JP7842811B2 - Filter device - Google Patents

Description

This invention relates to a filtering device equipped with a Fabry-Perot interference filter.

A photodetector is known that comprises a package with a window, a Fabry-Perot interference filter that transmits light incident through the window, and a photodetector that detects the light transmitted through the Fabry-Perot interference filter (see, for example, Patent Document 1).

Japanese Patent Publication No. 2016-211860

In the photodetector described above, it is desirable that the light transmitted through the Fabry-Perot interference filter be efficiently detected by the photodetector. In particular, when analyzing reflected light from an object under measurement using a general-purpose light source, the amount of reflected light tends to be small, making efficient detection of the light crucial.

To efficiently detect light, it is conceivable to use photodetectors such as photodiodes with large light-receiving areas. However, using photodetectors with large light-receiving areas may increase the noise component in the signal output from the photodetector.

The present invention aims to provide a light detection device capable of high sensitivity and high accuracy detection.

The present invention provides a photodetector comprising: a package with a window for injecting light; a Fabry-Perot interference filter disposed within the package and transmitting light incident through the window; and a photodetector disposed within the package, away from the Fabry-Perot interference filter, for detecting light transmitted through the Fabry-Perot interference filter. The Fabry-Perot interference filter comprises: a substrate having a first surface on the window side and a second surface on the photodetector side; a first layer structure disposed on the first surface, with a first mirror portion and a second mirror portion facing each other via an air gap and having a variable distance between them; and a lens portion integrally provided on the second surface side, for focusing light transmitted through the first mirror portion and the second mirror portion onto the photodetector.

In the photodetector described above, the Fabry-Perot interference filter has a lens that focuses the light transmitted through the first and second mirrors onto the photodetector. This allows even a photodetector with a small light-receiving area to efficiently receive the light transmitted through the first and second mirrors into that area. In other words, by using a photodetector with a small light-receiving area, it is possible to efficiently detect the light transmitted through the Fabry-Perot interference filter while reducing the noise component in the signal output from the photodetector. However, when the light-receiving area of the photodetector becomes smaller, high precision is required in the position of the lens relative to the photodetector (especially in the direction perpendicular to the optical axis). In the photodetector described above, since the lens is located after the first and second mirrors, the distance between the lens and the photodetector is smaller compared to the case where the lens is located before the first and second mirrors, thus relaxing the precision required for the position of the lens relative to the photodetector. Furthermore, since the lens portion is integrally provided on the second surface side of the substrate constituting the Fabry-Perot interference filter, the positional displacement of the lens portion relative to the photodetector is less likely to occur compared to cases where the lens portion is attached separately to a support member (for example, a support member that supports the Fabry-Perot interference filter while it is separated from the photodetector within the package). Therefore, the above-described photodetector enables highly sensitive and accurate detection.

In the optical detection device of the present invention, the lens portion may be formed on the second surface side of the substrate. In this configuration, since there is no interface between the substrate and the lens portion, optical loss can be suppressed, and peeling of the lens portion can be prevented. Furthermore, the lens portion can be easily formed with high positional accuracy during the semiconductor manufacturing process.

In the light detection device of the present invention, the lens portion may be provided directly or indirectly on the second surface. This configuration improves the stress balance of the Fabry-Perot interference filter compared to the case where the lens portion is formed on a part of the substrate. Furthermore, it allows for greater freedom in the shape (such as the curvature of the lens surface) that the lens portion can adopt.

In the photodetector of the present invention, the Fabry-Perot interference filter further comprises a second layer structure arranged on the second surface and configured to correspond to the first layer structure. The second layer structure has an aperture through which light transmitted through the first and second mirror portions passes, and the lens portion may be positioned within the aperture. This configuration suppresses displacement of the lens portion even if it is separate from the substrate. Furthermore, while suppressing an increase in the thickness of the Fabry-Perot interference filter, the light-gathering function of the lens portion can be improved by increasing its thickness, for example, by the amount the lens portion is positioned within the aperture. Moreover, by positioning the entire lens portion within the aperture, damage and contamination of the lens portion can be prevented.

In the photodetector of the present invention, the Fabry-Perot interference filter further comprises a second layer structure disposed on the second surface and configured to correspond to the first layer structure. The second layer structure has an opening through which light transmitted through the first and second mirror portions passes, and the lens portion may be attached to the second layer structure so as to close the opening. This configuration improves the stress balance between the first and second surface sides of the substrate in the Fabry-Perot interference filter. Furthermore, it increases the degree of freedom in the shape (such as the curvature of the lens surface) that the lens portion 50 can take.

In the light detection device of the present invention, when viewed from the direction of light incidence, the outer edge of the lens portion may be located inward from the outer edge of the window portion and outward from the outer edge of the light-receiving area of the photodetector. This configuration allows light transmitted through the first mirror portion and the second mirror portion to be efficiently incident onto the light-receiving area of the photodetector.

According to the present invention, it is possible to provide a light detection device capable of high sensitivity and high accuracy detection.

This is a cross-sectional view of the photodetector according to the first embodiment. Figure 1 is a plan view of the light detection device shown. Figure 1 is a plan view of the Fabry-Perot interference filter of the photodetector shown. Figure 3 is a cross-sectional view of a Fabry-Perot interference filter along the IV-IV line. Figure 4 is a cross-sectional view of a modified Fabry-Perot interference filter. This is a cross-sectional view of the light detection device according to the second embodiment. Figure 6 is a cross-sectional view of the Fabry-Perot interference filter of the photodetector shown. Figure 7 is a cross-sectional view of a modified Fabry-Perot interference filter. This is a cross-sectional view of the photodetector according to the third embodiment. Figure 9 is a cross-sectional view of the Fabry-Perot interference filter of the photodetector shown. Figure 10 is a cross-sectional view of a modified Fabry-Perot interference filter. Figure 10 is a cross-sectional view of a modified Fabry-Perot interference filter. Figure 10 is a cross-sectional view of a modified Fabry-Perot interference filter. Figure 10 is a cross-sectional view of a modified Fabry-Perot interference filter. Figure 10 is a cross-sectional view of a modified Fabry-Perot interference filter. This is a cross-sectional view of a reference example of a Fabry-Perot interference filter.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and duplicate parts are omitted.
[First Embodiment]
[Configuration of the light detection device]

As shown in Figure 1, the photodetector 1A comprises a package 2. Package 2 is a CAN package having a stem 3 and a cap 4. The cap 4 is integrally formed by side walls 5 and a top wall 6. The top wall 6 faces the stem 3 in a direction parallel to line L. The stem 3 and cap 4 are made of, for example, metal and are hermetically joined to each other.

