MIXSEL2 - Nano-Tera 2016

download MIXSEL2 - Nano-Tera 2016

of 28

Transcript of MIXSEL2 - Nano-Tera 2016

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    1/28

    Vertical integration of

    ultrafast semiconductor lasersand their applicationsnano-tera.ch

    Prof. Ursula Keller (PI)

    Dr. Matthias Golling

    Sandro Link

    Dominik Waldburger

    Cesare Alfieri

    Prof. Thomas Südmeyer

    Dr. Stephane Schilt

    Dr. Valentin Wittwer

    Nayara Jornod

    Dr. Jacques Morel

    Dr. Laurent Devenoges

    Dr. Deran Maas

    Dr. Thomas Paul

    Dr. Gábor Csúcs

    II

    Start MIXSEL II: 1. Nov. 2013 (current review after 2.5 years)

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    2/28

    Outline

    1)  Requirements for stabilized frequency combs

    based on modelocked lasers

    2)  New gigahertz frequency comb sources

    1) Diode-pumped Yb-doped solid-state lasers

    2) 

    Frequency comb stabilization with PCFs3)  Frequency comb stabilization with Si3N4 

    3)  New gigahertz frequency comb sources

    1) Semiconductor thin disk lasers: VECSELs, MIXSELs2) Dual comb modelocked lasers

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    3/28

    Laser pulse as a superposition of many frequencies

    •  A continuous wave laser emits in one or only few frequencies

    •  Typical femtosecond laser pulse trains are generated with a

    superposition of millions of single frequencies (1 femtosecond = 10-15 s)•  Single frequencies are phase locked with intracavity modulator

    (or saturable absorber): “modelocking”

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    4/28

    Magnification: 100'000 x 

    Modelocked laser can give a „frequency ruler“

    Magnification: 

    100'000 x ! Spectrum of a fs modelocked laser consists of millions of fine lines

    ! Line spacing is given by pulse repetition frequency  f rep:

    !t   =1

     f rep

    Line spacing was stabilized in the 1980’s:referred to as “timing jitter stabilization”

    Patent D. Cotter (1985, British Telecom)

     Actively modelocked flashlamp-pumped Nd:YAG laser (1986)M. J. W. Rodwell, D. M. Bloom, K. J. Weingarten, IEEE J. Quantum Electr. 25, 817, 1989

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    5/28

    Magnification: 100'000 x 

    Modelocked laser can give a „frequency ruler“

    Magnification: 

    100'000 x ! Spectrum of a fs modelocked laser consists of millions of fine lines

    ! Femtosecond laser is for frequency the same as a ruler for length:

    .... but the „zero“ of the frequency ruler was not stabilized!

    Solution given how to stabilize the zero of the frequency ruler:

    H.R. Telle, G. Steinmeyer, A. E. Dunlop, J. Stenger, D. H. Sutter, U. Keller  

     Appl. Phys. B 69, 327 (1999)

    ! Line spacing is given by pulse repetition frequency  f rep and can be stabilized

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    6/28

    T = 2.7 fs @800 nm 

    Ultrashort pulse generation

    1as

    Time

    F

    W

    H

    M

    p

    s

    e

    w

    d

    h

     s

    e

    20001990198019701960

      ear

    10 fs

    100 fs

    1 ps

    1 fs

    10 ps

    Ti:sapphire laser!5.5 fs with !200 mW

    dye laser27 fs with !10 mW

    compressed 

    Science 286, 1507, 1999 

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    7/28

    Carrier Envelope Offset (CEO)

    frequency

    f CEO

    f n = n f rep + f CEO

    H.R. Telle, G. Steinmeyer, A.E. Dunlop, J. Stenger, D.H. Sutter and U. Keller, Appl. Phys. B 69, 327 (1999)

    0

    t

    Mode-locked pulse train

    Pulse envelope

     A(t ) 

    !    c  = 2.7 fs @800 nm

    CEO phase

     f CEO   =!" 

