Research on solid state lasers in Poland; status, applications, prospects

Research on solid state lasers in Poland; status, applications, prospects WAT Jan K. Jabczyński Institute of Optoelectronics Military University of Technology 00 908 Warszawa, ul Kaliskiego jjabczynski@wat.edu.pl www.ztl.wat.edu.pl 1

Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fibre Lasers: - 1.5-µm fibre lasers @ Wroclaw University of Technology - doubled clad pulsed MOFPA @ IOE Microchips - 1.06 µm stabilised microchips @ WUT - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8 - mj Q-switched oscillator - 2 - mj eye safe intracavity OPO - Raman lasers QML lasers @ IOE + CTU Prospects: - CW & Q-switched diode pumped infrared lasers for medicine - hybrid lasers for remote sensing 2

3-µm Q-switched Er:YAG laser up 140 mj single shot high rep rate, 20 mj, 90 Output energy[mj]... 80 70 60 50 40 30 20 10 free running Q-switching 0 440 450 460 470 480 490 500 Supply voltage[v] group of prof. A. Zając: azajac@wat.edu.pl 3

Output energy [mj] 140 120 100 80 60 40 20 Upc = 1.35 kv Upc = 2.4 kv 0 35 40 45 50 55 60 Pump energy [J] Pulse output energy vs. pump energy for two values of voltage applied to Pockels cell Hypothetical Er:YAG laser interaction with gelatine. The crater on the left was achieved for free-running pulses, and on the right for Q-switch pulses. Oscilloscope picture of the shortest Q-switch pulse generated by Er:YAG laser. Lower trace laser pulse, upper trace voltage course applied to Pockels cell group of prof. A. Zając: azajac@wat.edu.pl 4

Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fibre Lasers: - 1.5 µm fibre Lasers @ Wroclaw University of Technology - double-clad MOPFA @ IOE Microchips - 1.06 µm stabilised microchips @ WTU - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8-mJ Q-switched oscillators - 2-mJ eye safe intracavity OPO - Raman lasers QML lasers @ IOE + CTU Prospects: - Q-switched Tm lasers for medicine - hybrid lasers for remote sensing 5

Femtosecond oscillators at Warsaw University & Institute of Physical Chemistry Ti:Al 2 O 3 multipass amplifier, 10 Hz, 1-2mJ, 60fs, Ti:Al 2 O 3 regenerative amplifier, cryogenics cooling, 1-10kHz, 0.5-2mJ, 80fs, group of prof. Cz. Radzewicz: Czeslaw.Radzewicz@fuw.edu.pl 6

Femtosecond NOPCPA s Non collinear Optical Parametric Chirped Pulse Amplifiers Pump beam: II harm Q-switched Nd laser seed beam: stretched pulse of Ti:Al 2 O 3 MLlaser non collinear optical parametric amplification in BBO crystal Aim: > 50 mj, < 30 fs Demonstrated in 1st stage 4-pass amplifier 6 mj @ 10 Hz after compression 4.5 mj & 30 fs 0.15 TWatt group of prof. Cz. Radzewicz: Czeslaw.Radzewicz@fuw.edu.pl 7

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Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fibre Lasers: - 1.5 µm fibre lasers @ Wrocław University of Technology - double-clad MOFPA @ IOE Microchips - 1.06 µm stabilised microchips @ WTU - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8-mJ Q-switched oscillators - 2-mJ eye safe intracavity OPO - Raman lasers QML lasers @ IOE + CTU Prospects: - Q-switched Tm lasers for medicine - hybrid lasers for remote sensing 9

1.55-µ µm CW fiber lasers CW Tunable, narrow bandwidth fiber lasers 5 0 Moc wyjściowa [dbm] -5-10 -15-20 -25-30 -35-40 -45-50 1545 1546 1547 1548 1549 1550 1551 1552 Długość fali [nm] CW multi-wavelength fiber lasers -10 Moc wyjściowa [dbm] -20 I =32 ma d -30-40 -50-60 -70 1520 1530 1540 1550 1560 1570 1580 Długość fali [nm] group of prof. K. Abramski: krzysztof.abramski@pwr.wroc.pl 10 1553 1554 1555

1.55-µm ML fiber lasers Światłowodowe lasery erbowe pracy impulsowej Active ML laser ps pulses, frequency muliplying up to GHz Passive ML laser 0.1 ps pulses, coupled solitons, soliton packets -20 Moc optyczna [dbm] -25-30 -35-40 -45 30.52 nm -50 1530 1540 1550 1560 1570 1580 1590 1600 Długość fali [nm] group of prof. K. Abramski: krzysztof.abramski@pwr.wroc.pl 11

Pulsed double-clad MOFPA system HT @ 940 nm HR @ 1064 nm S3 y z y z HT @ 940 nm HR @ 1064 nm x x nonabsorbed pump power Yb-doped LMA fiber S2 HR @ 1064 nm S1 amplified signal oscilloscope Nd:YVO laser: f r = 10-40 khz 3,5 W (85 µj) dla 40 khz 2,5 W (250 µj) dla 10 khz t pulse (min.) = 10,6 ns diaphragm power meter pulse generator polarizer Faraday rotator optical isolator group of prof. A. Zając: azajac@wat.edu.pl λ 2 polarizer HR@1064 nm HT@ 808 nm 12

Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fibre Lasers: - 1.5 µm fibre Lasers @ Wroclaw University of Technology - double-clad MOFPA @ IOE Microchips - 1.06 µm stabilised micochips @ WUT - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8-mJ oscillators - 2-mJ eye safe intracavity OPO - Raman lasers QML lasers @ IOE + CTU Prospects: - Q-switched Tm lasers for medicine - hybrid lasers for remote sensing 13

1.06-µm stabilised, tunable microchips for metrology 8 7 6 5 4 3 54,9 2 1 42,0 110GHz 1 TEC, 2 dioda, 3 GRIN, 4 SSDPL, 5 Brewster plate,, 6 KTP, 7- mirror,, 8 tables (XY), a) SF operation b) temperature change T=19,2 o C up T=24,5 o C T=5,3 o C enables tunig in the range: ν 0 ~ 110GHz@1064nm Laser stabilizowany Nd:YAG/KTP Radiator 1064nm&532nm Lustro dichroiczne 1064nm Sprzęgacz światłowodowy 532nm Fotodetektor (sygnał R) Moduł Peltier'a (Przestrajanie termiczne) Układ automatycznej regulacji Siatka Bragga @1064nm Fotodetektor (sygnał T) 14

Microchip lasers @ IOE Types of microchips developed in last years: - 1.06-µm epitaxial Cr:YAG/Nd:YAG µchips - pigtailed, 0.532 µm/1.064 µm CW Nd:YVO 4 µchips - 1.54-µm SELG µchips; CW or Q-switched Applications: - interferometry - range finders - remote sensing - special group of dr K. Kopczyński: kkopczynski@wat.edu.pl 15

Pigtailed CW SF microchip lasers 532 nm cw 8 mw 1064 nm cw 10 mw 4 mm FSR=500GHz FSR=150GHz 20 mm 90 mm FSR=50GHz group of dr K. Kopczyński: kkopczynski@wat.edu.pl 16

Pulse train generation of Cr 4+: YAG/Nd:YAG Repetition rate up to 15 khz Pulse length 0.8-2 ns Pulse energy < 6µJ Peak power 3 kw group of dr K. Kopczyński: kkopczynski@wat.edu.pl 17

1.5-µm CW generation in Strong Erbium Laser Glass µchip Yb 1.7 x 10 21 cm -3 Er 0.75 x 10 20 cm -3 1.0 x 10 20 cm -3 1.3 x 10 20 cm -3 g e n e r o w a n a m o c ś r e d n ia [m W ] 180 160 140 120 100 80 60 40 20 0 SELG - 1 SELG - 2 SELG - 3 0 0,2 0,4 0,6 0,8 1 moc średnia diody padaj ąca na ośrodek aktywny [W] P out = 150 mw cw η = 0.16, P out = 300 mw q-cw η = 0.194. group of dr K. Kopczyński: kkopczynski@wat.edu.pl 18

1.34-µm Nd:YAG/V:YAG microchips Nd:YAG gain medium V:YAG saturable absorber Undoped YAG for better thermal management Mirrors are deposited directly on crystal end faces PUMP BEAM YAG Nd:YAG group of prof.h. Jelinkova: Hjelin@trojafjfi.cvut.cz 19

1.34-µm Nd:YAG/V:YAG microchips; summary t E out P peak P mean L rez CW 6.2 ns 37 µj 6 kw 420 mw 16.7 mm Higher pulse energy and laser mean power Stable linearly polarized output emission at 1338 nm CW 1.7 ns 15 µj 9 kw 120 mw 4.7 mm Shorter pulse length and higher peak power group of prof.h. Jelinkova: Hjelin@trojafjfi.cvut.cz 20

Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fibre Lasers: - 1.5 µm fibre Lasers @ Wroclaw Technical University - double-clad MOPA @ IOE Microchips - 1.06 µm stabilised microchips @ WTU - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8- mj, Q-switched 2.1-ns oscillator - 2- mj eye safe intracavity OPO - intracavity Raman lasers QML lasers @ IOE + CTU Prospects: - Q-switched Tm lasers for medicine - hybrid lasers for remote sensing 21

Side pumped Nd:YAG slab oscillator intracavity Raman lasers KTP intracavity OPO resonator up to 2 mj /5ns @ 1.57 µm Nd:YAG slab 600-W qcw FAC LD stack Pockels cell (or Cr:YAG) Q-switched) 8 mj / 2.1 ns, 50 Hz @1.064 µm 4 mj / 2 ns, 50 Hz @ 0.532 µm group of prof. Jabczyński, jjabczynski@wat.edu.pl 22

Crystals for Raman lasers BaWO 4 KGd(WO 4 ) 2 (KGW) Dimensions 6 mm x 6 mm x 33 mm 4 mm x 4 mm x 40 mm Raman shift 925 cm -1 901 cm -1 (E C 2 ) 768 cm -1 (E//C 2 ) Raman gain (1.06 µm) 39.4 cm/gw 18.6 cm/gw group of prof. Jabczyński, jjabczynski@wat.edu.pl group of prof.h. Jelinkova: Hjelin@trojafjfi.cvut.cz 23

