JP2001264829A - Source of white pulsed light - Google Patents
Source of white pulsed lightInfo
- Publication number
- JP2001264829A JP2001264829A JP2000081994A JP2000081994A JP2001264829A JP 2001264829 A JP2001264829 A JP 2001264829A JP 2000081994 A JP2000081994 A JP 2000081994A JP 2000081994 A JP2000081994 A JP 2000081994A JP 2001264829 A JP2001264829 A JP 2001264829A
- Authority
- JP
- Japan
- Prior art keywords
- pulse light
- excitation pulse
- white
- nonlinear medium
- pulsed light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、導波路型光非線形
媒質に励起パルス光を入射して広帯域かつ平坦性に優れ
た白色パルス光を発生させる白色パルス光源に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white pulse light source for generating excitation light in a waveguide type optical nonlinear medium to generate white light having a wide band and excellent flatness.
【0002】なお、近年、スーパーコンティニウム(Su
percontinuum) 光と呼ばれる超広帯域の白色パルス光が
通信用や計測用の光源として注目されている。[0002] In recent years, SuperContinium (Su
Percontinuum) Ultra-wideband white pulse light called light is attracting attention as a light source for communication and measurement.
【0003】[0003]
【従来の技術】白色パルス光源は、図3に示すように、
励起パルス光源1と導波路型光非線形媒質2から構成さ
れる。励起パルス光源1から出射された励起パルス光
は、導波路型光非線形媒質2を伝搬する際に3次の非線
形光学効果を誘起し、広帯域の白色パルス光を発生す
る。ここで、導波路型光非線形媒質2における励起パル
ス光の伝搬距離をzとし、入射端をz=0、出射端をz
=Lとする。2. Description of the Related Art As shown in FIG.
It comprises an excitation pulse light source 1 and a waveguide type optical nonlinear medium 2. Excitation pulse light emitted from the excitation pulse light source 1 induces a third-order nonlinear optical effect when propagating through the waveguide-type optical nonlinear medium 2, and generates broadband white pulse light. Here, the propagation distance of the excitation pulse light in the waveguide type optical nonlinear medium 2 is z, the incident end is z = 0, and the emission end is z.
= L.
【0004】このような白色パルス光源について、文献
1(特開平8−234249号公報「コヒーレント白色
光源」)では、導波路型光非線形媒質の分散スロープと
分散の大きさを規定し、この分散スロープが小さいほど
広帯域の白色パルス光が発生することを明らかにしてい
る。そして、導波路型光非線形媒質として単一モード光
ファイバを用いた実験で、図4に示すような広帯域で平
坦性に優れた白色パルス光が得られたことを示してい
る。なお、図4には、励起パルス光のスペクトルも共に
示している。[0004] Regarding such a white pulse light source, Document 1 (Japanese Patent Application Laid-Open No. 8-234249, "Coherent White Light Source") specifies the dispersion slope and the magnitude of dispersion of a waveguide type optical nonlinear medium, and disperses the dispersion slope. It is clear that the smaller the is, the wider the white pulse light is generated. An experiment using a single-mode optical fiber as the waveguide type optical nonlinear medium has shown that white pulse light with excellent flatness over a wide band as shown in FIG. 4 was obtained. FIG. 4 also shows the spectrum of the excitation pulse light.
【0005】また、文献1では、励起パルス光の伝搬方
向に分散値が減少する導波路型光非線形媒質を用いるこ
とにより、発生する白色パルス光の帯域が増加すること
も示している。Document 1 also shows that the band of generated white pulse light increases by using a waveguide type optical nonlinear medium whose dispersion value decreases in the propagation direction of the excitation pulse light.
【0006】また、文献2(特開平11−174503
号公報「白色パルス光源」)では、さらに広帯域でかつ
高い平坦性を有する白色パルス光を発生させるため新技
術が開示されている。[0006] Reference 2 (Japanese Patent Laid-Open No. 11-174503)
Japanese Patent Publication No. “White pulse light source”) discloses a new technique for generating white pulse light having a wider band and higher flatness.
【0007】図5は、文献2の白色パルス光源に用いら
れる導波路型光非線形媒質の波長−分散値特性を示す。
図において、横軸は波長、縦軸は分散値を示す。励起パ
ルス光の中心波長λ0 における導波路型光非線形媒質の
分散値D(λ0,z)として、入射端(z=0)で正の値を
とり、励起パルス光の伝搬方向に向かって減少する特性
を有するようにする。FIG. 5 shows a wavelength-dispersion value characteristic of a waveguide type optical nonlinear medium used for a white pulse light source of Document 2.
