Principle

Principle

Optical Frequency Comb Generator is an Electro-Optic (LiNbO3) modulator inside a Fabry-Perot cavity. It generates thousands of sidebands (discrete spectra) and a wide comb span (>6THz) modulated by microwave. An interval between sidebands is completely equal to a modulation frequency. All of components are passive and a center frequency is as same as a frequency of input stabilized laser. It fully Covers C-band of DWDM optical communications. Modulation frequency 10GHz(waveguide), 25GHz(waveguide) as standard models are now on sale.

Outline of Absolute Distance Meter Absolute distance Meter measures obejects in 5 meters range with high accuracy 1μm using Optical Comb Interferometer. Resolution achieves 0.1nm in specified condition. There is no need zero setting while measuring, therefore real time measurements are realized which help various industries and applications. This system is non-contact and non-destructive to obejects. Industries and Applications Industries Wind-power, Turbine, Aerospace, Ship, Railway Automotive ; Engines, Flames Heavy equipments ; Tires, Body Applications Alignment, Positioning, Installation, Inspection, Reverse engineering, Health monitoring, etc.

**Industries**：Wind-power, Turbine, Aerospace, Ship, Railway

Automotive ; Engines, Flames

Heavy equipments ; Tires, Body Applications：Alignment, Positioning, Installation, Inspection, Reverse engineering, Health monitoring, etc.

Non-contact 3D Profilometer measures surface shape of objects in mm~ meters range sith high accuracy 1μm using Optical Comb Interferometer. There is no need zero setting while measuring, therefore high speed measurements are realized which help various industries and applications. This system is non-contact and non-destructive to objects.

**Industries**：Wind-power, Turbine, Aerospace, Ship, Railway

Automotive ; Engines, Flames

Heavy equipments ; Tires, Body

Impellers

**Applications**：Non-destructive test, Alignment, Positioning, Health monitoring, etc.

Multipoint Vibrometer measures vibrations of objects at 100 points simultaneously. There is no need scanning laser using built-in Optical Comb Interferometer, therefore complicated vibrations are visualized in real time which help various industries and applications. Accuracy is up to 1μm. This system is non-contact and non-destructive to objects. Microscopic samples are also available.

**産業分野**： Wind-power, Turbine, Aerospace, Ship, Railway

Automotive ; Engines, Flames

Heavy equipments ; Tires, Body

MEMS industries

**Applications**： Inspection of various vibrations ; Surface Waves, Ultrasonic Waves, Solid of revolution, Amplitude, Noise, etc.

Optical Comb of fm spacing is generated from the input stabilized laser of frequency f0. The laser-under-test with frequency fx generates beat signal of frequency fb with the k-th order of the comb sideband. The frequency fx is calculated by the equation fx=f0+k*fm+ fb.

◆Applications:Laser frequency stabilization, Phase locking for Tera-Hertz(THz) synthesis, Spectroscopy, Optical measurement, etc.

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「Absolute Optical Frequency Measurement by Optical Frequency Comb」

We developed an absolute optical frequency measurement system by optical comb into all-in-one unit and released as a product, "Optical Frequency Counter". By introducing this device to your laboratory, you can apply optical frequency standard.

◆Example : Precise measurement for the output frequency of the light source

- Fluctuation of the output frequency of the light source can be observed in the form of microwave signal.

- MF-5802A shows the behavior of the light source, which cannot be observed by the conventional methods.

■Phase-Locked Tera-Hertz(THz)-frequency Synthesis Using Optical Frequency Comb Generator

Optical Frequency Comb Generator(OFCG) is an absolute optical frequency grid because OFCG creates a broad comb of equally spaced frequencies and the comb has rigid phase differences. Using this grid, difference frequency (νTHz) between (ν0) and (ν1) is phased-locked to RF (fm). Therefore, it can obtain stable phase-locked Tera-Hertz(THz) frequency.