A wiring board 7 is fixed to the inner surface 3a of the stem 3, for example, by adhesive. The substrate material of the wiring board 7 can be, for example, silicon, ceramic, quartz, glass, or plastic. A photodetector 8 and a temperature compensation element such as a thermistor (not shown) are mounted on the wiring board 7. The photodetector 8 is arranged on a line L within the package 2. More specifically, the photodetector 8 is arranged within the package 2 such that the center line of its light-receiving area coincides with line L. The photodetector 8 is an infrared detector such as a quantum sensor using InGaAs, a thermopile, or a bolometer. When detecting light in the ultraviolet, visible, and near-infrared wavelength ranges, a silicon photodiode can be used as the photodetector 8. The light-receiving area of the photodetector 8 may consist of one light-receiving section or multiple light-receiving sections. The photodetector 8, which has a light-receiving area composed of multiple light-receiving units, can be, for example, a photodiode array, a CCD image sensor, or a CMOS image sensor. Alternatively, multiple photodetectors 8 may be mounted on a wiring board 7. In that case, the collection of light-receiving units of the multiple photodetectors 8 can be considered as the light-receiving area.

Multiple spacers (supports) 9 are fixed to the wiring board 7, for example, by adhesive. The multiple spacers 9 are arranged within the package 2 so as to sandwich or surround the photodetector 8 and the temperature compensation element. As the material for each spacer 9, for example, silicon, ceramic, quartz, glass, plastic, etc., can be used. The Fabry-Perot interference filter 10A is fixed to the multiple spacers 9, for example, by adhesive. The Fabry-Perot interference filter 10A is arranged on a line L within the package 2. More specifically, the Fabry-Perot interference filter 10A is arranged within the package 2 such that the center line of its light-transmitting region 10a coincides with line L. The spacers 9 support the Fabry-Perot interference filter 10A in a state where it is separated from the photodetector 8 (i.e., a space is formed between the Fabry-Perot interference filter 10A and the photodetector 8). In other words, the Fabry-Perot interference filter 10A and the photodetector 8 are arranged within the package 2 in a state where they are separated from each other. Furthermore, the spacer 9 may be integrally formed with the wiring board 7. Also, the Fabry-Perot interference filter 10A may be supported by a single spacer 9, rather than multiple spacers 9. Additionally, the spacer 9 may be integrally formed with the Fabry-Perot interference filter 10A.

Multiple lead pins 11 are fixed to the stem 3. More specifically, each lead pin 11 penetrates the stem 3 while maintaining electrical insulation and airtightness between it and the stem 3. Each lead pin 11 is electrically connected by wires 12 to the electrode pads on the wiring board 7, the terminals of the photodetector 8, the terminals of the temperature compensation element, and the terminals of the Fabry-Perot interference filter 10A. This allows for the input and output of electrical signals to the photodetector 8, the temperature compensation element, and the Fabry-Perot interference filter 10A, respectively.

Package 2 has an opening 2a. More specifically, the opening 2a is formed in the top wall 6 of the cap 4 such that its centerline coincides with line L. A light-transmitting member 13 is positioned on the inner surface 6a of the top wall 6 so as to close the opening 2a. The light-transmitting member 13 extends into the opening 2a and to the inner surface 5a of the side wall 5, hermetically sealing the opening 2a. The light-transmitting member 13 transmits light within the measurement wavelength range of the light detection device 1A. The light incident surface 13a of the light-transmitting member 13 is substantially flush with the outer surface of the top wall 6 at the opening 2a. Such a light-transmitting member 13 is formed by placing glass pellets inside the cap 4 with the opening 2a facing downwards and melting the glass pellets. In other words, the light-transmitting member 13 is made of fused glass. In package 2, the portion of the light-transmitting member 13 located inside the opening 2a functions as a window 15 that allows light to enter package 2 from the outside. Furthermore, a plate-shaped light-transmitting member 13 made of, for example, glass, quartz, silicon, germanium, or plastic may be airtightly bonded to the inner surface 6a of the top wall 6 so as to close the opening 2a. In that case, the area within the opening 2a functions as a window 15. In other words, the area within the opening 2a functions as a window 15 regardless of the presence or absence of the light-transmitting member 13.

A plate-shaped bandpass filter 14 is fixed to the light-emitting surface 13b of the light-transmitting member 13 (the surface facing the light-incident surface 13a in a direction parallel to the line L) by means of an adhesive, for example. The bandpass filter 14 selectively transmits light within the measurement wavelength range of the photodetector 1A. The bandpass filter 14 has a dielectric multilayer film made of _a combination of a high refractive index material such as _TiO2 or _Ta2O5 and a low refractive index material such as _SiO2 or _MgF2 . The bandpass filter 14 may also be formed on the light-emitting surface 13b of the light-transmitting member 13 by means of vapor deposition, for example.

The positional and relative sizes of each part when viewed from a direction parallel to line L (the direction of light incidence to the window portion 15) are as follows. As shown in Figure 2, the centerline of the window portion 15 (i.e., the centerline of the aperture 2a), the centerline of the light-transmitting member 13, the centerline of the bandpass filter 14, the centerline of the light-transmitting region 10a of the Fabry-Perot interference filter 10A, and the centerline of the light-receiving region 8a of the photodetector 8 coincide with line L. The outer edges of the window portion 15, the light-transmitting member 13, the light-transmitting region 10a, and the light-receiving region 8a are, for example, circular in shape. The outer edges of the bandpass filter 14, the Fabry-Perot interference filter 10A, and the photodetector 8 are, for example, rectangular in shape.

The outer edge of the window portion 15 (i.e., the inner edge of the opening 2a) is located inside the outer edge of the light-transmitting member 13, the outer edge of the bandpass filter 14, and the outer edge of the Fabry-Perot interference filter 10A, and outside the outer edge of the light-transmitting region 10a and the outer edge of the light-receiving region 8a. The outer edge of the light-receiving region 8a is located inside the outer edge of the light-transmitting region 10a. The outer edge of the bandpass filter 14 is located inside the outer edge of the light-transmitting member 13 and outside the outer edge of the Fabry-Perot interference filter 10A. Note that "when viewed from a predetermined direction, one outer edge is located inside the other outer edges" means "when viewed from a predetermined direction, the other outer edges surround one outer edge" and "when viewed from a predetermined direction, the other outer edges include one outer edge." Furthermore, "when viewed from a given direction, one outer edge is located outside the other outer edges" means "when viewed from a given direction, one outer edge surrounds the other outer edges" or "when viewed from a given direction, one outer edge includes the other outer edges."

