JP2003043249A - Polarizing functional element, optical isolator, laser diode module and method for manufacturing polarizing functional element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polarizing functional element having a polarizing film in which a light transmitting dielectric grating and a conductive metal film are alternately arranged in a plurality of numbers to form a stripe structure in one body so that the reflection dispersion of the incident light is suppressed and loss of light is prevented. SOLUTION: The polarizing functional element is provided with a light transmitting substrate 1 and the following polarizing film 4 having such a stripe structure as integrated with the substrate 1. The polarizing film 4 is produced by alternately arranging a plurality of ultrathin and smooth metal thin films 3a, 3b having 5 to 20 nm film thickness as aimed specification and within ±10% variance of the thickness and the light transmitting dielectric gratings 2a, 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization function element, an optical isolator, a laser diode module, and a manufacturing method of the polarization function element.

[0002]

2. Description of the Related Art Conventionally, it has been known to construct a polarization functional element having a stripe structure by alternately laminating a large number of light-transmitting dielectric gratings and conductive metal films (Japanese Patent Laid-Open No. 60-60).
97304). When the incident light is incident from the direction perpendicular to the stacking direction, this polarization function element absorbs the component parallel to the layer and transmits the component orthogonal to the layer, and thus can exhibit the polarization function.

However, in the polarization function element, since a large number of light-transmitting dielectric gratings and conductive metal films are simply laminated alternately, the metal film is extremely thin so as to prevent reflection dispersion of incident light. If formed into a shape, the laminated structure may be separated from the metal film. Further, there is a limit to the number of layers that can be taken into consideration due to peeling due to a metal film, and thus there is a limit to the thickness in the layering direction, so that light with a large beam diameter cannot enter.

In addition, a magneto-optical crystal body having a Faraday effect is provided as a substrate, a large number of parallel concave grooves having a predetermined width and depth are provided on the surface of the substrate, and a metal layer is formed as a metal thin film in the groove of the substrate. It is proposed to form a Faraday rotator integrated with a polarizer by filling and forming (Patent No. 3).
067026).

In this Faraday rotator, it is necessary to maintain a predetermined width and to provide a large number of parallel fine grooves with a depth larger than the width on the surface of a hard magneto-optical crystal such as garnet. However, the groove processing is extremely difficult in practice, and it is also difficult to precisely control the processing of precisely digging a minute groove to a predetermined depth and filling the metal layer in the groove.

On the other hand, elongated fine irregularities are formed on the plate surface of the quartz substrate, a semiconductor thin film is formed on the entire surface of the irregularities, and then the thin film formed on the side surfaces of the irregularities is left and the surface of the irregularities is formed. In addition, the thin film formed on the bottom surface is removed, and a transparent body having a refractive index similar to that of the quartz substrate is fixed to the surface from the inside of the recess to form a striped polarizing film in which quartz and semiconductor thin films are alternately arranged. Has been proposed to be integrated with the substrate (Japanese Patent Laid-Open No. 4-256904).

According to the manufacturing process, first, a semiconductor thin film is formed on the entire surface of the unevenness by high-frequency sputtering. However, since it is difficult for this entire surface film to adhere to the side surface of the unevenness to a uniform thickness, it is used as a polarizing film. It is difficult to control the thickness of the thin film used on the side surface with high precision. In particular, when the film thickness is large, incident light is reflected and dispersed, resulting in a large optical loss, and the performance deteriorates.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a striped structure in which a plurality of light-transmitting dielectric gratings and conductive metal films are alternately arranged is formed, and the reflection dispersion of incident light is suppressed. An object of the present invention is to provide a polarization functional element and an optical isolator which are provided with a polarizing film capable of preventing the occurrence of light loss and are excellent in performance such as light transmittance and polarization performance.

It is an object of the present invention to provide a laser diode module having a large oscillation output and a stable output even for the same electric input.

The present invention provides a polarization functional element which is capable of forming a conductive metal film in an extremely thin shape so as to suppress reflection dispersion of incident light and prevent occurrence of light loss, and which is excellent in performance such as light transmittance and polarization performance. An object of the present invention is to provide a method for manufacturing a polarization functional element that can be manufactured easily and at low cost.

[0011]

According to a first aspect of the present invention, there is provided a polarization functional element comprising a light-transmissive substrate, a target specification film thickness of 5 to 20 nm, and a variation in thickness. Is formed by providing a polarizing film having a striped structure in which a plurality of ultrathin and smooth conductive metal thin films in the range of ± 10% are alternately arranged with a light transmissive dielectric grating in a structure integrated with a substrate.

