JP5115737B2 - Wavelength demultiplexing spectrometer - Google Patents

Description

  The present invention relates to an optical element for accurately performing demultiplexing spectroscopy on an optical signal having a specific wavelength among optical signals having a number of wavelengths.

  In recent years, with the development of science and technology, fine optical elements are required in various fields. In particular, in the communication field, the transmission of information is changing from radio waves to light, and wavelength demultiplexing spectroscopic optical elements are used to separate the wavelengths of multiplexed and transmitted light. Accuracy is required.

  Conventionally, such an optical element has been manufactured by depositing an inorganic substance on a glass substrate, or by exposing a transparent member such as a stone wall or glass to an electronic boom exposure and etching process. The cost is very high because it is complicated and difficult to mass-produce.

  Therefore, in recent years, a method of manufacturing an optical element by thermal imprinting has been proposed as a simpler manufacturing method. In thermal imprinting, it is possible to create an optical element by creating a mold for creating an optical element and pressing the mold against a transfer resin that forms the optical element. Mass production is possible.

  While such a wavelength demultiplexing spectroscopic element can demultiplex very accurately, there is a problem that light of a desired wavelength cannot be demultiplexed due to extremely slight distortion and deformation of the element. .

  When manufacturing such a wavelength demultiplexing spectroscopic optical element, the element itself may be slightly distorted, the element itself may be slightly distorted, and deformation due to temperature (heat) may occur. In the spectroscopic optical element, the design demultiplexing wavelength to be demultiplexed may deviate from the actual demultiplexing wavelength, and the demultiplexing efficiency of the wavelength for which demultiplexing is planned decreases.

  As described above, in the conventional wavelength demultiplexing spectroscopic optical element, the width of the wavelength to be demultiplexed is extremely narrow. Therefore, when an abnormality such as a slight distortion occurs in the manufactured element, light of a desired wavelength is efficiently separated. There is a problem that it becomes difficult to wave.

  By the way, the wavelength of many light to be transmitted is transmitted with a certain wavelength interval so that the demultiplexed light is not confused. Therefore, as seen in the conventional wavelength demultiplexing spectroscopic optical element, the wavelength to be demultiplexed is not so high that it is necessary to be very sharp, and it does not overlap with the wavelength of light transmitting other signals. The demultiplexing wavelength may be somewhat broad. In consideration of factors such as changes in the temperature of the element, if the wavelength of the light to be demultiplexed is somewhat broad, demultiplexing can be performed more reliably corresponding to the wavelength.

  In order to broaden the wavelength to be demultiplexed in this way, there is a method of stacking periodic irregularities as described in Patent Document 1 (WO 2004-113974 A1 pamphlet), for example. There is a problem that its production becomes very complicated because it becomes very large.

In Patent Document 2 (Japanese Patent Laid-Open No. 8-129772), an oxide layer is sequentially formed from the surface of a diffraction grating for an optical pickup made of a synthetic resin, and the thickness of the first layer is 1 / 20λ.
To 1 / 2λ SiO ₂ layer, the second layer is a 1 / 8λ ZrO ₂ and Ta ₂ O ₅ mixture layer, the same ZrO ₂ and TiO ₂ mixture layer, or the same thickness ZrO ₂ , TiO ₂ and Al ₂ O ₃
An invention of a diffraction grating for synthetic resin optical pickups in which an SiO ₂ layer having a thickness of 1 / 3λ is formed as the mixture layer and the third layer is disclosed. However, the synthetic resin pickup circuit grating described in Patent Document 2 has a predetermined thickness with respect to the wavelength of the incident light as described above on the upper surface of the protruding grating and the surface of the recess between the gratings. It has a structure in which three layers having thickness are laminated. In this way, forming different types of oxide films corresponding to the wavelength of incident light requires extremely advanced techniques. Further, the oxide film as described above is not formed on the side surface of the projection formed on the synthetic resin pickup circuit grid.
WO 2004-113974 A1 pamphlet Japanese Patent Application Laid-Open No. 8-129772

It is an object of the present invention to provide a wavelength demultiplexing spectroscopic optical element that has no polarization dependency and high productivity.
Another object of the present invention is to provide a wavelength demultiplexing spectroscopic optical element capable of demultiplexing light of a target wavelength even if the element is somewhat distorted or deformed due to temperature change or humidity change. Yes.

The wavelength demultiplexing spectroscopic optical element according to the present invention is a wavelength demultiplexing spectroscopic optical element in which regular polygonal cylinders or cylinders of four or more square pillars periodically formed in the X direction and Y direction of the resin top layer are formed. ,
The surface of regular polygonal cylinders or cylinders formed in large numbers on the resin top layer is covered with 1 to 10 metal oxide layers, and the oxide on the top surface of the regular polygonal cylinders or cylinders. When the thickness of the layer is 100%, the thickness of the oxide layer on the side wall surface of the regular polygonal column or cylinder is in the range of 20 to 80%, and the maximum thickness and the minimum thickness of the side wall surface are The ratio (minimum thickness / maximum thickness) is 0.9 or more and 1 or less, there is no polarization dependence, and broadband light can be demultiplexed.

The metal oxide layer is preferably at least one metal oxide layer selected from the group consisting of HfO ₂ , Ta ₂ O ₅ , ZrO ₂ , TiO ₂ and SiO ₂ .
In the wavelength demultiplexing spectroscopic optical element of the present invention, the average thickness of the oxide layer on the top surface of the polygonal column or cylinder is preferably in the range of 4 to 500 nm.

