Polarizing function element, optical isolator, laser diode module and method of producing polarizing function element

• US 7,002,742 B2
• Filed: 09/19/2001
• Issued: 02/21/2006
• Est. Priority Date: 09/20/2000
• Status: Expired due to Fees

• Current Assignee: Namiki Seimitsu Houseki Kabushiki Kaisha
• Original Assignee: Namiki Seimitsu Houseki Kabushiki Kaisha
• Inventors: Imaizumi, Nobuo, Sato, Toshimichi, Kasai, Yoshihito, Shiroki, Kenichi
• Primary Examiner(s): Juba, Jr., John
• Application Number:
  US10/130,474
• Publication Number:
  US 20030007251A1
• Time in Patent Office: 1,616 Days
• Field of Search: 359/486, 359/483, 359/485, 359/900
• US Class Current: 359/484.03
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• CPC Class Codes: G02B 5/204 in which spectral selection is performed by means of a conductive grid or array, e.g. frequency selective surfaces for use with wavelengths longer than the infrared light H01Q15/0006
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: Y10S 359/90 Methods

Abstract

This invention has the polarizing function of polarizing an input beam and a non-reflecting function of suppressing reflection of the input beam, wherein at least one side of a light-transmissive substrate 1 has a polarizing portion 4 with a striped structure formed by multiple alternating light-transmissive dielectric layers 2a, 2b . . . and metallic film layers 3a, 3b . . . . Its characteristics are improved if the metallic film layers are very thin and flat, with a target thickness in the range from 5 to 20 nm and variation of film thickness within the range of ±10%.

Claims

1. A polarizing function element that has the polarizing function of polarizing an input beam and a non-reflecting function of suppressing reflection of the input beam, in which at least one side of a light-transmissive substrate has a polarizing portion with a striped structure formed by multiple alternating light-transmissive dielectric layers and metallic film layers;

wherein the metallic film layers are thin and flat, having a target film thickness within the range from 5 to 20 nm and variation of film thickness within the range of ±

10%, and a Faraday rotator is used as the light-transmissive substrate.

2. A polarizing function element of claim 1, wherein the polarizing portion is formed with a thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.

3. An optical isolator incorporating a polarizing function element having the polarizing function of polarizing an input beam and a non-reflecting function of suppressing reflection of the input beam, in which at least one side of a light-transmissive substrate has a polarizing portion with a striped structure formed by multiple alternating light-transmissive dielectric layers and metallic film layers;

wherein the metallic film layers are thin and flat, having a target film thickness within the range from 5 to 20 nm and variation of film thickness within the range of ±

10%, and a Faraday rotator is used as the light-transmissive substrate.

4. An optical isolator of claim 3, wherein the polarizing portion is formed with a thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.

5. A laser diode module in which is mounted an optical isolator incorporating a polarizing function element having the polarizing function of polarizing an input beam and a non-reflecting function of suppressing reflection of the input beam, in which at least one side of a light-transmissive substrate has a polarizing portion with a striped structure formed by multiple alternating light-transmissive dielectric layers and metallic film layers;

wherein the metallic film layers are thin and flat, having a target film thickness within the range from 5 to 20 nm and variation of film thickness within the range of ±

10%, and a Faraday rotator is used as the light-transmissive substrate.

6. A laser diode module of claim 5, wherein the polarizing portion is formed with a thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.

7. A method of manufacturing a polarizing function element, comprising the steps of:

providing a light-transmissive substrate,

forming a base layer of a specified thickness on the light-transmissive substrate to form a light-transmissive dielectric layer;

forming multiple parallel parts of a base lattice of the base layer separated by a given interval on the light-transmissive substrate;

forming a metallic film layer, by vapor deposition at an angle on each side of the base lattice to form a metal plated base lattice; and

filling in remaining intervals between the metallic film layer and the base lattice with dielectric material to form a striped structure,

wherein dielectric layers and metallic film layers are arranged in a striped structure, with the light transmissive substrate so that the striped structure of the light-transmissive substrate polarizes an input beam and suppresses reflection of the input beam.

