JPS62166301A - Polygonal prism - Google Patents

Abstract

PURPOSE:To form an inexpensive polygonal prism with an optical interference filter by vapor-depositing an optical interference filter directly on side faces of a polygonal prism. CONSTITUTION:Optical interference filters 8 and 9 are vapor-deposited directly on two of side faces of a pentagonal prism 7. Those optical interference filters 8 and 9 consists of at least two kinds of layers among a layer material with a low refractive index, a layer of material with a high refractive material, and a layer of material with a refractive index between 1 and the refractive index of the high-refractive-index material. The optical interference filter 8 transmits light with wavelength lambda1 and reflects light with wavelength lambda2 and the optical interference filter 9, on the other hand, reflects the light with the wavelength lambda1 and transmits the light with the wavelength lambda2. Further, a reflection preventive film 10 which prevents both light beams with the wavelengths lambda1 and lambda2 is vapor-deposited directly on the incidence surface of the pentagonal prism 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polygonal prism used in an optical multiplexer/demultiplexer used in wavelength multiplexing optical communications, optical information processing, and the like.

[Conventional technology]

At least two types of layers are alternately overlapped among a layer of a low refractive index material, a layer of a high refractive index material, and a layer of a material having a refractive index between 1 and the refractive index of the high refractive index material. When forming a structured optical interference filter on the side surface of a polygonal prism made of optical glass or optical crystal, conventionally, the optical interference filter vacuum-deposited on an optical glass substrate is index-matched on the side surface of the polygonal prism. I tried to attach it with adhesive.

Now, FIGS. 4 and 5 show examples of conventional pentagonal prisms. This pentagonal prism has a structure in which an optical interference filter 2.3 and an antireflection film 4 formed by vacuum deposition on an optical glass substrate 1 are bonded to a pentagonal prism 6 with a refractive index matching adhesive 5. It has become.

Here, the optical interference filter 2 transmits light of wavelength λ1,
It has a characteristic of reflecting light of wavelength λ2.

On the other hand, the optical interference filter 3 reflects the light of wavelength λ1,
It has a characteristic of transmitting light with wavelength λ2. The antireflection film 4 has a characteristic of transmitting both the wavelength λ and the wavelength λ2.

As shown in Figure 5, light with center wavelength λ1 and light with center wavelength λ2
When the light passes through the optical glass substrate 1, the antireflection film 4, and the refractive index matching adhesive 5 and enters the pentagonal prism 6, the light with the center wavelength λ1 passes through the refractive index matching adhesive 5 and the optical interference. The light passes through a filter 2 and an optical glass substrate 1 and is emitted. On the other hand, the light with the center wavelength λ2 passes through the refractive index bonding adhesive 5 and is reflected by the optical interference filter 2, and then exits from the refractive index matching adhesive 5, the optical interference filter 3, and the optical glass substrate 1. become. Thereby, the light with the center wavelength λ1 and the light with the center wavelength λ2 are separated.

[Problem that the invention seeks to solve]

However, in the above-described conventional structure in which the optical interference filter substrate is bonded to the side surface of the polygonal prism, the optical interference filter 2.3 is formed on the optical glass substrate 1 by vapor deposition.
It is necessary to bond the polygonal prism 6 directly or after processing such as cutting, to the side surface of the polygonal prism 6 with the refractive index matching adhesive 5. Therefore, polygonal prisms having an optical interference filter function have become expensive. Further, the thickness of the optical glass substrate 1 on which the optical interference filter 2.3 is formed by vapor deposition is about 0.5 to 1 mm.

Therefore, when the optical interference filter 2.3 is used by adhering the optical glass substrate 1 formed by vapor deposition to the side surface of the polygonal prism 6, the positional shift of the emitted light due to the refraction of the light on the optical glass substrate 1 will occur. must be taken into consideration. Therefore, as a method of reducing the amount of positional deviation of the emitted light on the optical glass substrate 1, a method of optically polishing the optical glass substrate 1 to make it thinner has been adopted. However, this structure has the disadvantage that the polygonal prism having an optical interference filter function becomes even more expensive due to the addition of a research process.

The object of the present invention was made in view of the above-mentioned drawbacks, and is to provide an inexpensive polygonal prism having an optical interference filter function.