Furthermore, the wavelength demultiplexing spectroscopic optical element of the present invention is a value when the wavelength width (half width) W _{50 of the} demultiplexed wavelength is ½ of the maximum light intensity of the demultiplexed light of the wavelength to be demultiplexed. Is preferably in the range of 10 to 40 nm.

  Still further, the wavelength demultiplexing spectroscopic optical element of the present invention. It is preferable that the resin top layer and the metal oxide layer constituting the wavelength demultiplexing spectroscopic optical element have a relationship represented by the following formulas (I) and (II).

Further, the wavelength demultiplexing spectroscopic optical element according to the present invention has a regular regularity in which a large number of square polygonal cylinders or cylinders formed on the surface of the resin top layer are pressed against the resin layer with a mold. It is preferable that the top layer and the resin forming the regular polygonal column or the cylinder more than the square column are acrylic resin, styrene resin, polycarbonate resin, cyclic olefin type. It is preferable to contain at least one resin selected from the group consisting of a resin, a thiopheno resin, and a phenol resin.

The polygonal column or cylinder formed here is a regular quadrangle or cylinder having the same period (P) in the X-axis and Y-axis directions, and its width (A) is in the range of 20 to 60% of the period (P). Preferably there is.
In addition, the period (P), which is the sum of the width (A) of the regular polygonal column or cylinder equal to or greater than the quadrangular prism and the gap (E) between the adjacent regular polygonal column or cylinder equal to or greater than the quadrangular prism, is normally 100 to 100. It is in the range of 1200 nm.

  The wavelength demultiplexing spectroscopic optical element of the present invention has, on the surface of the resin top layer 20, a regular polygonal column 22 or a cylinder 24 that is a square column or more formed in a large number by being integrated with the resin top layer 20. The surfaces of the resin top layer 20 and the regular polygonal columns 22 or cylinders 24 that are quadrangular columns or more are covered with a thin metal oxide that transmits light, and the regular polygonal columns 22 or columns 24 that are quadrangular columns or more. When the thickness of the metal oxide layer on the top surface of 100% is 100%, the thickness of the metal oxide layer on the side wall surface of the regular polygonal column 22 or cylinder 24 having a quadrangular column or more is in the range of 20 to 80%. The ratio of the maximum thickness and the minimum thickness of the sidewall metal oxide layer is 0.9 or more and 1 or less.

  In this way, by forming the thickness of the metal oxide layer on the side surface of the regular polygonal prism 22 or the cylinder 24 that is equal to or greater than the square prism within the above range and thinner than the upper surface, the wavelength of light demultiplexed by this element can be increased. can do. That is, for example, a wavelength demultiplexing spectroscopic optical element in which protrusions are formed on the surface of the resin top layer using the nanoprinting method has a very narrow demultiplexing wavelength, and the wavelength to be demultiplexed due to slight distortion of the element is small. It may change.

  If the wavelength demultiplexing spectroscopic optical element does not change in the demultiplexing accuracy of this element, it is sufficient to demultiplex light of a single wavelength, and it is desirable that the demultiplexing width is narrow in order to eliminate noise. However, the usage environment of such a wavelength demultiplexing spectroscopic optical element is not constant. For example, the wavelength demultiplexing spectroscopic optical element may be distorted due to changes in operating temperature or humidity. Since the element has a very fine structure, distortion may occur in the wavelength demultiplexing spectroscopic element in the manufacturing process. When the wavelength demultiplexing spectroscopic optical element is distorted in this way, the spectral characteristics inherent to the wavelength demultiplexing spectroscopic optical element may be deviated, and the demultiplexing efficiency of light of the planned wavelength decreases. There are things to do. On the other hand, in the optical communication method, it is necessary to set the wavelength of the light to be used in consideration of the sideband, resonance, etc. of the light to be demultiplexed, and the wavelength of the light used for transmitting different information is so approximate. There is nothing.

Therefore, even if the wavelength of light separated by the wavelength demultiplexing spectroscopic optical element becomes somewhat broad, there is almost no influence on the amount of received information.
On the other hand, if the target light cannot be demultiplexed due to distortion or the like generated in the wavelength demultiplexing spectroscopic optical element, it means that optical communication itself cannot be performed.

  As a result of considering the advantages and disadvantages of widening the demultiplexing wavelength in the wavelength demultiplexing spectroscopic optical element, the present inventor has reached the conclusion that the advantage of widening the demultiplexing wavelength is great if it is within a certain range. did.

Such widening of the demultiplexing wavelength is achieved by forming a large number of regular polygonal cylinders or cylinders more than quadrangular prisms at a constant pitch in the X-axis direction and Y-axis direction on the surface of the resin top layer used so far. In addition, a transparent thin metal oxide layer is formed on the surface, and the thickness of the metal oxide layer is increased at the top of a regular polygonal column or cylinder of a quadrangular column or more, and the thickness of the top at the side wall. On the other hand, it was found that the demultiplexed wavelength can be broadened by making the thickness uniform within a predetermined range.

  And even by making the demultiplexing wavelength broad in this way, the characteristics of this wavelength demultiplexing spectroscopic optical element are not impaired, and conversely even if some distortion occurs in the element, As with normal devices, demultiplexing spectroscopy can be performed. Furthermore, there is no polarization dependency, and the productivity is high because it can be obtained by laminating as few as 1 to 10 layers.

