NeoDUV Project: Neodymium doped fiber lasers for high-power blue/DUV emission

High-power, compact and robust pure blue and deep-UV (DUV) laser sources are of great interest for multiple applications. Blue laser sources are required for Alkaline-earth atom laser cooling as well as for many other applications in the field of biomedicine, underwater laser detection and submarine communications.

Laser sources in DUV spectral range, which is still little explored, are of growing interest for applications that concern the treatment and the micro-structuring of large gap materials or the compounds analysis by LIBS or LIF techniques and protein detection.

To take up the challenge of generating new laser wavelengths in the blue and DUV, the CIMAP (Caen) and LP2N (Bordeaux) laboratories and their industrial partners iXblue Photonics now Exail (Lannion) and Oxxius (Lannion) propose to develop fully-fibered laser sources based on novel Nd-doped fibers and non-linear frequency conversions.
The first step will be to design and fabricate quasi single-mode Nd-doped fibers for 880-930 nm laser emission with (1) a large core to reduce the non-linear effects (stimulated Brillouin and Raman scattering) in single-frequency and pulsed regimes and (2) a polarization maintaining (PM) design to generate linearly-polarized output laser beam. In addition, the design of the fiber should allow an all-fiber laser configuration to meet the robustness and power stability criteria necessary for industrial grade.

The achievement of new PM/LMA Nd-doped fibers will be followed by the development of two specific novel quasi all-fibered multi-Watt-level laser systems: a 2W single-frequency CW laser near 460 nm and a 1W nanosecond pulsed laser in the DUV near 225 nm. These fiber laser systems will be based on the Master-Oscillator Power-Amplifier configuration (MOPA). The realization of quasi all-fiber multi-watt-level CW/pulsed MOPAs in the 880-930 nm window will require the development, the test and the integration of specific high-end PM fiber components (Mode Field Adapters, fiber tapers, endcaps and dedicated multimode signal/pump combiners with LMA fibers).
Robust CW blue radiation in the near 461 nm window will be generated using single-pass Second Harmonic Generation (SHG) in long periodically-poled nonlinear crystals.

The combination of a high-power (>10W) infrared single-frequency laser with SHG will enable for instance watt-level blue radiation generation at 461 nm suitable for Sr atom cooling. The availability of a reliable compact and powerful laser at this wavelength will enable advanced fundamental physic experiments like laser cooled Strontium atom interferometers. This system will be then used as seed to generate intense (>200mW) DUV radiation at 230m using robust monolithic enhancement doubling cavity development by Oxxius. Pulsed DUV laser emission near 225 nm will be based on a Nd-doped fiber laser systems operating in nanosecond/picosecond (1-50 ns, <100ps) pulsed regime near 920 nm and two optimized non-linear conversion stages using bulk crystals (LBO, BBO, CLBO…). In order to achieve the high peak-power (>20 kW) necessary for efficient fourth-harmonic generation, we plan to develop a nanosecond actively Q-switched and linearly-polarized Nd-doped fiber laser emitting an average power of >30 W near 900 nm at a repetition rate near 50 kHz.

Goals of the project:

One of the objectives of the project is to propose elegant prototypes of blue/UV lasers both in CW single-frequency and pulsed regimes. The close collaboration between academic and industry partners will lead to the exploration of the commercial potential of laser systems and help manage the shift from precompetitive research to commercial products with strong economic impact.

Project funded by: Agence Nationale de la Recherche (ANR)