In the light detection device 1A configured as described above, when light is incident from the outside through the window 15, the light-transmitting member 13, and the bandpass filter 14 onto the light-transmitting region 10a of the Fabry-Perot interference filter 10A, light having a predetermined wavelength is selectively transmitted. The light that has passed through the light-transmitting region 10a of the Fabry-Perot interference filter 10A is incident onto the light-receiving region 8a of the photodetector 8 and detected by the photodetector 8.
[Configuration of a Fabry-Perot interference filter]

As shown in Figures 3 and 4, the Fabry-Perot interference filter 10A has a light-transmitting region 10a on the line L that transmits light corresponding to the distance between the first mirror and the second mirror. The light-transmitting region 10a is, for example, a cylindrical region. Within the light-transmitting region 10a, the distance between the first mirror and the second mirror is controlled with extremely high precision. In other words, the light-transmitting region 10a is a region within the Fabry-Perot interference filter 10A where the distance between the first mirror and the second mirror can be controlled to a predetermined distance in order to selectively transmit light having a predetermined wavelength, and is a region through which light having a predetermined wavelength corresponding to the distance between the first mirror and the second mirror can be transmitted.

The Fabry-Perot interference filter 10A comprises a rectangular plate-shaped substrate 21. The substrate 21 has a first surface 21a and a second surface 21b that face each other in a direction parallel to the line L. The first surface 21a is the surface on the window portion 15 side (i.e., the light incident side). The second surface 21b is the surface on the photodetector 8 side (i.e., the light emission side). A first layer structure 30 is arranged on the first surface 21a. A second layer structure 40 is arranged on the second surface 21b.

The first layer structure 30 is constructed by laminating a first anti-reflective layer 31, a first laminate 32, a first intermediate layer 33, and a second laminate 34 on the first surface 21a in this order. An air gap S is formed between the first laminate 32 and the second laminate 34 by the frame-shaped first intermediate layer 33. The substrate 21 is made of, for example, silicon, quartz, glass, etc. If the substrate 21 is made of silicon, the first anti-reflective layer 31 and the first intermediate layer 33 are made of, for example, silicon oxide. The thickness of the first intermediate layer 33 is, for example, several tens of nanometers to several tens of micrometers.

The portion of the first laminate 32 corresponding to the light-transmitting region 10a functions as the first mirror portion 35. The first laminate 32 is constructed by alternately stacking multiple polysilicon layers and multiple silicon nitride layers one layer at a time. Preferably, the optical thickness of each polysilicon layer and silicon nitride layer constituting the first mirror portion 35 is an integer multiple of 1/4 of the central transmission wavelength. The first mirror portion 35 may be directly disposed on the first surface 21a without the first anti-reflective layer 31.

The portion of the second laminate 34 corresponding to the light-transmitting region 10a functions as the second mirror portion 36. The second mirror portion 36 faces the first mirror portion 35 via an air gap S in a direction parallel to the line L. The second laminate 34 is constructed by alternately stacking multiple polysilicon layers and multiple silicon nitride layers one layer at a time. Preferably, the optical thickness of each polysilicon layer and silicon nitride layer constituting the second mirror portion 36 is an integer multiple of 1/4 of the central transmission wavelength.

In the first laminate 32 and the second laminate 34, a silicon oxide layer may be placed instead of a silicon nitride layer. Furthermore, in addition to the materials mentioned above, titanium oxide, tantalum oxide, zirconium oxide, magnesium fluoride, aluminum oxide, calcium fluoride, silicon, germanium, zinc sulfide, and the like can be used as materials for each layer constituting the first laminate 32 and the second laminate 34.

In the second laminate 34, multiple through-holes 34b are formed in the portion corresponding to the void S, extending from the surface 34a opposite to the first intermediate layer 33 to the void S. These multiple through-holes 34b are formed to such an extent that they do not substantially affect the function of the second mirror portion 36. The multiple through-holes 34b were used to remove a portion of the first intermediate layer 33 by etching, thereby forming the void S.

A first electrode 22 is formed on the first mirror portion 35 so as to surround the light-transmitting region 10a. A second electrode 23 is formed on the first mirror portion 35 so as to include the light-transmitting region 10a. The first electrode 22 and the second electrode 23 are formed by doping the polysilicon layer closest to the void S in the first laminate 32 with impurities to reduce its resistance. A third electrode 24 is formed on the second mirror portion 36. The third electrode 24 faces the first electrode 22 and the second electrode 23 across the void S in a direction parallel to the line L. The third electrode 24 is formed by doping the polysilicon layer closest to the void S in the second laminate 34 with impurities to reduce its resistance. The size of the second electrode 23 is preferably such that it includes the entire light-transmitting region 10a, but it may be approximately the same size as the light-transmitting region 10a.

The first layer structure 30 is provided with a pair of first terminals 25 and a pair of second terminals 26. The pair of first terminals 25 face each other across a light-transmitting region 10a. Each first terminal 25 is located within a through-hole extending from the surface 34a of the second laminate 34 to the first laminate 32. Each first terminal 25 is electrically connected to the first electrode 22 via wiring 22a. The pair of second terminals 26 face each other across the light-transmitting region 10a in a direction perpendicular to the direction in which the pair of first terminals 25 face each other. Each second terminal 26 is located within a through-hole extending from the surface 34a of the second laminate 34 to the interior of the first intermediate layer 33. Each second terminal 26 is electrically connected to the second electrode 23 via wiring 23a and to the third electrode 24 via wiring 24a.

Trenches 27 and 28 are provided on the surface 32a of the first laminate 32 on the side of the first intermediate layer 33. Trench 27 extends in an annular shape to surround the connection portion between the wiring 23a and the second terminal 26. Trench 27 electrically insulates the first electrode 22 from the wiring 23a. Trench 28 extends in an annular shape along the inner edge of the first electrode 22. Trench 28 electrically insulates the first electrode 22 from the region inside the first electrode 22 (i.e., the region where the second electrode 23 exists). Trench 29 is provided on the surface 34a of the second laminate 34. Trench 29 extends in an annular shape to surround the first terminal 25. Trench 29 electrically insulates the first terminal 25 from the third electrode 24. The regions within each of the trenches 27, 28, and 29 may be made of insulating material or may be voids.

The second layer structure 40 is constructed by laminating the second anti-reflective layer 41, the third laminate 42, the second intermediate layer 43, and the fourth laminate 44 on the second surface 21b in this order. The second anti-reflective layer 41, the third laminate 42, the second intermediate layer 43, and the fourth laminate 44 each have the same configuration as the first anti-reflective layer 31, the first laminate 32, the first intermediate layer 33, and the second laminate 34, respectively. Thus, the second layer structure 40 has a laminated structure symmetrical to the first layer structure 30 with respect to the substrate 21. In other words, the second layer structure 40 is configured to correspond to the first layer structure 30. The second layer structure 40 has the function of suppressing warping of the substrate 21.

