JP7302313B2 - optical module - Google Patents

Description

The present disclosure relates to optical modules.

2. Description of the Related Art An optical module is known that includes a light-emitting portion that emits light from a semiconductor light-emitting element and MEMS (Micro Electro Mechanical Systems) that scans the light from the light-emitting portion (see Patent Documents 1 and 2, for example). Such an optical module can draw characters, figures, and the like by scanning light from the light-emitting portion along a desired path using MEMS.

JP-A-2007-3591 JP 2013-200562 A

Miniaturization is required for the optical module. Further, the MEMS includes a mirror that scans the light from the light emitting section by oscillating. It is desirable that the MEMS mirror has a large mechanical deflection angle.

Accordingly, it is an object of the present invention to provide an optical module capable of enlarging the mechanical deflection angle of the mirror while achieving miniaturization.

An optical module according to the present disclosure includes a light-forming portion that forms light, and a protective member that defines a first space that houses the light-forming portion and seals the light-forming portion. The light forming unit includes a laser diode and a MEMS that includes a mirror that scans the light from the laser diode and that is arranged such that the mirror is exposed within the first space. The pressure in the first space is lower than the atmospheric pressure and 0.15 atmospheres or more.

According to the present disclosure, it is possible to provide an optical module capable of increasing the mechanical deflection angle of the mirror while achieving miniaturization.

FIG. 1 is a schematic perspective view showing the structure of an optical module according to Embodiment 1. FIG. FIG. 2 is a schematic perspective view showing the structure of the optical module according to Embodiment 1. FIG. FIG. 3 is a schematic perspective view showing the structure of the optical module of Embodiment 1 with the cap removed. FIG. 4 is a schematic perspective view showing the structure of the optical module of Embodiment 1 with the cap removed. FIG. 5 is a schematic diagram showing the structure of the optical module according to the first embodiment. FIG. 6 is a schematic diagram showing the structure of the optical module according to the first embodiment. FIG. 7 is a flow chart showing an outline of a method for manufacturing an optical module according to Embodiment 1. FIG. FIG. 8 is a schematic perspective view showing the structure of the cap before welding. FIG. 9 is a schematic cross-sectional view showing a state where the cap is welded to the base. FIG. 10 is a schematic cross-sectional view showing the cap being welded to the base. FIG. 11 is a diagram showing the relationship between the pressure in the first space and the mechanical deflection angle of the mirror.

[Description of Embodiments of the Present Disclosure]
First, the embodiments of the present disclosure are listed and described. An optical module of the present disclosure includes a light-forming portion that forms light, and a protective member that defines a first space that accommodates the light-forming portion and seals the light-forming portion. The light forming unit includes a laser diode and a MEMS that includes a mirror that scans the light from the laser diode and that is arranged such that the mirror is exposed in the first space. The pressure in the first space is lower than the atmospheric pressure and 0.15 atmospheres or more.

In the optical module of the present disclosure, the MEMS including the mirror exposed to the first space is sealed with the protective member. Therefore, miniaturization can be achieved compared to an optical module including a MEMS sealed in a package. Also, in the optical module of the present disclosure, the pressure inside the first space is lower than the atmospheric pressure. Therefore, it is possible to suppress the air resistance that the mirror exposed in the first space receives. Therefore, the mechanical deflection angle of the mirror can be increased. On the other hand, when the pressure in the first space is less than 0.15 atm, the effect of increasing the mechanical deflection angle of the mirror is saturated. Therefore, the pressure in the first space is set to 0.15 atmospheric pressure or higher. Thus, according to the optical module of the present disclosure, it is possible to increase the mechanical deflection angle of the mirror while achieving miniaturization.

In the above optical module, the pressure in the first space may be 0.8 atmospheres or less. By setting the pressure in the first space to 0.8 atm or less in this manner, the mechanical deflection angle of the mirror can be further increased.

In the above optical module, the laser diode may be a semiconductor laser chip. By doing so, it is possible to further reduce the size of the optical module. Here, the semiconductor laser chip refers to a laser diode that is not enclosed in a metal container such as a CAN type, and the chip is exposed in the first space.

