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Optical pulse compressor, optical function generator, optical pulse compression method, and optical function generation method

外国特許コード F110005732
整理番号 Y0368WO
掲載日 2011年9月12日
出願国 アメリカ合衆国
出願番号 55364904
公報番号 20070025728
公報番号 7428096
出願日 平成16年3月23日(2004.3.23)
公報発行日 平成19年2月1日(2007.2.1)
公報発行日 平成20年9月23日(2008.9.23)
国際出願番号 JP2004003937
国際公開番号 WO2004092810
国際出願日 平成16年3月23日(2004.3.23)
国際公開日 平成16年10月28日(2004.10.28)
優先権データ
  • 特願2003-109708 (2003.4.15) JP
  • 2004JP003937 (2004.3.23) WO
発明の名称 (英語) Optical pulse compressor, optical function generator, optical pulse compression method, and optical function generation method
発明の概要(英語) A small-sized, high-functionality optical pulse compressor capable of generating a low-power, high-repetition-frequency ultrashort pulse train used for ultrafast optical communication and photometry, and a simple-structure optical function generator for realizing an arbitrary time waveform.
The optical pulse compressor comprises and optical Fourier transform device (F) having an optical phase modulator ( 9 ) driven by the repetition-frequency of an input optical pulse train and a dispersive medium ( 8 ), for converting the shape of an input optical pulse frequency spectrum into its time waveform, and an optical filter ( 3 ) inserted ahead of the optical Fourier transform device (F), for reducing the spectrum width of an input optical pulse, wherein the optical Fourier transform device (F) converts a small-spectrum-width optical pulse output from the optical function generator generates an optical pulse.
The optical function generator generates an optical pulse having an arbitrary time waveform by reproducing, as it is, a spectrum waveform-shaped arbitrarily by an optical filter on a time-axis by the optical Fourier transform device (F).
従来技術、競合技術の概要(英語) BACKGROUND ART
General optical pulse compression technology can be broadly divided into a pulse compression technique using an optical fiber and a pair of diffraction gratings (first conventional technique) and a pulse compression technique based on soliton effect using a dispersion-decreasing fiber (second conventional technique).
When a strong optical pulse is launched into a fiber, the first conventional technique converts the pulse into a broadband rectangular pulse having a linear chirp by normal dispersion and non-linearity (self-phase modulation effect) of the fiber.
Then, the linearly chirped pulse is dispersion-compensated through anomalous dispersion realized artificially by the pair of diffraction gratings, and the width of the input pulse is greatly reduced (non-patent documents 1 and 2).
Non-patent document 2 reports an example of compressing an optical pulse train having a repetition frequency of 10 GHz and a pulse width of 7.1 ps to 720 fs at a wavelength of 1548 nm.
The second conventional technique compresses a soliton pulse width by decreasing the anomalous dispersion value of the fiber adiabatically while maintaining the soliton property along the direction of propagation (by changing the dispersion gradually).
The principle used here is that a soliton keeps a constant level of energy by automatically varying the pulse width with a change in dispersion (non-patent documents 3 and 4).
Non-patent document 4 reports an example of compressing, with the use of a dispersion-decreasing fiber, an optical pulse train having a repetition frequency of 10 GHz and a pulse width of 3 ps to 170 fs at a wavelength of 1550 nm.
Conventional optical function generators and optical pulse shapers (third conventional technique) use a lens and a diffraction grating or an arrayed waveguide grating to change the amplitude and phase of each frequency component of the pulse independently (non-patent documents 5 and 6).
Letting the input time waveform be u(t) and its spectrum be U(omega ), the output time waveform be v(t) and its spectrum be V(omega ), and the transfer function of pulse shaping in the time domain be g(t) and the transfer function of pulse shaping on the spectrum be G(omega ), the relationship in the frequency domain can be expressed as follows:
V(omega )=G(omega )U(omega )
The relationship in the time domain can be expressed as follows:
(Equation image 1 not included in text)
Non-patent Document 1
W. J. Tomlinson, R. J. Stolen, and C. V. Shank, "Compression of optical pulses chirped by self-phase modulation in fibers," J. Opt. Soc. Am. B, Vol. 1, pp. 139-149, 1984
Non-patent Document 2
K. Tamura, T. Komukai, T. Yamamoto, T. Imai, E. Yoshida, and M. Nakazawa, "High energy, sub-picosecond pulse compression at 10 GHz using a fiber/fiber-grating pulse compressor," Electron.
