JP3533199B2 - Wavelength converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength conversion device used for wavelength division multiplexing optical communication and the like. Next-generation ultra-high-speed optical communication networks essentially require various all-optical optical elements. The wavelength conversion device of the present invention is
It is an important network component used for optical ATM switching switching and routing.

[0002]

2. Description of the Related Art In the current optical communication, a wavelength multiplexing system for dividing a communication wavelength band into tens to hundreds of narrow band channels is used to dramatically increase the communication line capacity per optical fiber at low cost. ing. In this method, the wavelength of each channel is fixed for transmission and reception, so if the wavelength of one wavelength-multiplexed communication channel can be converted to another wavelength, the communication path can be freely converted. Therefore, for example, when it is necessary to transfer an optical signal that can effectively use an empty channel from one channel to another channel, it is necessary to convert the wavelength of the optical signal. The method of wavelength conversion in wavelength division multiplexing optical communication is detailed in Reference Document 1, for example. In this document, the method of wavelength conversion is (a) Optelectronic (O / E-E / O) Wavele
ngth Conversion, (b) Optical Grating Wave1e
ngth Conversion, (c) Wave- mixing Wavelength
It is classified into three types, Conversion. The method (a) is a method in which an optical signal is once converted into an electrical signal, the wavelength is changed by the electrical method, and then the optical signal is returned. (B)
The above method is a method using a diffraction grating. In the method of (c), the signal light and the control light are simultaneously incident on a material having a non-linear optical effect and mixed under the action of the non-linear optical effect,
The wavelength is converted. The principle of wavelength conversion by the method (c) will be described with reference to FIG.

In FIG. 12, a plate-shaped nonlinear optical material 3 is used.
One of the surfaces of 1 is a signal light 32 and a control light 3 having different frequencies.
3. Simultaneously irradiate. When light is incident on a substance, polarization occurs in the substance, and electromagnetic waves or light are generated when the polarization vibrates. Therefore, the light emitted from the substance is the incident light,
It is governed by this polarization property. In the non-linear optical material 31, this polarization changes due to, for example, the second-order or third-order non-linear characteristic of the energy of the incident light.
A non-linear optical material 31
From the opposite side, it is possible to output various signal components of the sum or difference between the fundamental frequency and the harmonic of the signal light 32 and the control light 33, that is, the wavelength-converted light 34.

However, many of the conventional nonlinear optical materials are
The nonlinear optical effect is small and the wavelength conversion efficiency is extremely poor. On the contrary, if the nonlinear optical effect is large, high speed cannot be obtained, and in the case of organic materials, it may decompose or oxidize and the material stability is insufficient. In many materials, it was far from practical use because the temperature of liquid helium was required to enable the operation.

[0005]

As described above, in the wavelength conversion method in the conventional optical communication, the all-optical method using the non-linear optical material of (c) is theoretically capable of ultra-high speed operation. In addition, since it is relatively easy to change the wavelength, it can be said that it is suitable for use in wavelength division multiplexing optical communication. However, all of the conventionally known nonlinear optical materials have extremely small effects of nonlinear polarization, and it has been difficult to practically apply them to wavelength conversion elements. Therefore, generally, the wavelength conversion method of (a) in which an optical signal is once converted into an electric signal and then the wavelength is changed is adopted. However, in the method of (a), an optical signal-
Since the conversion operation of the signal format of the electric signal, the electric signal-optical signal is performed, and the operation of the device used for the conversion of these signal formats is usually much slower than the transmission speed of the optical signal, As a result, there has been a problem that the original high speed of optical transmission cannot be sufficiently exhibited.

An object of the present invention is to provide a practicable all-optical wavelength conversion element. Further, in a wavelength conversion device using such an all-optical wavelength conversion element, wavelength conversion is effective. To realize a suitable configuration for functioning.

[0007]

The inventors of the present invention have previously described, as shown in Reference 2, a substance Sr having a one-dimensional copper oxide single-chain (Cu-O) structure using transition metal copper. ₂ CuO
₃ has a large two-photon absorption (TPA) characteristic, 1.5
It was found that the effect of the third-order nonlinear polarization is extremely large in the wavelength region longer than μm. One-dimensional copper oxide single chain (C
The effect of such third-order nonlinear polarization in a material having a (uO) structure is due to the SrC of the one-dimensional cuprate double-chain material.
It also occurs in uO ₂ , and further, in one-dimensional copper oxide single-chain material Ca ₂ CuO ₃ and one-dimensional copper oxide double-chain material CaCuO ₂ in which strontium Sr in these materials is replaced by calcium Ca It is clear that will also appear. Based on these findings, the present invention proposes a suitable application of a material having a one-dimensional copper oxide single-chain structure or a one-dimensional copper oxide double-chain structure to a wavelength conversion device .