In the above optical module, the partial pressure of oxygen (O ₂ ) in the first space may be 0.03 atm or higher. A coating film made of oxide may be formed on the facet of the laser diode. By setting the partial pressure of oxygen to 0.03 atm or higher, it is possible to suppress detachment of oxygen atoms from the coating film. Therefore, the durability of the laser diode can be improved.

In the above optical module, the moisture concentration in the first space may be 3000 ppm or less. Thereby, the durability of the laser diode can be improved.

In the above optical module, the laser diode may emit infrared light. By doing so, the optical module can be used for sensing applications, for example.

The optical module may further include a plurality of laser diodes and a filter for combining light emitted from the plurality of laser diodes. With such a configuration, light emitted from a plurality of laser diodes can be combined by the filter and the combined light can be emitted.

In the above optical module, the plurality of laser diodes may include a red laser diode that emits red light, a green laser diode that emits green light, and a blue laser diode that emits blue light. With such a configuration, light of a desired color can be formed.

[Details of the embodiment of the present disclosure]
Next, embodiments of an optical module according to the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
First, Embodiment 1 will be described with reference to FIGS. 1 to 6. FIG. FIG. 1 is a schematic perspective view showing the structure of an optical module according to Embodiment 1. FIG. FIG. 2 is a schematic perspective view showing the structure of the optical module viewed from a different viewpoint from that of FIG. FIG. 3 is a perspective view corresponding to the state in which the cap 40 of FIG. 1 is removed. FIG. 4 is a perspective view corresponding to the state in which the cap 40 of FIG. 2 is removed. FIG. 5 is a schematic diagram on the XY plane showing the cap 40 in cross section and the other parts in plan view. FIG. 6 is a schematic diagram in the XZ plane showing the cap 40 in cross section and the other parts in plan view.

1 to 6, an optical module 1 according to the present embodiment includes a light forming portion 20 that forms light, and a protective member 2 that surrounds the light forming portion 20 and seals the light forming portion 20. Prepare. The protective member 2 includes a base 10 as a base body and a cap 40 as a lid welded to the base 10 . In other words, the light forming section 20 is hermetically sealed by the protective member 2 . The light forming part 20 is housed within a first space 40A surrounded by the base 10 and the cap 40 .

The base 10 has a plate-like shape. The light forming portion 20 is arranged on one main surface 10A of the base portion 10 . The cap 40 is placed in contact with one main surface 10A of the base 10 so as to cover the light forming section 20 . A plurality of lead pins 51 are installed on the base portion 10 so as to penetrate from the other main surface 10B side of the base portion 10 to the one main surface 10A side and project to both the one main surface 10A side and the other main surface 10B side. It is A first space 40A surrounded by the base 10 and the cap 40 is filled with a gas from which moisture is reduced (removed), such as dry air. The pressure in the first space 40A is lower than the atmospheric pressure and is 0.15 atmospheres or higher. The pressure in the first space 40A is preferably 0.8 atmospheres or less, more preferably 0.2 atmospheres or more and 0.4 atmospheres or less. The pressure in the first space 40A can be obtained by measuring the volume of the gas enclosed in the first space 40A at 20° C. and 1 atm using a mass spectrometer, for example. In the present embodiment, the partial pressure of oxygen within the first space 40A is 0.03 atm or higher. The partial pressure of oxygen in the first space 40A can be measured using a mass spectrometer, for example. In the present embodiment, the moisture concentration in first space 40A is 3000 ppm or less. The moisture concentration in the first space 40A can be measured using, for example, a mass spectrometer. A window 42 is formed in the cap 40 . A glass member in the form of a parallel plate, for example, is fitted in the window 42 . In the present embodiment, the protective member 2 is an airtight member that keeps the inside airtight.

3 to 6, light forming section 20 includes base member 4, laser diodes 81, 82, 83, filters 97, 98, 99, aperture member 55, and MEMS 120. As shown in FIG.

The base member 4 includes an electronic temperature adjustment module 30 , a base plate 60 and a MEMS base 65 . The electronic temperature control module 30 includes a heat absorbing plate 31 and a heat radiating plate 32 having flat plate shapes, and a semiconductor column 33 arranged between the heat absorbing plate 31 and the heat radiating plate 32 with an electrode interposed therebetween. Heat absorption plate 31 and heat dissipation plate 32 are made of alumina, for example. The electronic temperature control module 30 is arranged on one main surface 10A of the base 10 so that the heat sink 32 is in contact with the one main surface 10A of the base 10 .