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「Phase-Locked Tera-Hertz(THz)-frequency Synthesis Using Optical Frequency Comb Generator」

- T.Kanemura, H.Kondo, T.Furukawa, Y.Hirakawa, E.Hoashi, S.Yoshihashi, H.Horiike and E.Wakai "Measurement of Li target thickness in the EVEDA Li Test Loop", Fusion Engineering and Design, Vol.98-99, pp.1991-1997 (2015)
- T.Kanemura, H.Kondo, E.Hoashi, S.Y.Suzuki, N.Yamaoka, H.Horiike, T.Furukawa, Y.Hirakawa and E.Wakai "Evaluation of applicability of laser-based distance meter to measure Li-jet thickness for IFMIF/EVEDA project", Fusion Engineering and Design, Vol.89, Issues.7-8, pp.1642-1647 (2014)
- S.Xiao, L.Hollberg, N.R.Newbury and S.A.Diddams. "Toward a low-jitter 10GHz pulsed source with an optical frequency comb generator", Optics Express, Vol.16, No.12 (2008)
- M.Kourogi, Y.Kawamura, Y.Yasuno, H.Oyaizu, H.Miyao, K.Imai. "Programmable High speed (~1MHz) Vernier-mode-locked Frequency-Swept Laser for OCT imaging", Proceedings of SPIE BiOS, Vol.6847, 68470Z (2008)
- Z.Jiang, D.E.Leaird, C.Huang, H.Miao, M.Kourogi, K.Imai and A.M.Weiner. "Spectral Line-by-Line Pulse Shaping on an Optical Frequency Comb Generator", IEEE Journal of Quantum Electronics, Vol.43, No.12, pp.1163-1174 (2007)
- M.Kourogi, K.Imai and B.Widiyatmoko. "Advances in Electro-Optic Modulator based Frequency Combs", Proceedings of LEOS2005 Summer Topical Meeting, WB2.1 (2005)
- K.Imai, B.Widiyatmoko and M.Kourogi. "High finesse waveguide cavity optical frequency comb generator", Proceedings of ECOC2004, We4.P.044 (2004)
- S.J. Lee, B.Widiyatmoko, M.Kourogi and M.Ohtsu. " Ultrahigh Scanning Speed Optical Coherence Tomography.", Japan Journal of Applied Physics, Vol.40 (2001) pp. L878-L880
- M.Kourogi, B.Widiyatmoko, K.Imai and M.Ohtsu "Generation of Expanded Optical Frequency Combs", Book Editor by A.N Luiten, " Frequency Measurements and Control", Springer-Verlag Berlin Heidelberg 2001, pp 315-335
- Th.Udem, J.Reichert, T.W.Hansch, and M.Kourogi. "Absolute Optical Frequency Measurement of the Cesium D2 Line", Phys. Rev. A 62, 031801 (2000)
- M.Kourogi, B.Widiyatmoko, K.Imai and M.Ohtsu, "Continuous tuning of an electrically tunable external cavity semiconductor laser.", Optics letters Vol 15, No 16, pp. 1165-1167 August 2000
- A.Onae, K.Okumura, J.Yoda, K.Nakagawa, A.Yamaguchi, M.Kourogi, K.Imai and B.Widiyatmoko, "Towards an accurate frequency standard at 1.5 um based on acetylene overtone transition" Conference on Precision Electromagnetic measurement" (IEEE Trans Instrumentation and measurement, Vol.48, No.2, April 1999)
- K.Imai, M.Kourogi, B.Widiyatmoko and M.Ohtsu, "12 THz frequency difference measurement and noise analysis of an optical frequency comb in optical fiber", IEEE.J.Quantum Electronics , Vol 35, NO:4, April 1999
- B.Widiyatmoko, M.Kourogi, and M.Ohtsu, " Linking of two optical frequency comb by heterodyne optical phase locking", IEEE Photonics Technology Letters, Vol.11, NO 4. April 1999