In the figure, the horizontal axis represents wavelength and the vertical axis represents dispersion value. The dispersion value D (λ 0 , z) of the waveguide-type optical nonlinear medium at the center wavelength λ 0 of the pump pulse light takes a positive value at the incident end (z = 0), and is directed toward the propagation direction of the pump pulse light. To have decreasing properties.
【0008】さらに、励起パルス光の伝搬距離zの範囲
L1 ≦z≦L(ただし0≦L1<L)で、分散値D(λ,
z) がピーク波長λp(z)において極大値D(λp(z),z)
を有し、さらにこの極大値が正となる伝搬距離zの範囲
で、分散値D(λ,z)が0となる2つの零分散波長λ
1(z)およびλ2(z)を有する構成とする。Further, in a range L 1 ≦ z ≦ L (where 0 ≦ L 1 <L) of a propagation distance z of the pump pulse light, a dispersion value D (λ,
z) is a local maximum D (λ p (z), z) at the peak wavelength λ p (z).
And two zero-dispersion wavelengths λ where the dispersion value D (λ, z) becomes 0 in the range of the propagation distance z where the maximum value is positive.
1 (z) and λ 2 (z).
【0009】この白色パルス光源における白色パルス光
の発生および成長の原理について説明する。白色パルス
光は、2段階の過程を経て発生し成長する。すなわち、
ソリトン圧縮によるスペクトル広がり過程と、ソリトン
が分散性波動に変化することによるスペクトルの矩形化
・平坦化の過程である。導波路型光非線形媒質に入射さ
れた励起パルス光は、中心波長λ0 における導波路型光
非線形媒質の分散値D(λ0,z)が正(異常分散)となる
伝搬距離zの範囲で、ソリトン圧縮を受けてスペクトル
が広がる。伝搬距離zに伴って分散値D(λ0,z)が減少
し、2つの零分散波長λ1(z),λ2(z)が励起パルス光の
中心波長λ0 に近づくと、スペクトルの両端の波長領域
は分散値が負(正常分散)の領域に入るが、励起パルス
光は全体としてソリトン性を維持してスペクトルが広が
り続ける。The principle of generation and growth of white pulse light in this white pulse light source will be described. White pulse light is generated and grown through a two-step process. That is,
These are the process of spectral broadening by soliton compression and the process of rectangularizing and flattening the spectrum by changing the soliton into a dispersive wave. The excitation pulse light incident on the waveguide-type optical nonlinear medium has a propagation distance z in which the dispersion value D (λ 0 , z) of the waveguide-type optical nonlinear medium at the center wavelength λ 0 is positive (anomalous dispersion). The spectrum is expanded by soliton compression. When the dispersion value D (λ 0 , z) decreases with the propagation distance z and the two zero-dispersion wavelengths λ 1 (z) and λ 2 (z) approach the center wavelength λ 0 of the pump pulse light, the spectrum Although the wavelength regions at both ends fall within the region where the dispersion value is negative (normal dispersion), the spectrum of the excitation pulse light continues to spread while maintaining the soliton properties as a whole.
【0010】さらに、伝搬距離zに伴って分散値D(λ
0,z)が減少し続けると、スペクトルの両端の波長領域
は正常分散に負けてソリトン性を失って分散性波動に変
化し、その降伏点でスペクトル広がりは止まる。ところ
が、励起パルス光の中心波長λ0 に近い波長領域では、
分散値が依然として正(異常分散)であり、スペクトル
は広がり続けるので、降伏点での光のエネルギー密度が
増大し、角状のスペクトルが成長する。そして、2つの
零分散波長がさらに励起パルス光の中心波長に近づく
と、降伏点もその中心波長に近づくので、平坦なスペク
トルが形成される。Further, the variance D (λ
As (0 , z) continues to decrease, the wavelength region at both ends of the spectrum loses the normal dispersion, loses soliton properties, and changes to a dispersive wave, and the spectrum spread stops at the yield point. However, in the wavelength region near the center wavelength λ 0 of the pump pulse light,
Since the dispersion value is still positive (anomalous dispersion) and the spectrum continues to spread, the energy density of light at the breakdown point increases, and a square spectrum grows. When the two zero-dispersion wavelengths further approach the center wavelength of the excitation pulse light, the breakdown point also approaches the center wavelength, so that a flat spectrum is formed.
【0011】[0011]
【発明が解決しようとする課題】ところで、文献2に示
す白色パルス光源では、導波路型光非線形媒質に入射す
る励起パルス光の瞬時光周波数が、励起パルス光の時間
軸上における前縁から後縁にかけて一定である(チャー
プ0)としていた。By the way, in the white pulse light source disclosed in Document 2, the instantaneous optical frequency of the excitation pulse light incident on the waveguide type optical nonlinear medium is changed from the front edge to the rear edge on the time axis of the excitation pulse light. It was constant over the edge (chirp 0).