The third laminate 42, the second intermediate layer 43, and the fourth laminate 44 have openings 40a formed to include the light-transmitting region 10a. The center line of the opening 40a coincides with line L. The opening 40a is, for example, a cylindrical region and has approximately the same diameter as the light-transmitting region 10a. The opening 40a opens on the light-emitting side, and the bottom surface of the opening 40a extends to the second anti-reflective layer 41. The opening 40a allows light transmitted through the first mirror portion 35 and the second mirror portion 36 to pass through.

A light-shielding layer 45 is formed on the light-emitting surface of the fourth laminate 44. The light-shielding layer 45 is made of, for example, aluminum. A protective layer 46 is formed on the surface of the light-shielding layer 45 and on the inner surface of the opening 40a. The protective layer 46 is made of, for example, aluminum oxide. By setting the thickness of the protective layer 46 to 1 to 100 nm (preferably about 30 nm), the optical influence of the protective layer 46 can be ignored.

A lens portion 50 is integrally provided on the second surface 21b side of the substrate 21. The lens portion 50 is formed on the portion of the substrate 21 on the second surface 21b side. The light-emitting surface 50a of the lens portion 50 is formed by a part of the second surface 21b. The center line of the lens portion 50 (i.e., the center line of the light-emitting surface 50a) coincides with line L. When viewed from a direction parallel to line L, the outer edge of the lens portion 50 is located inside the outer edge of the window portion 15 of the package 2 and outside the outer edge of the light-receiving area 8a of the photodetector 8 (see Figure 2). Here, the lens portion 50 has approximately the same diameter as the light-transmitting area 10a. The light-emitting surface 50a is covered by a second anti-reflective layer 41 and a protective layer 46 at the bottom surface of the opening 40a. The lens portion 50 focuses the light transmitted through the first mirror portion 35 and the second mirror portion 36 onto the light-receiving area 8a of the photodetector 8.

The lens portion 50 is configured as a Fresnel lens. For example, the diameter of the lens portion 50 is approximately 750 μm, and when the substrate 21 is made of silicon, the refractive index of the lens portion 50 is 3.5. Furthermore, the number of circles in the Fresnel lens is 3 to 60, the height of the irregularities is 1 to 25 μm, and the spacing between circles is 5 to 150 μm. Such a lens portion 50 is formed by patterning a resist onto the second surface 21b of the substrate 21 using a 3D mask or the like, and then performing etch-back.

As shown in Figure 5, the lens portion 50 may be configured as a convex lens having a light-emitting surface 50a that is convex on the light-emitting side. For example, the diameter of the lens portion 50 is approximately 750 μm, and when the substrate 21 is made of silicon, the refractive index of the lens portion 50 is 3.5. Furthermore, the height of the light-emitting surface 50a, which is convex on the light-emitting side, is 60 to 80 μm. Such a lens portion 50 is formed by patterning a resist on the second surface 21b of the substrate 21 using a 3D mask or the like, and then performing etch-back.

In the Fabry-Perot interference filter 10A configured as described above, when a voltage is applied between the first electrode 22 and the third electrode 24 via the pair of first terminals 25 and the pair of second terminals 26, an electrostatic force corresponding to the voltage is generated between the first electrode 22 and the third electrode 24. This electrostatic force attracts the second mirror portion 36 towards the first mirror portion 35 fixed to the substrate 21, thereby adjusting the distance between the first mirror portion 35 and the second mirror portion 36. Thus, in the Fabry-Perot interference filter 10A, the distance between the first mirror portion 35 and the second mirror portion 36 is variable.

The wavelength of light transmitted through the Fabry-Perot interference filter 10A depends on the distance between the first mirror portion 35 and the second mirror portion 36 in the light transmission region 10a. Therefore, by adjusting the voltage applied between the first electrode 22 and the third electrode 24, the wavelength of transmitted light can be appropriately selected. At this time, the second electrode 23 is at the same potential as the third electrode 24. Therefore, the second electrode 23 functions as a compensating electrode to maintain the flatness of the first mirror portion 35 and the second mirror portion 36 in the light transmission region 10a.

In the photodetector 1A, for example, by changing the voltage applied to the Fabry-Perot interference filter 10A (i.e., changing the distance between the first mirror section 35 and the second mirror section 36 in the Fabry-Perot interference filter 10A), the light transmitted through the light-transmitting region 10a of the Fabry-Perot interference filter 10A is detected by the photodetector 8, thereby obtaining a spectral spectrum. At this time, in the Fabry-Perot interference filter 10A, the light transmitted through the first mirror section 35 and the second mirror section 36 is focused by the lens section 50 onto the light-receiving region 8a of the photodetector 8.

In the Fabry-Perot interference filter 10A, the light transmission region 10a (as described above, the region of the Fabry-Perot interference filter 10A in which the distance between the first mirror portion 35 and the second mirror portion 36 can be controlled to a predetermined distance in order to selectively transmit light having a predetermined wavelength, and the region in which light having a predetermined wavelength corresponding to the distance between the first mirror portion 35 and the second mirror portion 36 can be transmitted) can be considered as the region inside the first electrode 22 (i.e., the region in which the second electrode 23, which functions as a compensating electrode, exists) when viewed from a direction parallel to the line L, or it can be considered as the region corresponding to the aperture 40a when viewed from a direction parallel to the line L.
[Mechanism of Action and Effects]

In the photodetector 1A, the Fabry-Perot interference filter 10A has a lens portion 50 that focuses the light transmitted through the first mirror portion 35 and the second mirror portion 36 onto the photodetector 8. This allows even a photodetector 8 with a small light-receiving area 8a to efficiently receive the light transmitted through the first mirror portion 35 and the second mirror portion 36 into the light-receiving area 8a. In other words, by using a photodetector 8 with a small light-receiving area 8a, it is possible to efficiently detect the light transmitted through the Fabry-Perot interference filter 10A while reducing the noise component in the signal output from the photodetector 8. Here, when the light-receiving area 8a of the photodetector 8 is small, high precision is required in the position of the lens portion 50 relative to the photodetector 8 (especially in the direction perpendicular to the optical axis). In the photodetector 1A, since the lens section 50 is located downstream of the first mirror section 35 and the second mirror section 36, the distance between the lens section 50 and the photodetector 8 is reduced compared to the case where the lens section 50 is located upstream of the first mirror section 35 and the second mirror section 36. This reduces the required precision for the position of the lens section 50 relative to the photodetector 8. Furthermore, since the lens section 50 is integrally provided on the second surface 21b side of the substrate 21 constituting the Fabry-Perot interference filter 10A, the position of the lens section 50 relative to the photodetector 8 is less likely to shift compared to the case where the lens section 50 is attached to the spacer 9 separately from the Fabry-Perot interference filter 10A. Therefore, the photodetector 1A enables highly sensitive and accurate detection.