- B.Widiyatmoko, M.Kourogi, K.Imai and M.Ohtsu, " Second harmonics generation of optical frequency comb at 1.55um using periodically poled lithium niobate", Opt.Lett. Vol 24, No5, March 1, 1999
- K.Imai, Y.Zhao, M.Kourogi , B.Widiyatmoko and M.Ohtsu, "Accuracy of optical frequency comb generation in optical fiber" Opt.Lett . Vol 24. No.4, February 15,1999
- M.Kourogi, B.Widiyatmoko, K.Imai and M.Ohtsu, "Accurate relative frequency cancellation between two independent lasers" Opt.Lett. Vol 24, No1, pp.16-18 January 1, 1999
- C. Ishibashi, M.Kourogi, K.Imai, B.Widiyatmoko, A.Onae and H.Sasada "Absolute frequency measurement of the saturated absorption lines of methane at the 1.66 um region, Optics communications Vol.161, pp 223-226 (1999)
- T.Udem, A.Huber, J.Reichert, B.Gross, M.Prevedelli, M.Weitz, M.Kourogi and T.W. Hansch."Phase-Coherent Frequency Measurement of the Hydrogen 1S-2S Transition", Proceedings of the XIII International Conference on Laser Spectroscopy (ICOLS’97), Z.J.Wang, Z.M.Zhang and Y.Z.Wang eds., World Scientific, Singapore (1998)
- A.Huber, Th.Udem, B.Gross, J.Reichert, M.Kourogi, K.Pachucki, M.Weitz and T.W. Hansch. "Hydrogen-Deuterium 1S-2S Isotope Shift and the Structure of the Deuteron", Phys. Rev. Lett., 80, 468 (1998)
- K.Imai, M.Kourogi, and M.Ohtsu, " 30-THz span optical frequency comb generation by self-phase modulation in optical fiber.", IEEE.Journal. Q.Electron. Vol. 34, No. 1, pp. 54-60, 1998
- M.Kourogi, B.Widiyatmoko, and M.Ohtsu," 3.17 THz Frequency Difference measurement between lasers using two optical frequency comb generator", IEEE Photonics Technology Letters, Vol.8, NO 4. April 1996
- T. Saitoh, M. Kourogi, and M.Ohtsu. " Expansion of span-width of an optical frequency comb using a higher harmonic wave modulation.", IEEE Photon. Technol. Lett. Vol. 8, No. 6. pp.1379-1381, 1996
- M.Kourogi, T. Enami, and M.Ohtsu. " A coupled-cavity monolithic optical frequency comb generator.", IEEE Photon.Techol. Lett., Vol. 8, No. 12. Pp 1698-1700, 1996
- M.Kourogi, B.Widiyatmoko, T.Takeuchi, and M.Ohtsu, "Limit of optical frequency comb generation due to material dispersion", IEEE.J.Quantum Electronics Vol 31, NO.12, December 1995
- T.Kanemura, H.Kondo, E.Hoashi, S.Y.Suzuki, N.Yamaoka, H.Horiike, T.Furukawa, Y.Hirakawa and E.Wakai "Evaluation of applicability of laser-based distance meter to measure Li-jet thickness for IFMIF/EVEDA project", Fusion Engineering and Design, Vol.89, Issues.7-8, pp.1642-1647 (2014)
- M.Kourogi, B.Widiyatmoko, T.Enami, and M.Ohtsu, "Study on the development of Optical Frequency Difference Measurement using Optical frequency comb generator". Technical report of IEICE, OPE94-114,LQE93-93 (1995) ( in Japanese)
- M.Kourogi, T.Enami, M.Ohtsu: " Monolithic optical frequency comb generator". IEEE Photon Technol Lett, Vol 6, No 2, pp 214-217 (1994)
- M.Kourogi, K. Nakagawa, and M.Ohtsu, " Wide span optical frequency comb generator for accurate optical frequency difference measurement.", IEEE J. Quantum Electronics, Vol. 29 No. 10. pp 2693-2701, 1993