In the polarization function element according to the second aspect of the present invention, the polarization films in which the respective stripe structures are parallel to each other are provided on both surfaces of the substrate.

A polarization function element according to a third aspect of the present invention is constituted by providing a laminated film of a polarizing film having a stripe structure and a light-transmitting dielectric film as a non-reflective film in an integrated structure with a silicon substrate. ing.

In the polarization function element according to a fourth aspect of the present invention, a laminated film in which a plurality of stripe-structured polarizing films and light-transmitting dielectric films are alternately laminated is used as a non-reflective film so as to be integrated with the silicon substrate. It is configured by providing.

According to a fifth aspect of the present invention, there is provided a polarization function element, which comprises a light-transmissive substrate and has a target specification film thickness of 5 to 5.
± 10% variation in thickness in any of the 20 nm range
A striped structure in which a plurality of ultra-thin and smooth conductive metal thin films are alternately arranged with a light-transmitting dielectric lattice, and the striped lattice has different directions at angles corresponding to the rotation angle of the Faraday rotation crystal. It is configured by providing a polarizing film inclined to the both sides of the substrate.

In the polarization functional element according to claim 6 of the present invention, a Faraday rotation crystal is provided as a substrate, and a polarizing film having a stripe structure is formed on the Faraday rotation crystal, and is formed on the polarization film. It is configured by providing a laminated film with a light-transmitting dielectric film as a non-reflective film integrally with the Faraday rotation crystal.

An optical isolator according to a seventh aspect of the present invention is constructed by assembling the polarization function element according to the fifth or sixth aspect as an optical isolator element.

A laser diode module according to an eighth aspect of the present invention is constructed by assembling and mounting the optical isolator according to the seventh aspect.

According to a ninth aspect of the present invention, there is provided a method for manufacturing a polarization functional element, comprising a light-transmissive substrate, forming a dielectric layer on the substrate, and then separating the dielectric layer with a predetermined distance. A plurality of parallel dielectric base lattices are formed, and a conductive metal thin film is formed by vapor-depositing a conductive metal on one side surface of the dielectric base lattice in an oblique direction. A dielectric additional layer is formed to fill the remaining space of the body-based grating, and a striped polarizing film sandwiching a conductive metal thin film from the dielectric additional layer and the dielectric base grating is formed integrally with the substrate. Has been done.

In the method of manufacturing a polarization functional element according to a tenth aspect of the present invention, a conductive metal thin film is deposited on the dielectric base grid by depositing a conductive metal from different oblique directions on each side surface of the dielectric base grid. It is designed to be formed on both sides.

According to the eleventh aspect of the present invention, in the method of manufacturing a polarization functional element, the target specification film thickness is in the range of 5 to 20 nm, and the thickness variation is within ± 10% and is extremely thin and smooth. A polarizing film having a stripe structure, in which a plurality of conductive metal thin films are alternately arranged with a light-transmitting dielectric grating, is formed integrally with the substrate.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, referring to the accompanying drawings, the illustrated embodiment is shown in FIG. 12 when the polarizing filter element shown in FIGS. 1 and 8 to 11 is constituted as a polarization functional element. The case where the optical isolator element is configured as a polarization function element is mentioned. Further, as an application example of the optical isolator element, the optical isolator shown in FIG. 13 and the laser diode module shown in FIG. 14 are mentioned. In the embodiments relating to the polarization function element, the same components are denoted by common reference numerals.

The polarization function element comprises a substrate 1, a light-transmitting dielectric grating 2a, 2b ... And a conductive metal thin film 3a, 3b.
.. is arranged in parallel with each other, and the basic configuration is to provide the polarizing film 4 having a striped structure in parallel with the substrate 1 in an integrated structure. As the substrate 1, a silicon substrate is provided when forming a polarization filter element, and a Faraday rotation crystal body is provided when forming an optical isolator element.

In the polarization function element, the variation in thickness is ± 1 when the target specification film thickness is in the range of 5 to 20 nm.
Ultra-thin and smooth conductive metal thin films 3a, 3b in 0% range ...
Are arranged side by side with the light-transmitting dielectric gratings 2a, 2b ... Alternately, so that the polarizing film 4 having a striped structure is formed.

