Laser & Fiber Electronics Group

Institute of Telecommunications, Teleinformatics and Acoustics

Wrocław University of Technology

Group members

• Head: Professor Krzysztof M. Abramski

• Staff: • Dr. Arkadiusz Antończak • Dr. Paweł Kaczmarek • Dr. Adam Wąż • Dr. Grzegorz Dudzik • Dr. Michał Nikodem (on leave to Princeton University, Department Of

Electronics)

• PhD students: • Jarosław Sotor• Maciej Nowak• Grzegorz Soboń• Paweł Kozioł • Karol Krzempek• Rafał Lewicki (on leave to Rice University, Laser Science Group)• Natalia Trela (on leave to Heriott-Watt University, Laser and Photonics

Applications Group)

• 12 MSc students

Our research

1. Fiber lasers and amplifiers:• MOPA systems• Optical frequency combs

2. Solid state diode pumped single frequency microchip lasers

3. Laser micromachining 4. Laser-fiber vibrometry

2-stage All-Fiber MOPA setup

P. Kaczmarek, G. Soboń, A. Antończak, J. Sotor, K.M. Abramski, „Fiber-MOPA sources of coherent radiation”, Bulletin of The Polish Academy of Sciences, Vol. 56, Issue 4 (2010)

~37 dB gain 1540-1570 nm 4.8 W output power (ŋ = 24%)

Output signals (SNR > 50 dB)Experimental setup

Features:

Dual-stage all-in-fiber MOPA system

4.8 W output power (CW mode)

1550 nm eye-safe region

Signle-frequency tunable (1540 – 1570 nm)

potential source for nonlinear frequency conversion, Tm3+ laser and amplifier pumping

Self-made additional equipment

Water-cooler Laser Diode Temperature Controller

Cooling blocks for 3*10W diodes High Power Laser Diode Temperature Controller

2-stage MOPA – pulsed regime

Power Amplifier

Output

Pre-amplifier

Pulse-shaping effect

G. Sobon, P. Kaczmarek, A. Antonczak, J. Sotor, A. Waz, K.M. Abramski, „Pulsed Fiber-MOPA source operating at 1550 nm with pulse distortion pre-compensation”, Optical Fiber Communication Conference and Exposition OFC 2011 paper- in review

Pulse distortion

8 ns output pulse Peak power vs. Repetition rate

Features:

8 ns pulses

tunable repetition rate (> 10 kHz)

Pulse-shaping system (pulse distortion pre-compensation)

100 ns flat-top pulses with high energy

potential source for military, LIDAR, free-space telecom, etc.

3-stage Fiber-MOPA system

IsolatorWDM

Coupler

Er3+ doped fiber

Isolator99/1%

Coupler

DFB seed 1550 nm

Pump Combiner

99.9/0.1% Coupler

Output

WDM Coupler

Mode-stripper

Isolator

1% 1%

0,1%

99,9%

FC/APC High-powerPump

Combiner

Pump LDs λ = 915 nm, P = 35W Double-Clad LMA

Er3+/Yb3+ (15 m)

Isolator

Mode-stripper

Pump LDs λ = 980 nmP = 750 mW

Back-scattered light monitor

1st stage output power monitor

Double-Clad Er3+/Yb3+ doped

fiberPump LDs λ = 975 nm

P = 10 W

2nd stage output power monitor

Passive DC LMA

Taper splices

35W diodes Pump injection system LMA Fiber Tapered splice

Features:

All-in-fiber design

Large Mode Area (LMA) Erbium-Ytterbium fiber used (25 μm core diameter)

6 * 35W pumping power (915 nm)

High output power expected (~20W)

Cladding mode-stripper

169 MHz repetition rate, passively mode locked fiber laser

Features:

nonlinear polarization rotation operation principal

169 MHz fundamental repetition rate

1,2m of cavity length (30cm of Er3+ fiber)

111 fs pulses

30 mW of average output power

1550nm working wavelength (Eye-safe region)

Michał Nikodem, Krzysztof Abramski, „169 MHz repetition frequency all-fiber passively mode-locked Erbium doped fiber laser,” Optics Communications 283, 109-112 (2010).

Michał Nikodem, Grazyna Tomczyk, Aleksander Budnicki, Krzysztof Abramski, „Investigation of passively mode-locked erbium doped fiber ring laser due to nonlinear polarization rotation,” Opto-electronics Review, Vol. 16, No.2, 123-127 (2008).

Optical frequency comb stabilization

Michał Nikodem, Krzysztof Abramski, „Controlling the frequency of the Frequency Shifted Feedback fiber laser using injection-seeding technique,” Optics Communications 283 (2010), pp. 2202-2205.