A base plate 60 and a MEMS base 65 are arranged on the heat absorbing plate 31 so as to be in contact with the heat absorbing plate 31 . The base plate 60 has a plate-like shape. The base plate 60 has one principal surface 60A having a rectangular shape (square shape) in plan view. One main surface 60A of the base plate 60 includes a lens mounting area 61, a chip mounting area 62, and a filter mounting area 63. As shown in FIG. The chip mounting region 62 is formed in a region including one side of one main surface 60A along the one side. The lens mounting area 61 is adjacent to the chip mounting area 62 and arranged along the chip mounting area 62 . The filter mounting area 63 is arranged along the other side in an area including the other side facing the one side of the main surface 60A. The chip mounting area 62, the lens mounting area 61 and the filter mounting area 63 are parallel to each other.

The thickness of the base plate 60 in the lens mounting region 61 and the thickness of the base plate 60 in the filter mounting region 63 are equal. The lens mounting area 61 and the filter mounting area 63 are included in the same plane. The thickness of the base plate 60 in the chip mounting area 62 is larger than that in the lens mounting area 61 and the filter mounting area 63 . As a result, the height of the chip mounting area 62 (the height based on the lens mounting area 61, that is, the height in the direction perpendicular to the lens mounting area 61) is higher than the lens mounting area 61 and the filter mounting area 63. It's becoming

A flat first submount 71, a second submount 72, and a third submount 73 are arranged on the chip mounting area 62 along one side of the main surface 60A. A second submount 72 is arranged so as to be sandwiched between the first submount 71 and the third submount 73 . A red laser diode 81 as a first laser diode is arranged on the first submount 71 . A green laser diode 82 as a second laser diode is arranged on the second submount 72 . A blue laser diode 83 as a third laser diode is arranged on the third submount 73 . In this embodiment, the laser diodes 81, 82, 83 are semiconductor laser chips. The height of the optical axes of the red laser diode 81, the green laser diode 82, and the blue laser diode 83 (the distance between the reference plane and the optical axis when the lens mounting area 61 of one main surface 60A is used as the reference plane; Z-axis direction ) are adjusted and matched by the first submount 71 , the second submount 72 and the third submount 73 .

A first lens 91 , a second lens 92 and a third lens 93 are arranged on the lens mounting area 61 . The first lens 91, the second lens 92 and the third lens 93 respectively have lens portions 91A, 92A and 93A whose surfaces are lens surfaces. In the first lens 91, the second lens 92 and the third lens 93, the lens portions 91A, 92A and 93A and the regions other than the lens portions 91A, 92A and 93A are integrally molded. The central axes of the lens portions 91A, 92A, and 93A of the first lens 91, the second lens 92, and the third lens 93, that is, the optical axes of the lens portions 91A, 92A, and 93A are respectively the red laser diode 81, the green laser diode 82, and the optical axis of the lens portions 91A, 92A, and 93A. It coincides with the optical axis of the blue laser diode 83 . A first lens 91, a second lens 92, and a third lens 93 convert the spot size of the light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83, respectively (the beam shape on a certain projection plane is changed to shaping into the desired shape). Light emitted from the red laser diode 81, the green laser diode 82, and the blue laser diode 83 is converted into collimated light by the first lens 91, the second lens 92, and the third lens 93, respectively.

A first filter 97 , a second filter 98 and a third filter 99 are arranged on the filter mounting area 63 . A first filter 97 is arranged on a straight line connecting the red laser diode 81 and the first lens 91 . A second filter 98 is arranged on a straight line connecting the green laser diode 82 and the second lens 92 . A third filter 99 is arranged on a straight line connecting the blue laser diode 83 and the third lens 93 . The first filter 97, the second filter 98, and the third filter 99 each have a plate-like shape with principal surfaces parallel to each other. The first filter 97, the second filter 98 and the third filter 99 are, for example, wavelength selective filters. First filter 97, second filter 98 and third filter 99 are, for example, dielectric multilayer filters.