As an example, let's consider a case where the diameter of the light-transmitting region 10a of the Fabry-Perot interference filter 10A is 750 μm, and the diameter of the light-receiving region 8a of the photodetector 8 is 100 μm. In this case, if the Fabry-Perot interference filter 10A is not provided with a lens portion 50, only the light with a diameter of 100 μm will enter the light-receiving region 8a of the photodetector 8 from the light-transmitting region 10a of the Fabry-Perot interference filter 10A. In other words, only a portion of the light that passes through the light-transmitting region 10a of the Fabry-Perot interference filter 10A can be utilized.

In contrast, when the Fabry-Perot interference filter 10A is equipped with a lens 50, almost all of the light transmitted through the light-transmitting region 10a of the Fabry-Perot interference filter 10A enters the light-receiving region 8a of the photodetector 8. In other words, almost all of the light transmitted through the light-transmitting region 10a of the Fabry-Perot interference filter 10A can be utilized. This is particularly important when analyzing reflected light from an object being measured using a general-purpose light source, as the amount of reflected light tends to be small. Therefore, efficiently detecting light in this manner is extremely important.

However, if the diameter of the light-receiving area 8a of the photodetector 8 is 100 μm, then the focusing position of the light collected by the lens portion 50 requires an accuracy of ±50 μm or less. In other words, the position of the lens portion 50 relative to the light-receiving area 8a of the photodetector 8 also requires similar accuracy. In the Fabry-Perot interference filter 10A, such accuracy can be achieved by integrally providing the lens portion 50 on the second surface 21b side of the substrate 21.

Furthermore, by providing a lens function to the window portion 15 of package 2, it is possible to achieve high-sensitivity detection in the photodetector 1A. However, considering the mounting accuracy of the cap 4 on the stem 3, the diameter of the window portion 15 needs to be sufficiently larger than the diameter of the light transmission area 10a of the Fabry-Perot interference filter 10A, for example, 1500 μm. Also, an accuracy of approximately ±50 μm is required for the position of the window portion 15 relative to the light-receiving area 8a of the photodetector 8. Therefore, if active alignment is not performed during the mounting of the cap 4 on the stem 3, there is a risk that light will not enter the light-receiving area 8a of the photodetector 8. Thus, because the lens portion becomes larger and active alignment is required, the configuration in which the window portion 15 has a lens function offers less cost advantage compared to the configuration in which the lens portion 50 is integrally provided on the second surface 21b side of the substrate 21.

Furthermore, in the photodetector 1A, since the lens portion 50 is integrally provided on the second surface 21b side of the substrate 21 constituting the Fabry-Perot interference filter 10A, only alignment with respect to the photodetector 8 needs to be considered when mounting the Fabry-Perot interference filter 10A. Therefore, assembly can be significantly simplified compared to the case where the lens portion 50 is attached to the spacer 9 separately from the Fabry-Perot interference filter 10A. Also, in semiconductor manufacturing processes where the Fabry-Perot interference filter 10A is manufactured at the wafer level, the lens portion 50 can also be integrally provided on the second surface 21b side of the substrate 21 at the wafer level. This allows for the easy manufacture of a Fabry-Perot interference filter 10A with a compact lens portion 50 that offers high positional accuracy.

Furthermore, in the photodetector 1A, the lens portion 50 is formed on the second surface 21b side of the substrate 21. In this configuration, since there is no interface between the substrate 21 and the lens portion 50, optical loss can be suppressed, and peeling of the lens portion 50 can be prevented. Also, the lens portion 50 can be easily formed with high positional accuracy during the semiconductor manufacturing process. Furthermore, when the substrate 21 is made of silicon, the refractive index of the lens portion 50 becomes 3.5. Because the lens portion 50 can be formed from a high refractive index material in this way, the distance between the photodetector 8 and the Fabry-Perot interference filter 10A can be shortened, making it possible to miniaturize the photodetector 1A. Moreover, since the light-emitting surface 50a of the lens portion 50 is located at the bottom surface of the aperture 40a, damage and contamination of the light-emitting surface 50a can be prevented.

Furthermore, in the light detection device 1A, when viewed from the direction of light incidence, the outer edge of the lens portion 50 is located inward from the outer edge of the window portion 15 and outward from the outer edge of the light-receiving area 8a of the photodetector 8. This configuration allows light transmitted through the first mirror portion 35 and the second mirror portion 36 to be efficiently incident onto the light-receiving area 8a of the photodetector 8. For example, it is difficult to obtain such an effect in a configuration in which the lens is integrally provided on the light-receiving area 8a of the photodetector 8. By integrally providing the lens portion 50, which has a size equal to or greater than the light-transmitting area 10a of the Fabry-Perot interference filter 10A, on the Fabry-Perot interference filter 10A side, the detection efficiency of light transmitted through the Fabry-Perot interference filter 10A can be maximized.
[Second Embodiment]

As shown in Figure 6, the photodetector 1B differs primarily from the photodetector 1A described above in the configuration of the Fabry-Perot interference filter 10B. As shown in Figure 7, in the Fabry-Perot interference filter 10B, the lens portion 50 is constructed separately from the substrate 21. The lens portion 50 has a light-emitting surface 50a that is convex towards the light-emitting side, and a flat light-incident surface 50b. The light-incident surface 50b of the lens portion 50 is fixed to the surface of the protective layer 46 on the photodetector 8 side, for example, by adhesive, while closing the opening 40a. In other words, the lens portion 50 is attached to the second layer structure 40 so as to close the opening 40a. Alternatively, an optical resin may be used as the adhesive for attaching the lens portion 50 to the second layer structure 40, and this optical resin may be filled into the opening 40a.

The center line of the lens portion 50 coincides with line L. When viewed from a direction parallel to line L, the outer edge of the lens portion 50 is located inside the outer edge of the window portion 15 of the package 2, and outside the outer edge of the light-receiving area 8a of the photodetector 8. Here, the lens portion 50 has a diameter larger than the light-transmitting area 10a. For example, the diameter of the lens portion 50 is approximately 1000 μm, and if the lens portion 50 is made of silicon, its refractive index is 3.5. Furthermore, the height of the light-emitting surface 50a, which is convex towards the light-emitting side, is 50 to 400 μm.

Furthermore, as shown in Figure 8, the lens portion 50 may be configured as a Fresnel lens. For example, the diameter of the lens portion 50 is approximately 1000 μm, the thickness of the substrate of the lens portion 50 is 200 μm, and if the lens portion 50 is made of silicon, the refractive index of the lens portion 50 is 3.5. Also, the number of circles in the Fresnel lens is 10 or more, the height of the irregularities is 40 μm or less, and the spacing between circles is 50 μm or less.

