Optical filter
An optical filter includes a first mirror that has a first uniform thickness, a second mirror that has a second uniform thickness, and a spacer that is positioned between the first mirror and the second mirror. The spacer has a variable thickness along a first axis of the optical filter. In some implementations, a thickness profile of the spacer, along the first axis, includes one or more portions that have a non-linear slope with an absolute value that is greater than zero.
1. An optical filter, comprising:
a first mirror that has a first uniform thickness;
a second mirror that has a second uniform thickness; and
a spacer that is positioned between the first mirror and the second mirror, wherein:
the spacer has a variable thickness along a first axis of the optical filter,
a first edge of the spacer has a minimum thickness of the variable thickness along the first axis of the optical filter,
a second edge of the spacer has a maximum thickness of the variable thickness along the first axis of the optical filter,
a thickness profile of the spacer, along the first axis, has a slope with an absolute value that is greater than zero,
the variable thickness increases continuously along the slope and from the first edge to the second edge, and
a variation in center wavelength, across a region of the optical filter that is parallel to a second axis of the optical filter, is less than a variation defined as
D
×
R
×
(
1
-
1
-
〚
(
W
2
/
R
)
〛
2
)
,
wherein the D is the slope,
wherein the W is a filter width, and
wherein the R is a length of a coating tool arm.
2. The optical filter of claim 1 , wherein the second axis is orthogonal to the first axis, and wherein the optical filter is configured to pass light associated with a spectral range across the region of the optical filter that is parallel to the second axis.
3. The optical filter of claim 1 , wherein a variation in thickness across the region of the spacer that is parallel to the second axis satisfies a spacer thickness threshold.
4. The optical filter of claim 1 , wherein the optical filter is configured to pass light associated with a plurality of spectral ranges that comprises at least one of:
one or more portions of an ultraviolet light spectral range,
one or more portions of a visible light spectral range,
one or more portions of a near-infrared light spectral range,
one or more portions of a short-wave infrared light spectral range,
one or more portions of a mid-wave infrared light spectral range; or
one or more portions of a long-wave infrared light spectral range.
5. The optical filter of claim 1 , wherein the optical filter is configured to pass light associated with a plurality of spectral ranges, and
wherein the spacer is configured to transmit greater than a threshold percentage of light associated with a spectral range that is within the plurality of spectral ranges.
6. The optical filter of claim 1 , wherein the spacer is formed using an etching procedure in coordination with a grayscale lithography procedure.
7. The optical filter of claim 1 , further comprising:
a third mirror that has a third uniform thickness; and
an additional spacer that is positioned between the third mirror and one of the first mirror and the second mirror,
wherein the additional spacer has another variable thickness along the first axis of the optical filter.
8. The optical filter of claim 7 , wherein a thickness profile of the additional spacer, along the first axis, includes one or more portions that have a non-linear slope with an absolute value that is greater than zero.
9. The optical filter of claim 1 , further comprising:
one or more blocking components disposed on a surface of at least one of the first mirror, the second mirror, or the spacer.
10. A wafer, comprising:
a plurality of optical filters,
wherein an optical filter, of the plurality of optical filters, includes:
a first mirror that has a first uniform thickness;
a second mirror that has a second uniform thickness; and
a spacer that is positioned between the first mirror and the second mirror,
the spacer having a variable thickness along a first axis of the optical filter,
one or more of:
a first edge of the spacer having a minimum thickness of the variable thickness along the first axis of the optical filter, or
a second edge of the spacer having a maximum thickness of the variable thickness along the first axis of the optical filter,
the variable thickness increasing continuously along a slope of the spacer that one or more of begins at the first edge or ends at the second edge, and
a variation in center wavelength, across a region of the optical filter that is parallel to a second axis of the optical filter, being less than a variation defined as
D
×
R
×
(
1
-
1
-
〚
(
W
2
/
R
)
〛
2
)
,
wherein the D is the slope,
wherein the W is a filter width, and
wherein the R is a length of a coating tool arm.
11. The wafer of claim 10 , wherein, for each optical filter, of the plurality of optical filters,
the second axis is orthogonal to the first axis, wherein the optical filter is configured to pass light associated with a spectral range across the region of the optical filter that is parallel to the second axis.
12. The wafer of claim 10 , wherein the wafer has a radius X and each of the plurality of optical filters has a width Y, and
wherein a number of the plurality of optical filters is greater than or equal to 2πXY.
13. The wafer of claim 10 , wherein each optical filter, of the plurality of optical filters, is configured to provide a matching spectral filtering performance.
14. The wafer of claim 10 , wherein each optical filter, of the plurality of optical filters, further comprises:
a third mirror that has a third uniform thickness; and
an additional spacer that is positioned between the third mirror and one of the first mirror and the second mirror, wherein at least one of:
the additional spacer has another variable thickness along the first axis of the optical filter, or
a thickness profile of the additional spacer, along the first axis, includes one or more portions that have a non-linear slope with an absolute value that is greater than zero.
15. The wafer of claim 10 , wherein each optical filter, of the plurality of optical filters, further comprises:
one or more blocking components disposed on a surface of at least one of the first mirror or the second mirror.
16. An optical filter, comprising:
a first mirror;
a second mirror; and
a spacer that is positioned between the first mirror and the second mirror, wherein:
the spacer has a variable thickness along a first axis of the optical filter, and one or more of:
a first edge of the spacer having a minimum thickness of the variable thickness along the first axis of the optical filter, or
a second edge of the spacer having a maximum thickness of the variable thickness along the first axis of the optical filter,
the variable thickness increasing continuously along slope of the spacer towards one or more of the first edge or the second edge, and
a variation in center wavelength, across a region of the optical filter that is parallel to a second axis of the optical filter, is less than a variation defined as
D
×
R
×
(
1
-
1
-
〚
(
W
2
/
R
)
〛
2
)
,
wherein the D is the slope,
wherein the W is a filter width, and
wherein the R is a length of a coating tool arm.
17. The optical filter of claim 16 , wherein the first edge of the spacer has the minimum thickness of the variable thickness along the first axis of the optical filter.
18. The optical filter of claim 17 , wherein the second edge of the spacer has the maximum thickness of the variable thickness along the first axis of the optical filter.
19. The optical filter of claim 16 , wherein the slope is a linear slope from the first edge of the spacer to the second edge of the spacer.
20. The optical filter of claim 16 , wherein the spacer has a uniform thickness along the second axis of the optical filter, and
wherein the spacer comprises at least one of a silicon (Si) material, a hydrogenated silicon (Si:H) material, an amorphous silicon (a-Si) material, a silicon nitride (SiN) material, a germanium (Ge) material, a hydrogenated germanium (Ge:H) material, a silicon germanium (SiGe) material, a hydrogenated silicon germanium (SiGe:H) material, a silicon carbide (SiC) material, a hydrogenated silicon carbide (SiC:H) material, a silicon dioxide (SiO 2 ) material, a tantalum pentoxide (Ta 2 O 5 ) material, a niobium pentoxide (Nb 2 O 5 ) material, a niobium titanium oxide (NbTiO x ) material, a niobium tantalum pentoxide (Nb 2 TaO 5 ) material, a titanium dioxide (TiO 2 ) material, an aluminum oxide (Al 2 O 3 ) material, a zirconium oxide (ZrO 2 ) material, an yttrium oxide (Y 2 O 3 ) material, an aluminum nitride (AlN), or a hafnium oxide (HfO 2 ) material.
21. The optical filter of claim 16 , wherein the slope is a linear slope.