More specifically, the first filter 97 reflects red light. The second filter 98 transmits red light and reflects green light. The third filter 99 transmits red light and green light and reflects blue light. Thus, the first filter 97, the second filter 98 and the third filter 99 selectively transmit and reflect light of specific wavelengths. As a result, the first filter 97 , the second filter 98 and the third filter 99 combine the lights emitted from the red laser diode 81 , the green laser diode 82 and the blue laser diode 83 .

The aperture member 55 is arranged on the heat absorbing plate 31 . The aperture member 55 is arranged on the side opposite to the second filter 98 when viewed from the third filter 99 . Aperture member 55 has a flat plate shape. The aperture member 55 has a through hole 55A penetrating through the aperture member 55 in the thickness direction. In the present embodiment, the cross section perpendicular to the extending direction of the through hole 55A has a circular shape. Aperture member 55 is arranged such that through hole 55A is located in a region corresponding to the optical path of the light beams combined in first filter 97, second filter 98 and third filter 99. FIG. The through hole 55A extends along the optical path of the light multiplexed in the first filter 97, the second filter 98 and the third filter 99. FIG. The light emitted from the laser diodes 81, 82, 83 has an elliptical shape in a cross section perpendicular to the direction of travel of the light. In the cross section perpendicular to the light traveling direction, the diameter of the through hole 55A is smaller than the long axis of the light combined by the filters 97, 98, 99, and the light combined with the central axis of the through hole 55A Aperture member 55 is arranged such that the axes coincide. As a result, the shape of the cross section perpendicular to the traveling direction of the lights combined by the filters 97 , 98 , 99 is shaped to be smaller than the inner diameter of the through hole 55</b>A of the aperture member 55 .

The MEMS base 65 has a triangular prism (right triangular prism) shape. The MEMS base 65 is placed on the heat absorbing plate 31 so as to contact the heat absorbing plate 31 on one side of the triangular prism. A MEMS 120 including a mirror 121 is positioned on the other side of the MEMS base 65 . The MEMS base 65 and the MEMS 120 are arranged on the side opposite to the third filter 99 when viewed from the aperture member 55 . In this embodiment, mirror 121 has a disk-like shape. The mirror 121 is arranged so as to be exposed to the first space 40A. The MEMS 120 is arranged so that the mirror 121 is located in the area corresponding to the optical path of the light shaped in the aperture member 55 . Mirror 121 can be swung in a desired direction and angle. As a result, the light shaped at the aperture member 55 can be scanned by the MEMS 120 including the mirror 121 .

Referring to FIG. 5, red laser diode 81, lens portion 91A of first lens 91, and first filter 97 are aligned in a straight line along the light emission direction of red laser diode 81 (aligned in the Y-axis direction). ) are placed. The green laser diode 82, the lens portion 92A of the second lens 92, and the second filter 98 are arranged side by side on a straight line along the light emission direction of the green laser diode 82 (side by side in the Y-axis direction). The blue laser diode 83, the lens portion 93A of the third lens 93, and the third filter 99 are arranged side by side on a straight line along the light emission direction of the blue laser diode 83 (side by side in the Y-axis direction).

The emission direction of the red laser diode 81, the emission direction of the green laser diode 82, and the emission direction of the blue laser diode 83 are parallel to each other. The main surfaces of the first filter 97, the second filter 98 and the third filter 99 are inclined by 45° with respect to the emitting direction (Y-axis direction) of the red laser diode 81, the green laser diode 82 and the blue laser diode 83, respectively. there is

Between the base 10 and the base plate 60 and MEMS base 65 an electronic temperature regulation module 30 is arranged. A heat absorbing plate 31 is placed in contact with the base plate 60 and the MEMS base 65 . The heat sink 32 is arranged in contact with one main surface 10A of the base 10 . In this embodiment, the electronic temperature adjustment module 30 is a Peltier module (Peltier element) that is an electronic cooling module. In this embodiment, by applying a current to the electronic temperature adjustment module 30, the heat of the base plate 60 in contact with the heat absorbing plate 31 is transferred to the base 10, and the base plate 60 and the MEMS base 65 are cooled. As a result, the temperatures of laser diodes 81, 82, 83 and MEMS 120 are adjusted to appropriate temperature ranges. Also, by maintaining the temperatures of the red laser diode 81, the green laser diode 82, and the blue laser diode 83 within appropriate ranges, it is possible to accurately form light of a desired color. Furthermore, by adjusting the MEMS 120 to an appropriate temperature, it is possible to improve the operational stability against temperature changes.