Michał Nikodem, Ewelina Kluzniak, Krzysztof Abramski, „Wavelength tunability and pulse duration control in frequency shifted feedback Er-doped fiber lasers,” Optics Express 17, 3299-3304 (2009).

Long-term frequency fluctuations less than 0,93 MHz

Single frequency Nd:YAG/KTP laser

22 ln

cFSR

where:Δn = 0,0844 – is the natural birefringence of KTP (nz - ny), l2 – geometrical length of KTP

mm11n

cl

G

22

L0

l1

Nd:YAG KTP

HR@1064nmAR@532nm

AR@808nmHR@1064nm & 532nm

Brewster plate

P0, 0

532 nm

1064 nm

l2

LOSS@1064nm

FSR

Antończak Arkadiusz, Sotor Jarosław, Abramski Krzysztof: Single frequency green laser with birefringent filter. W: Proceedings of 2006 8th International Conference on Transparent Optical Networks with 5th European Symposium on Photonic Crystals.., Nottingham, UK, June 18-22, 2006. Vol. 4 / [Ed. M. Marciniak]. Piscataway, NJ : IEEE, cop. 2006.pp. 178-180

Single frequency Nd:YAG/KTP laser

single frequency / TEM00 mode operation,

output power (at pumping power: P808 = 1W):> 50mW @ 532nm~ 4mW @ 1064nm

110GHz frequency tune:

∆ν0 ~ 110GHz@1064nm(220GHz@532nm)

Antończak Arkadiusz, Sotor Jarosław, Abramski Krzysztof: Single frequency microchip solid state diode pumped lasers. Bulletin of the Polish Academy of Sciences. Technical Sciences. 2008, vol. 56, nr 2, s. 113-116

Nd:YAG/BIBO – 473nm for underwater vibrometry

output power @P808 = 1W~ 20mW @ 473nm

good beam quality - TEM00

Antończak Arkadiusz, Sotor Jarosław, Matysiak Mateusz, Abramski Krzysztof: Blue 473-nm solid state diode pumped Nd: YAG/BiB0 microchip laser. Opto-Electronics Review, 2010, vol. 18, nr 1, pp. 71-74,

Microchip laser stabilized by fiber Bragg grating

0 15 30 45 60

Tem perature [°C ]

1063.60

1063.80

1064.00

Wav

elen

gth

[n

m]

m easured point

polynom ial fit

non-atherm al package

Differential Amplifier & PID

Radiator

Nd:YAG/ KTP1064nm&532nm

Dichroic mirror

1064nm

PIN-diode(transmited signal)

Thermoelectric cooler

Stabilized laser

PIN-diode(reflected signal)

Athermal housedFBG @1064nm

532nm

Fibre Coupler 50:50%

Power Amplifier

Temperature Controller of the

Fibre Bragg Grating

Power Supply &Temperature

Controller of the LD

(VOA)

IsolatorTo Optical Spectrum Analyser

frequency stability at the level of 10-7, simple frequency stabilization ofthe laser for metrological purposes.

1063.79 1063.81 1063.83 1063.85

W avelength [nm ]

-100.0

-90.0

-80.0

-70.0P

ower

leve

l [dB

m]

10°C

15°C

20°C

25°C

35°C

45°C

55°C

ΔλΔλmm = 0,35pm/ = 0,35pm/ooC => C => ((93MHz/93MHz/ooC)C)

Antończak Arkadiusz, Sotor Jarosław, Abramski Krzysztof: Single frequency solid state laser stabilized by FBG. W: Proceedings of 2008 10th Anniversary International Conference on Transparent Optical Networks with 7th European Symposium on Photonic Crystals, Athens, Greece, June 22-26, 2008.

Fast Frequency Control of Microchip Lasers

HVamplifierHSA - 01

CurrentamplifierTA - 01

300Vpp

RF amplifierB = 300MHz

SR 445

Spectrumanalyser

HP 8592L

Programmablecounter

PFL - 32

PLL

TLC2932

Ku=25V/V

PIN diode (Hamamatsu)G8376-01

Pump: 808nm 400mW

Thermo-ElectricCooler

Radiator

LL - 02CC 1064

Power supplyMPL 2500

LiNbO3Nd:YAG

Reference compact laser(thermally controled)

Slave laser(electrooptically controled)

LP filter 1

LP filter 2Variableattenuator0 - 100dB

1E -5 1E -4 1E-3 0.01 0.1 1 10 1E+2Averaging tim e [s ]