When the polarization function element is mounted, the optical surface is arranged perpendicular to the optical axis or assembled at an angle of about 8 °, but the metal thin films 3a, 3b ... Have a film thickness of 5 ± 10. When it is less than% nm, the TE loss becomes small due to the normal incidence, and it does not function as a polarizer. On the other hand, the inclination angle is 8 ° and the film thickness of the metal thin films 3a, 3b ... Is 20 ± 10%.
When the thickness is greater than or equal to nm, the TM loss increases, the insertion loss increases, and the performance deteriorates. Therefore, none of them can achieve the target characteristics.

Since the metal thin films 3a, 3b ... Are extremely thin and smooth with few irregularities, the metal thin films 3a, 3b.
The polarizing film 4 according to ... Can be configured to suppress reflection dispersion of incident light, prevent occurrence of optical loss, and keep TM loss small and TE loss large. In addition, the polarizing film 4 having a striped structure is formed of a silicon substrate or a substrate 1 made of a Faraday rotation crystal.
Since it is formed on the above, the film itself can be configured to have a strong integral structure.

By forming a light-transmitting dielectric film 5 on the polarizing film 4 in addition to the striped polarizing film 4, there is no reflection from the polarizing film 4 and the light-transmitting dielectric film 5. The film 6 is formed. The non-reflective film 6 can more reliably suppress the reflection dispersion of incident light and prevent the occurrence of light loss, so that the anti-reflection film 6 can be configured as a polarization functional element having excellent properties such as light transmittance and polarization performance.

When manufacturing a polarization filter element as the polarization function element, the substrate 1 is made of BK in addition to the silicon crystal.
-7 glass, lead glass, germanium crystal, and lithium niobate crystal are used. Dielectric grating 2a, 2b
... is SiO ₂ , TiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ ,
It can be formed of a dielectric material such as ZrO ₂ . Metal thin film 3
The a, 3b ... Can be formed from a conductive metal such as tantalum, silver, copper, or aluminum.

When manufacturing the polarization filter element, first, as shown in FIG. 2, a dielectric base layer 20 having a predetermined thickness is formed on the plate surface of the silicon substrate 1 by sputtering or vacuum evaporation. Next, a striped mask is placed on the surface of the dielectric base layer 20, and a plurality of dielectric bases that are parallel to each other at predetermined intervals are formed by X-ray lithography, ECR, and etching, as shown in FIG. The gratings 20a, 20b ... Are formed at a predetermined interval.

Molecular beam epitaxy (MBE), atomic layer epitaxy (ALE), sputtering, vacuum deposition, or the like is applied to the dielectric base gratings 20a, 20b, ... And a conductive metal is slanted upward as shown in FIG. By skipping further, the metal thin films 30a, 30b ... Are formed in a thin film shape. Since this conductive metal is exclusively blown from diagonally above toward one side surface of the dielectric base lattices 20a, 20b ...
The metal thin films 30a, 30b ... Can be formed thinly and precisely. However, the conductive metal is the dielectric base gratings 20a, 20
Although it adheres also to the upper surface of b ..., this can be removed in a later process.

After forming the metal thin films 30a, 30b ..., As shown in FIG. 5, dielectric base gratings 20a, 20b are formed.
The dielectric material 21 of the same material as the above is filled in the remaining space between the metal thin films 30a, 30b ... And the dielectric base gratings 20a, 20b ... By sputtering or vacuum deposition. Next, FIG.
As shown in FIG. 3, excess dielectric material 21 and metal thin film 3 are formed until the upper surfaces of the dielectric base gratings 20a, 20b ... Are exposed.
0a and 30b are removed by polishing or the like.

.. can be formed from the dielectric material 21 and the dielectric addition layer 2 can be formed.
Dielectric gratings 2a, 2b ... Can be formed from 1a, 21b ... And dielectric base gratings 20a, 20b. Further, the dielectric film 2a, 2b ... And the metal thin films 3a, 3b can form the polarizing film 4 having a striped structure as a basic form.

When the multilayer structure laminated film including the polarizing film 4 is formed as the antireflection film 6, at least the dielectric film 5 is laminated and laminated on the polarizing film 4 having the striped structure as shown in FIG. Using the dielectric film 5 as a base layer, TiO ₂ / SiO ₂ , T
The antireflection film can be formed by further laminating a dielectric film of a ₂ O ₅ / SiO ₂ .