Next, the operation of the optical module 1 according to this embodiment will be described. Referring to FIG. 5, red light emitted from red laser diode 81 travels along optical path _L1 . This red light is incident on the lens portion 91A of the first lens 91, and the spot size of the light is converted. Specifically, for example, red light emitted from a red laser diode 81 is converted into collimated light. The red light whose spot size has been converted by the first lens 91 travels along the optical path L ₁ and enters the first filter 97 .

Since the first filter 97 reflects red light, the light emitted from the red laser diode 81 further travels along the optical path L ₄ and enters the second filter 98 . Since the second filter 98 transmits red light, the light emitted from the red laser diode 81 further travels along the optical path L ₄ and enters the third filter 99 . Since the third filter 99 transmits red light, the light emitted from the red laser diode 81 further travels along the optical path L ₄ and reaches the aperture member 55 . The light reaching the aperture member 55 is shaped by the aperture member 55 , travels further along the optical path L ₄ , and reaches the mirror 121 .

Green light emitted from the green laser diode 82 travels along the optical path _L2 . This green light enters the lens portion 92A of the second lens 92, and the spot size of the light is converted. Specifically, for example, green light emitted from a green laser diode 82 is converted into collimated light. The green light whose spot size has been converted by the second lens 92 travels along the optical path L ₂ and enters the second filter 98 .

Since the second filter 98 reflects green light, the light emitted from the green laser diode 82 further travels along the optical path L ₄ and enters the third filter 99 . Since the third filter 99 transmits green light, the light emitted from the green laser diode 82 further travels along the optical path L ₄ and reaches the aperture member 55 . The green light reaching the aperture member 55 is shaped by the aperture member 55, travels further along the optical path _L4 , and reaches the mirror 121. FIG.

Blue light emitted from the blue laser diode 83 travels along the optical path _L3 . This blue light enters the lens portion 93A of the third lens 93, and the spot size of the light is converted. Specifically, for example, blue light emitted from a blue laser diode 83 is converted into collimated light. The blue light whose spot size has been converted by the third lens 93 travels along the optical path L ₃ and enters the third filter 99 .

Since the third filter 99 reflects blue light, the light emitted from the blue laser diode 83 further travels along the optical path L ₄ and reaches the aperture member 55 . The blue light reaching the aperture member 55 is shaped by the aperture member 55 , travels further along the optical path L ₄ , and reaches the mirror 121 .

In this way, the light (multiplexed light) formed by combining the red, green, and blue lights reaches the mirror 121 along the optical path _L4 . Then, referring to FIG. 6, the combined light is scanned by driving the mirror 121, and the combined light emitted to the outside of the cap 40 through the window 42 along the optical path _L10 forms characters, figures, etc. be drawn.

Next, a method for manufacturing the optical module 1 according to the first embodiment will be described. Referring to FIG. 7, in the method of manufacturing optical module 1 according to the first embodiment, first, in step (S10), base 10 and light including laser diodes 81, 82, 83 arranged on base 10 A step of preparing a first structure including the formation portion 20 is performed. In this step (S10), a first structure including a base portion 10 and a light forming portion 20, in which various parts including the laser diodes 81, 82, 83 are combined according to the above description based on FIGS. 3 and 4, is prepared. .

Next, as a step (S20), a step of welding cap 40 to base 10 is performed. Referring to FIG. 8 , cap 40 before welding includes first portion 401 , second portion 402 , third portion 403 and fourth portion 404 . When viewed in plan in the Z-axis direction, the outer shape of the first portion 401 is a rectangular shape with rounded corners. The second portion 402 has a tubular shape. The first portion 401 is connected so as to block one opening of the second portion 402 . An annular third portion 403 is arranged so as to cross (perpendicularly) the Z-axis direction. The third portion 403 is connected to the portion surrounding the other opening of the second portion 402 . The third portion 403 is connected so as to include the outer circumference of the second portion 402 when viewed in plan in the Z-axis direction. An annular fourth portion 404 is arranged on the side opposite to the second portion when viewed from the third portion 403 . The fourth portion 404 is connected so as to include the outer periphery of the third portion 403 when viewed in plan in the Z-axis direction. The fourth portion 404 extends to cross (perpendicularly) the third portion. The fourth portion 404 is a portion welded to the main surface 10A.