0.1

1

10

1E+2

1E+3

1E+4

1E +5

1E+6

1E +7

1E+8

Squ

are

root

of A

llan

Var

ianc

e

[H

z]

w ithout stab ilisation

0 100 200 300T im e t [s ]

0

100

200

300

Offs

et fr

eque

ncy

[MH

z]

Free running case

w ithout stab ilisation

w ith stab ilisation TEC + EO M (= 0,68 m s)

Free running case

EO M + TEC stabilisation

1 0 H z

fm = 1kHz fm = 5kHz fm = 10kHz fm = 50kHz

fm = 100kHz fm = 500kHz fm = 800kHz fm = 1,5MHz

Sensitivity X: 5MHz/div, Y: 10dB/div, Ref: -20dBm, UEOM = 10 Vpp

Antończak Arkadiusz, Abramski Krzysztof: Frequency control of microchip lasers. W: Joint Conference of the German Society of Applied Optics (DGaO) and the Section of Optics of the Polish Physical Society. 106th Conference of the DGaO, Wrocław, 17-20 May, 2005, Deutsche Gesallschaft fur Angewandte Optik,

Single frequency green (532nm) laser with YVO4 beam displacer -

conception

o-ray

e-ray

YVO4 optical axis plane2m

m

5mm

0.5m

m

L0= 16mm

l1

Nd:YVO4

KTPYVO4 (walk-off)

l2

LOSS - opposite polarization

P0, 0

532 nm

1064 nm

l3

LOSS - Lyot filter

Crystals cutting and single frequency laser configuration with YVO4 beam displacer

J.Z. Sotor, A.J. Antończak, K.M. Abramski, “Single-longitudinal mode Nd:YVO4/YVO4/KTP green solid state laser,” Opto−Electronics Review 18(1), 75–79,(2010),

J.Z. Sotor, A.J. Antończak, K.M. Abramski, „Single frequency, monolithic solid state laser”, Patent application, P383937, 02.07.2009.

Features:

• birefringent filter formed by YVO4 beam displacer and KTP crystal,•possibility of monolithic realization,•resistant to environmental hazards.

Monolithic single frequency laser

Designed and manufactured monolithic laser resonator consist of three crystals bonded together with UV adhesive. Total resonator dimension:• 2x2x10.5mm,• 1x1x10.5mm (extended single frequency operation range)

J.Z. Sotor, G. Dudzik, A.J. Antończak, K.M. Abramski, “Single-longitudinal mode, monolithic, green solid-state laser”, Applied Physics B, (2010), revised and accepted,J.Z. Sotor, A.J. Antończak, K.M. Abramski, „Single frequency, monolithic green DPSS laser”, Photonics West 2010, SPIE, Vol. 7578, 75782J (2010).

Practical realization of single frequency DPSS laser

Experimental set-up of single frequency DPSS laser

Monolithic single frequency laser – parameters

Features:• single frequency operation temperature range with mode hopping (Fig.a),• output power @532nm up to 160mW (Fig.b),• output power stability ±0.75% (Fig.c),• long term frequency stability 3·10-8 (Fig.d),• Gaussian beam profile with M2 at the level of 1.2

a) b) c)

d)

J.Z. Sotor, A.J. Antończak, K.M. Abramski, Single-longitudinal mode miniature, green solid state laser, Europhoton 2010, Hamburg 29.08–3.09.2010J.Z. Sotor, A.J. Antończak, K.M. Abramski, Single frequency monolithic solid state green laser as a potential source for vibrometry systems, 9th Int. Confercnceo n Vibration Measarcments laser and Noncontact Techniques, Ancona 2010

EMF electrooptical sensor based on microchip lasers

Spectral analysis in the case of the electric field

measurement E = 80V/m and the frequency

FRF = 5MHz (X: 20MHz/div)

Electric field sensor calibration in TEM line

antenna

electrode

crystal LiNbO3

laser beam

P0

n2n1

LiNbO3

L0

l1 l2

2/22112

U

tU

lnln

ct

Pumping diode= 808 nm

LiNbO3

Nd: YVO4

All dielectric sensorAntenna

SignalProcessing

PIN diode

dResonator

Fabry-Perota

R

R

nd

cC

1

2

AutomaticFrequency

Control

C

Fibercoupler

PIN diode

PINdiode

Pumping diode = 808 nm

Local oscillator

LiNbO3

Nd:YVO4

Nd:YVO4

All dielectric sensor

Polarizationmaintain fiber

Antenna

SignalProcessing

Fiber

coupler

Antończak Arkadiusz, Abramski Krzysztof: Microchip laser antenna, Proceedings of 2005 7th International Conference on Transparent Optical Networks with 4th European Symposium on Photonic Crystals, Barcelona, Spain, July 3-7, 2005. vol. 2 Piscataway, IEEE, pp. 359-362

Laser micromachining

Semiconductors:Si (silicon), Ge (germanium), GaAs (g allium arsenide), InP (indium phosphide),

Ceramics and glass:Al2O3 (alumina), AlN (aluminum nitride), LTCC ceramics, fused silica, BK7, etc.