As described above, according to the present invention, the one-dimensional copper oxide single layer such as Sr ₂ CuO ₃ or Ca ₂ CuO ₃ is used as the nonlinear optical material of the wavelength conversion element in the wavelength conversion device for performing all-optical wavelength conversion. Chain material or a one-dimensional copper oxide double-chain material such as SrCuO ₂ or CaCuO ₂ is used to perform wavelength conversion by using the third-order nonlinear optical property, thereby improving the wavelength conversion efficiency. to realize wavelength conversion device with high ultra-high speed.

FIG. 1 schematically shows the basic structure of a wavelength conversion device according to the present invention. In FIG. 1, as a material of the wavelength conversion element 1, for example, Sr ₂ CuO ₃ which is a one-dimensional copper oxide single chain substance or SrCuO _{2 which} is a one-dimensional copper oxide double chain substance is used. Sr ₂ C
uO ₃ or SrCuO ₂ exhibits a third-order nonlinear polarization characteristic with respect to the level change of the input light. Therefore, as shown, when simultaneously incident a first input beam 2 and the second input light 3 of frequency f ₂ of the frequency f ₁ in the wavelength conversion element 1,
Due to the mixing action of the _third -order nonlinear polarization characteristics, f ₃ = 2
Third-order nonlinear polarization P ⁽³⁾ (f with frequency f ₁ -f ₂
And _3), f ₄ = 2f ₂ -f ₁ of the third-order non-linear polarization P ⁽³ having a ^frequency) (f ₄₎ is generated, as a result, the first output light 4 having a respective frequency second Output light 5 is generated. In other words, the frequency f ₁ or f ₂ of the input light can be converted to a new frequency f ₃ = 2f ₂ −f ₁ or f ₄ = 2f ₁ −f ₂ for optical output.

The wavelength conversion device according to the present invention can have the following configurations (1) to (5) . (1) For the nonlinear optical material of the wavelength conversion element, one-dimensional cupric acid is used.
Having a single-chain structure of a compound or a double-chain structure of one-dimensional copper oxide
Wavelength change using a third-order nonlinear optical property.
A wavelength conversion device for converting wavelengths into a wavelength conversion element.
The means for injecting the first input light of f ₁ and the wavelength conversion element
Means for injecting a second input light of frequency f ₂ and wavelength conversion
Frequency of light emitted from the element f ₃ = 2f ₂ −f
Either _one component or the frequency f ₄ = component of 2f ₁ -f ₂
And means for selecting the light of one component as the output light.
Configuration of the wavelength conversion device are. (2) First input light frequency f ₁ and output light frequency f
₃ is a frequency of the channel, each of the wavelength-multiplexed optical communication, the difference between the frequency f ₁ and frequency f ₂ of the second input light first input light and delta, the frequency difference between channels and δ , M is a positive integer or zero, the frequency f ₂ of the second input light is determined so as to satisfy the relational expression Δ = | f ₂ −f ₁ | = (2m + 1) δ / 2. The configuration of the wavelength conversion device described in (1) above. (3) The wavelength converter according to the above (1) or (2) , which is used in a wavelength band longer than 1.52 μm. (4) The substance having a one-dimensional copper oxide single chain structure is S
r ₂ CuO ₃ or Ca ₂ CuO ₃ having a one-dimensional copper oxide double chain is SrCuO ₂ or CaC.
uO ₂ which is characterized in that (1) to (3)
The configuration of the wavelength conversion device according to any one of 1. (5) A substance having a one-dimensional copper oxide single chain structure is S
A substance that is a mixture of r ₂ CuO ₃ and Ca ₂ CuO ₃ and has a one-dimensional copper oxide double chain structure is SrCuO ₂ and C.
(1) which is a mixture of aCuO ₂
The configuration of the wavelength conversion device according to any one of (1) to (3) .

CuO which is an oxide of copper as a transition metal element
Are arranged so that copper ions and oxygen ions form a specific crystal structure, but only a specific crystal orientation has no special property. However, a substance such as mica that is easily cleaved is called a layered substance and exhibits a two-dimensional property. Thus, some materials may have special properties in particular directions. Such substances also exist in transition metal oxides.