8. A method of manufacturing a polarizing function element as described in claim 7, wherein the metallic film layer is deposited on each side of the base lattice at angles that are different from one another.

9. A method of manufacturing a polarizing function element as described in claim 7 or 8, wherein a polarizing portion of the polarizing function element includes a striped structure of dielectric layers and metallic film layers, which are thin and flat having a target film thickness within the range from 5 to 15 nm and variation of film thickness within the range of ±

10%.

10. A method of manufacturing a polarizing function element of claim 7, wherein the polarizing portion is formed with a thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.

11. A polarizing function element, comprising:

a light-transmissive substrate; and

a polarizing portion having flat shape with a specified constant thickness, formed by multiple alternating light-transmissive dielectric layers and metallic film layers integrally formed with one another to form a striped structure, wherein the striped structure polarizes an input beam and suppresses reflection of the input beam,

and wherein at least one side of said light-transmissive substrate has said polarizing portion integrated therewith in such manner that the striped structure comprises the layers of the light-transmissive dielectric layers and metallic film layers alternating laterally across the light-transmissive substrate and the polarizing portion is integrated with the light-transmissive substrate.

12. A polarizing function element as described in claim 11, wherein said polarizing portion is formed with a thickness of substantially 390 nm so as to function effectively as the polarizing/non-reflective film.

13. A polarizing function element of claim 11, wherein a total thickness of the polarizing portion formed is substantially ¼

λ

, where λ

is a wavelength of the input beam.

14. A polarizing function element, comprising:

a light-transmissive substrate;

a polarizing portion having flat shape with a specified constant thickness, formed by multiple alternating light-transmissive dielectric layers and metallic film layers integrally formed with one another to form a striped structure, wherein the striped structure polarizes an input beam and suppresses reflection of the input beam,

wherein at least one side of said light-transmissive substrate has said polarizing portion integrated therewith in such manner that the striped structure comprises the layers of the light-transmissive dielectric layers and metallic film layers alternating laterally across the light-transmissive substrate and the polarizing portion functions as a polarizing/non-reflective film integrated with the light-transmissive substrate, and

a separate light-transmissive dielectric layer is added to the polarizing portion to form a stacked portion that functions as a polarizing/non-reflective film.

15. A polarizing function element as described in claim 14, wherein said stacked portion comprises multiple layers with dielectric layers alternating with polarizing portions.

18. A polarizing function element of claim 15, wherein the polarizing portions are formed with a combined total thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.

16. A method of manufacturing a polarizing function element, comprising the steps of:

providing a light-transmissive substrate,

formins a base layer of a specified thickness on the light-transmissive substrate to form a light-transmissive dielectric layer;

forming multiple parallel parts of a base lattice of the base layer separated by a given interval on the light-transmissive sublstrate;

forming a metallic film layer, by vapor depostion at an angle on each side of the base lattice to form a metal plated base lattice; and

filling in remaining intervals between the metallic film layer and the base lattice with dielectric material to form striped structure wherein dielectric layers and metallic film layers are arranged in a spriped structure, with the light transmissive substrate so that the striped structure of the light-transmissive substrate polarizes an input beam and suppresses reflection of the input beam.

17. A polarizing function element, comprising:

a light-transmissive substrate;

a polarizing portion having flat shape with a specified constant thickness, formed by multiple alternating light-transmissive dielectric layers and metallic film layers integrally formed with one another to form a striped structure, wherein the striped structure polarizes an input beam and suppresses reflection of the input beam,

wherein both sides of said light-transmissive substrate have said polarizing portion integrated therewith respectively in such manner that each striped structure comprises the layers of the light-transmissive dielectric layers and metallic film layers alternating laterally across the light-transmissive substrate and each polarizing portion functions as a polarizing/non-reflective film integrated with the light-transmissive substrate.

19. A polarizing function element of claim 17, wherein the polarizing portions formed on both sides of said light transmissive substrate have a combined total thickness of substantially ¼

λ

, where λ

is a wavelength of the input beam.