Referring to FIG. 9 , cap 40 is placed on base 10 such that laser diodes 81 , 82 , 83 and MEMS 120 are surrounded by base 10 and cap 40 . More specifically, the fourth portion 404 of the cap 40 before welding is arranged to contact the main surface 10A of the base 10 over the entire circumference.

Then, the cap 40 before welding and the first structure are welded using the welding device 43 . Welding device 43 includes a first electrode 411 , a second electrode 412 and a container 413 . The first electrode 411 has a rectangular parallelepiped shape. The first electrode 411 is formed with a recess 411A having a shape corresponding to the first portion 401 and the second portion 402 of the cap 40 . The second electrode 412 has a rectangular parallelepiped shape. The second electrode 412 is formed with a concave portion 412A having a shape into which all the plurality of lead pins 51 can be inserted. The container 413 has an internal space 413A that can accommodate the first electrode 411 and the second electrode. The container 413 includes a valve 414 for introducing air or oxygen gas from the outside into the internal space 413A. A vacuum pump 415 is connected to the container 413 to reduce the pressure in the internal space 413A. A pressure gauge 416 for measuring the pressure in the internal space 413A is connected to the container 413 .

The first portion 401 and the second portion 402 of the cap 40 are inserted into the recess 411A of the first electrode 411 . At this time, the third portion 403 and the first electrode 411 are arranged so as to be in contact with each other. Next, a plurality of lead pins 51 are inserted into the recess 412A of the second electrode 412. As shown in FIG. At this time, the main surface 10B of the base 10 and the second electrode 412 are arranged so as to be in contact with each other. Then, the pressure inside the first space 40A is reduced while the pressure inside the first space 40A is being measured by the pressure gauge 416 . After the base 10 and the cap 40 are welded together, the pressure in the first space 40A is adjusted to be lower than the atmospheric pressure and equal to or higher than 0.15 atm. Next, the base 10 and the cap 40 are welded together by energizing between the third portion 403 and the main surface 10A while pressing the first electrode 411 in the direction of the arrow _S1 . As a result, a bonding region 405 between the cap 40 and the base 10 is formed as shown in FIG.

It is difficult for the cap 40 shown in FIG. 8 to ensure flatness with respect to the main surface 10A in the outer peripheral region of the opening. In particular, when the cap 40 is formed by pressing, the cap 40 tends to be distorted. Therefore, when it is left still on the main surface 10A, part of the outer peripheral region is separated from the base portion 10, and a gap may partially occur between the main surface 10A and the third portion 403. If welding is performed with a partial gap between the main surface 10A and the third portion 403, leakage occurs due to poor welding. Welding as described above can reduce joint failure between the base 10 and the cap 40 . Therefore, the first space 40A surrounded by the base 10 and the cap 40 can be made more reliably airtight.

Here, in optical module 1 according to the present embodiment, laser diodes 81 , 82 , 83 and MEMS 120 are sealed with protective member 2 . Therefore, miniaturization can be achieved. In addition, since the pressure in the first space 40A is lower than the atmospheric pressure and equal to or higher than 0.15 atm, the air resistance that the mirror 121 receives can be suppressed. Therefore, the mechanical deflection angle of mirror 121 can be increased. As described above, according to the optical module 1 of the present embodiment, the mechanical deflection angle of the mirror 121 can be increased while miniaturization is achieved.

In the above embodiment, the partial pressure of oxygen in the first space 40A is 0.03 atm or higher. The above partial pressure of oxygen in the first space 40A is achieved by welding the base 10 and the cap 40 together while adjusting the composition of the gas introduced into the internal space 413A of the container 413 . A coating film made of oxide may be formed on the end faces of the laser diodes 81 , 82 , 83 . By setting the partial pressure of oxygen to 0.03 atm or higher, it is possible to suppress detachment of oxygen atoms from the coating film. Therefore, the durability of the laser diodes 81, 82, 83 can be improved.