From the above steps, the metal thin films 3a, 3b ...
Is formed to have a target specification film thickness in the range of 5 to 20 nm and a thickness variation of ± 10%. On the other hand, the dielectric gratings 2a, 2b ... May be formed with a width of about 50 to 300 nm, and the height of the stripe structure may be formed with a height of about 200 to 1000 nm.

When the polarizing filter element is manufactured as described above, when the film thickness of the target specification is in the range of 5 to 20 nm and the variation in the thickness is within ± 10%, it is extremely thin and has a smooth conductive surface with few irregularities. Since the polarizing film 4 having the striped structure is formed by providing the metal thin films 3a, 3b, ..., The reflection dispersion of the incident light is suppressed, the optical loss is prevented, the TM loss is small and the TE loss is large. Can be configured. At the same time, by forming the non-reflective film 6 from the polarizing film 4 and the dielectric layer 5, a polarizing filter element having excellent performance such as light transmittance and polarization performance can be constructed.

In terms of steps, the X-ray lithography method and E
A plurality of dielectric base lattices 20a, 20b ... Are formed at a predetermined height by applying the CR or etching method, and molecular beam epitaxy (MBE) or atomic layer epitaxy (A
Since the metal thin films 3a, 3b ... Are formed by LE), sputtering, vacuum deposition, or the like, the polarizing filter element can be constructed at a low cost by a simple process.

In order to confirm its effectiveness, a silicon crystal (Si) is used as a substrate, a dielectric lattice is formed from silicon dioxide (SiO ₂ ), and a metal thin film is formed from silver (Ag),
By forming a non-reflective film using silicon dioxide (SiO ₂ ) as a base layer, the thickness of the metal thin film (target value): 20 n
A polarizing functional element having m, a period width of 220 nm and a height of 400 nm was manufactured.

When the metal thin film had a target film thickness of 20 nm, TM loss: about 0.014 dB and TE loss: about 23.5 dB were obtained. In addition, if the film thickness variation is + 10% and the film thickness is 22 nm, TM
Loss: about 0.017 dB, TE loss: about 25.0 dB
When the film thickness variation is −10% and the film thickness is 18 nm, the TM loss is about 0.011 dB and the T
E loss: It became about 22.0 dB.

Here, a material having a small TM loss and a large TE loss is excellent in characteristics, and TE is 20 nm.
Loss: Since 20 dB or more is preferable, the target specification film thickness is 20 nm and the thickness variation is within ± 10% of 2
Even with 2 nm and 18 nm film thickness, the light transmittance,
It can be configured as a polarization function element having excellent performance such as polarization performance.

When the polarization function element is mounted, the optical surface is arranged perpendicular to the optical axis or 8 ° as described above.
The metal thin film 3a, which can be assembled at a certain angle,
When the film thickness of 3b ... Is 5 ± 10% nm or less, TM loss becomes 0.002 dB and TE loss becomes 2.5 dB due to vertical incidence, and thus it does not function as a polarizer. On the other hand, the inclination angle is 8 ° and the film thickness of the metal thin films 3a, 3b ...
When it becomes ± 10% nm or more, TM loss becomes 0.24 dB, TE loss becomes 48 dB, and insertion loss becomes large and performance deteriorates. Therefore, none of them can achieve the target characteristics.

In the above-described embodiment, the case where the antireflection film 6 is provided only on one surface of the silicon substrate 1 has been described, but as shown in FIG. 8, the dielectric gratings 2a, 2b ... 2a, 2b.
And polarizing films 4 and 4 having a striped structure formed of conductive metal thin films 3a, 3b ... 3a, 3b ...
It is provided on both surfaces of the substrate 1 including the dielectric films 5 and 5. As a result, the performance as a polarization functional element can be improved and the polarization extinction ratio can be increased.

Further, in the above-mentioned embodiment, the dielectric layer 5
The non-reflective film 6 was formed by stacking the film on the polarizing film 4 having a striped structure, and as shown in FIG. , Which are formed on the surface of the dielectric film 5 and are formed on the surface of the dielectric film 5, and the polarizing film 4 having a striped structure formed by the conductive metal thin films 3a, 3b. 1
And an integral structure.