【0012】本発明は、励起パルス光の瞬時光周波数に
着目し、広帯域かつ高い平坦性を有する白色パルス光を
発生させるための励起パルス光のピーク強度を低減する
ことができる白色パルス光源を提供することを目的とす
る。The present invention focuses on the instantaneous optical frequency of the excitation pulse light, and provides a white pulse light source capable of reducing the peak intensity of the excitation pulse light for generating white pulse light having a wide band and high flatness. The purpose is to do.
【0013】[0013]
【課題を解決するための手段】本発明は、文献2に示す
白色パルス光源において、導波路型光非線形媒質に入射
する励起パルス光の瞬時光周波数が、励起パルス光の前
縁から後縁にかけて増大することを特徴とする。According to the present invention, in the white pulse light source disclosed in Document 2, the instantaneous optical frequency of the excitation pulse light incident on the waveguide type optical nonlinear medium is changed from the leading edge to the trailing edge of the excitation pulse light. It is characterized by increasing.
【0014】[0014]
【発明の実施の形態】図1は、本発明の白色パルス光源
の実施形態を示す。図において、本発明の白色パルス光
源は、励起パルス光源1と導波路型光非線形媒質2との
間にチャープ付与手段3を挿入した構成である。チャー
プ付与手段3では、励起パルス光の瞬時光周波数が励起
パルス光の前縁から後縁にかけて増大するチャーピング
を与える構成である。このようなチャープ付与手段3と
しては、電気光学的効果または光非線形効果を利用した
光位相変調手段を用いることができる。なお、励起パル
ス光源1が同様のチャーピングを有する励起パルス光を
出力できる構成であってもよい。FIG. 1 shows an embodiment of a white pulse light source according to the present invention. In the figure, the white pulse light source of the present invention has a configuration in which a chirp applying means 3 is inserted between an excitation pulse light source 1 and a waveguide type optical nonlinear medium 2. The chirp imparting means 3 is configured to give chirping in which the instantaneous optical frequency of the excitation pulse light increases from the leading edge to the trailing edge of the excitation pulse light. As such chirp imparting means 3, an optical phase modulation means utilizing an electro-optical effect or an optical nonlinear effect can be used. The excitation pulse light source 1 may be configured to output excitation pulse light having similar chirping.
【0015】また、導波路型光非線形媒質2は、図5に
示す文献2の白色パルス光源に用いられる波長−分散値
特性を示す。このような導波路型光非線形媒質2に、上
記のチャーピングを与えた励起パルス光を入射すると、
励起パルス光はソリトン効果による圧縮過程の他に、導
波路型光非線形媒質2の異常分散の効果によってチャー
ピングが補償され、パルス圧縮を受ける。The waveguide type optical nonlinear medium 2 has a wavelength-dispersion value characteristic used for the white pulse light source of Document 2 shown in FIG. When the excitation pulse light having the above chirping is incident on such a waveguide type optical nonlinear medium 2,
Excitation pulse light is subjected to pulse compression in which chirping is compensated for by the anomalous dispersion effect of the waveguide type optical nonlinear medium 2 in addition to the compression process by the soliton effect.
【0016】図2は、励起パルス光のピーク強度に対す
る白色パルス光のスペクトル幅の関係を示す。本発明の
瞬時光周波数が増大する励起パルス光を用いた場合と、
従来の瞬時光周波数が一定の励起パルス光を用いた場合
を比較した。このように、瞬時光周波数が増大する励起
パルス光を用いると、従来の瞬時光周波数が一定の励起
パルス光を用いた場合と比べて、より小さいピーク強度
の励起パルス光で白色パルス光を発生できることが確認
された。FIG. 2 shows the relationship between the peak intensity of the excitation pulse light and the spectrum width of the white pulse light. When using the excitation pulse light increasing the instantaneous optical frequency of the present invention,
A comparison was made between the case where a conventional excitation pulse light having a constant instantaneous optical frequency was used. As described above, when the excitation pulse light whose instantaneous optical frequency is increased is used, white pulse light is generated with the excitation pulse light having a smaller peak intensity as compared with the conventional excitation pulse light whose instantaneous optical frequency is constant. It was confirmed that it was possible.
