Optical Frequency Comb Generation from a ... - Semantic Scholar
Optical Frequency Comb Generation from a Monolithic Microresonator Pascal Del‘Haye, Albert Schliesser, Olivier Arcizet, Tobias Wilken, Ronald Holzwarth and Tobias Kippenberg Max-Planck-Institute for Quantum Optics, Germany Frontiers in Optics 2007/Laser Science XXIII September 2007
Frequency Combs Kerr lens mode-locked laser:
cavity roundtrip time τ = 1 / f rep
Aperture Ti:Al2O3
pulse train chirped mirror
outcoupling mirror
pump Pulse train in time domain
Equidistant lines in frequency domain.
f n = f CE + n ⋅ f rep
n = Integer number
2π ⋅ f rep =
Hz S. T. Cundiff. Phase stabilization of ultrashort optical pulses. Journal Of Physics D-Applied Physics, 35(8):R43–R59, April 2002. 2 P. Del‘Haye – Kerr Combs – FIO 2007
Toroid Microcavities on-a-Chip
• Optical whispering gallery modes with very long photon lifetimes: Q>108 can be obtained Photon lifetimes of several 100 ns Finesse in excess of 1,000,000 • Small mode volume • Silicon compatible Built on a silicon wafer Integration with other function
Vahala Group
Armani, Kippenberg, Spillane, Vahala, Nature 421, 925-928 (2003). P. Del‘Haye – Kerr Combs – FIO 2007
3
Toroidal Microcavities Fabrication using standard microfabrication techniques (b)
(a)
2 μm silica layer on silicon wafer
Silica pads on silicon wafer after lithography, HF-etching
CO2 laser beam
silica silicon
(c)
Free standing silica discs after XeF2 dry etching
Ultra-high-Q: Q=ωτ up to 6x108
CO2 laser assisted reflow Wavelength λ=10.6 μm absorbed by silica, silicon transparent
P. Del‘Haye – Kerr Combs – FIO 2007
4
Tapered Fiber Coupling critical coupling
Ecavity
Et
T=|E-E|2=0
T
Taper-microcavity junction exhibits extremely high ideality (coupling losses 0 for λ > 1300 nm:
For wavelengths > 1300 nm, material and waveguide dispersion can be compensated!
P. Del‘Haye – Kerr Combs – FIO 2007
9
Dispersion Measurement Utilizing a fiber laser frequency comb to measure the FSR of a microcavity. foffset
Distance between cold microcavity modes:
Δf = f offset + n ⋅ f rep
n = Number of fiber comb lines between two microcavity resonances
P. Del‘Haye – Kerr Combs – FIO 2007
10
Dispersion Measurement ωFSR1
ωFSR2
ωFSR3
ωFSR4
ω 1516 nm
Dispersion of a cold toroidal microcavity: ~3 MHz/FSR 1577 nm
Accumulated dispersion in a 70 μm diameter microcavity over a wavelength range of 61 nm [1577nm…1516nm] P. Del‘Haye – Kerr Combs – FIO 2007
11
Microcavity combs?
Are the lines equidistant?!
P. Del‘Haye – Kerr Combs – FIO 2007
12
Frequency combs for metrology Unknown optical frequency Frequency comb lines with known frequencies (Mode spacing ~ 100 MHz)
νN-2
ν0
νN-1
νN
νN+1 ν
Radio frequency beat note with νB = νN - ν0 The beat note frequency can be measured with radio frequency counters.
Hz P. Del‘Haye – Kerr Combs – FIO 2007
13
Equidistance of Comb Lines Superimposing two frequency combs...
Kerr Comb
Fiber Laser Comb
Multi-Heterodyne1) ωbeat1
Measurement: ωbeat2
1 THz
ωbeat3 100 MHz
optical frequency (THz)
ωbeat1
ωbeat2
RF beat notes
Photodiode
Fiber Laser Comb Line (100 MHz spacing) Kerr Comb Line (1 THz spacing)
ωbeat3 Beat Note
radio frequency (MHz)
An equidistant beat note spectrum can be generated by superimposing two equidistant combs. P. Del‘Haye – Kerr Combs – FIO 2007
1) Schliesser, Brehm, Keilmann, van der Weide, Optics Express, 13, 1929 (2005)
14
Equidistance of Comb Lines Optical Domain
Fiber Laser Comb
⊗
Radio Frequency Domain Beat note spectrum:
=
Kerr Comb
Kerr lines are proved to be equidistant to a level of 2 kHz = 1 x 10 200 THz
-13
First demonstration of frequency comb generation in a monolithic microcavity! P. Del‘Haye – Kerr Combs – FIO 2007
15
Counting the sidebands
Frequency Counter
P. Del‘Haye – Kerr Combs – FIO 2007
16
Counting the sidebands Accuracy relative to the optical carrier: 5.5 mHz / 200 THz = 3 · 10 -17
Allan deviation: N −1 1 2 σA = ⋅ ∑ ( yi +1 − yi ) Measure of the relative accuracy 2( N − 1) i =1 that can be obtained with a certain gate time.