Nd:YAP/KGW Raman triangle laser D Nd:YAP Cr:YAG KGW 1.St Stokes E//C2 1.1756 µm E C2 1.1957 µm Raman pulse length ~1 ns Raman output energy 90 µj Peak power 90 kw Mean power 1.3 mw KGW E// //C2 1.08 µm 1.176 µm KGW E C2 1.08 µm 1.196 µm 24

Nd:YAG vs. Nd:YAP Raman triangle-slab lasers Wavelength (first Stokes) Energy Nd:YAG/BaWO 4 1.180 µm 1.46 mj Nd:YAP/BaWO 4 1.199 µm 165 µj Pulse length 3.5 ns 1.7 ns 25

Contents Q-switched Er laser @ IOE Ultrafast Lasers @ Warsaw University Fiber Lasers: - Mode Locked Lasers @ Wroclaw Technical University - MOPA @ IOE Microchips - 1.06 µm stabilised microchips @ WTU - green, eye safe microchips @ MUT - 1.3 µm V:YAG Q-switched microchips @ CTU & CRYTUR Side pumped, multi-wavelength laser @ IOE - 8-mJ oscillators - 2-mJ eye safe intracavity OPO - Raman lasers QML lasers @ IOE + CTU Prospects: - Q-switched Tm lasers for medicine - hybrid lasers for remote sensing 26

Types of QML lasers Passive QML: - bulk saturable absorbers (Cr 4+ :YAG, V 3+ :YAG) - multi quantum wells saturable absorbers (MQW-SA) - Stankov s nonlinear mirror + Q-switch Active QML: - AO Mode Locker + EO Q-switch - AO Q-switch Mode Locker (AO-QML) group of prof. Jabczyński, jjabczynski@wat.edu.pl 27

AO-QML Nd:YVO 4 laser pumped by 20 W FCB 4 3 P cw = 0.2357( P - 2.16) T oc = 66% ; best case P qcw = 0.1848(P - 2.16) Z-cavity, 40.6 MHz, R=1000, R=1000 Output Power [ W ] 2 1 0 0 5 10 15 Pump Power [ W ] Output power vs. Pump power AOM LDBS 25W laser diode with beam shaper, AM- 0.3% Nd:YVO 4, AOM- acousto-optic cell, cavity frequency match to radio frequency c/2l cav =40.7 MHz, L cav = 3690 mm group of prof. Jabczyński, jjabczynski@wat.edu.pl 28

Results of AO-QML Nd:YVO 4 laser Best case: - 3 W average power @ 30 khz rep.rate - 130 µj QML envelope; 120-150 ns FWHM - 30 µj ML pulse with τ < 1 ns FWHM 1GHz DSA 601 scope 500 MHz TDS3052 scope group of prof. Jabczyński, jjabczynski@wat.edu.pl 29

MQW-SA-QML side pumped Nd:YAG slab laser M2 A LD M1 r=1m Nd:YAG M3 MQW 758D R= 50 % (40%) Pump: 600-W qcw LD @ 123 A, 33 Hz, 200 us gain medium : single bounce triangle Nd:YAG slab V-type cavity of 140 cm E out = 2 mj, 6 pulses, 95 ps, 0.8 mj/single pulse 0.65 mj, 3 pulses, 65 ps, 0.2 mj/ single pulse group of prof. Jabczyński, jjabczynski@wat.edu.pl group of prof. V. Kubecek, kubecek@troja.fjfi.cvut.cz 30

MQW-SA-QML side pumped Nd:YAG slab laser 700 600 500 SH intensity 400 300 200 100 Shortest 3-pulse enevelope 0 10 20 30 40 50 60 translation [mm] Autocorrelation trace Passive negative feedback E out = 2 mj, 6 pulses, 95 ps, 0.8 mj/single pulse 0.65 mj, 3 pulses, 65 ps, 0.2 mj/ single pulse group of prof. Jabczyński, jjabczynski@wat.edu.pl group of prof. V. Kubecek, kubecek@troja.fjfi.cvut.cz 31

WAT Summary & Prospects R-D focused on definite applications 1.9-µm diode pumped CW & Q-switched Tm laser for medicine: preliminary results CW: up to 6 W Q- switched: 2 mj / 15 ns, 300 Hz Diode pumped CW & Q-switched Er laser for medicine Hybrid eye safe Q-switched lasers for special applications - tunable Q-switched Ho:YAG laser pumped by Tm fiber laser - Q-switched Er:YAG laser pumped by Er fiber laser 32

WAT Acknowledgment to: prof. H. Jelinkova, Czech Technical University, Prague prof. V. Kubecek, Czech Technical University, Prague dr K. Nejezchleb, CRYTUR, Turnov, Czech Republik prof. Cz. Radzewicz, Warsaw University prof. K. Abramski, Wrocław University of Technology prof. A. Zając, Military University of Technology dr K. Kopczyński, Military University of Technology 33