Continously tunable single-mode rare-earth doped pumped laser arrangement

• US 5,317,576 A
• Filed: 02/01/1993
• Issued: 05/31/1994
• Est. Priority Date: 12/26/1989
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Ball, Gary A., Leonberger, Frederick, Glenn, William H.
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US08/013,117
• Time in Patent Office: 484 Days
• Field of Search: 372/6, 372/69, 372/102, 372/92, 385/37
• US Class Current: 372/6
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/06737 Fibre having multiple non-coaxial cores, e.g. multiple active cores or separate cores for pump and gain
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/07 consisting of a plurality of parts, e.g. segments H01S3/067 takes precedence
• CPC Class Codes: H01S 3/08031 Single-mode emission
• CPC Class Codes: H01S 3/08086 Multiple-wavelength emission
• CPC Class Codes: H01S 3/094007 Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
• CPC Class Codes: H01S 3/094019 Side pumped fibre, whereby pump light is coupled laterally into the fibre via an optical component like a prism, or a grating, or via V-groove coupling
• CPC Class Codes: H01S 3/094038 End pumping
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/23 Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
• CPC Class Codes: H01S 3/2383 Parallel arrangements

Abstract

A tunable optical waveguide laser arrangement includes a solid optical waveguide capable of guiding light along an axis between axially spaced ends thereof and being at least in part of an excitable material that emits light in response to stimulation by light. Stimulating light is launched into the waveguide for axial propagation therein and attendant emission of light by the excitable material. Two end reflectors are situated in the waveguide, each at one of the axially spaced ends thereof and extending normal to the axis to delimit a laser cavity. Each of the reflectors is constituted by a Bragg grating consisting of a multitude of axially consecutive grating elements constituted by periodic refractive index perturbations with a given periodicity. The length of the cavity, the peak reflectivity of the Bragg gratings and the gain of the excitable material are so coordinated with one another as to enable lasing in only a single longitudinal mode. The length of that portion of the optical waveguide that incorporates the two Bragg gratings and an intervening region of the optical waveguide is uniformly controlledly varied with attendant continuous tuning of the laser output wavelength without longitudinal mode hopping.

Claims

1. A tunable optical waveguide laser arrangement comprising:

a solid optical waveguide guiding light along an axis between axially spaced ends thereof and being located within a portion of an excitable material that emits coherent light in response to stimulation by pump light;

means for launching said pump light into the waveguide for axial propagation therein and attendant emission of coherent light by the excitable material;

two end reflectors each situated in the waveguide at one of the axially spaced ends thereof and extending normal to the axis to delimit a laser cavity, each of said reflectors being constituted by a Bragg grating consisting of a plurality of axially consecutive grating elements constituted by periodic refractive index perturbations with a given periodicity, the length of said cavity, the narrow peak reflectivity of said Bragg gratings and the frequency response of the gain of the excitable material being coordinated with one another such that lasing occurs only at a single longitudinal mode; and

means for uniformly controlledly varying the length of that portion of said optical waveguide that incorporates the two Bragg gratings and an intervening region of said optical waveguide such that attendant continuous tuning of the laser output wavelength occurs without longitudinal mode hopping.

2. The arrangement as defined in claim 1, wherein said material exhibits a gain that exceeds a lasing threshold only by an amount small enough for the product of gain and grating reflectivity to rise to a level at which lasing takes place only for said at most few longitudinal modes.

3. The arrangement as defined in claim 1, wherein the other of said reflectors is constituted by another grating substantially identical to said one Bragg grating and axially delimiting said laser cavity at said other end.