In addition, the case where a single antireflection film 6 is provided from the polarizing film 4 and the dielectric film 5 has been described, but as shown in FIG. 10, the light-transmitting dielectric layers 5 and 5'and the polarizing film. 4,4 '
Alternatively, a plurality of layers and may be alternately laminated to form the multi-layered antireflection film 6 ′ with the silicon substrate 1 in an integrated structure. In this embodiment, the first dielectric film 5 has a thickness of 224 nm.
To about 218 nm in thickness of the first-layer polarizing film 4,
The dielectric film 5'of the second layer is formed into
The polarizing film 4'of the layer may be formed to have a thickness of about 279 nm.

Although the metal thin films 3a, 3b ... Are formed on one side surface of the dielectric base gratings 20a, 20b ..., the gold thin films 3a, 3b are shown in FIG.
, 3a ', 3b' ... are dielectric base gratings 20a, 20
It can be provided on both sides of b ... In this case, the direction in which the conductive metal is blown from the vapor deposition source may be controlled so as to fly from different directions on each side.

When an optical isolator element is manufactured as the embodiment, the substrate 1 is mainly made of a Faraday rotation crystal having a garnet structure such as TbBiFe garnet.
Hard magnetic garnet that is magnetically saturated without an external magnetic field, cadmium other than garnet, manganese, mercury, tellurium, etc. are used. The dielectric gratings 2a, 2b ... And the metal thin films 3a, 3b ... Can be formed of the same material as that of the above-described polarization filter element.

When manufacturing the optical isolator element,
As shown in FIG. 12, the Faraday rotation crystal is used as the substrate 1, and the striped structures of the polarizing films 4 and 4 (however, the non-reflective dielectric film is omitted) from the above-described steps are set to the Faraday rotation angle. It may be provided on both sides of the substrate 1 made of a Faraday rotation crystal body with a corresponding inclination of about 45 ° (inclination direction is indicated by a dot in the figure). In this optical isolator element, the anti-reflection films on both surfaces exert the polarization function and also function to increase the light transmittance, so that an optical isolator with low optical loss and excellent characteristics can be constructed.

Using the optical isolator element, as shown in FIG.
As shown in FIG. 3, a magnet 7 having a cylindrical shape and a metal holder 8 such as stainless steel are provided. By fitting and fixing and assembling the whole including the magnet 7 inside the metal holder 8, it is possible to construct a small-sized optical isolator having high performance and excellent characteristics.

As the optical isolator element, for example, T of hard magnetic garnet (see Japanese Patent Laid-Open No. 9-328398) which is magnetically saturated in the garnet without an external magnetic field.
It can be formed by using a b-Bi-Fe-Ga-Al-O-based substrate. According to this optical isolator element, since it is not necessary to assemble a magnet, the optical isolator can be made small and inexpensive.

With the optical isolator 10 shown in FIG.
As shown by 4, a semiconductor laser chip 11 serving as a light source, a heat sink 12 of the semiconductor laser chip 11, a cylindrical lens 13 that collects laser light oscillated from the semiconductor laser chip 11, an optical fiber 14, and a ferrule made of zirconia for fixing the optical fiber 14 15, module case 1
A laser diode module can be constructed by assembling 6 together.

This laser diode module can be configured to have a large oscillation output and a stable output for the same electric input, as compared with a conventional optical isolator using a polarizing film.

[0051]

As described above, according to the polarization function element according to the first aspect of the present invention, the polarizing functional element is provided with the light-transmissive substrate, and the target specification film thickness is in the range of 5 to 20 nm. By providing a polarizing film having a striped structure in which a plurality of extremely thin and smooth conductive metal thin films with a variation of ± 10% are alternately arranged with a light transmissive dielectric lattice, the metal thin film can be formed. Since it is formed to be extremely thin and smooth without unevenness, reflection dispersion of incident light by the metal film can be suppressed, TM loss can be kept small and TE loss can be kept large. Since it is formed on the above, the film itself can be configured to have a strong integral structure, and can be configured as a polarization functional element having excellent properties such as light transmittance and polarization performance.

According to the polarization function element of the second aspect of the present invention, the polarization extinction ratio can be increased and the performance of the polarization filter element can be increased by providing the polarization films having the stripe structures parallel to each other on both sides of the substrate. Can be configured as

According to the polarization function element of the third aspect of the present invention, the laminated film of the polarizing film having the stripe structure and the light-transmitting dielectric film is provided as a non-reflective film in an integrated structure with the silicon substrate. Thus, the polarization extinction ratio can be further increased, and a polarization filter element having excellent performance can be constructed.