In the light detection device 1B configured as described above, the lens portion 50 is integrally provided on the second surface 21b side of the substrate 21. Therefore, similar to the light detection device 1A described above, high-sensitivity and high-precision detection is possible.

Furthermore, in the light detection device 1B, the lens portion 50 is attached to the second layer structure 40 so as to close the opening 40a. This configuration improves the stress balance between the first surface 21a and the second surface 21b of the substrate 21 in the Fabry-Perot interference filter 10B. It also increases the degree of freedom in the shape that the lens portion 50 can take (such as the curvature of the lens surface, including the light-emitting surface 50a). Note that the lens portion 50 may not completely close the opening 40a, and the inside and outside of the opening 40a may be in communication. In that case, the generation of stress due to the expansion and contraction of air inside the opening 40a can be suppressed.

Furthermore, in the light detection device 1B, the lens section 50 is positioned between multiple spacers 9 (see Figure 6), which lowers the center of gravity of the Fabry-Perot interference filter 10B, thereby improving the stability of the Fabry-Perot interference filter 10B.

Furthermore, when attaching the lens portion 50 to the second layer structure 40, the opening 40a can be used as the alignment reference, allowing the lens portion 50 to be mounted accurately and easily.

Furthermore, in semiconductor manufacturing processes, if the Fabry-Perot interference filter 10B is manufactured at the wafer level, the lens portion 50 can also be mounted at the wafer level, making it easy to manufacture a Fabry-Perot interference filter 10B having a small lens portion 50 with high positional accuracy.
[Third Embodiment]

As shown in Figure 9, the photodetector 1C differs primarily from the photodetector 1A described above in the configuration of the Fabry-Perot interference filter 10C. As shown in Figure 10, in the Fabry-Perot interference filter 10C, the lens portion 50 is configured separately from the substrate 21. The lens portion 50 is positioned within the opening 40a and is provided on the protective layer 46. In other words, the lens portion 50 is indirectly provided on the second surface 21b of the substrate 21 via the second anti-reflective layer 41 and the protective layer 46. Alternatively, the lens portion 50 may be directly provided on the second surface 21b of the substrate 21 without the second anti-reflective layer 41 and the protective layer 46.

The lens portion 50 is configured as a Fresnel lens. For example, the diameter of the lens portion 50 is approximately 750 μm. The number of circles in the Fresnel lens is 10 to 50, the height of the irregularities is 5 to 40 μm, and the spacing between circles is 5 to 50 μm. Such a lens portion 50 is formed by methods such as patterning a resist (resin) using a 3D mask, or by using a mold.

As shown in Figure 11, the lens portion 50 may be configured as a convex lens having a light-emitting surface 50a that is convex on the light-emitting side. For example, the diameter of the lens portion 50 is approximately 750 μm. The height of the light-emitting surface 50a, which is convex on the light-emitting side, is 100 to 400 μm. Such a lens portion 50 can be formed by methods such as patterning the resist (resin) using a 3D mask, patterning and curing the resist (resin) using a conventional mask, or using a mold.

Furthermore, as shown in Figures 12 and 13, the lens portion 50, which is constructed separately from the substrate 21, may be fixed within the opening 40a, for example, by adhesive. In this case as well, the lens portion 50 may be indirectly provided on the second surface 21b of the substrate 21 via the second anti-reflective layer 41 and the protective layer 46, or it may be directly provided on the second surface 21b of the substrate 21 without the second anti-reflective layer 41 and the protective layer 46.

As shown in Figure 12, when the lens portion 50 is configured as a Fresnel lens, for example, the diameter of the lens portion 50 is approximately 750 μm, the thickness of the substrate of the lens portion 50 is 200 μm, and if the lens portion 50 is made of silicon, the refractive index of the lens portion 50 is 3.5. Furthermore, the number of circles in the Fresnel lens is five or more, the height of the irregularities is 30 μm or less, and the spacing between circles is 80 μm or less.

As shown in Figure 13, when the lens portion 50 is configured as a convex lens, for example, the diameter of the lens portion 50 is approximately 750 μm, and when the lens portion 50 is made of silicon, the refractive index of the lens portion 50 is 3.5. Furthermore, the height of the light-emitting surface 50a, which is convex towards the light-emitting side, is 50 to 400 μm.

In the light detection device 1C configured as described above, the lens portion 50 is integrally provided on the second surface 21b side of the substrate 21. Therefore, similar to the light detection device 1A described above, high-sensitivity and high-precision detection is possible.

Furthermore, in the light detection device 1C, the lens portion 50 is provided directly or indirectly on the second surface 21b of the substrate 21. This configuration improves the stress balance of the Fabry-Perot interference filter 10C compared to the case where the lens portion 50 is formed on a portion of the substrate 21. It also allows for greater freedom in the shape of the lens portion 50 (such as the curvature of the lens surface, including the light emission surface 50a).

Furthermore, in the light detection device 1C, the lens portion 50 is positioned within the aperture 40a. This configuration suppresses misalignment of the lens portion 50, even if it is separate from the substrate 21. Additionally, while suppressing an increase in the thickness of the Fabry-Perot interference filter 10C, the light-gathering function of the lens portion 50 can be improved by increasing its thickness, for example, by the amount by which it is positioned within the aperture 40a. Moreover, by positioning the entire lens portion 50 within the aperture 40a, damage and contamination of the lens portion 50 can be prevented.

Furthermore, when attaching the lens portion 50 to the second surface 21b of the substrate 21, the opening 40a can be used as the alignment reference so that the lens portion 50 fits within the opening 40a, allowing for accurate and easy mounting.

Furthermore, in semiconductor manufacturing processes, when the Fabry-Perot interference filter 10C is manufactured at the wafer level, the lens portion 50 can also be mounted at the wafer level, making it easy to manufacture a Fabry-Perot interference filter 10C with a compact lens portion 50 that has high positional accuracy.

Furthermore, as shown in Figures 14 and 15, the second layer structure 40 does not necessarily have to be formed on the second surface 21b of the substrate 21. Even in this case, the stress balance of the Fabry-Perot interference filter 10C can be improved compared to the case where the lens portion 50 is formed on a part of the substrate 21. Additionally, the degree of freedom in the shape that the lens portion 50 can take (such as the curvature of the lens surface, including the light-emitting surface 50a) can be greatly increased.

As shown in Figure 14, when the lens portion 50 is configured as a convex lens, for example, the diameter of the lens portion 50 is approximately 1000 μm, and when the lens portion 50 is made of silicon, the refractive index of the lens portion 50 is 3.5. Furthermore, the height of the light-emitting surface 50a, which is convex towards the light-emitting side, is 50 to 400 μm. Note that a light-shielding layer 45 may be formed on the second surface 21b side of the substrate 21, surrounding the lens portion 50.