P.Del’Haye, A. Schliesser, O. Arcizet, T. Wilken, K. Vahala, R. Holzwarth, T. J. Kippenberg (arXiv:0708.0611) P. Del‘Haye – Kerr Combs – FIO 2007
17
Thermal drift of the modespacing
Kerr comb modes Stabilized reference comb modes P. Del‘Haye – Kerr Combs – FIO 2007
ω
18
Kerr Comb Actuators Two control variables to define all lines of a frequency comb: Microcavity comb: Modelocked Laser: Carrier envelope offset frequency fCEO Pump frequency fP Repetition rate frep Mode spacing Δν Controlled by pump power Pump power control
Pump frequency control
pump beat P. Del‘Haye – Kerr Combs – FIO 2007
sideband beat 19
Stability of the Kerr Comb Lock Gatetime 1s Modespacing Locked with microcavity pump power Pump Frequency Standard lock of a diode laser to a reference laser
P. Del‘Haye – Kerr Combs – FIO 2007
20
Conclusion
Summary • Frequency combs spanning 500 nm have been generated • Equidistance has been proved to a level of 7.3x10-18 • Locking has been demonstrated Advantages • Monolithic on-chip design • High power per comb line (1 mW/combline can be easily achieved) • High repetition rate (>100 GHz) Single comb lines accessible Future Research • Increase cavity diameter for mode spacings in the microwave domain • Generate octave spanning spectra • Time domain behaviour?!
P. Del‘Haye – Kerr Combs – FIO 2007
Future Applications • Pulse shaping • Spectrometer calibration • Multi-channel telecommunication 21
Funding Max Planck Generalverwaltung via an Independent Max Planck Junior Research Group
MPQ
Marie Curie Reintegration Grant (IRG) Marie Curie Excellence Grant (EXT) NIM Initiative
Nano-Science European Research Area
P. Del‘Haye – Kerr Combs – FIO 2007
22
Acknowledgments
Tobias Kippenberg Group Leader
Olivier Arcizet (Postdoc)
Albert Schliesser (PhD) Cavity Cooling, combs
Remi Riviere (PhD) Cavity Cooling
Bastian Schroeter (Diplom) Biochemical Sensing
Remi Riviere (PhD) Cooling Project
Georg Anetsberger (Diplom) Mechanical Dissipation
Jens Dobrindt (Diplom) Cooling Theory
Xiaoqing Zhou (PhD) Coulomb Cooling
Yang Yang (PhD) Coulomb Cooling
Thank you for your attention! www.mpq.mpg.de/k-lab P. Del‘Haye – Kerr Combs – FIO 2007
23
End
P. Del‘Haye – Kerr Combs – FIO 2007
24
Frequency Combs Kerr lens mode-locked laser:
cavity roundtrip time τ = 1 / f rep
Aperture Ti:Al2O3
pulse train chirped mirror
outcoupling mirror
pump Pulse train in time domain
Equidistant lines in frequency domain.
f n = f CE + n ⋅ f rep
n = Integer number
2π ⋅ f rep =
Hz S. T. Cundiff. Phase stabilization of ultrashort optical pulses. Journal Of Physics D-Applied Physics, 35(8):R43–R59, April 2002. 2 P. Del‘Haye – Kerr Combs – FIO 2007
Toroid Microcavities on-a-Chip
• Optical whispering gallery modes with very long photon lifetimes: Q>108 can be obtained Photon lifetimes of several 100 ns Finesse in excess of 1,000,000 • Small mode volume • Silicon compatible Built on a silicon wafer Integration with other function
Vahala Group
Armani, Kippenberg, Spillane, Vahala, Nature 421, 925-928 (2003). P. Del‘Haye – Kerr Combs – FIO 2007
3
Toroidal Microcavities Fabrication using standard microfabrication techniques (b)
(a)
2 μm silica layer on silicon wafer
Silica pads on silicon wafer after lithography, HF-etching
CO2 laser beam
silica silicon
(c)
Free standing silica discs after XeF2 dry etching
Ultra-high-Q: Q=ωτ up to 6x108
CO2 laser assisted reflow Wavelength λ=10.6 μm absorbed by silica, silicon transparent
P. Del‘Haye – Kerr Combs – FIO 2007
4
Tapered Fiber Coupling critical coupling
Ecavity
Et
T=|E-E|2=0
T
Taper-microcavity junction exhibits extremely high ideality (coupling losses 0 for λ > 1300 nm:
For wavelengths > 1300 nm, material and waveguide dispersion can be compensated!
P. Del‘Haye – Kerr Combs – FIO 2007
9
Dispersion Measurement Utilizing a fiber laser frequency comb to measure the FSR of a microcavity. foffset
Distance between cold microcavity modes:
Δf = f offset + n ⋅ f rep
n = Number of fiber comb lines between two microcavity resonances
P. Del‘Haye – Kerr Combs – FIO 2007
10
Dispersion Measurement ωFSR1
ωFSR2
ωFSR3
ωFSR4
ω 1516 nm
Dispersion of a cold toroidal microcavity: ~3 MHz/FSR 1577 nm
Accumulated dispersion in a 70 μm diameter microcavity over a wavelength range of 61 nm [1577nm…1516nm] P. Del‘Haye – Kerr Combs – FIO 2007
11
Microcavity combs?