According to the polarization function element of the fourth aspect of the present invention, a laminated film in which a plurality of stripe-structured polarizing films and light-transmitting dielectric films are alternately laminated is used as a non-reflective film and integrated with a silicon substrate. By providing it in the structure, the polarization extinction ratio can be further increased, and a polarization filter element having excellent performance can be configured.

According to the polarization function element of the fifth aspect of the present invention, the Faraday rotation crystal is provided as the substrate, the target specification film thickness is in the range of 5 to 20 nm, and the thickness variation is ± 10. % The ultra-thin and smooth conductive thin metal film in the range of% is arranged alternately with the light-transmitting dielectric lattice, and the lattice of the stripe structure is different by the angle corresponding to the rotation angle of the Faraday rotation crystal. By providing the polarizing films inclined in the direction on both surfaces of the substrate, reflection dispersion can be suppressed and a large optical loss can be prevented from occurring, so that the optical isolator element having excellent performance can be configured.

According to the polarization function element of claim 6 of the present invention, a Faraday rotation crystal is provided as a substrate, and a polarizing film having a stripe structure is formed on the Faraday rotation crystal.
By providing a laminated film with a light-transmitting dielectric film formed on this polarizing film as a non-reflective film in an integrated structure with the Faraday rotation crystal, reflection dispersion can be reliably suppressed and large optical loss can be prevented. Therefore, it can be configured as an optical isolator element having excellent performance.

According to the optical isolator according to the seventh aspect of the present invention, by assembling the optical isolator element according to the fifth or sixth aspect, it is possible to construct a high performance, excellent characteristic, inexpensive, and small size.

According to the laser diode module of the eighth aspect of the present invention, by mounting the optical isolator of the seventh aspect, it is possible to obtain a large oscillation output and a stable output for the same electric input. Can be configured.

According to the method for manufacturing a polarization function element according to the ninth aspect of the present invention, a conductive metal thin film is formed by obliquely depositing a conductive metal on one side surface of the dielectric base lattice. A polarizing film that suppresses the reflection dispersion of incident light and prevents the occurrence of light loss can be reliably formed, and a polarization functional element having excellent performance such as light transmittance and polarization performance can be easily manufactured and obtained at a low cost.

According to the method of manufacturing a polarization functional element according to the tenth aspect of the present invention, a conductive metal thin film is deposited on the dielectric base lattice in different diagonal directions on each side of the dielectric base lattice to form a conductive metal thin film on the dielectric base. By forming it on both sides of the grating, it is possible to efficiently and easily form a polarizing film that suppresses the reflection dispersion of incident light and prevents the occurrence of optical loss.

According to the method for manufacturing a polarization functional element according to claim 11 of the present invention, when the film thickness of the target specification is in the range of 5 to 20 nm, the variation in thickness is extremely thin within ± 10%. Since a polarizing film with a striped structure in which a plurality of smooth conductive metal thin films are alternately arranged with a light-transmitting dielectric grating is formed integrally with the substrate, the metal thin film can be made extremely thin and smooth with few irregularities. Since it can be formed, the reflection dispersion of incident light by the metal film can be suppressed, the occurrence of optical loss can be prevented, and the TM loss can be reduced and T
It can be configured as a polarization functional element capable of maintaining a large E loss.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a polarization filter element as a polarization function element according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a step of forming a dielectric base layer in the first step in the manufacturing process of the polarization function element of FIG.

FIG. 3 is an explanatory diagram showing a step of forming a dielectric base grating subsequent to the step of FIG.

FIG. 4 is an explanatory diagram showing a step of forming a metal thin film subsequent to the step of FIG.

FIG. 5 is an explanatory diagram showing a step of forming a dielectric additional layer subsequent to the step of FIG.

FIG. 6 is an explanatory diagram showing a step of removing a dielectric addition layer and a surplus portion of a metal thin film subsequent to the step of FIG. 5;

FIG. 7 is an explanatory diagram showing a step of forming a dielectric film to be a non-reflective film, following the step of FIG. 6;

FIG. 8 is an explanatory diagram showing a polarization function element in which polarizing films are provided on both surfaces of a substrate as a modification of FIG.

9 is an explanatory diagram showing a polarization functional element provided with a non-reflection film in which a dielectric film and a polarization film are laminated in this order as a modification of FIG.

10 is an explanatory diagram showing a polarization function element provided with a multi-layered antireflection film as a modified example of FIG. 1. FIG.