Metals and alloys:Titanium, tungsten, molybdenum, tantalum, indium, stainless steel, copper, aluminum,

Plastics and Polymers:Poly-methyl methacrylate (PMMA), Teflon (PTFE), polyamide,

Examples of laser micromachining

150μm diameter, silicon

Laser microdrilling

60μm x 60μm square hole in a silicon chip with a thickness of 350μm,

micro-holes in fuel injection systems

diamond cutting 0.4 mm thick sapphire tungsten slit 0.01mm thick 0.1mm

Laser microcutting

Examples of laser micromachining

aluminum block with a group of squares separated 500μm 100μm gap

Laser micromilling

structure 2,5D structure 3D structure 3D diameter 1,4mm

micro-antenna applications

50μm holes in the packaging of biomedical

microvia through PCB microlenses (polymer)

Other:

Laser color marking

ColorPower

[W]Speed [mm/s]

Hatching [mm]

Repetition

Frequency [kHz]

RED (light) 8 50 0,03 100RED (dark) 10 50 0,04 100GREEN (light) 8 50 0,05 90GREEN (dark) 10 100 0,01 100BLUE (light) 10 100 0,05 100BLUE (dark) 12 150 0,05 100GOLD (light) 15 250 0,05 100GOLD (dark) 12 200 0,05 100BROWN 14 25 0,05 100SILVER 10 250 0,05 100PURPLE (light) 9 100 0,02 100PURPLE (dark) 12 100 0,04 100NAVY (blue) 8 25 0.01 100

Red / raspberry color

Blue

Green

Yellow/ gold

Fast prototyping of PCB (Printed Circuit Board) using laser

micromachining

For different substrates:a) FR-2 b) CEM-1; c) FR-4

Resolution tested up to 5 mils (~120μm)

Technology useful for:circuit boards, RFID,micro-strip antennas,etc.

- without preparation of photographic film

Idea of single channel laser – fiber vibrometer

P. R. Kaczmarek, M. Kazimierski,A. Waz and K. M. Abramski Laser-Fiber Vibrometry/Velocimetry Using Telecommunications Devices Proc. SPIE 5503, pp 329-33, 2004

4 – Channel Fiber-Laser Vibrometer

A. T. Waz, P. R. Kaczmarek and K. M. Abramski Laser-fibre vibrometry at 1550 nm, Meas. Science and Technology vol. 20 105301 (8pp), 2009

A. Waz, P. Kaczmarek, M. Nikodem and K. M. Abramski WDM optocommunication technology used for multipoint vibrometry Proc. SPIE 7098, 2008

Vibrometry signal processing

Data acquisition software

4 – Channel Fiber-Laser Vibrometer

Green laser vibrometry based on single frequency microchip laser

FMDemodulator

Mirror

/4

PBS

+2fB

RF Spectrum Analyzer

Brag CellfB = 80MHz

+fB

/4

Moving object

Polarization 45o

Single Frequency Solid State Green Laser

(532nm)

Polariser

Mirror

PBS

+fB

/4 Moving objectPolarization 45o

Brag CellfB = 80MHz

PBS

BS

FMDemodulator

RF Spectrum Analyzer

Single Frequency Solid State Green Laser

(532nm)

Second Photodetector

0

5

10

15

20

25

30

35

40

45

0 2 4 6 8 10 12 14 16 18 20

S/N

ratio

[dB]

Laser output power @532nm [mW]

RBW 200kHz

RBW 510kHz

RBW 1MHz

S/N ratio versus laser output power (L = 0.25m)

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600

S/N

ratio

[dB]

Distance to moving object [cm]

RBW 200kHz

RBW 510kHz

RBW 1MHz

S/N ratio versus distance to the moving object (PLASER_= 10.5mW)

Arkadiusz J. Antończak, Paweł Kozioł, Jarosław Z. Sotor, Paweł R. Kaczmarek, Adam T. Wąż, Krzysztof M. Abramski, Elementary experiments in green laser vibrometry, 9th International Conference on Vibration Measurements by Laser and Noncontact Techniques, Advances and Applications, Ancona, 22-25 June 2010 / Ed. Enrico Primo Tomasini. Bellingham, Wash.: SPIE

Laser & Fiber Electronics Group

Thank you for your attention!