providing a passive guide for pump light, and the second fiber (14) formed of a material, such as Nd:YAG which has amplifying properties at the signal frequency. The signal to be amplified propagates through the second fiber (14) resulting in amplification of the signal. The first fiber (12) is pumped from one or both ends, utilizing a cone shaped rod (50) which is optically coupled thereto. A plurality of pump light sources (60) are mounted on the end face (58) of the rod (50) to introduce collimated pump light into the large end (52) of the cone shaped rod (50). Total internal reflections on the cone walls compress the pump light to a small, fiber-size diameter end (54) for propagation through the pump fiber (12) and absorption by the active fiber (14). The pump light sources (60) are offset from the axis (72) of the rod (50) to excite high order modes in the pump fiber (12) to enhance absorption by the active fiber (14). The pump light sources (60) preferably comprise high power laser diodes (64) and collimating microlenses (62). By utilizing the cone-shaped rod (50) to couple light from the high power laser diodes (64) to the pump fiber (12), high pump power densities can be achieved, yielding increased amplification.
Inventors
- 👤 Herbert John Shaw
- 👤 Michel J.F. Digonnet
- 👤 Robert A. Lacy
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 18:14
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; H; H01; H01S; H01S3/00; H01S3/09; H01S3/091; H01S3/094; H01S3/094003; H01S3/094011; H01S3/094019; H01S3/094069
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
216 words
A fiber optic amplifier, characterized by: a first fiber (12) having a first refractive index; a second fiber (14), formed of a laser material, having a second refractive index higher than said first refractive index, said fibers (12, 14) positioned in close proximity to form an interaction region (16) for transferring light from said first fiber (12) to said second fiber (14); a cone shaped rod (50), comprising: a first fiber sized end (54) for introducing light into one end of said first fiber (12); a second end (52) having a diameter substantially larger than said first end (54); a plurality of pump light sources (60), mounted to introduce pump light into said second end (52), said cone shaped rod focusing the pump light from said second end (52) to said first fiber sized end (54) for introduction into said first fiber (12) and .for propagation through said first fiber (12) to the interaction region (16) to pump said second fiber (14) and cause an electronic population inversion in said laser material; and said plurality of pump light sources (60) offset from the axis (72) of said cone shape rod (50) to excite high order modes in said first fiber (12) to enhance absorption of the pump light by said laser material of second fiber (14).
Claim 2
Dependent Claim
216 words
A fiber optic amplifier, characterized by: a first fiber (12) having a first refractive index; a second fiber (14), formed of a laser material, having a second refractive index higher than said first refractive index, said fibers (12, 14) positioned in close proximity to form an interaction region (16) for transferring light from said first fiber (12) to said second fiber (14); a cone shaped rod (50), comprising: a first fiber sized end (54) for introducing light into one end of said first fiber (12); a second end (52) having a diameter substantially larger than said first end (54); a plurality of pump light sources (60), mounted to introduce pump light into said second end (52), said cone shaped rod focusing the pump light from said second end (52) to said first fiber sized end (54) for introduction into said first fiber (12) and .for propagation through said first fiber (12) to the interaction region (16) to pump said second fiber (14) and cause an electronic population inversion in said laser material; and said plurality of pump light sources (60) offset from the axis (72) of said cone shape rod (50) to excite high order modes in said first fiber (12) to enhance absorption of the pump light by said laser material of second fiber (14).
Claim 3
Dependent Claim
30 words
A fiber optic amplifier, as defined in claim 1, further characterized in that said cone shaped rod (50) and said first fiber (12) are integrally formed from the same material.
Claim 4
Dependent Claim
48 words
A fiber optic amplifier, as defined in claim 1, further characterized in that said first fiber (12) and said second fiber (14) each include respective planar surfaces (34, 36) along at least a portion of their length, said planar surfaces (34, 36) juxtaposed to form the interaction region.
Claim 5
Dependent Claim
21 words
A fiber optic amplifier, as defined by claim 1, further characterized in that said light sources (60) produce substantially collimated light.
Claim 6
Dependent Claim
38 words
A fiber optic amplifier, as defined in claim 4, further characterized in that said light sources (60) comprise: a laser diode (64); and a collimating microlens (62), disposed between said laser diode (64) and said second end (52).
Claim 7
Dependent Claim
140 words
A fiber optic amplifier, as defined in claim 2, additionally characterized by: a second cone shaped rod (50), comprising: a first fiber sized end (54), for introducing light into the other end of said first fiber (12); a second end (52), having a diameter substantially larger than said first end (54) of said second rod (50); and a plurality of second pump light sources (60) for introducing pump light into said second end (52) of said second rod (50), said second cone shaped rod (50) focusing said light into said first fiber sized end (54) of said second rod (50) for introduction into said other end of said first fiber (12) and for propagation through said first fiber (12) to the interaction region (16) to pump said second fiber (14) and cause an electronic population inversion in said laser material.
Claim 8
Dependent Claim
42 words
A fiber optic amplifier, as defined in claim 5, further characterized in that said laser diode (6-4) is oriented such that its lengthwise dimension is normal to a radial line. (80) passing through the axis (72) of said cone shaped rod (50).
Claim 9
Dependent Claim
30 words
A fiber optic amplifier, as defined in claim 1, further characterized in that said rod (50) is comprised of glass and said second optical fiber (14) is comprised of Nd:YAG.
Claim 10
Dependent Claim
35 words
A fiber optic amplifier, as defined in claim 5, further characterized in that the length of the emitting area of said laser diode (64) is no greater than the radius of said first fiber (12).
Claim 11
Independent Claim
88 words
A method of pumping an optical fiber, formed of laser material, said method characterized by: supplying pump light to one end (52) of a cone shaped rod (50) by mounting plural light sources (60) at respective locations removed from the central axis (72) of said cone shaped rod (50) to excite high order modes at the other end (54) of said cone shaped rod (50); and optically coupling the other end (50) of said cone shaped rod (50) to pump the laser material of said optical fiber (14).
Claim 12
Independent Claim
88 words
A method of pumping an optical fiber, formed of laser material, said method characterized by: supplying pump light to one end (52) of a cone shaped rod (50) by mounting plural light sources (60) at respective locations removed from the central axis (72) of said cone shaped rod (50) to excite high order modes at the other end (54) of said cone shaped rod (50); and optically coupling the other end (50) of said cone shaped rod (50) to pump the laser material of said optical fiber (14).
Claim 13
Dependent Claim
47 words
A method of pumping an optical amplifier, as defined in claim 10, further characterized in that the step of supplying pump light comprises: placing a collimating microlens (62) between a laser source (64) and said one end (52) of said rod (50) to collimate said pump light.
References Cited (Backward Citations)
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