By the way, the transition metal oxide Sr ₂ CuO
_{Although 3} has a crystal structure as shown in FIG. 2, it exhibits a one-dimensional property and is called a pseudo one-dimensional substance. In the crystal structure shown in FIG. 2, the b-axis is the direction of the one-dimensional chain. The characteristics of such a pseudo one-dimensional substance are described in, for example, Reference Document 3
As is clarified in the paper, it is typified by the fact that the light absorption in the mid-infrared wavelength range greatly differs depending on the crystal axis direction. Substances that are quasi-one-dimensional substances and are transition metal oxides are categorized as substances with strong correlation because the interaction between electrons in the substances is likely to have a special relationship, and research on high-temperature superconductivity phenomena Recently, research has become active in relation to.

FIG. 3 shows a one-dimensional copper oxide single chain substance Sr ₂
It shows the wavelength dependence of the two-photon absorption β of CuO ₃ . As can be seen from the figure, in a region where the wavelength is shorter than 1.52 μm, the absorption β becomes large and almost no light is transmitted, so that it cannot be used. This substance has a small absorption β in the wavelength region longer than 1.52 μm and becomes considerably transparent, but becomes more transparent in the wavelength region longer than 1.6 μm. In the future, if the crystal growth technology of this material is improved to obtain more pure crystals, 1.5μ
The absorption near m may be smaller, but at present, C band, L band and L of 1.52 μm or more
The + band will be a practical region as a wavelength conversion element (C band: 1520-1580 nm, L band: 15
60-1620 nm, L + band: 1600 nm-16
50 nm).

Further, SrCuO _{2 which} is a one-dimensional copper oxide double-chain substance having a double-chain structure in one-dimensional copper oxide is also used as Sr ₂
Since it has almost the same optical absorption and non-linear optical characteristics as CuO ₃ , this material can be applied to a wavelength conversion element without any particular problem. In addition, these substances Sr ₂ CuO
₃ , C substance in which strontium Sr in SrCuO ₂ is replaced with calcium Ca belonging to Group 2 of the same periodic table
a ₂ CuO ₃ , CaCuO ₂ , or Sr ₂ CuO ₃
And Ca ₂ CuO ₃ mixture, SrCuO ₂ and CaCu
It is clear that there is no problem even with a mixture of O ₂ .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to ITU-T, in wavelength division multiplexing optical communication, a frequency of 193.1 THz (wavelength of 155) is used.
It is recommended to set wavelengths on a frequency grid arranged at intervals of 100 THz (about 0.8 nm) based on 2.525 nm, that is, 1.552525 μm. Here, an embodiment will be described with respect to a wavelength conversion device of a wavelength division multiplexing optical communication device that is wavelength-divided according to the recommendation.

As described with reference to FIG. 1, in the wavelength conversion element 1, a new frequency f is obtained from two input lights of frequencies f ₁ and f ₂ (where f ₂ > f ₁ ) due to the third-order nonlinear optical characteristic. The formula of wavelength conversion for generating the light of ₃ , f ₄ is given by f ₃ = 2f ₁ −f ₂ f ₄ = 2f ₂ −f ₁ , but assuming Δ = f ₂ −f ₁ , it is shown in FIG. As described above, the respective lights are arranged in the order of f ₃ , f ₁ , f ₂ , and f _{4 so} as to be separated by Δ on the frequency axis, and f ₁ −f ₃ = Δ, f ₄
−f ₁ = 2Δ. Here, the input light of the frequency f ₁ is the signal light, and the input light of the frequency f ₂ is the control light. In a wavelength division multiplexing optical communication device, if it is assumed that the wavelength conversion device performs arbitrary switching between signal light channels,
Since the frequency f _{1 of the} signal light is the current frequency of the light of a certain channel, in order for the frequency f ₃ or f _{4 of} the wavelength-converted output light to become the frequency of the light of another channel, the frequency difference is f ₁ −f ₃ = Δ or f ₄ −f ₁ = 2Δ
Should be an integer multiple of the size of the channel spacing. That is, δ is the channel interval (frequency difference),
When n and n ′ are arbitrary positive integers, it is necessary that 2Δ = nδ or Δ = n′δ.

