50W single-mode linearly polarized high peak power pulsed fiber laser

43 %
57 %
Information about 50W single-mode linearly polarized high peak power pulsed fiber laser

Published on January 30, 2008

Author: nufchas

Source: slideshare.net

Description

We demonstrate 50W single-mode linearly polarized high peak power pulsed fiber laser with tunable ns–µs pulse durations and kHz–MHz repetition rates capable to address a wide range of applications: frequency conversion, LIDAR and others.

50W single-mode linearly polarized high peak power pulsed fiber laser with tunable ns-µs pulse durations and kHz-MHz repetition rates V. Khitrov*, B. Samson, D. Machewirth, K. Tankala * Presenting author www.nufern.com 1 1 www.nufern.com

• 10 ~ 100W linearly polarized pulsed fiber lasers have been demonstrated (IPG Photonics, Aculight, Sandia Labs and others) – 0.1~0.5mJ pulse energies, 1~10ns pulse durations – Near diffraction limited beam (M2 < 1.5) – Yb-doped large mode area (LMA) double clad fiber – Operating wavelengths 1060-1080nm – Limited set of parameters per device, typical sets • High rep rate ~1MHz, low energy <0.1mJ, high average power 50~100W • Low rep rate <50kHz, high energy ~0.5mJ, low average power ~10W • We demonstrate 50W single-mode linearly polarized high peak power pulsed fiber laser with tunable ns-µs pulse durations and kHz-MHz repetition rates capable to address a wide range of applications: frequency conversion, LIDAR and others www.nufern.com 2 2

PM LMA Yb-doped double clad fiber – key component Glass Cladding • Silica fiber with high optical damage threshold • 20-40μm core, low NA<0.1 for good beam quality • 200-400μm cladding, high NA~0.5 for efficient pump coupling LMA core High NA • High Yb concentrations for short fiber lengths cladding • Hi birefringence for single polarization Challenges for high power pulsed polarized fiber lasers • Nonlinear effects: SBS, SRS, Self Phase Modulation, Four Wave Mixing – limiting output power, broadening narrow spectral linewidth and destroying integrity of output spectrum • Polarization control problems – power de-coupling from fundamental linearly polarized mode to parasitic higher order modes www.nufern.com 3

Principal design High power isolator High Master Low power power oscillator pre-amp amplifier • Master Oscillator Power Fiber Amplifier (MOPFA) design – flexible all-fiber format • Low power semiconductor laser diode as seed source • High power PM LMA fiber based amplifier www.nufern.com 4

Fiber Design Coil Technique • Yb-doped LMA 30/250μm fiber • Utilizes differential bend loss of • Low core NA (0.06) fundamental and higher order modes • 0.46 NA cladding • 8 cm coil maintains single-mode linear • High birefringence (2.5x10-4) polarization operation Bend Loss at 1060 nm 1.E+03 1.E+01 1.E-01 (dB/m) Fast Pol 1.E-03 1.E-05 1.E-07 Slow Pol 1.E-09 50 100 150 200 Coil Diameter (mm) www.nufern.com 5 5

Choice of seed pulsed lasers • Pulsed Nd:YAG, Yb:YAG lasers • Microchip lasers • Semiconductor diode seeded multi-stage fiber amplifiers • Q-switch fiber lasers Semiconductor diode advantages • Robust PM fiber-coupled output • Flexible pulse repetition rates 10kHz-50MHz • Flexible pulse durations 2ns-10µs • Suitable output for seeding the multi-stage fiber amplifier (~0.5W peak power) www.nufern.com 6

S M P M Yb -dope d fib e r P M LMA Yb -dope d 30/ 0 μ fib e r 25 m 1064nm S ig na l/pump S ig na l/pump puls e d fibe r fibe r MO m ultiple xe r m ultiple xe r P M is o P M is o P M is ola tor 1064nm puls e d s ig na l 976nm pump 976nm pump 976nm pump 976nm pump • 0.5W peak power seed laser • 2-stage SM preamplifier • High power amplifier based on 3m of PM-LMA-YDF-30/250 fiber • Up to 92 W of coupled pump power (at 976nm, ~3nm line width) through signal/pump multiplexers www.nufern.com 7 7

• Output power increases linearly with pump power • 51 W (10ns, 350kHz) output achieved with 92 Wcoupled pump • Slope efficiency 60%, overall optical efficiency 56% • Polarization Extinction Ratio 15dB www.nufern.com 8 8