As shown in Figure 15, when the lens portion 50 is configured as a Fresnel lens, for example, the diameter of the lens portion 50 is about 1000 μm, the thickness of the substrate of the lens portion 50 is 200 μm, and if the lens portion 50 is made of silicon, the refractive index of the lens portion 50 is 3.5. Also, the number of circles in the Fresnel lens is 10 or more, the height of the irregularities is 40 μm or less, and the spacing between circles is 50 μm or less. In addition, a light-shielding layer 45 may be formed on the second surface 21b side of the substrate 21 so as to surround the lens portion 50.
[Variations]

Although the first, second, and third embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. For example, the materials and shapes of each component are not limited to those described above; various materials and shapes can be used.

Furthermore, the lens portion 50 may be integrally provided on the second surface 21b side of the substrate 21. In other words, at the time of manufacturing each of the Fabry-Perot interference filters 10A, 10B, and 10C, the lens portion 50 may be provided as part of each Fabry-Perot interference filter 10A, 10B, and 10C, downstream of the first mirror portion 35 and the second mirror portion 36.

The second layer structure 40 does not need to have a symmetrical laminated structure with respect to the substrate 21, as long as it is configured to correspond to the first layer structure 30. If the second layer structure 40 has a layer structure that can suppress warping of the substrate 21 compared to the case where the second layer structure 40 is not provided, then the second layer structure 40 can be said to be configured to correspond to the first layer structure 30.

Furthermore, the bandpass filter 14 may be provided on the light incident surface 13a of the light-transmitting member 13, or it may be provided on both the light incident surface 13a and the light emission surface 13b of the light-transmitting member 13.

Furthermore, when viewed from a direction parallel to line L, the outer edge of the light-transmitting region 10a of each Fabry-Perot interference filter 10A, 10B, and 10C may be located outside the outer edge of the window portion 15. In this case, the proportion of light that enters the light-transmitting region 10a from the light incident from the window portion 15 increases, and the utilization efficiency of the light incident from the window portion 15 improves. Also, even if the position of the window portion 15 relative to the light-transmitting region 10a is slightly misaligned, the light incident from the window portion 15 will still enter the light-transmitting region 10a, thus relaxing the positional accuracy requirements during the assembly of the light detection devices 1A, 1B, and 1C.
[Reference example]

As shown in Figure 16, the Fabry-Perot interference filter 100 comprises a first substrate 101, a second substrate 102, a first mirror section 103, a second mirror section 104, a first electrode 105, a second electrode 106, and a lens section 107. The Fabry-Perot interference filter 100 has, for example, a light transmission region 110a with line L as its centerline.

The first substrate 101 and the second substrate 102 are stacked on top of each other in a direction parallel to line L. The surface 101a of the first substrate 101 is bonded to the surface 102a of the second substrate 102. The first mirror portion 103 is provided in the portion of the first substrate 101 corresponding to the light-transmitting region 110a. The second mirror portion 104 is provided in the portion of the second substrate 102 corresponding to the light-transmitting region 110a. The first mirror portion 103 and the second mirror portion 104 face each other with an air gap S in a direction parallel to line L. The first electrode 105 is provided on the first substrate 101 so as to surround the first mirror portion 103 when viewed from a direction parallel to line L. The second electrode 106 is provided on the second substrate 102 so as to surround the second mirror portion 104 when viewed from a direction parallel to line L. The first electrode 105 and the second electrode 106 face each other with an air gap S in a direction parallel to the line L.

On the surface 102b of the second substrate 102 opposite to the first substrate 101, a groove 102c is formed so as to surround the second mirror portion 104 and the second electrode 106 when viewed from a direction parallel to line L. The portion of the second substrate 102 surrounded by the groove 102c is a diaphragm-shaped retaining portion 102d, which is displaceable in a direction parallel to line L. Alternatively, the diaphragm-shaped retaining portion 102d may be formed by forming a groove on the surface 102a of the second substrate 102 so as to surround the second mirror portion 104 and the second electrode 106 when viewed from a direction parallel to line L. Furthermore, the diaphragm-shaped retaining portion may be formed by forming a groove on the surface 101b or surface 101a of the first substrate 101 so as to surround the first mirror portion 103 and the first electrode 105 when viewed from a direction parallel to line L. In this case, the portion of the first substrate 101 surrounded by the groove can be displaced in a direction parallel to line L, with the grooved portion acting as a diaphragm-shaped retaining part. Alternatively, instead of the diaphragm-shaped retaining part, the retaining part may be composed of multiple beams arranged radially around line L.

In the Fabry-Perot interference filter 100, when a voltage is applied between the first electrode 105 and the second electrode 106, an electrostatic force corresponding to that voltage is generated between the first electrode 105 and the second electrode 106. This electrostatic force attracts the portion of the second substrate 102 surrounded by the groove 102c towards the first substrate 101, adjusting the distance between the first mirror portion 103 and the second mirror portion 104. Then, light having a wavelength corresponding to the distance between the first mirror portion 103 and the second mirror portion 104 passes through the first mirror portion 103 and the second mirror portion 104 from the first substrate 101 to the second substrate 102.

The lens portion 107 is integrally provided on the surface 102b side of the second substrate 102. The lens portion 107 focuses the light transmitted through the first mirror portion 103 and the second mirror portion 104. The lens portion 107 is provided directly or indirectly on the surface 102b as a Fresnel lens. Alternatively, the lens portion 107 may be provided directly or indirectly on the surface 102b as a convex lens. Furthermore, the lens portion 107 may be formed as either a Fresnel lens or a convex lens on the portion of the second substrate 102 facing the surface 102b.

As an example, light transmitted through the first mirror section 103 and the second mirror section 104 is focused by the lens section 107 to a photodetector located inside or outside the package housing the Fabry-Perot interference filter 100 (a photodetector positioned away from the Fabry-Perot interference filter 100). With the Fabry-Perot interference filter 100 configured as described above, since the lens section 107 is integrally provided on the surface 102b side of the second substrate 102, high-sensitivity and high-precision detection is possible in the subsequent photodetector.

The specific configuration of the Fabry-Perot interference filter 100 will be described below. The first substrate 101 and the second substrate 102 are each formed in a rectangular plate shape using various types of glass, such as soda-lime glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, or alkali-free glass, or quartz. The thickness of the first substrate 101 is, for example, about 500 μm. The thickness of the second substrate 102 is, for example, about 200 μm. The surface 101a of the first substrate 101 and the surface 102a of the second substrate 102 are joined to each other by, for example, a plasma polymerization film.