Lett. Vol. 31, pp. 2194-2195, 1995
Non-patent Document 3
S. V. Chernikov, D. J. Richardson, E. M. Dianov, and D. N. Payne, "Picosecond soliton pulse compressor based on dispersion decreasing fiber," Electron.
Lett. Vol. 28, pp. 1842-1844, 1992
Non-patent Document 4
M. Nakazawa, E. Yoshida, K. Kubota, and Y. Kimura, "Generation of 170 fs, 10 GHz transform-limited pulse train at 1.55 mu m using a dispersion-decreasing, erbium-doped active soliton compressor," Electron.
Lett. Vol. 30, pp. 2038-2040, 1994
Non-patent Document 5
A. M. Weiner, J. P. Heritage, and E. M. Kirschner, "High-resolution femtosecond pulse shaping," J. Opt. Soc. Am. B, Vol. 5, pp. 1563-1572, 1988
Non-patent Document 6
K. Okamoto, T. Kominato, H. Yamada, and T. Goh, "Fabrication of frequency spectrum synthesizer consisting of arrayed-waveguide grating pair and thermo-optic amplitude and phase controllers," Electron.
Lett. Vol. 35, pp. 733-734, 1999

特許請求の範囲(英語) [claim1]
1. An optical function generator comprising: an optical pulse generator for generating an optical pulse train;
an optical Fourier transform circuit for converting the shape of the frequency spectrum of the optical pulse input from the optical pulse generator to a time waveform, the optical Fourier transform circuit having an optical phase modulator driven at the repetition frequency of the input optical pulse train from the optical pulse generator and a dispersive medium;
and
an optical filter for shaping the spectrum of the input optical pulse and determining the time waveform of the output optical pulse in accordance with frequency characteristics, the optical filter being inserted before the optical Fourier transform circuit,wherein the optical Fourier transform circuit generates an optical pulse having a desired time waveform depending on the function form of the frequency characteristics of the optical filter, by reproducing, directly in the time domain, the spectrum shaped as desired by the optical filter.
[claim2]
2. An optical function generator according the claim 1, wherein a Fourier-transform-limited pulse is used as the input optical pulse.
[claim3]
3. An optical function generator according to claim 1, wherein the optical phase modulator is driven at a clock frequency reproduced from the input optical pulse train, and linearly chirps the input optical pulse;
and the dispersive medium gives group-velocity dispersion.
[claim4]
4. An optical function generator according to claim 1, wherein, in the optical Fourier transform circuit,the dispersive medium gives group-velocity dispersion to the optical pulse output from the optical filter;
the optical phase modulator is driven at a clock frequency reproduced from the input optical pulse train, and linearly chirps the optical pulse output from the dispersive medium;
and
the dispersive medium receives the optical pulse output from the optical phase modulator, gives group-velocity dispersion again, and compensates for the remaining chirp.
[claim5]
5. An optical function generator according to claim 1, wherein, in the optical Fourier transform circuit,the optical phase modulator is driven at a clock frequency reproduced from the input optical pulse train, and linearly chirps the optical pulse output from the optical filter;the dispersive medium gives group-velocity dispersion to the optical pulse output from the optical phase modulator;
and
the optical phase modulator receives the optical pulse output from the dispersive medium, gives another linear chirp, and compensates for the remaining chirp.
[claim6]
6. An optical function generator according to claim 1, wherein the chirp rate K of phase modulation by the phase modulator and the group-velocity dispersion D of the dispersive medium satisfy a relationship of K=1/D.
[claim7]
7. An optical function generation method using an optical function generator comprising an optical pulse generator, an optical Fourier transform circuit, and an optical filter, the optical Fourier transform circuit having an optical phase modulator and a dispersive medium, the optical function generation method including: shaping the spectrum of an input optical pulse from the optical pulse generator, and determining the time waveform of the output optical pulse in accordance with frequency characteristics, by inserting the optical filter before the optical Fourier transform circuit;driving the optical phase modulator at the repetition frequency of the input optical pulse train;
and
generating an optical pulse having a desired time waveform, depending on the function form of the frequency characteristics of the optical filter, by reproducing, directly in the time domain, the spectrum shaped as desired by the optical filter, by means of the optical Fourier transform circuit.
  • 発明者/出願人(英語)
  • NAKAZAWA MASATAKA
  • HIROOKA TOSHIHIKO
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
米国特許分類/主・副
  • 359/326
  • 359/238
  • 359/245
  • 398/81
  • 398/147
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