SOW_-_Er_fiber_fabrication.doc

FA9451-13-R-0363

10 July 2012

Development and Fabrication of Very Large Mode Area Erbium Doped Photonic Crystal Fiber

STATEMENT OF WORK

1.0 Background

A pulsed eye-safe illuminator is needed in conjunction with a high power laser weapon. Pulsed lasers operating at 1550 nm are considered to be eye-safe and prime candidates for an illuminator. Several methods exist to produce laser emission at a wavelength of 1550nm. These can include bismuth doped silica, Raman, and an erbium or erbium/ytterbium doped fiber lasers. Bismuth-doped silica is considered to be immature technology and currently has rather low efficiencies. Many years of development will probably be required to fully mature bismuth technology. Raman is also a prime candidate but many such systems cannot be pulsed at the rate required for an illuminator. In addition, in order to reach the energy per pulse required for an illuminator, a very large mode area fiber will be necessary. Raman laser technology with very large mode area fibers is current largely an unexplored region. Finally, usage of erbium in a fiber comprised of silica or other materials has been shown to directly lase at 1550 nm.

A system comprised of very large mode area ytterbium doped silica rod has been demonstrated to be capable of generating pulse energies in the range required for an illuminator at the non-eye safe wavelength of 1.04 microns. A similar type of very large mode area rod or fiber doped with erbium or erbium/ytterbium will be required to support high pulse energies at 1550 nm. The host matrix may be silica, phosphate, germinate, or some other form of glass. The focus of this effort will be on the design and fabrication of a very large mode area silica glass photonic crystal fibers doped with Erbium or Erbium/Ytterbium.

2.0. Project Objectives

1. Design and optimization of a single mode very large mode area erbium or erbium/ytterbium doped photonic crystal fiber in silica glass. The diameter of the core should be greater than 50 microns. The pump cladding should be optimized for pumping at 976 and 1480 nm.

2. Investigation and optimization of the design of an erbium or erbium/ytterbium doped photonic crystal fiber that is bendable having a core diameter of at least 80 microns.

3. Fabrication and testing of 100 m of very large mode area erbium or erbium/ytterbium photonic crystal fiber having a core diameter greater than 50 microns.

3.0.

Deliverables:

1. 100 m of the very large mode area erbium or erbium/ytterbium doped photonic crystal fiber having a core diameter in excess of 50 microns.

2. A final report

4.0 Project duration & Cost

Total project length: 12 months + 3 months for preparation of final report

Total cost: $126K For all deliverable hardware: Must comply with system safety requirements contained in MIL-STD 882D, Section 4 “General Requirements” for any deliverable systems or hardware. Must identify safety-critical components of those systems or hardware, and software interfaces with those components. Must test and verify the safety-critical hardware for safety acceptance. AFRL/Det 8 SE

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FOR OFFICIAL USE ONLY

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