By the way, of the two output lights of the frequencies f ₃ and f ₄ , the output light of the frequency f ₃ is f ₃ = 2f ₁ −f ₂
Accordingly, since the harmonic components 2f ₁ of twice the signal light is obtained by the wavelength conversion, since the disturbing light does not want to output, as shown in FIG. 5, almost unnecessary f ₃ is between channels intermediate set the size of Δ to come to the position, to cut only a narrow band filter the light component of the frequency f _3, the optical component of the frequency f ₃ can be prevented from entering the communications channel.

For example, in order for f _{3 to} be located exactly in the center between the channels, Δ = (m + 1/2) δ = (2m + 1) δ / 2 where m is a positive integer or zero. Good. From this, Δ may be set to a half integer multiple of δ, and the frequency f of the control light may be set so as to satisfy such a condition.
Decide on ₂ . In FIG. 5, m = 3, and Δ = (3 + 1 /
2) Shows the correspondence between light and channels when δ = 3.5 δ. Then, f ₂ is defined as f ₂ = f ₁ + Δ = f ₁ +3.5 δ. The example of FIG. 4, FIG. 5, but was of the case of f _2> f _1, be a f ₂ <f _1, it is possible to determine the f ₂ obtained in the same procedure. However, f ₂
In the case of <f ₁ , the light array on the frequency axis in FIG. 4 is in the order of f ₄ , f ₂ , f ₁ , f ₃ as shown in FIG.
The correspondence between light and channels is as shown in FIG.

In FIG. 5, the light of f ₂ and f ₃ located exactly in the middle between the channels on the frequency axis is almost cut by the narrow band filter provided in each channel, so that the output to the channel is not generated. To be done.

FIG. 8 shows an example of band transmission characteristics of a narrow band filter provided for each channel. Each narrow band filter has a characteristic curve in which the center frequency of the band transmission characteristic is set to the center frequency of the channel, and the characteristic curve abruptly attenuates in the middle of the channel interval δ. Therefore, the control light of the frequency f ₂ illustrated in FIG. 8 is excluded from both adjacent channels. Although the wavelength conversion is described in the frequency domain in the above description, the frequency f of light and the wavelength λ
The relationship is f = c / λ (where light speed c = 29979
2458 m / s), the frequency f ₁ ,
The corresponding wavelengths of f ₂ , f ₃ and f ₄ are λ ₁ , λ ₂ ,
Letting λ ₃ and λ _4, and using the above relationship, the wavelength conversion formula is (1 / λ ₃ ) = 2 * (1 / λ ₁ ) − (1 / λ ₂ ) (1 / λ ₄ ) = 2 It can be expressed as * (1 / λ ₂ )-(1 / λ ₁ ). Next, a specific example is shown.

The wavelength of the signal light of a certain channel that carries a signal to be communicated is λ ₁ = 1560.61 nm (192.
1 THz) and another wavelength λ ₂ = 1588.30 nm
Substituting the light of (188.75 THz) as the control light in the above equation, λ ₃ = 1533.86 nm (195.45 TH
z), λ ₄ = 1617.00 nm (185.4 THz)
Is obtained. That is, λ ₃ = 1533.86 nm light and λ
_Although light of ₄ = 1617.00 nm is generated, since λ ₃ has a wavelength shorter than 1560 nm, it is outside the range of the L band and does not correspond to the center wavelength of the channel. On the other hand, λ ₄ is in the range of the L band and corresponds to the center wavelength of the channel, so that it is effective signal light. That is, the wavelength conversion is performed from the L band channel of wavelength λ _{1 to} the L band channel of wavelength λ ₄ .

[0022] In the wavelength conversion using the wavelength conversion element Sr ₂ CuO _3, the wavelength conversion action occurs only when both lambda ₁ and lambda ₂ light is irradiated continuously irradiated with lambda ₂ of the control light Continuing on, the non-linear effect in Sr ₂ CuO ₃ responds very quickly and follows up to the picosecond level, so the time dependence of the generated light of λ ₃ or λ ₄ is λ ₁ which is the signal light. It becomes almost the same as the time dependence of light. In addition,
Since the light of λ ₃ becomes unnecessary light, it is blocked by a narrow band wavelength filter.

If λ ₁ is the wavelength of the signal light of a certain channel and λ ₂ is the wavelength of the control light, the wavelength λ ₄ of the output light can be arbitrarily changed only by changing the wavelength of λ _2. You can If the signal light of the wavelength λ ₁ is intensity-modulated and temporally changes at the logic levels of HIGH and LOW, the light of the wavelength λ ₄ output after being converted in wavelength is also the light of the wavelength λ ₁ . The signal light changes its intensity with the same time dependence as.