Next, the wavelength demultiplexing spectroscopic optical element of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an example of a wavelength demultiplexing spectroscopic optical element according to the present invention in which a number of regular quadrangular prisms are formed on the surface of a resin top layer, and FIG. It is a figure which shows the example of the formed wavelength demultiplexing spectroscopy optical element of this invention, and FIG. 3 is a figure which shows the mutual relationship of many regular square pillars formed in the surface of resin-made top layers. FIG. 4 is a sectional view schematically showing a longitudinal section of a regular polygonal cylinder or cylinder.

  As shown in FIGS. 1 and 2, the wavelength demultiplexing spectroscopic optical element of the present invention is integrated with the resin top layer 20 on the surface of the resin top layer 20 laminated on the transparent substrate 10. A large number of regular polygonal prisms 22 or cylinders 24 that are more than quadrangular prisms are formed.

  The transparent substrate 10 is formed of a transparent member such as optical glass, polysulfone, or polyethersulfone. The refractive index of the resin top layer is (n2), and the refractive index of the resin substrate 10 is (n1). The difference (n2-n1) between the refractive index (n2) of the resin top layer and the refractive index (n1) of the transparent substrate 10 is usually 0.01 to 0.35, preferably 0.06 to Within the range of 0.3. The base material and the top layer resin may be selected so as to have such a refractive index difference.

  In the wavelength demultiplexing spectroscopic optical element of the present invention, a large number of regular polygonal cylinders or cylinders of regular quadrangular prisms or more are formed on the surface of the resin top layer. In FIG. 1, a regular quadrangular prism is shown by a number 22, and a cylinder is shown by a number 24 in FIG. 2.

  In the wavelength demultiplexing spectroscopic optical element according to the present invention, the regular polygonal column or cylinder formed on the surface of the resin top layer is formed of the same resin as that forming the resin top layer. That is, a columnar body such as a regular quadrangular column or a cylinder formed on the surface of the resin top layer of the wavelength demultiplexing spectroscopic optical element of the present invention has a pattern opposite to the columnar body to be formed on the resin top layer. By contacting the mold in which the is formed under heating, a columnar body in which the irregularities formed in the mold are reversed can be formed.

Therefore, the resin forming the columnar body formed on the surface of the top layer is the same thermoplastic resin as the resin top layer.
In the present invention, the columnar body is a regular polygonal column or a cylinder greater than a regular quadrangular column. Here, the polygonal prism is a regular polygonal prism that is equal to or more than a regular quadrangular prism, and is a prism that is equal in length to each side in the cross section, such as a regular quadrangular prism, a regular pentagonal prism, a regular hexagonal column, a regular octagonal prism, and a regular dodecagonal prism. . Furthermore, as the number of corners of the regular polygonal column gradually increases, it becomes closer to a cylinder, and in the present invention, a cylinder can be used as the columnar body. Among them, a shape that can equalize the width (A) of the columnar bodies in the X-axis and Y-axis directions is preferable because polarization dependency does not easily appear, and a cylinder, a quadrangular column, an octagonal column, or the like is preferably used.

In this way, in the present invention, by making the columnar body a regular polygonal column or a cylinder that is equal to or greater than a regular quadrangular column, the wavelength width of the demultiplexed light can be widened, and the cross-sectional shape that is not a regular polygonal column is, for example, Even if a rectangular prism is used, the demultiplexed light cannot be broadened. The accuracy of “positive” in the regular polygonal column is most preferable if the length of each side in the cross section is the same, but if it is a deviation of 10% or less, preferably 5% or less of the length of the side. In the present invention, it is regarded as a “regular polygonal column”. Even if a regular polygonal column such as a regular quadrangular column or a columnar body other than a cylinder that deviates from the above definition is used, the effect exhibited by the present invention does not appear.

As shown in FIGS. 1 and 2, the columnar body composed of regular polygonal columns or cylinders as described above is formed with the same period in the X-axis direction and the Y-axis direction of the resin top layer.
In this columnar body, as shown in FIG. 3, when the width (thickness) of the columnar body is A and the gap between adjacent columnar bodies is E, the period (P) can be represented by A + E.

Specifically, the width (A) of the columnar body is usually 20 to 60% of the period (P), preferably 30.
The gap width (E) between adjacent columnar bodies is in the range of ˜50% and is usually 40 of the period (P).
It is in the range of -80%, preferably 50-70%. Thus, by setting the width (A) of the columnar body as described above with respect to the period (P), information is transmitted / received using light of a wavelength that is highly useful when used for optical communication. be able to.

  Therefore, in the wavelength demultiplexing spectroscopic optical element of the present invention, the period of the formed columnar body is usually 100 to 1200 nm. When ultraviolet light demultiplexing is performed, 950 to 1050 nm and visible light demultiplexing are performed. When performing a wave, it is 270-400 nm.

By changing the column width (A), gap width (E), and period (P) length within the above range, the wavelength to be demultiplexed can be controlled. Note that. In FIG. 3, for convenience, (A), (E), and (P) are described using regular square columns, but the same applies to a cylindrical column or other polygonal column.

  In the wavelength demultiplexing spectroscopic optical element of the present invention, the surface of the columnar body formed of the same resin as that forming the resin composition top layer on the surface of the resin top layer as described above has transparency. It is covered with a metal coating.