    0

    2# T  R

    !" 0T  R   =

    1

     f rep

     E t ( ) =   A t ( )exp   i! ct  + i" 0 (t )( )

    Electric field

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    8/28

     f rep : pulse repetition rate frequency ,  f CEO : carrier envelope offset frequency

    How can we measure the frequency comb offset ?

     f rep 

     f CEO = 2 f 1 –  f 2 

     f CEO 

     f 2  2f 1 

    2f 1 = 2 f CEO + 2n f rep 

     f 2 =  f CEO + 2n f rep 

     f 1 

     f 1 =  f CEO + n f rep 

    octave spanning modelocked spectrum

    Mode beating of fundamental and second harmonic frequency comb f -to-2f  interference technique:  f CEO = 2 f 1 –  f 2 

    H.R. Telle, G. Steinmeyer, A.E. Dunlop, J. Stenger, D.H. Sutter and U. Keller, Appl. Phys. B 69, 327 (1999)

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    9/28

    Frequency combs from modelocked lasers

    unlocked repetition rate: f rep unlocked CEO: f CEO time average

    free-running passively modelocked laser 

    ! Femtosecond laser is for frequency the same as a ruler for length:

    .... but the „zero“ of the frequency ruler was not stabilized!

    Solution given how to stabilize the zero of the frequency ruler:

    H.R. Telle, G. Steinmeyer, A. E. Dunlop, J. Stenger, D. H. Sutter, U. Keller  

     Appl. Phys. B 69, 327 (1999)

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    10/28

    Optical Frequency Combs

    THz

    MHz

    undefined, optical

    frequency

    frequency

    intensity

    phase-stable link:

    optical to microwave

    intensity

    frequency

    beat 

    frequency

    intensity f rep, low

    f rep, high

    High gigahertz pulse repetition rate frequency combs: 

    •  higher power per mode

    • 

    easier to access individual lines•  more compact laser system

    GHz

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    11/28

    GHz oscillators w/o amplification or compression

    most recentmultimode

    pump diode

    Yb:CALGO

    SESAMoutput

    coupler 

    1-GHz cavity

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    12/28

    f rep

     = 1.8 GHz = 59.4 fs

    P av = 3.0 W P pk  = 24.3 kW

    = 1059.7 nm

    Combine ultrashort pulses & high power 

    !"#$ &'()

    #$*(+

    ,"!

    -

    Self-starting modelocking

    Reliable & robust pumping

    Compact & stable cavity

     A. Klenner et al., Opt. Express, vol. 22, no. 9, pp. 11884-11891, 2014

    !  p

    ! 0

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    13/28

    Si3N4 waveguide

    Substrate: Oxide-clad Silicon

    Top-Cladding: SiO2

    Cross section: 690 nm x 900 nm

    Length: 7.5 mm

    Bend radius: > 100 !m

    Nonlin. coeff.: " = 3.25 W-1m-1 @1055 nmD. J. Moss, R. Morandotti, A. L. Gaeta, and M.Lipson, Nature Photon. 7, 597-607 (2013)

    Silicon Nitride (Si3N4)

    •  VIS to 6 !m, negligible two-

    photon absorption at 1 !m

    •  10 times higher nonlinear index n2than silica

    •  CMOS-compatible

    600 800 1000 1200 1400 1600

    −60

    −40

    −20

    0

    wavelength (nm)

      s  p  e  c   t  r  a   l  p  o  w  e  r   (   d   B  c   )

     

    36 pJ

    one octave2f f

    680 nm 1360 nm

     A. S. Mayer, A. Klenner, A. R. Johnson, K. Luke, M. R. E. Lamont, Y. Okawachi, M. Lipson, A. L. Gaeta, U. Keller,Opt. Express 23, 15440-15451 (2015)

    0 0.2 0.4 0.6 0.8 1

    −80

    70

    −60

    −50

    −40

    −30

    −20

    −10

    0

     frep= 1.025 GHzRBW = 30 kHz f

    CEO,1 f

    CEO,2

    frequency (GHz)

      a  m  p   l   i   t  u   d  e   (   d   B  c   )

    > 40 dB

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    14/28

    Benefits of Si3N4 waveguide

    multimode

    pump diode

    Yb:CALGO

    SESAMoutput

    coupler 

    1-GHz cavity

      p  e  a   k  p  o  w  e  r   (   k   W   )

    repetition rate (GHz)

    0.34 kW

    First self-referenced frequency comb based on SCG in Si3N4 Chip 

    Moreover:

    •  First CEO-Stabilization with extra-

    cavity SCG requiring < 1kW

    •  304 mrad: Lowest RPN of any

    stabilized gigahertz diode-

    pumped solid state laser to date

    Towards stabilized multi-GHz DPSSLs and

    Semiconductor Disk Laser

    23.5 kW

     

    .

    .

    .

    .

    .