9 to 11 show an embodiment of the wavelength conversion device.

FIG. 9 is a schematic diagram of a wavelength conversion device, in which 10 is a wavelength conversion device, 11 is a wavelength conversion element made of a nonlinear optical material according to the present invention, and 12 is only an optical signal of frequency f _s. , 13 is a signal optical fiber, 13 is a control optical fiber through which control light of frequency f _c is transmitted,
Reference numerals 14 and 15 are lenses for focusing light, 16 is an output optical fiber, and 17 is a narrow band filter. Further, the frequencies f _s , f _c , f ₀₁ , and f ₀₂ used in the following description correspond in sequence to f ₁ , f ₂ , f ₃ , and f ₄ in the description of FIGS. 3 to 7.

The lights emitted from the signal optical fiber 12 and the control optical fiber 13 enter the wavelength conversion element 11 through the lens 14. In the wavelength conversion element 11 of the nonlinear optical material, the signal light and the control light are mixed, and as a result of the nonlinear optical effect, f ₀₁ = 2f _s −f _c and f ₀₂ =
Generates two light 2f _c -f _s. Further, part of the incident light passes through the wavelength conversion element 11 as it is. Therefore, behind the wavelength conversion element 11, f _s , f _c ,
Four lights of f ₀₁ and f ₀₂ are emitted. Of these, f _s , f
Lights _c and f ₀₁ are unnecessary and should be cut. Therefore, the light emitted from the wavelength conversion element 11 is collected by the lens 15 and is incident on the narrow band filter 17, and the specific wavelength f
Only ₀₂ is transmitted and guided to the output optical fiber 16.

FIG. 10 shows the band transmission characteristics of the narrow band filter 17. Since it has a bandwidth for transmitting the signal light of f ₀₂ and has a characteristic of abruptly attenuating in the intermediate region between the adjacent channels as shown in FIG. 8, f _s , f _c , f ₀₁ other than f ₀₂ are obtained. It also blocks the light.

The control light emitted from the control light source, which is a semiconductor laser whose oscillation frequency is stabilized at f _c , is guided to the control optical fiber 13. Only when the control light is on, the signal light of the frequency f _s transmitted to the signal optical fiber 12 is converted into the light of the frequency f _{02 by} the wavelength conversion element 11. At this time, since f ₀₂ = 2f _c −f _s , the frequency f _{c of the} control light is an intermediate frequency (f _s + f ₀₂ ) / 2 between f _s and f ₀₂ . Further, when the control light is off, only the signal light of f _s which is incident from the signal optical fiber 12 is emitted from the wavelength conversion element 11, so f _s is cut by the narrow band filter 17 and is output to the output optical fiber 16. Is not transmitted.

FIG. 11 shows an example of the configuration of the integrated wavelength converter 20 when the wavelength conversion device 10 of FIG. 9 has an integrated structure. Optical waveguides 22 and 23 formed on the substrate 21
The light guided by illuminates the nonlinear optical material 24. The output light from the non-linear optical material 24 passes through the optical waveguide 25, is cut by the narrow band filter 26 to remove light of an unnecessary wavelength, and is output. The substrate 21 is not particularly limited as long as it is a material capable of forming a waveguide. The nonlinear optical material 24 may form a waveguide. Further, the narrow band filter 26 only needs to have a wavelength selection action, and may be a diffraction grating or a prism.

[0030]

As described above, according to the present invention, a wavelength conversion device using a nonlinear optical material, which has been difficult to realize in the past, can be realized with high efficiency, and it is necessary to convert an optical signal into an electric signal for wavelength conversion. It is now possible to perform wavelength conversion operation at ultra-high speed without changing the optical signal. As a result, the circuit of the optical communication device can be simplified, ultra-high density integration can be facilitated, and the device can be downsized and the cost can be reduced. <References> 1: Wavelength Conversion Technologies for WDM Net
work Applications [JOURNAL OF LIGHT TECHNOLOGY VOL
14, NO6,955-966] 2: Physical Review Letters 85 (10) 2204-2207 (200
0) [Ultrafast Optical Nonlinearity in the Quasi-One
-Dimensional Motr Insulator Sr ₂ CuO ₃ ] 3: Physical Review Letters 76 (14) 2579-2582 (199
6) (Singularities in Optical Spectra of Quantum Spi
n Chains]

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a basic configuration of a wavelength conversion element according to the present invention.