The metal oxide used here is one of HfO ₂ , Ta ₂ O ₅ , ZrO ₂ , TiO ₂ and SiO ₂ , and these metal oxides can be used alone. They can also be used in combination.
The refractive index of the resin top layer and the metal oxide layer have a specific formula (in order that the resin top layer and the metal oxide layer constituting the wavelength demultiplexing spectroscopic optical element have a predetermined relationship) By having the relationship represented by I) and (II), the operational effects exhibited by the present invention become more prominent.

In the formula (II), it is preferably 0.35 or less, and a large difference in refractive index is not preferable because the sideband becomes large.
Moreover, the layer which consists of such a metal oxide may be a single layer, and can combine 1-10 layers, Preferably it is 1-3 metal oxide layers. If the number of stacked layers is too large, the light transmission in the wavelength demultiplexing spectroscopic optical element of the present invention may be reduced, and the shape of the formed metal oxide layer is the shape of the columnar body. It may be different and the demultiplexing characteristics may be impaired. Also, increasing the number of layers increases the number of processes and decreases productivity.

  Since the wavelength demultiplexing spectroscopic optical element of the present invention has a characteristic of selectively transmitting light of a specific wavelength, the thickness of the metal oxide film at the top part 31 of the columnar part is usually 4. It is in the range of ˜500 nm, preferably in the range of 6 to 450 nm.

  FIG. 4 shows a cross section of a portion where columnar bodies (polygonal columns or cylinders of quadrangular columns or more) 22 and 24 formed by the resin forming the resinous top layer 20 are formed on the surface of the resin top layer 20. It is shown.

  As apparent from FIG. 4, in the wavelength demultiplexing spectroscopic optical element of the present invention, the top portions 31 of the columnar bodies 22 and 24, the side walls 33 of the columnar bodies 22 and 24, and the columnar bodies 22 and 24 are not formed. The surface 35 of the resin top layer 20 is covered with a metal oxide layer.

  In the wavelength demultiplexing spectroscopic optical element of the present invention, the thickness of the metal oxide layer at the top portion 31 of the columnar bodies 22 and 24 is increased, and the thickness of the metal oxide layer at the side wall 33 of the columnar bodies 22 and 24 is decreased. To do.

FIG. 4 shows a mode in which two metal oxide layers of a first metal oxide layer 41 and a second metal oxide layer 42 are formed.
In the wavelength demultiplexing spectroscopic optical element of the present invention, when the thickness of each metal oxide layer at the top 31 of the columnar bodies 22 and 24 is 100%, the side walls 33 of the columnar bodies 22 and 24 are arranged. The thickness of the metal oxide layer is 20 to 80%. Furthermore, it is especially preferable to set it within the range of 30 to 50%. Furthermore, the metal oxide layer is desirably formed uniformly. In particular, in the side wall 33 of the columnar body, it becomes difficult to ensure the uniformity of the metal oxide layer as the thickness of the metal oxide layer increases, and the sideband becomes larger because the pattern shape of the columnar body collapses. , Polarization dependence can be observed. In the present invention, the pattern shape is a regular polygonal column or cylinder of a quadrangular column or more, and the gap is prepared. Further, the thickness is 80% or less, preferably 50% with respect to the thickness of the top oxide metal layer of 100%. By keeping the thickness, a highly uniform metal oxide film having a ratio of the maximum thickness to the minimum thickness (minimum thickness / maximum thickness) of 0.9 to 1 can be formed. Further, when the thickness of the metal oxide layer on the side wall 33 of the columnar body is less than 20% with respect to the thickness of the top metal oxide layer, the wavelength width that can be demultiplexed by the wavelength demultiplexing spectroscopic optical element is widened. do not do.

  The thickness of the metal oxide layer at the top 31 of the columnar bodies 22 and 24 and the thickness of the metal oxide layer at the side wall 33 are, for example, the surface of the wavelength demultiplexing spectroscopic optical element formed as shown in FIG. It is possible to measure by magnifying the cross section of the above using a magnifying means such as an electron microscope and actually measuring it. As shown in FIG. 10, the cross section is obtained by cutting out the vertical cross section of the wavelength demultiplexing spectroscopic optical element and measuring the thicknesses of the metal oxide layers on the top and side walls. Further, as shown in FIG. 11, the surface of the resin formed by thermal imprinting is observed in advance, the diameter of the top of the formed columnar body 24 is measured, and metal oxide layers 41 and 42 are formed. After that, the thickness (maximum thickness) of the metal oxide layer formed on the side wall can be measured by measuring the diameter of the top of the columnar body again.

In the present invention, the thickness (maximum thickness) measured by surface observation is 20 to 80% of the top thickness.
As described above, the thickness of the metal oxide on the side walls 33 of the columnar bodies 22 and 24 is made smaller than the thickness of the respective metal oxide layers on the top portions 31 of the columnar bodies 22 and 24 as described above. The value of the wavelength width (half-value width: W ₅₀ ) that is ½ of the maximum luminous intensity of the demultiplexed light of the wavelength of becomes wide, and is usually 10 to 40 nm, preferably 10 to 30 nm.

  In FIG. 4, the columnar body 22or24 is formed on the surface of the resin top layer 20, the first metal oxide layer 41a is formed on the top portion 31, and the second metal oxide layer 41a is formed thereon. A cross-sectional view of the finished state is shown. In the present invention, the first metal oxide layer 41b of the side wall is also formed on the side wall 33 of the columnar body 22or24 on the surface of the resin top layer 20, and the second metal oxide layer 41b of the side wall is formed thereon. Furthermore, the first metal oxide layer 41 and the second metal oxide layer 42 are also formed in the concave portion 35 between the stacked columnar bodies 22or24 and the adjacent columnar bodies 22or24.

