Silicon-germanium based optical filter

Patent metadata

Field	Value
Publication number	US-10168459-B2
Application number	US-201615365540-A
Country	US
Kind code	B2
Filing date	Nov 30, 2016
Priority date	Nov 30, 2016
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

An optical filter may include a substrate. An optical filter may include a set of optical filter layers disposed onto the substrate. The set of optical filter layers including a first subset of optical filter layers. The first subset of optical filter layers may include a silicon-germanium (SiGe) with a first refractive index. An optical filter may include a second subset of optical filter layers. The second subset of optical filter layers may include a material with a second refractive index. The second refractive index being less than the first refractive index.

First claim

What is claimed is:

1. An optical filter, comprising:
a substrate;
a set of optical filter layers disposed onto the substrate,
the set of optical filter layers including:
a first subset of optical filter layers,
the first subset of optical filter layers comprising silicon-germanium (SiGe) with a first refractive index; and

a second subset of optical filter layers,
the second subset of optical filter layers comprising a material with a second refractive index,
the second refractive index being less than the first refractive index.

2. The optical filter of claim 1 , where the material includes at least one of:
a silicon dioxide (SiO 2 ) material,
an aluminum oxide (Al 2 O 3 ) material,
a titanium dioxide (TiO 2 ) material,
a niobium pentoxide (Nb 2 O 5 ) material,
a tantalum pentoxide (Ta 2 O 5 ) material,
a magnesium fluoride (MgF 2 ) material,
a zirconium oxide (ZrO 2 ) material,
a yttrium oxide (Y 2 O 3 ) material,
a silicon nitride (S 3 N 4 ),
a boron based material, or
a phosphorous based material.

3. The optical filter of claim 1 , where the first subset of optical filter layers are high refractive index material layers (H) and the second subset of optical filter layers are low refractive index material layers (L); and
where the set of optical filter layers are arranged in at least one of:
an (H-L) m order,
an (H-L) m -H order, or
an L-(H-L) m order,
where m is a quantity of alternating H and L layers.

4. The optical filter of claim 1 , where the first refractive index is greater than 3 at a spectral range of approximately 800 nanometers (nm) to approximately 1100 nm.

5. The optical filter of claim 1 , where the first refractive index is greater than 3.5 at a spectral range of approximately 800 nanometers (nm) to approximately 1100 nm.

6. The optical filter of claim 1 , where the first refractive index is approximately 4 at a wavelength of approximately 900 nanometers (nm) to approximately 1100 nm.

7. The optical filter of claim 1 , where the first refractive index is greater than approximately 3 at a spectral range of approximately 1400 nanometers (nm) to approximately 1700 nm.

8. The optical filter of claim 1 , where the first refractive index is greater than approximately 3.4 at a spectral range of approximately 1500 nanometers (nm) to approximately 1600 nm.

9. The optical filter of claim 1 , where the first refractive index is greater than approximately 3.6 at a spectral range of approximately 1500 nanometers (nm) to approximately 1600 nm.

10. The optical filter of claim 1 , where the first subset of optical filter layers is annealed.

11. The optical filter of claim 1 , where the first subset of optical filter layers is hydrogenated.

12. The optical filter of claim 1 , where the first subset of optical filter layers is nitrogenated.

13. The optical filter of claim 1 , where the first subset of optical filter layers includes between 5% and 100% gennanium.

14. The optical filter of claim 1 , where the first subset of optical filter layers is doped with at least one of:
a phosphorous based dopant,
a nitrogen based dopant, or
a boron based dopant.

15. The optical filter of claim 1 , where the second refractive index is less than 3 at a spectral range of approximately 800 nanometers (nm) to approximately 1100 nm.

16. The optical filter of claim 1 , where the second refractive index is less than 2.5 at a spectral range of approximately 800 nanometers (nm) to approximately 1100 nm.

17. The optical filter of claim 1 , where the second refractive index is less than 2 at a spectral range of approximately 800 nanometers (nm) to approximately 1100 nm.

18. The optical filter of claim 1 , where the optical filter is a band pass filter.

19. The optical filter of claim 1 , where the optical filter is annealed.

20. An optical filter, comprising:
a substrate; and
a high refractive index material layer and a low refractive index material layer disposed onto the substrate to filter incident light,
wherein a first portion of the incident light with a first spectral range is to be reflected by the optical filter and a second portion of the incident light with a second spectral range is to be passed through by the optical filter,
the high refractive index material layer being hydrogenated silicon-germanium (SiGe:H), and
the low refractive index material layer being silicon dioxide (SiO 2 ).

21. The optical filter of claim 20 , where layers of the optical filter are deposited via a sputtering procedure.

22. The optical filter of claim 20 , further comprising:
an anti-reflective coating.

23. An optical system, comprising:
an optical transmitter to emit near-infrared (NIR) light;
an optical filter to filter an input optical signal and provide a filtered input optical signal,
the input optical signal including the NIR light from the optical transmitter and ambient light from an optical source,
the optical filter including a set of dielectric thin film layers,
the set of dielectric thin film layers including:
a first subset of layers of silicon-germanium with a first refractive index, and
a second subset of layers of a material with a second refractive index less than the first refractive index, and

the filtered input optical signal including a reduced intensity of ambient light relative to the input optical signal; and

an optical receiver to receive the filtered input optical signal and provide an output electrical signal.

24. The optical system of claim 23 , where the optical filter is associated with greater than 80% transmissivity at approximately 950 nm.

25. The optical system of claim 23 , where the optical filter is associated with greater than 80% transmissivity at approximately 1550 nm.

26. The optical system of claim 23 , where the first subset of layers are hydrogenated.

27. The optical system of claim 23 , where the optical filter is annealed.

Assignees

• Viavi Solutions Inc

Inventors

• Ockenfuss Georg J

Classifications

• C23C14/14

  Metallic material, boron or silicon · CPC title

• C23C14/06

  characterised by the coating material ({C23C14/0021} , C23C14/04 take precedence) · CPC title

• C23C14/5806

  Thermal treatment · CPC title

• C23C14/352 Primary

  using more than one target (C23C14/56 takes precedence) · CPC title

• G02B5/207 Primary

  comprising semiconducting materials · CPC title