Cladding-pumped fiber structure

• US 5,966,491 A
• Filed: 05/15/1997
• Issued: 10/12/1999
• Est. Priority Date: 11/22/1995
• Status: Expired due to Term

• Current Assignee: Furukawa Electric North America Incorporated (Furukawa Electric Company Limited)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: DiGiovanni, David John
• Primary Examiner(s): NGO, HUNG NHAT
• Application Number:
  US08/856,708
• Time in Patent Office: 880 Days
• Field of Search: 385/123, 385/127, 385/146, 385/88, 385/89, 385/90, 385/91, 385/92, 385/93, 372/6
• US Class Current: 385/127
• CPC Class Codes: C03B 2201/12 doped with fluorine C03B2201/14 takes precedence
• CPC Class Codes: C03B 2201/28 doped with phosphorus
• CPC Class Codes: C03B 2201/31 doped with germanium
• CPC Class Codes: C03B 2201/34 doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers
• CPC Class Codes: C03B 2203/12 Non-circular or non-elliptical cross-section, e.g. planar core
• CPC Class Codes: C03B 37/01234 to form longitudinal grooves, e.g. by chamfering
• CPC Class Codes: H01S 3/06708 Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering optical fibres as passive waveguides G02B6/02
• CPC Class Codes: H01S 3/06729 Peculiar transverse fibre profile
• CPC Class Codes: H01S 3/094003 the pumped medium being a fibre
• CPC Class Codes: H01S 3/094007 Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
• CPC Class Codes: H01S 3/094069 Multi-mode pumping
• CPC Class Codes: H01S 3/1608 erbium

Abstract

A cladding-pumped fiber structure, suitable for use as a laser, provides for efficient clad-to-core energy transfer. The outside interface of the pump-clad is constructed from a rod-shaped preform by local melt-displacement using an open flame.

Claims

1. Apparatus comprising a fiber including a core of size and transparency for transmitting electromagnetic wave energy of a first wavelength, the core being encompassed within a contacting pump cladding for receiving and transferring pump energy to the core, the pump cladding forming an interface with an enveloping second cladding, both core and pump cladding being composed of silica-rich glass, in which the interface is multiple-sided,

CHARACTERIZED IN THAT

the interface contains longitudinal, parallel troughs projecting into the pump cladding, a longitudinal pump trough being of a depth of at least 3%, as measured relative to the radial distance from the center of the fiber to a plane making glancing contact with the interface on either side of the trough.

2. Apparatus of claim 1 in which the core is rare-earth doped, in which transferred energy pumps rare earth in the core to an excited state which upon relaxation emits output radiation of the first wavelength.

3. Apparatus of claim 2 comprising an amplifier.

4. Apparatus of claim 2 comprising a laser.

5. Apparatus of claim 2 in which the core contains erbium.

6. Apparatus of claim 5 in which the core contains erbium and ytterbium.

7. Apparatus of claim 1 further comprising an energy source coupled to the fiber.

8. Apparatus of claim 7 in which the energy source is a diode array and in which output of diodes of the array are coupled to the fiber by converging waveguides.

9. Apparatus of claim 8 in which diodes of the array are lasers, and in which the core contains erbium.

10. Apparatus of claim 1 in which the interface comprises from 3 to 6 troughs of a total area of at least 15% of the total interfacial area.