     

    fCEO

    = 73.9 MHz

     .

    span = 2 MHz

    RBW = 3 kHz

    100 averages

     

    −0.8   −0.4 0 0.4 0.8

    −60

    −50

    −40

    −30

    −20

    −10

    0

    frequency offset (MHz)

      s  p  e  c   t  r  a   l  p  o  w  e  r   (   d   B  c   )

    − −

     

       l

     

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    15/28

    Si3N4 waveguide instead of PCFs

    D. J. Moss, R. Morandotti, A. L. Gaeta, and M.Lipson, Nature Photon. 7, 597-607 (2013)

    Silicon Nitride (Si3N4)

    •  VIS to 6 !m, negligible two-

    photon absorption at 1 !m

    •  10 times higher nonlinear index n2than silica

    •  CMOS-compatible

    Vision: Full integration

      p  e  a   k  p  o  w  e  r   (   k   W   )

    repetition rate (GHz)

    0.34 kW

    Moreover:

    •  First CEO-Stabilization with extra-

    cavity SCG requiring < 1kW

    •  304 mrad: Lowest RPN of any

    stabilized gigahertz diode-

    pumped solid state laser to date

    Towards stabilized multi-GHz DPSSLs and

    Semiconductor Disk Laser

    23.5 kW

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    16/28

    Outline

    1)  Requirements for stabilized frequency combs

    based on modelocked lasers

    2)  New gigahertz frequency comb sources

    1) Diode-pumped Yb-doped solid-state lasers

    2) 

    Frequency comb stabilization with PCFs3)  Frequency comb stabilization with Si3N4 

    3)  New gigahertz frequency comb sources

    1) Semiconductor thin disk lasers: VECSELs, MIXSELs2) Dual comb modelocked lasers

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    17/28

    OPSLs = OP-VECSELs

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    18/28

    GHz oscillators w/o amplification or compression

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    19/28

    Overview and Highlight Laser Development

    1 mW

    10 mW

    100 mW

    1 W

    10 W

    Averageoutputp

    ower

    100 fs 1 p

    Pulse duration

     'VECSEls Keller'

     'MIXSELs'

     'VECSELs others'

    100 mW

    1 W

    10 W

    100 W

    1 kW

    10 kW

    Peakpower

    100 fs 1 ps 10 ps

    Pulse duration

     'Peak Power VECSELs Keller'

     'Peak Power MIXSELs '

     'Peak Power VECSELs others'

    shorter pulses

    higher peak power

    Laser development

    world leading andsignificant progress:

    First

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    20/28

    1 mW

    10 mW

    100 mW

    1 W

    10 W

    Averageoutputpower

    100 fs 1 pPulse duration

     'VECSEls Keller'

     'MIXSELs'

     'VECSELs others'

    Highlight: First sub-100-fs VECSEL

    Start

    shortest pulse duration from any

    fundamentally modelocked SDL

    pulse duration:   96 fs

    average output power: 100 mW

    repetition rate: 1.64 GHz

    peak power:   560 W

    Todaydone

    1.0

    0.8

    0.6

    0.4

    0.2

    0.0norm.intensity

    -400 -200 0 200 400time [fs]

    4

    3

    2

    1

    0

     ph  a s  e  [  r  a d  ]  

    !p = 96.1 fs

    1.0

    0.8

    0.6

    0.4

    0.2

    0.0

    norm.spec.intensity

    1060104010201000wavelength [nm]

    4

    3

    2

    1

    0

     s  p e c  t  r  al   ph  a s  e  [  r  a d  ]  

    FWHM:17.5 nm

     FROG OSA

    -80

    -60

    -40

    -20

    0

    intensity

    [dBc]

    6420-2-4-6offset frequency [MHz]

    f rep = 1.64 GHz span: 15 MHzRBW: 100 Hz

    -60

    -40

    -20

    0

    intensity

    [dBc]

    2015105

    frequency [GHz]

    RBW: 300 kHz

    VECSEL:

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    21/28

    1 mW

    10 mW

    100 mW

    1 W

    10 W

    Averageoutputpower

    100 fs 1 pPulse duration

     'VECSEls Keller'

     'MIXSELs'

     'VECSELs others'

    Highlight: First sub-300-fs MIXSEL

    Sub 300 fs MIXSEL any power

    End of year 3 milestone already done!

    pulse duration:   184 fs

    average output power: 115 mW

    repetition rate: 4.33 GHz

    center wavelength: 1048 nm 

    Todaydone

    1.0

    0.8

    0.6

    0.4

    0.2

    0.0

    autocorrelation

    [arb.u.]