  This is because the full width at half maximum when not coated with the metal oxide as described above is about 2 to 3 nm, the wavelength of light that can be demultiplexed is expanded 5 to 10 times. Even if distortion occurs in the demultiplexing spectroscopic optical element and the demultiplexing characteristics fluctuate, satisfactory demultiplexing can be performed. On the other hand, in order to transmit and receive different information, generally, light having a wavelength shifted by about 50 to 200 nm is used. Therefore, even if the half-value width of the demultiplexed wavelength is widened as described above, Are not mixed, and the accuracy of optical communication does not change at all.

In FIG. 5, the light demultiplexed by the wavelength demultiplexing spectroscopic optical element of the present invention is indicated by a solid line, and the light demultiplexed by the wavelength demultiplexing spectroscopic optical element not forming the metal oxide layer is indicated by a broken line. .
As is apparent from FIG. 5, the wavelength to be demultiplexed becomes wider by adopting the configuration of the present invention.

In the present invention, the value when the wavelength width (half width) W ₅₀ is ½ of the maximum wavelength of the light to be demultiplexed is usually in the range of 10 to 40 nm, preferably in the range of 10 to 30 nm. Is in. By taking a wide half-value width in this way, even if distortion occurs in the wavelength demultiplexing spectroscopic optical element, signals in that region can be reliably captured.

  In other words, for example, when transmitting, receiving, and transmitting sound, data, and images with light, it is common to transmit and receive signals in the wavelength range of 1310 nm, 1490 nm, and 1550 nm, for example, and these wavelengths are separated. Therefore, even if the demultiplexing area is widened as in the present invention, it does not occur that an optical signal carrying other information is picked up.

The wavelength demultiplexing spectroscopic optical element of the present invention can be manufactured by applying various techniques.
As a suitable example for producing a wavelength demultiplexing spectroscopic optical element having particularly high accuracy among various manufacturing techniques, it is preferable to employ a combination of a nanoimprint method and a vapor deposition method.

  The nanoimprint method forms a mold having a pattern opposite to the columnar body to be formed, transfers the pattern formed on the mold while heating to the thermoplastic resin top layer, and forms the resin top layer. In this method, a large number of columnar bodies are formed at once on the surface, and a metal oxide layer is formed on the surface of the columnar bodies thus formed by a dry process such as vacuum deposition.

  A method of forming a large number of columnar bodies on the resin top layer by the nanoimprint method is already known, and in the present invention, a columnar body on the order of nanometers can be produced using such a technique.

  A metal vapor deposition film is formed on the columnar body thus formed. In the present invention, when the thickness of the metal oxide layer at the top of the columnar body is 100%, the oxidation of the side wall of the columnar body is performed. By setting the thickness of the material layer to 20 to 80%, preferably 30 to 50%, the demultiplexing wavelength can be broadened.

In this way, in order to adjust the deposition amount of the metal oxide on the side wall of the columnar body, the metal oxide is deposited at an angle θ with respect to the side wall 33 of the columnar portion 22 or 24. Here, although the angle θ varies depending on the degree of vacuum and temperature, it is usually set within the range of 0 to 35 degrees, preferably 0 to 20 degrees.
Thus, by forming the metal oxide film at a predetermined angle, the thickness of the metal oxide layer on the side wall of the columnar body can be uniformly formed within a specific range.

  If the thickness of the columnar body is lower than 20%, the half-value width of the demultiplexed light cannot be widened as described above, and if the thickness exceeds 80%, the metal oxide formed on the side wall 33 is made uniform. Can not be attached to.

In addition, the temperature conditions at the time of performing vapor deposition as described above are usually 20 to 120 ° C., the atmospheric pressure is usually set in the range of 10 ⁻⁸ to 10 ⁻⁵ Pa, and the wavelength demultiplexing in which the columnar body is formed. It is preferable to perform vapor deposition while rotating the spectroscopic optical element.

  By depositing a metal oxide as described above, a metal oxide film having a thickness of usually 4 to 500 nm, preferably 6 to 450 nm is formed on the top of the columnar body. In this way, by setting the thickness of the metal oxide layer on the side wall of the columnar body to a predetermined thickness with respect to the top of the columnar body, the optical characteristics of the wavelength demultiplexing spectroscopic optical element can be broadened. .

In addition, when metal oxide is vapor-deposited on the side walls of the columnar bodies 22 and 24, the thickness of the metal oxide deposited on the side walls may be different as shown in FIG. In general, as shown in FIG. 12, the metal oxide vapor deposition layer is thickest in the vicinity of the top of the side wall, and the vapor deposition thickness of the metal vapor deposition layer tends to be thin as it approaches the bottom of the side wall. In the present invention, it is preferable to select the deposition conditions so that there is no difference between the maximum thickness and the minimum thickness of the deposited metal on the side wall, and in the present invention, the ratio between the maximum thickness and the minimum thickness of the oxide layer on the side wall. (Minimum thickness / maximum thickness) is 0.9 or more and 1 or less.