【0017】[0017]
【発明の効果】以上説明したように、本発明の白色パル
ス光源では、瞬時光周波数が増大する励起パルス光を導
波路型光非線形媒質に入射することにより、広帯域かつ
高い平坦性を有する白色パルス光を発生させるための励
起パルス光のピーク強度を低減させることができる。As described above, according to the white pulse light source of the present invention, the excitation pulse light whose instantaneous optical frequency increases is incident on the waveguide type optical nonlinear medium, so that a white pulse having a wide band and high flatness is obtained. The peak intensity of the excitation pulse light for generating light can be reduced.
【図1】本発明の白色パルス光源の実施形態を示す図。FIG. 1 is a diagram showing an embodiment of a white pulse light source according to the present invention.
【図2】励起パルス光のピーク強度に対する白色パルス
光のスペクトル幅の関係を示す図。FIG. 2 is a diagram showing the relationship between the peak intensity of excitation pulse light and the spectrum width of white pulse light.
【図3】従来の白色パルス光源の構成を示す図。FIG. 3 is a diagram showing a configuration of a conventional white pulse light source.
【図4】文献1の白色パルス光源で発生する白色パルス
光のスペクトルの例を示す図。FIG. 4 is a diagram showing an example of a spectrum of white pulse light generated by a white pulse light source of Document 1.
【図5】文献2の白色パルス光源に用いられる導波路型
光非線形媒質の波長−分散値特性を示す図。FIG. 5 is a diagram showing a wavelength-dispersion value characteristic of a waveguide type optical nonlinear medium used for a white pulse light source of Literature 2.
1 励起パルス光源 2 導波路型光非線形媒質 3 チャープ付与手段 DESCRIPTION OF SYMBOLS 1 Excitation pulse light source 2 Waveguide type optical nonlinear medium 3 Chirp providing means
フロントページの続き (72)発明者 川西 悟基 東京都千代田区大手町二丁目3番1号 日 本電信電話株式会社内 Fターム(参考) 2K002 AB27 AB32 DA06 HA25 Continuation of the front page (72) Inventor Satoru Kawanishi 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2K002 AB27 AB32 DA06 HA25
Claims (1)
励起パルス光源と、前記励起パルス光を入射して白色パ
ルス光を発生する長さL [m] の導波路型光非線形媒質
とを備え、 前記励起パルス光の中心波長λ0 における前記導波路型
光非線形媒質の分散値D(λ0,z) [ps/nm/km] は、入射
端(z=0)で正の値をとり、前記励起パルス光の伝搬
方向に向かって減少する特性を有し、さらに前記励起パ
ルス光の伝搬距離zの範囲L1 ≦z≦L(ただし0≦L
1<L)で、分散値D(λ,z) がピーク波長λp(z)におい
て極大値D(λp(z),z) を有し、さらにこの極大値が正
となる伝搬距離zの範囲で、分散値D(λ,z)が0 [ps
/nm/km] となる2つの零分散波長λ1(z)およびλ2(z)を
有する構成である白色パルス光源において、 前記導波路型光非線形媒質に入射する前記励起パルス光
の瞬時光周波数が、励起パルス光の前縁から後縁にかけ
て増大することを特徴とする白色パルス光源。 1. An excitation pulse light source that generates an excitation pulse light having a center wavelength λ 0 , and a waveguide-type optical nonlinear medium having a length L [m] that receives the excitation pulse light and generates a white pulse light. The dispersion value D (λ 0 , z) [ps / nm / km] of the waveguide-type optical nonlinear medium at the center wavelength λ 0 of the pump pulse light is a positive value at the incident end (z = 0). In addition, it has a characteristic of decreasing in the propagation direction of the excitation pulse light, and further has a range L 1 ≦ z ≦ L (where 0 ≦ L) of the propagation distance z of the excitation pulse light.
1 <L), the dispersion value D (λ, z) has a maximum value D (λ p (z), z) at the peak wavelength λ p (z), and the propagation distance z at which this maximum value is positive. , The variance D (λ, z) is 0 [ps
/ nm / km] in a white pulse light source having two zero dispersion wavelengths λ 1 (z) and λ 2 (z), wherein instantaneous light of the excitation pulse light is incident on the waveguide type optical nonlinear medium. A white pulse light source wherein the frequency increases from the leading edge to the trailing edge of the excitation pulse light.
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017532587A (en) * | 2014-08-29 | 2017-11-02 | エーエスエムエル ホールディング エヌ.ブイ. | Method and apparatus for spectrally expanding radiation |
-
2000
- 2000-03-23 JP JP2000081994A patent/JP2001264829A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017532587A (en) * | 2014-08-29 | 2017-11-02 | エーエスエムエル ホールディング エヌ.ブイ. | Method and apparatus for spectrally expanding radiation |
US10670978B2 (en) | 2014-08-29 | 2020-06-02 | Asml Holding N.V. | Method and apparatus for spectrally broadening radiation |
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