NMIJ-BIPM Joint Workshop 2007 Optical Frequency Comb - Comb, Fiber and ...
Optical Fiber and its Application .... OCT (Optical Coherence Tomography). OCT.
Highly Nonlinear Fibers and Their Applications Masaaki HIRANO Optical Communications R&D Laboratories, Sumitomo Electric Industries, Ltd. NMIJ-BIPM Joint Workshop 2007 Optical Frequency Comb - Comb, Fiber and Metrology Tsukuba, 2007.05.18 1/20
Outline 1. Silica Fiber Technology and Highly Nonlinear Fiber 2. Supercontinuum Generation in Fiber 3. Comparison of Highly Nonlinear Fiber to Photonic Crystal Fiber 4. Summary
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Optical Fiber and its Application Major Application: Optical Signal Transmission
Profile of Single Mode Fiber (SMF) Refractive Index; n
Core
Cladding 10mm
Core GeO2 – SiO2
125mm
Cladding pure SiO2
Coating 250mm 3/20
Optical Fiber as Functional Devices - Optical Amplifier (Er-Doped Fiber) - Optical Filter (Fiber Bragg Grating) - Dispersion Compensating Fiber - Image Guiding Fiber - Fiber Laser (Yb-doped Fiber, Er-doped Fiber)
- Highly Nonlinear Fiber (HNLF)
4/20
…
Efficiency of Nonlinearity Generation in Fiber SiO2 Glass: Low Nonlinearity BUT…
Fiber shows High Nonlinearity - Tight Confinement of Optical Power into Small Core Area - Ultimately Low Attenuation ( 1350 [nm]
0.2 [dB/km] 1310 [nm]
Zero Dispersion Wavelength 8/20
HNLF Application for Future Photonic Network HNLF Coil
Signal (Probe)
Short-Pulse Laser Source
Pumping Optical Amplifier
Wavelength Conversion Pump Four Wave Mixing (FWM) Signal
(SC Generation) Cross Phase Modulation (XPM), Self Phase Modulation (SPM), SRS, FWM…
Idler (Newly Generated)
l2
l1
l
Raman Amplifier Pump
Supercontinuum Generation
Stimulated Raman Scattering (SRS) l 9/20
l
l
SC Generation for Telecomm Light Source ps Pulsed Laser with Watts Peak Power HNLF
SC Generation
“Telecomm” Multiwavelength Light Source Proposed by NTT in 1993 7.6ps, 100W (Peak)
1224 – 1394nm
(Dl = 170nm)
T. Morioka, et al., Electronics Letters 29, 862-864 (1993). 10/20
Highly Efficient SC Generation in “DFDF” 10 Input
5 0 -5 1450
Output 1500 1550 1600 1650 Wavelength [nm]
Dispersion [ps/nm/km]
Dispersion [ps/nm/km]
Dispersion Flattened and Decreasing Fiber (DFDF) 10 5 0 -5 0
250 500 750 Length [m]
1000
Evaluated Broadband SC Spectrum
Peak=3W ML-EDFL Mode-locked EDF ring laser
280nm
DFDF (1km) OSA
Intensity [a.u., dB]
Input Pulse: 10GHz, 3ps
0 DFDF -10 -20 -30 Uniform Disp. Fiber -40 1350 1450 1550 1650 1750 Wavelength [nm]
T. Okuno et al., IEEE Photonics Technol. Letters 10, 72-74 (1998). T. Okuno et al., Electronics Letters 39, 972-974 (2003). 11/20
Octave Spanning SC generation fs Pulsed Laser with kilo-Watts Peak Power HNLF Input Pulse: HNLF 75MHｚ, 210fs Ave. = 89mW, Peak=2kW
Ultrabroad SC Generation
(10m)
Output [a.u., dB]
0
12/20
1140 – 2400 nm (Dl = 1260nm)
-20
-40 1000
1400
1800 2200 Wavelength [nm]
2600
- Metrology
Intensity
Possible Applications SHG
- Spectroscopy
Absorbance
1000
1400 1800 Wavelength [nm]
2200
Water
800
1000 1200 1400 Wavelength [nm]
- OCT (Optical Coherence Tomography) OCT
… 13/20
Ophthalmologic Examination
SC Spectrum Shape Control?
Measured&Calculated Dispersion [ps/km/nm]
Spectral Modification by Fiber Characteristics? +10
Measured (1520-1640)
+5 0
HNLF-3 +6.7ps/km/nm
l0 =1535nm +0.3
l0 ~1377nm
-0.14
-5
HNLF-2 HNLF-1
Pump -10 1300 1350
1400
1450 1500 1550 Wavelength [nm]
1600
1650 1700
Relation between Dispersion Characteristics and SC-Spectra Shape ?
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Dispersion [ps/km/nm]
SC-Spectra with Different Dispersion
Intensity [dBm/nm]
+10 0 HNLF-3
HNLF-2
-10
+10 HNLF-3
+5
HNLF-2
0
HNLF-1
-5 -10 1300
1400 1500 1600 Wavelength [nm]
1700
HNLF-1
-20 -30 920nm -40 900
1110nm 1100
1380nm
1300 Wavelength [nm]
1500
1700
SC-Spectra Shape (Wavelength Range, Ripple, etc.) : Controlled by HNLF Dispersion Characteristics 15/20
SC Generation in Photonic Crystal Fiber
Photonic Crystal Fiber (PCF) Photograph of supercontinuum generation in PCF University of Bath, http://www.bath.ac.uk/physics/groups/cppm/pcf_supercontinuum.php
16/20
HNLF or PCF? HNLF
PCF
g [/W/km]
10~30
10~100
Zero-Disp. Wavelength [nm]
>1350
>700
SC Spectral Range Dispersion Controllability Coupling Loss [dB]
800 ~ 2500nm
400~2000nm
High
Difficult
~0.1dB/end
~1dB/end
Polarized Mode Coupling Low PMD (~0.1ps/√km)
or PMF
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High PMD or PMF
Zero-disp. Wavelength (l0) [nm]
Dispersion Controllability of HNLF 1610 1590
GeO2-SiO2
1530 -1.0
(Calculation) D+=1%
1570 1550
D+=3% Core
Dl0 ~ 8nm/%
Dl0 ~ 33nm/% -0.5
0
0.5
1.0
Relative core diameter change [%] Zero-disp. Wavelength (l0) [nm]
Longitudinal Dispersion Uniformity
PCF… ?
1550
Dl0 < +/- 1.0nm
1540 1530 1520
18/20
Sumitomo Fabricated 0
1.0
2.0
Fiber Length [km]
3.0
Longitudinal Uniformity for SC Spectrum
Intensity [dBm/nm]
Five 1-m-long Samples from one Spool 1m
1m
1m
1m
1m
A
B
C
D
E
0 -10 -20 -30 -40 -50 800
19/20
966 ~ 974nm Dl=8nm 1000
1200 1400 Wavelength [nm]
1600
1800
Conclusion Highly Nonlinear Fibers - Promising Optical Devices for Future Photonic Network
SC generation in Silica-Based HNLF -SC Spectrum Shape Control by Dispersion Characteristics of HNLF
SC Generation in PCF or HNLF? - PCF: VIS – NIR SC Spectral Range due to Dispersion Flexibility PMD and Dispersion Fluctuation Large - HNLF: NIR Limited SC Spectral Range PMD and Dispersion Fluctuation
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Negligible