• Pulse duration 10ns, rep rate 350kHz • Near diffraction limited output M2 = 1.24 www.nufern.com 9 9

• 1064nm central wavelength, 0.8 nm spectral width • No sign of SBS or SRS • Moderate spectral broadening www.nufern.com 10

• Stable 50W output at 50kHz-50MHz pulse repetition rates • Pulse durations 2.5ns-200ns • Pulse energies up to 1mJ at 50kHz rep rate www.nufern.com 11

Pulse shapes at 200ns duration and 50kHz rep rate from MO (left) and amplifier output (right) • Strong pulse distortion (collapsing towards leading edge) at the output at low repetition rates • Due to Yb inversion depletion • Results in extremely high peak power in the beginning of the pulse causing detrimental non- linear effects like SBS, SRS, etc. • Pulse engineering applied to seed laser is required to correct pulse distortion * • >1mJ possible to achieve with corrected pulse shapes * - K.T.Vu, A.Malinowski, D.J.Richardson, F.Ghiringhelli, L.M.B.Hickey, M.N.Zervas “Adaptive pulse shape control in a diode-seeded nanosecond fiber MOPA system”, Optics Express, Vol 14, No 23, 2006, pp. 10996- 11001 www.nufern.com 12

532nm power (W) 18 16 14 12 10 8 34% SHG efficiency 6 4 2 0 0 10 20 30 40 50 60 1064nm power (W) • 3x3x15mm LBO crystal operating at room temperature, single-pass SHG, ~70µm beam size • 17 W (10ns, 350kHz) output at 532nm achieved with 50W 1064nm input • 34% SHG efficiency close to 40% theoretical efficiency www.nufern.com 13

Summary • Demonstrated high power pulsed, monolithic fiber laser – Robust all-fiber MOPFA design – 51W average output power – 1064nm wavelength, 0.8nm linewidth – Flexible 2ns-0.2µs pulse durations, 50kHz-50MHz repetition rates, up to 1mJ pulse energy – PER = 15dB, M2 = 1.24 – 56% optical efficiency – 17W at 532nm, 34% frequency doubling efficiency limited by available crystal • Practical design to address a number of applications: frequency conversion, LIDAR and other applications www.nufern.com 14 14

Add a comment

Related presentations

Related pages

50W single-mode linearly polarized high peak power pulsed ...

50W single-mode linearly polarize d high peak power pulsed fiber laser with tunable ns-µs pulse dur ations and kHz-MHz repetition rates V. Khitrov*, B ...
Read more

SPIE | Proceeding | 50W single-mode linearly polarized ...

50W single-mode linearly polarized high peak power pulsed fiber laser with tunable ns-μs pulse durations and kHz-MHz repetition rates
Read more

50W single-mode linearly polarized high peak power pulsed ...

We report our recent progress in the design and fabrication of a completely monolithic linearly-polarized pulsed Yb-doped fiber laser, with >10kW peak ...
Read more

50W single-mode linearly polarized high peak power pulsed ...

50W single-mode linearly polarized high peak power pulsed fiber laser with tunable ns-μs pulse durations and kHz-MHz repetition rates
Read more

High-peak-power, single-frequency, single-mode, linearly ...

We demonstrated a high-peak-power, single-frequency, single-mode, linearly polarized, nanosecond all-fiber ... power, single-frequency, pulsed fiber laser ...
Read more

High-peak-power, single-frequency, single-mode, linearly ...

High-peak-power, single-frequency ... single-mode, linearly polarized, ... linearly polarized, nanosecond all-fiber laser in master oscillator power ...
Read more

Eye-safe single-frequency single-mode polarized all-fiber ...

... single-mode linearly polarized, high peak power pulsed ... frequency single-mode polarized all-fiber ... polarized, high peak power pulsed laser ...
Read more

72kW HighPeakPower LinearlyPolarized SingleMode Pulsed ...

high power linearly polarized single mode ... PM fiber, high average power and high peak ... a high power polarized pulsed fiber laser ...
Read more

Eye-safe single-frequency single-mode polarized all-fiber ...

Eye-safe single-frequency single-mode polarized all-fiber pulsed laser with peak power ... single-mode linearly polarized, high peak power pulsed ...
Read more