FIG. 2 is an explanatory diagram showing a crystal structure of a one-dimensional copper oxide single chain substance Sr ₂ CuO ₃ that can be used in the present invention.

FIG. 3 is a graph showing the wavelength dependence of the two-photon absorption β of the one-dimensional copper oxide single-chain substance Sr ₂ CuO ₃ that can be used in the present invention.

FIG. 4 is an explanatory diagram showing the arrangement of input light and output light on the frequency axis when f ₂ > f _{1 in} the wavelength conversion element according to the present invention.

FIG. 5 is an explanatory diagram showing the correspondence between the arrangement of the input light and the output light on the frequency axis and the channel position when f ₂ > f ₁ of the wavelength conversion element according to the present invention.

FIG. 6 is an explanatory diagram showing an arrangement on the frequency axis of input light and output light in the case of f ₂ <f ₁ of the wavelength conversion element according to the present invention.

FIG. 7 is an explanatory diagram showing the correspondence between the array of input light and output light on the frequency axis and the channel position when f ₂ <f ₁ of the wavelength conversion element according to the present invention.

FIG. 8 is a graph showing an example of band transmission characteristics of a narrow band filter provided in each channel.

FIG. 9 is a schematic diagram of a wavelength conversion device according to an embodiment of the present invention.

FIG. 10 is a graph showing bandpass characteristics of a narrow band filter of each channel.

FIG. 11 is a schematic diagram showing a configuration example of an integrated wavelength converter when the wavelength conversion device according to one embodiment of the present invention has an integrated structure.

FIG. 12 is a diagram illustrating the principle of wavelength conversion by a nonlinear optical material.

[Explanation of symbols]

1: Wavelength conversion element 2: First input light 3: Second input light 4: First output light 5: Second output light 10: Wavelength converter 11: Wavelength conversion element 12: Optical fiber for signal 13: control optical fiber 14: Lens for focusing light 15: Lens for focusing light 16: Output optical fiber 17: Narrow band filter

─────────────────────────────────────────────────── ─── Continued Front Page (56) References Kishida H, Nature, June 22, 2000, vol. 405, 929-932 Kishida H, Phys. R ev. Lett. , October 22, 2001, Vol. 87, No. 17,177401-1-177401-4 (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/35 CA (STN) JISST file (JOIS)

Claims (5)

(57) [Claims] 1. A non-linear optical material for a wavelength conversion element is a primary optical material.
Original copper oxide single-chain structure or one-dimensional copper oxide double-chain structure
Using a material with
A wavelength conversion device that performs wavelength conversion, in which a first input light having a frequency f ₁ is incident on a wavelength conversion element.
The second input light of frequency f ₂ to the stage and the wavelength conversion element.
Means and the frequency of the light emitted from the wavelength conversion element.
Wavenumber f ₃ = 2f ₂ −f ₁ component or frequency f ₄ = 2f ₁ −
The light of one of the components of f ₂ is selected as the output light.
A wavelength conversion device characterized by comprising:
Place 2. The frequency f ₁ of the first input light and the frequency of the output light
The wave number f ₃ is the channel for each wavelength division multiplexing optical communication.
Of the second input light and the frequency f ₂ of the first input light.
Let Δ be the difference from the frequency f _{1 of the} power light, and
The number difference and [delta], where m is a positive integer or zero, relationship _{Δ = | f 2 -f 1 |} = (2m + 1) δ / 2 to the frequency f ₂ of the second input light is determined so as to satisfy
The wavelength conversion device according to claim 1, wherein 3. Used in a wavelength band longer than 1.52 μm
The method according to claim 1 or 2, characterized in that
Wavelength converter. 4. A substance having a one-dimensional copper oxide single-chain structure
Is Sr ₂ CuO ₃ or Ca ₂ CuO ₃ and
The material having the original copper oxide double chain is SrCuO ₂ or
CaCuO ₂ is characterized in that the claim 1 to claim
The wavelength conversion device according to any one of claim 3 . 5. A substance having a one-dimensional copper oxide single-chain structure
Is a mixture of Sr ₂ CuO ₃ and Ca ₂ CuO ₃ ,
A substance having a one-dimensional copper oxide double chain structure is SrCuO.
Claims characterized by being a mixture of ₂ and CaCuO _2.
The wavelength conversion device according to any one of claims 1 to 3 .