FIG. 11 is an explanatory diagram showing a polarization functional element in which metal thin films are provided on both surfaces of a dielectric base grating as a modification of FIG.

FIG. 12 is an explanatory diagram showing an optical isolator element as a polarization function element according to an embodiment of the present invention.

FIG. 13 is an explanatory diagram showing an optical isolator according to the present invention.

FIG. 14 is an explanatory diagram showing a laser diode module according to the present invention.

[Explanation of symbols]

1 Substrate (Silicon Substrate, Faraday Rotation Crystal) 2a, 2b ... Dielectric Lattice 20 Dielectric Base Layers 20a, 20b ... Dielectric Base Lattice 21a, 21b ... Dielectric Addition Layers 3a, 3b ... Metal Thin Film 4 Polarizing Film 5 Dielectric Body film 6, 6'non-reflective film 10 Optical isolator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Heiichi Sato             3-8-22 Nitta, Adachi-ku, Tokyo Namiki             Mitsuge Co., Ltd. F term (reference) 2H049 BA05 BA08 BA45 BB03 BB65                       BC01 BC25                 2H099 AA01 BA02 CA02 DA05                 2K009 AA07 BB01 CC03 DD03

Claims (11)

[Claims] 1. A polarizing functional element comprising a polarizing film having a stripe structure in which a plurality of light-transmitting dielectric gratings and conductive metal films are alternately arranged, and a polarizing film having a light-transmitting substrate and having a target specification film thickness. ± 1 variation in thickness in any of 5 to 20 nm range
A polarizing functional element characterized in that a polarizing film having a striped structure in which a plurality of ultra-thin and smooth conductive metal thin films in the range of 0% are alternately arranged with a light-transmitting dielectric grating is provided integrally with a substrate. . 2. The polarization function element according to claim 1, wherein polarizing films having stripe structures parallel to each other are provided on both surfaces of the substrate. 3. The polarized light according to claim 1, wherein a laminated film of a polarizing film having a stripe structure and a light-transmitting dielectric film is provided as a non-reflective film in an integrated structure with a silicon substrate. Functional element. 4. A laminated film in which a plurality of striped polarizing films and light transmissive dielectric films are alternately laminated is provided as a non-reflective film in an integrated structure with a silicon substrate.
The polarizing functional element according to. 5. A Faraday rotation crystal is provided as a substrate, and a target specification film thickness is in the range of 5 to 20 nm.
A striped structure in which a plurality of ultra-thin and smooth conductive metal thin films with a thickness variation of ± 10% are arranged alternately with a light-transmissive dielectric lattice, and the striped lattice corresponds to the rotation angle of the Faraday rotation crystal. The polarization function element according to claim 1, wherein the polarizing film is provided on both surfaces of the substrate, the polarizing films being inclined in different directions by corresponding angles. 6. A laminated film comprising a Faraday rotation crystal body as a substrate, a polarizing film having a stripe structure formed on the Faraday rotation crystal body, and a light-transmitting dielectric film formed on the polarization film. 6. The polarization function element according to claim 5, wherein is provided as a non-reflective film in an integrated structure with the Faraday rotation crystal. 7. An optical isolator comprising the polarization function element according to claim 5 or 6 assembled as an optical isolator element. 8. A laser diode module in which the optical isolator according to claim 7 is mounted and mounted. 9. A dielectric transparent substrate is provided, a dielectric layer is formed on the substrate, and a plurality of dielectric base gratings are formed in parallel with each other at a predetermined distance from the dielectric layer.
Conductive metal is obliquely deposited on one side of the dielectric base lattice to form a conductive metal thin film, and a dielectric addition layer is formed to fill the remaining gap between the conductive metal thin film and the dielectric base lattice. Then, a method of manufacturing a polarization function element, characterized in that a striped polarizing film sandwiching a conductive metal thin film from the dielectric additional layer and the dielectric base grating is formed integrally with a substrate. 10. A conductive metal thin film is formed on both sides of the dielectric base lattice by vapor-depositing a conductive metal in different oblique directions on each side surface of the dielectric base lattice. A method for manufacturing a polarization function element according to item 1. 11. An ultrathin and smooth conductive metal thin film having a target specification film thickness in the range of 5 to 20 nm and a thickness variation of ± 10% is alternated with a light transmissive dielectric grating. 11. The method for manufacturing a polarization function element according to claim 9, wherein a plurality of striped polarizing films arranged side by side are formed integrally with the substrate.