    -400 0 400delay [fs]

    4

    3

    2

    1

    0

     ph  a s  e  [  r  a d  ]  

    !p= 184 fs

    1.0

    0.8

    0.6

    0.4

    0.2

    0.0

    spectralintensity

    [arb.

    u.]

    1060105010401030wavelength [nm]

    4

    3

    2

    1

    0

     ph  a s  e  [  r  a d  ]  

    FWHM:7.4 nm

     

    !c=

    1048.2 nm

     FROG OSA

    -80

    -60

    -40

    -200

    intensity

    [dBc]

    -4 0 4offset frequency [GHz]

    span: 15 MHzRBW: 100 Hz

    f rep= 4.33 GHz

    -60

    -40

    -20

    0

    intensity

    [dBc]

    2520151050frequency [GHz]

    RBW 30kHz

    shortest pulse duration from a

    MIXSEL

    MIXSEL:

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    22/28

    Highlight: Invention of dual comb modelocked lasers

    Patent Application:

    Swiss Patent filed 2. Oct. 2014

    International Patent:WO 2016/049787 A1

    published 7. April 2016filed 30. Sept. 2015

    First journal publication:

    S. M. Link, A. Klenner, M. Mangold, C. A. Zaugg,M. Golling, B. W. Tilma, U. Keller

    Optics Express 23, 5521, 2015

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    23/28

    OC

    MIXSEL chipheatsink 

    etalon

    OC

    MIXSEL chipheatsink 

    etalon

    birefringent

    crystal

    Dual-comb MIXSEL

    S. M. Link, A. Klenner, M. Mangold, C. A. Zaugg, M. Golling, B. W. Tilma, U. Keller,

    Optics Express, vol. 23, No. 5, pp. 5521-5531, 2015

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    24/28

    Dual comb MIXSEL

    MIXSEL chip

    heatsink 

    etalon

    birefringent

    crystal

    1 Hz, 100 MHz[ ]

    !16 ns

    ! 4 ps

    ??

    •  cavity length adjustment hasno effect on other beam

    • 

    phase noise of two beams

    sharing the same cavity is

    uncorrelated

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    25/28

    Pulse shift on saturable absorber 

    time

    leading edgeexperiences

    absorption

    pulse shifts in time each round-trip

      s  a   t  u  r  a   b   l  e  a   b  s  o

      r   b  e  r

    S. M. Link, A. Klenner, U. Keller“Dual-comb modelocked lasers: semiconductor saturable absorber mirror decouples noise stabilization”Optics Express, vol. 24, No. 3, pp. 1889-1902, 2016

    spatial overlap temporal overlap

    1 feedback loop

    time706050 706050403020

    time70605040 605040

    spatial overlap NO temporal overlap

    2 feedback loops

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    26/28

    Stabilization of both pulse repetition rates

    Photodetector

    electronic reference

    phase-lockedloop circuit

    f rep,1

    Photodetector

     #f rep-20

    -10

    0

    amplitude[dBc]

    20151050frequency [MHz]

    span 20 MHzRBW 10 kHz

    2!f rep

    !f repDC

    stabilization of f rep,1  stabilization of #f rep

    electronic reference

    phase-lockedloop circuit multimode

    pump

     

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    27/28

    Stabilization of both pulse repetition rates

    -120

    -100

    -80

    -60-40

    -20

    0

    20

    40

    phase

    noise

    [dBc/Hz]

    10

    0  

    10

    2  

    10

    4  

    10

    6  

    10

    8

    offset frequency [Hz]

     s-pol free-running

     s-pol lock !f rep with pump

      and lock p-pol f rep with piezo p-pol free-running

     p-pol s-pol lock !f rep with pump

      and lock p-pol f rep with piezo

     

    phase noise MIXSEL

    s-polarized beam stabilized

    p-polarized beam stabilized

  • 8/17/2019 MIXSEL2 - Nano-Tera 2016

    28/28

    MIXSEL chip

    heatsink 

    etalon

    birefringent

    crystal

    Conclusion

    MIXSELModelocked Integrated

    External-Cavity Surface

    Emitting Laser

    robust & reliable

    cost-efficient

    broadband & high power

    high repetition rates

    A new class of 

    frequency combs is evolving

    MIXSEL: towards semiconductor basedfrequency combs and dual comb lasers

    D. J. H. C. Maas, et al., APB 88, 493 (2007)

    S. M. Link, et al.,Optics Express 23, 5521 (2015)

      p  e  a   k  p  o  w  e  r   (   k   W   )

    repetition rate (GHz)

    0.34 kW

    Silicon Nitride (Si3N4)