  By the way, in the wavelength demultiplexing spectroscopic optical element of the present invention, since the columnar body formed in the resin top layer is very fine, the wavelength of the present invention is caused by the stress applied to the columnar body when forming the cross section. Each member constituting the demultiplexing spectroscopic optical element may be subjected to stress deformation. In order to show an example of such stress deformation, an application is filed simultaneously with the filing of the present invention, and this occurs when a longitudinal section of the wavelength demultiplexing spectroscopic optical element of the present invention is formed under the application of stress. The stress deformation is submitted as Reference Figure 1. The wavelength demultiplexing spectroscopic optical element shown in FIG. 1 originally has a shape as shown in FIG. 4, but is deformed as shown in Reference FIG. 1 by the cross-section forming operation for observing the cross section. Sometimes. FIG. 13 shows a trace of the cross-sectional view shown in FIG. Since the stress is applied, the shape of the resin top layer 20 is crushed vertically as a whole, but the columnar body 22or24 on the surface of the resin top layer 20 is formed. The layer 41.42 is formed, and the metal oxide layer 41.42 has a metal oxide layer formed on the side wall of the columnar body, and the metal oxide film formed on the side wall It can be seen that there is a “maximum thickness” portion formed thick and a “minimum thickness” portion formed with a thin metal oxide layer.

Next, the wavelength demultiplexing spectroscopic optical element of the present invention will be described in detail with reference to examples of the present invention, but the present invention is not limited thereto.
[Example 1]
A small mold having a pattern area of 3 mm square was formed on 4 mm square metal silicon having a thickness of 1 mm.

A cylindrical recess having a period (P) of 1030 nm, a recess width (A) of 360 nm, a gap width (E) of 670 nm, and a height of 310 nm was formed on the surface of the center of the small mold.
Separately, a transparent resin top layer made of methacrylic resin (refractive index: 1.46) having a film thickness of 3 μm was formed on the surface of the transparent substrate layer made of alkali-free glass.

This transparent substrate was placed and fixed on the base material fixing base.
A press base to which a mold base is attached is installed in the apparatus on which the substrate fixing portion is placed, and the mold base manufactured as described above is attached to the press base.

With the atmospheric pressure in the apparatus maintained at 1013 hPa, the transparent substrate placed and fixed on the base material fixing base is heated to 140 ° C., and the mold base fixed to the press base is 1 M on the transparent substrate.
The unevenness formed on the surface of the mold base by contacting with the Pa pressure for 300 seconds is transferred to the surface of the resin top layer of the transparent substrate, and the substrate is fixed when the temperature of the transparent resin substrate drops to 110 ° C. The base was released from the transparent substrate.

The surface of a large number of cylinders standing from the surface of the resin top layer of the obtained wavelength demultiplexing spectroscopic optical element and the lattice of the cross section of the cylinder were observed using an electron microscope. As a result, it was confirmed that columnar protrusions having a period (P) of 1030 nm, a columnar width (A) of 360 nm, and a height of 310 nm were formed on the surface of the transparent resin top layer. The protrusions were erected vertically from the surface of the transparent resin top layer, and no deflation due to residual air was observed at the boundary line between the resin top layer and the protrusions.

The wavelength demultiplexing spectroscopic optical element thus obtained was irradiated with light of 1550 nm, and the half-value width of the transmitted light with respect to this light was measured and found to be 2 nm.
The wavelength demultiplexing spectroscopic element obtained as described above was adjusted to 10 ⁻⁶ Pa atmospheric pressure, the surface temperature of the element was set to 50 ° C. and set in a vapor deposition apparatus, and a columnar body as shown in FIG. The vacuum evaporation of Ta ₂ O ₅ (refractive index: 1.87) is performed for 5 minutes so that the angle θ with respect to the angle is 10 degrees, the thickness of the vapor deposition layer at the top of the columnar body is 200 nm, and the side wall of the columnar body The wavelength demultiplexing spectroscopic optical element of the present invention having a deposition thickness of 80 nm was measured. The deposition thickness of the side wall of the wavelength demultiplexing spectroscopic optical element thus obtained was 40% of the top, the maximum thickness of the deposition layer on the side wall was 80 nm, and the minimum thickness was 75 nm.

Further, HfO ₂ (refractive index: 1.77) was vapor-deposited under the same conditions as described above so that the thickness of the vapor-deposited layer at the top was 200 nm in the metal oxide layer obtained by vapor deposition. At this time, the deposition thickness (that is, the maximum thickness) on the side wall of the columnar body was 80 nm, and the minimum thickness was 75 nm.

The half-width at the reflection peak of the wavelength demultiplexing spectroscopic optical element that does not form the vapor deposition film obtained as described above was 2 nm, but by forming the vapor deposition film as described above, the wavelength demultiplexing spectroscopic optical element The full width at half maximum at the reflection peak was increased to 15 nm.
[Example 2]
The value of θ in FIG. 6 was set to 25 degrees, and a wavelength demultiplexing spectroscopic optical element was manufactured in the same manner as in Example 1.

The thickness of the vapor deposition film at the top of the columnar body of the obtained optical element is 200 nm for both Ta ₂ O ₅ and HfO ₂ , and the (maximum) thickness of the sidewall is 120 nm and 110 nm, respectively, and the minimum thickness is respectively 110 nm and 110 nm.