Are the lines equidistant?!
P. Del‘Haye – Kerr Combs – FIO 2007
12
Frequency combs for metrology Unknown optical frequency Frequency comb lines with known frequencies (Mode spacing ~ 100 MHz)
νN-2
ν0
νN-1
νN
νN+1 ν
Radio frequency beat note with νB = νN - ν0 The beat note frequency can be measured with radio frequency counters.
Hz P. Del‘Haye – Kerr Combs – FIO 2007
13
Equidistance of Comb Lines Superimposing two frequency combs...
Kerr Comb
Fiber Laser Comb
Multi-Heterodyne1) ωbeat1
Measurement: ωbeat2
1 THz
ωbeat3 100 MHz
optical frequency (THz)
ωbeat1
ωbeat2
RF beat notes
Photodiode
Fiber Laser Comb Line (100 MHz spacing) Kerr Comb Line (1 THz spacing)
ωbeat3 Beat Note
radio frequency (MHz)
An equidistant beat note spectrum can be generated by superimposing two equidistant combs. P. Del‘Haye – Kerr Combs – FIO 2007
1) Schliesser, Brehm, Keilmann, van der Weide, Optics Express, 13, 1929 (2005)
14
Equidistance of Comb Lines Optical Domain
Fiber Laser Comb
⊗
Radio Frequency Domain Beat note spectrum:
=
Kerr Comb
Kerr lines are proved to be equidistant to a level of 2 kHz = 1 x 10 200 THz
-13
First demonstration of frequency comb generation in a monolithic microcavity! P. Del‘Haye – Kerr Combs – FIO 2007
15
Counting the sidebands
Frequency Counter
P. Del‘Haye – Kerr Combs – FIO 2007
16
Counting the sidebands Accuracy relative to the optical carrier: 5.5 mHz / 200 THz = 3 · 10 -17
Allan deviation: N −1 1 2 σA = ⋅ ∑ ( yi +1 − yi ) Measure of the relative accuracy 2( N − 1) i =1 that can be obtained with a certain gate time.
P.Del’Haye, A. Schliesser, O. Arcizet, T. Wilken, K. Vahala, R. Holzwarth, T. J. Kippenberg (arXiv:0708.0611) P. Del‘Haye – Kerr Combs – FIO 2007
17
Thermal drift of the modespacing
Kerr comb modes Stabilized reference comb modes P. Del‘Haye – Kerr Combs – FIO 2007
ω
18
Kerr Comb Actuators Two control variables to define all lines of a frequency comb: Microcavity comb: Modelocked Laser: Carrier envelope offset frequency fCEO Pump frequency fP Repetition rate frep Mode spacing Δν Controlled by pump power Pump power control
Pump frequency control
pump beat P. Del‘Haye – Kerr Combs – FIO 2007
sideband beat 19
Stability of the Kerr Comb Lock Gatetime 1s Modespacing Locked with microcavity pump power Pump Frequency Standard lock of a diode laser to a reference laser
P. Del‘Haye – Kerr Combs – FIO 2007
20
Conclusion
Summary • Frequency combs spanning 500 nm have been generated • Equidistance has been proved to a level of 7.3x10-18 • Locking has been demonstrated Advantages • Monolithic on-chip design • High power per comb line (1 mW/combline can be easily achieved) • High repetition rate (>100 GHz) Single comb lines accessible Future Research • Increase cavity diameter for mode spacings in the microwave domain • Generate octave spanning spectra • Time domain behaviour?!
P. Del‘Haye – Kerr Combs – FIO 2007
Future Applications • Pulse shaping • Spectrometer calibration • Multi-channel telecommunication 21
Funding Max Planck Generalverwaltung via an Independent Max Planck Junior Research Group
MPQ
Marie Curie Reintegration Grant (IRG) Marie Curie Excellence Grant (EXT) NIM Initiative
Nano-Science European Research Area
P. Del‘Haye – Kerr Combs – FIO 2007
22
Acknowledgments
Tobias Kippenberg Group Leader
Olivier Arcizet (Postdoc)
Albert Schliesser (PhD) Cavity Cooling, combs
Remi Riviere (PhD) Cavity Cooling
Bastian Schroeter (Diplom) Biochemical Sensing
Remi Riviere (PhD) Cooling Project
Georg Anetsberger (Diplom) Mechanical Dissipation
Jens Dobrindt (Diplom) Cooling Theory
Xiaoqing Zhou (PhD) Coulomb Cooling
Yang Yang (PhD) Coulomb Cooling
Thank you for your attention! www.mpq.mpg.de/k-lab P. Del‘Haye – Kerr Combs – FIO 2007
23
End
P. Del‘Haye – Kerr Combs – FIO 2007
24