[Means for solving problems]

The polygonal prism according to the present invention includes at least a layer of a low refractive index material, a layer of a high refractive index material, and a layer of a material having a refractive index between the refractive index and the refractive index of the high refractive index material. The optical interference filter, which is composed of two types of layers that are alternately stacked, is deposited directly on the side surface of a prism, thereby achieving the above-mentioned purpose.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 is a schematic perspective view showing an embodiment of a polygonal prism according to the present invention, and FIG. 2 is a plan view of the same polygonal prism. A pentagonal prism 7 made of optical glass is used as the polygonal prism, and optical interference filters 8.9 are formed on two of its side surfaces by direct vapor deposition. This optical interference filter 8.9 includes at least one of a layer of a low refractive index material, a layer of a high refractive index material, and a layer of a material having a refractive index between 1 and the refractive index of the high refractive index material. 2 types of layer 0
It is composed of overlapping parts. The optical interference filter 8 has a wavelength λ
It has a characteristic of transmitting light of wavelength λ2 and reflecting light of wavelength λ2. On the other hand, the optical interference filter 9 has a characteristic of reflecting light of wavelength λ1 and transmitting light of wavelength λ2. Further, on the entrance surface of the pentagonal prism 7, an antireflection film 10 is formed by direct vapor deposition to prevent reflections at both wavelengths λ and λ2.

FIG. 2 is a diagram illustrating the function of the pentagonal prism shown in FIG. 1. When the light with the center wavelength λ1 and the light with the center wavelength λ2 enter the pentagonal prism 7 through the antireflection film 10, the light with the center wavelength λ1 passes through the optical interference filter 8 and exits. On the other hand, the light having the center wavelength λ2 is reflected by the optical interference filter 8 and then passes through the optical interference filter 9 and exits.

Thereby, the light having the center wavelength λ and the light having the center wavelength λ2 can be separated.

FIG. 3 is a plan view showing an embodiment of a polygonal prism pond according to the present invention. A quadrangular prism 11 made of optical glass is used as the polygonal prism, and optical interference filters 12 and 13 are formed by direct vapor deposition on parts of two opposing sides of the prism. The optical interference filter 12.13 is
At least two types of layers are overlapped among a layer of a low refractive index material, a layer of a high refractive index material, and a layer of a material having a refractive index between 1 and the refractive index of the high refractive index material. ing. The optical interference filter 12 transmits light of wavelength λ3,
It has the property of reflecting light of wavelength λ. On the other hand, the optical interference filter 13 has a characteristic of reflecting light of wavelength λ3 and transmitting light of wavelength λ4.

Furthermore, on the same surface as the side surface of the square prism 11 on which the optical interference filter 13 is formed, an antireflection film 14 that prevents reflection against both wavelengths λ3 and λ4 is directly deposited only on the light incident part. It is formed by

Here, when the light with the center wavelength λ3 and the light with the center wavelength λ4 enter the square prism 11 through the antireflection film 14, the light with the center wavelength λ3 passes through the optical interference filter 12 and exits. On the other hand, the light having the center wavelength λ4 is reflected by the optical interference filter 12 and then passes through the optical interference filter 13 and exits. As a result, the center wavelength λ of the light with the center wavelength λ3,
can be separated from the light.

〔Effect of the invention〕

As explained above, according to the present invention, a layer of a low refractive index material and a layer of a high refractive index material are provided on the side surfaces of a polygonal prism made of optical glass or optical crystal, and The optical interference filter, which is composed of alternating layers of at least two types of layers of substances with refractive indexes between the two, is directly deposited, so it is not possible to deposit the optical interference filter as in the conventional method. This not only eliminates the need to cut, polish, and bond the optical glass substrate to the side surface of the prism with a refractive index matching adhesive, but also almost eliminates the positional shift of the emitted light due to the refraction of the light on the optical glass substrate. Since there is no need to do so, it is possible to provide a polygonal prism having an optical interference filter function at a lower cost than in the past.

In addition, by using the polygonal prism according to the present invention, it is possible to provide an inexpensive optical multiplexer/demultiplexer.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing one embodiment of the polygonal prism according to the present invention, FIG. 2 is a plan view of the polygonal prism, and FIG. 3 is a schematic perspective view showing another embodiment of the polygonal prism according to the present invention. 4 is a schematic perspective view showing an example of a conventional polygonal prism, and FIG. 5 is a plan view of the same polygonal prism. 7... Pentagonal prism, 8.9... Optical interference filter, 10... Anti-reflection film, 11... Quadrilateral prism, 12.13. ...Optical interference filter, 14...
...Anti-reflective film. Applicant: NEC Corporation

Claims (1)

[Claims] In a polygonal prism made of optical glass or optical crystal, a layer of a low refractive index material, a layer of a high refractive index material, and a layer of a material having a refractive index between 1 and the refractive index of the high refractive index material. A polygonal prism characterized in that an optical interference filter composed of at least two types of layers alternately stacked is directly deposited on a side surface of the prism.