The obtained wavelength demultiplexing spectroscopic optical element had a half width of 20 nm, and the half width at the reflection peak of the wavelength demultiplexing spectroscopic optical element was widened. Although there was no practical problem, a slight side peak was observed.
[Comparative Example 1]
A wavelength demultiplexing spectroscopic element was manufactured in the same manner as in Example 1 with the value of θ in FIG. The thickness of the deposited film at the top of the obtained columnar body is _{2 for} both Ta ₂ O ₅ and HfO 2.
The thickness of the deposited film on the side wall was 00 nm (maximum) 150 nm and the minimum thickness 70 nm for the Ta ₂ O ₅ layer, and (maximum) thickness 100 nm and the minimum thickness 30 nm for the HfO ₂ layer. A vapor deposition film could not be uniformly formed on the side wall of the wavelength demultiplexing spectroscopic optical element.
Example 3
In Example 1, many regular octagonal prisms having a period (P) of 1030 nm, a height of 310 nm, and a width (A) of 360 nm were formed instead of the cylinder.

Using the element having a regular octagonal column as described above, a wavelength demultiplexing spectroscopic optical element was produced in the same manner as in Example 1.
The film thicknesses of Ta ₂ O ₅ and HfO ₂ at the top of the obtained optical element were both 200 nm, the (maximum) thickness of the sidewalls was 75 nm and 75 nm, respectively, and the minimum thicknesses were 70 nm and 68 nm, respectively.

The obtained wavelength demultiplexing spectroscopic optical element had a half width of 27 nm, and the half width at the reflection peak of the wavelength demultiplexing spectroscopic optical element was widened.
Example 4
A wavelength demultiplexing spectroscopic optical element was produced in the same manner as in Example 3 except that the Ta ₂ O ₅ layer was not deposited.

The film thickness of HfO _{2 at} the top was 400 nm, the (maximum) thickness of the side wall was 150 nm, and the minimum thickness was 140 nm.
The obtained wavelength demultiplexing spectroscopic optical element had a full width at half maximum at the maximum absorption point of the wavelength demultiplexing spectroscopic device, with a half width of 27 nm.
[Comparative Example 2]
In Example 1, a mold capable of forming the protrusions 52 shown in FIGS. 7 and 8 is used as the mold, the pitch width is 1030 nm, the height is 310 nm, the width in the X direction is 200 nm, and Y
A top layer having a large number of rectangular protrusions 52 having a direction width (A) of 400 nm was formed.

Ta ₂ O ₅ and HfO ₂ were deposited in the same manner as in Example 1 except that the pattern shape of the top layer was changed. The vapor deposition thicknesses of Ta ₂ O ₅ and HfO _{2 at} the top are 200 nm, and the (maximum) thicknesses of Ta ₂ O ₅ and HfO _{2 at} the sidewalls are 75 nm and 65 respectively.
The mn and the minimum thickness were 55 nm and 45 nm, respectively.

For this reason, the wavelength demultiplexing spectroscopic optical element obtained in Comparative Example 2 had a half-value width that was too wide at 50 nm, a large sub-peak, and polarization dependence.
[Comparative Example 3]
A wavelength demultiplexing spectroscopic optical element was produced in the same manner as in Comparative Example 2, except that the Ta ₂ O ₅ layer was not deposited.

Except that conditions were set as described above in the same manner as in Example 1, subjected to deposition of HfO _2, the deposition thickness of HfO ₂ at the top of the resulting optical element is a 400 nm, of HfO ₂ in the side wall A wavelength demultiplexing spectroscopic optical element having a deposition thickness of 140 nm was manufactured, and the maximum thickness of HfO _{2 on} the side wall was 140 nm and the minimum thickness was 90 nm.

For this reason, the wavelength demultiplexing spectroscopic optical element obtained in Comparative Example 3 had a half-value width that was too wide at 45 nm, and also had a large sub-peak and polarization dependency.
[Comparative Example 4]
Using the mold in which the ridges 62 are formed as shown in FIG. 9, the cycle (P) 1
A top layer having ridges 62 with ridges 62 extending in the Y direction was formed with ridges 62 having a height of 310 nm and a width of 310 nm in the X direction of 360 nm.

An optical element was produced in the same manner as in Example 1 except that the pattern shape of the top layer was changed. Deposition thicknesses of Ta ₂ O ₅ and HfO _{2 at} the top of the protrusion of the obtained optical element are 200 nm, 190
The deposition thickness of Ta ₂ O _{5 on} the sidewalls was 80 nm and 75 nm, but the maximum thickness was 80 nm and 75 nm, and the minimum thickness was 70 nm and 65 nm.

For this reason, the wavelength demultiplexing spectroscopic element obtained in Comparative Example 4 has an excessively wide half-value width of 60 nm, and the wavelength demultiplexing spectroscopic element also has polarization dependency.
[Comparative Example 5]
A wavelength demultiplexing spectroscopic optical element was produced in the same manner as in Comparative Example 4 except that the Ta ₂ O ₅ layer was not deposited.

The deposition thickness of HfO _{2 on} the top of the protrusion of the obtained optical element was 200 nm, and the deposition thickness of HfO _{2 on} the side wall was 80 nm, but the maximum thickness was 86 nm and the minimum thickness was 65 nm. .

  For this reason, the wavelength demultiplexing spectroscopic element obtained in Comparative Example 5 has an excessively wide half-value width of 60 nm, and the wavelength demultiplexing spectroscopic element also has polarization dependency.

  The wavelength demultiplexing spectroscopic optical element of the present invention can widen the half width by providing a coating layer having a specific thickness of a metal oxide on the surface of a columnar body formed on the surface of the resin top layer. .