The first substrate 101 has surfaces 101c and 101d formed on it, facing the surface 102a of the second substrate 102 via a gap S in a direction parallel to line L. Surface 101c is formed in a circular shape with line L as its centerline. Surface 101d is formed in an annular shape with line L as its centerline, surrounding surface 101c when viewed from a direction parallel to line L. The distance between surface 101c of the first substrate 101 and surface 102a of the second substrate 102 is smaller than the distance between surface 101d of the first substrate 101 and surface 102a of the second substrate 102. The groove 102c for forming the diaphragm on the second substrate 102 is formed in an annular shape with line L as its centerline. Surfaces 101c and 101d of the first substrate 101 are formed by etching the first substrate 101 from the surface 101a side. The groove 102c of the second substrate 102 is formed by etching the second substrate 102 from the surface 102b side.

The first mirror portion 103 is formed on the surface 101c of the first substrate 101. The second mirror portion 104 is formed on the surface 102a of the second substrate 102. The first mirror portion 103 and the second mirror portion 104 are, for example, a metal film, a dielectric multilayer film, or a composite film thereof, and are each formed in a circular film shape with line L as the center line.

The first electrode 105 is formed on the surface 101d of the first substrate 101. The second electrode 106 is formed on the surface 102a of the second substrate 102. The first electrode 105 and the second electrode 106 are formed of, for example, a metallic material, and each extends in an annular shape with line L as its centerline. The first electrode 105 is electrically connected via wiring (not shown) to an electrode pad (not shown) provided in an externally accessible area of the first substrate 101. This wiring is, for example, provided in a groove formed in the surface 101a of the first substrate 101. The second electrode 106 is electrically connected via wiring (not shown) to an electrode pad (not shown) provided in an externally accessible area of the second substrate 102. This wiring is, for example, provided in a groove formed in the surface 102a of the second substrate 102.

The lens portion 107 is formed from, for example, silicon, resin, or glass. The lens portion 107 is bonded to the area inside the groove 102c on the surface 102a of the second substrate 102, for example, by an optical resin. When viewed from a direction parallel to line L, the outer edge of the lens portion 107 includes the outer edge of the first mirror portion 103 and the outer edge of the second mirror portion 104.

A light-shielding layer 108 having an opening 108a is formed on the surface 101b of the first substrate 101. The light-shielding layer 108 is formed of, for example, a metallic material. The opening 108a is formed in a circular shape with line L as its centerline and functions as an aperture that focuses the light incident on the light-transmitting region 110a. An anti-reflective layer may be formed on at least the region of the surface 101b of the first substrate 101 facing the first mirror portion 103 (i.e., at least the region inside the opening 108a), and on at least the region of the surface 102b of the second substrate 102 facing the second mirror portion 104 (i.e., at least the region facing the lens portion 107).

1A, 1B, 1C…Photodetector; 2…Package; 8…Photodetector; 8a…Light-receiving area; 9…Spacer (support); 10A, 10B, 10C…Fabry-Perot interference filter; 15…Window; 21…Substrate; 21a…First surface; 21b…Second surface; 30…First layer structure; 35…First mirror section; 36…Second mirror section; 40…Second layer structure; 40a…Aperture; 50…Lens section; S…Gap.

Claims (13)

A package with a window for allowing light to enter,
A Fabry-Perot interference filter is placed inside the package and transmits the light incident from the window portion,
The system comprises a spacer that supports the aforementioned Fabry-Perot interference filter,
The aforementioned Fabry-Perot interference filter is
A substrate having a first surface on the window side and a second surface on the opposite side of the window ,
A first layer structure is provided with a first mirror portion and a second mirror portion arranged on the first surface, facing each other with a gap between them and having a variable distance between them,
It comprises a lens portion integrally provided on the second surface side, which collects the light that has passed through the first mirror portion and the second mirror portion,
The first layer structure is configured such that a first laminate including the first mirror portion, an intermediate layer, and a second laminate including the second mirror portion are laminated on the first surface.
The spacer supports the Fabry-Perot interference filter from the second surface side,
The filter device wherein the spacer is positioned so as to be spaced apart from the lens portion and so as to sandwich or surround the lens portion when viewed from the direction of incidence of the light .
The filter device according to claim 1, further comprising a bandpass filter disposed on the inner surface of the package for transmitting the light incident through the window. The filter apparatus according to claim 2, wherein, when viewed from the direction of incidence of the light, the outer edge of the bandpass filter is located outside the outer edge of the Fabry-Perot interference filter. The package further comprises a light-transmitting member disposed between the inner surface of the package and the bandpass filter,
The filter device according to claim 2 or 3, wherein, when viewed from the direction of incidence of the light, the outer edge of the bandpass filter is located inward from the outer edge of the light-transmitting member. The filter device according to claim 4, wherein, when viewed from the direction of incidence of the light, the outer edge of the window portion is located inward from the outer edge of the light-transmitting member, the outer edge of the bandpass filter, and the outer edge of the Fabry-Perot interference filter. The package includes side walls and a top wall,
An opening that functions as a window is formed in the aforementioned ceiling wall.
The light-transmitting member extends to the opening in the top wall and to the inner surface of the side wall.
The filter device according to claim 4 or 5, wherein the light incident surface of the light-transmitting member is substantially flush with the outer surface of the ceiling wall at the opening of the ceiling wall. The filter device according to any one of claims 1 to 6, wherein, when viewed from the direction of incidence of the light, the lens portion is located inside the gap. The Fabry-Perot interference filter has a first terminal and a second terminal provided on the first layer structure,
The filter device according to any one of claims 1 to 7, wherein, when viewed from the direction of incidence of the light, the first terminal and the second terminal are located outside the lens portion. The lens portion is formed on the second surface side of the substrate, as described in any one of claims 1 to 8. The filter device according to any one of claims 1 to 8, wherein the lens portion is provided directly or indirectly on the second surface. The aforementioned Fabry-Perot interference filter is
The second layer structure is further disposed on the second surface and configured to correspond to the first layer structure,
The second layer structure has an opening through which the light that has passed through the first mirror portion and the second mirror portion passes.
The filter device according to claim 10, wherein the lens portion is arranged within the aperture. The aforementioned Fabry-Perot interference filter is
The second layer structure is further disposed on the second surface and configured to correspond to the first layer structure,
The second layer structure has an opening through which the light that has passed through the first mirror portion and the second mirror portion passes.
The filter device according to any one of claims 1 to 8, wherein the lens portion is attached to the second layer structure so as to close the opening. The filter device according to any one of claims 1 to 12, wherein, when viewed from the direction of incidence of the light, the outer edge of the lens portion is located inward from the outer edge of the window portion.