  Therefore, the wavelength demultiplexing spectroscopic optical element of the present invention can very well demultiplex light of a predetermined wavelength even if the spectral wavelength fluctuates due to slight distortion, temperature change, etc. generated in the element. .

FIG. 1 is a perspective view of a wavelength demultiplexing spectroscopic optical element of the present invention. FIG. 2 is a perspective view showing another embodiment of the wavelength demultiplexing spectroscopic optical element of the present invention. FIG. 3 is a diagram illustrating the relationship between the columnar bodies. FIG. 4 is a cross-sectional view showing a cross section of the columnar body. It is a figure which shows typically the broadening of the half value width of the light in this invention. FIG. 6 is a schematic diagram showing the deposition angle. FIG. 7 is a perspective view showing an example of a wavelength demultiplexing spectroscopic optical element in which the shape of protrusions formed on the surface of a conventional resin top layer is not a regular polygon. FIG. 8 is a diagram showing an example of the shape of the protrusion in the wavelength demultiplexing spectroscopic optical element in which the shape of the protrusion formed on the surface of the conventional resin top layer is not a regular polygon. FIG. 9 is a schematic view schematically showing a conventional wavelength demultiplexing spectroscopic optical element in which a large number of protrusions on the surface of the resin top layer are formed. FIG. 10 shows an example of the measurement position of the metal oxide film formed on the surface in the wavelength demultiplexing spectroscopic optical element of the present invention. FIG. 11 is a diagram showing an example in which the thickness of the metal oxide film formed on the surface is measured without forming a cross section in the wavelength demultiplexing spectroscopic optical element of the present invention. FIG. 12 is a drawing schematically showing the “maximum thickness” and the “minimum thickness” of the metal oxide film generated on the side wall of the columnar body. FIG. 13 is a cross-sectional view for explaining the cross-sectional view shown in Reference FIG. 1, which is a modification of the element structure that occurs when the cross-section is cut out to examine the structure of the wavelength demultiplexing spectroscopic optical element of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Transparent substrate 20 ... Resin top layer 22 ... Regular polygonal column (regular square column)
24 ... Column 31 ... Top 33 of columnar part ... Side wall 35 ... Resin top Its surface 41 ... First metal oxide layer 41a ... First metal oxide on top Layer 41b ... Second metal oxide layer 42 on top part ... Second metal oxide layer 42a ... First metal oxide layer 42b on side wall ... Second metal oxide on side wall Layer 52... Projection 62.

Claims (9)

In the wavelength demultiplexing spectroscopic optical element in which regular polygonal cylinders or cylinders of a quadrangular prism or more formed periodically in the X direction and the Y direction of the resin top layer are formed,
The surface of regular polygonal cylinders or cylinders formed in large numbers on the resin top layer is covered with 1 to 10 metal oxide layers, and the oxide on the top surface of the regular polygonal cylinders or cylinders. When the thickness of the layer is 100%, the thickness of the oxide layer on the surface of the side wall of the regular polygonal column or cylinder is in the range of 20 to 80%, and the maximum thickness and the minimum thickness of the oxide layer on the side wall A wavelength demultiplexing spectroscopic optical element having a thickness ratio (minimum thickness / maximum thickness) of 0.9 or more and 1 or less, having no polarization dependence, and capable of demultiplexing broadband light . 2. The metal oxide layer according to claim 1, wherein the metal oxide layer is at least one metal oxide layer selected from the group consisting of HfO ₂ , Ta ₂ O ₅ , ZrO ₂ , TiO ₂ and SiO _2. Wavelength demultiplexing spectroscopic optical element.   2. The wavelength demultiplexing spectroscopic optical element according to claim 1, wherein the average thickness of the oxide layer on the top surface of the regular polygonal column and / or the cylinder is in the range of 4 to 500 nm. Characterized in that the value when the wavelength width (half width) W ₅₀ of demultiplexing wavelength of 1/2 the maximum amount of the demultiplexed light of the light wavelength to be the branching is in the range of 10~40nm The wavelength demultiplexing spectroscopic optical element according to claim 1. The wavelength according to claim 1, wherein the resin top layer and the metal oxide layer constituting the wavelength demultiplexing spectroscopic optical element have a relationship represented by the following formulas (I) and (II): Demultiplexing spectroscopic optical element.

  A large number of square prisms or cylinders formed on the surface of the resin top layer are formed by pressing a mold against the resin layer to form a columnar body with a certain regularity. 2. The wavelength demultiplexing spectroscopic element according to claim 1.   The top layer and a resin that forms a regular polygonal column or a cylinder that is a quadrangular column or more are at least one kind selected from the group consisting of acrylic resins, styrene resins, polycarbonate resins, cyclic olefin resins, and phenol derivative resins. 2. The wavelength demultiplexing spectroscopic optical element according to claim 1, further comprising a resin.   The period (P) is the same in the X-axis and Y-axis directions of the polygonal cylinder or cylinder above the regular square pole, and the width (A) of the regular polygonal cylinder or cylinder is in the range of 20 to 60% of the period (P). 2. The wavelength demultiplexing spectroscopic optical element according to claim 1, wherein: The period (P), which is the sum of the width (A) of the regular polygonal column or cylinder greater than or equal to the quadrangular prism and the gap (E) between the adjacent regular polygonal column or cylinder greater than or equal to the square prism, is in the range of 100 to 1200 nm. The wavelength demultiplexing spectroscopic optical element according to claim 1, wherein the wavelength demultiplexing spectroscopic optical element is provided.

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