In the above embodiment, the moisture concentration in the first space 40A is 3000 ppm or less. The moisture concentration in the first space 40</b>A is achieved by welding the base 10 and the cap 40 while introducing gas with reduced moisture such as dry air into the internal space 413</b>A of the container 413 . When moisture adheres to the laser diodes 81, 82, 83, the heat of the laser diodes 81, 82, 83 may decompose the organic matter contained in the moisture. If the decomposed organic matter adheres to the coating films formed on the end faces of the laser diodes 81, 82 and 83, the coating films will deteriorate and the durability of the laser diodes 81, 82 and 83 will be lowered. Therefore, by setting the moisture concentration in the first space 40A to 3000 ppm or less, the durability of the laser diode can be improved.

In the above embodiment, the window 42 is arranged in the region of the base 10 of the cap 40 facing the main surface 10A. With such a configuration, the stress applied to the glass member fitted in the window 42 when welding the cap 40 to the base 10 can be reduced compared to the case where the cap 40 is arranged on the second portion 402 . can. Therefore, the first space 40A can be kept in a good airtight state.

In the above embodiment, the optical module 1 includes the red laser diode 81, the green laser diode 82, and the blue laser diode 83. , red laser diode 81 , green laser diode 82 and blue laser diode 83 . Also, an infrared laser diode that emits infrared light may be used instead of one of these laser diodes. If an infrared laser diode is used, it may be a vertical cavity surface emitting laser (VCSEL). Alternatively, an element in which a plurality of VCSELs are arranged (VCSEL array) may be used.

Further, in the above embodiment, the case where wavelength selective filters are employed as the first filter 97, the second filter 98 and the third filter 99 is illustrated, but these filters are, for example, polarization synthesis filters. may Also, the case where chip-shaped laser diodes are employed as the laser diodes 81, 82, and 83 has been described, but the laser diode chip has a structure such as a CAN type, in which the chip is enclosed in a metal container. may be adopted.

An experiment was conducted to confirm the effect of increasing the mechanical deflection angle of the mirror 121 of the MEMS 120 by changing the pressure in the first space 40A in an optical module having a structure similar to that of the above embodiment. The experimental procedure is as follows.

As in the first embodiment, a structure in which red laser diode 81, green laser diode 82, blue laser diode 83, and MEMS 120 are sealed by base 10 and cap 40 is adopted to sample optical module 1. made. The voltage applied to MEMS 120 is 10V. The mechanical deflection angle (horizontal deflection angle) of the mirror 121 of the MEMS 120 was measured when the pressure in the first space 40A was changed from 1 atm to 5×10 ⁻⁵ atm.

FIG. 11 is a diagram showing the above measurement results for sample 1. In FIG. The horizontal axis indicates the pressure (atm) in the first space 40A, and the vertical axis indicates the mechanical deflection angle (°) of the mirror 121. FIG. Referring to FIG. 11, the mechanical deflection angle of mirror 121 is increased by reducing the pressure in first space 40A from 1 atm. Even if the pressure in the first space 40A is reduced to less than 0.15 atm, the effect of increasing the mechanical deflection angle of the mirror 121 is saturated. Therefore, it is preferable that the pressure in the first space 40A is lower than the atmospheric pressure and equal to or higher than 0.15 atm. Thus, according to the optical module 1 of the present disclosure, the mechanical deflection angle of the mirror 121 can be increased.

It should be understood that the embodiments disclosed this time are illustrative in all respects and not restrictive in any aspect. The scope of the present invention is defined by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

The optical module of the present disclosure is particularly advantageously applied when it is required to increase the mechanical deflection angle of the mirror while achieving miniaturization.

Reference Signs List 1 optical module 2 protective member 4 base member 10 base 10A, 10B, 60A main surface 20 light forming section 30 electronic temperature control module 31 heat absorption plate 32 heat dissipation plate 33 semiconductor column 40 cap 40A first space 42 window 43 welding device 51 lead pin 55 Aperture member 55A through hole 60 base plate 61 lens mounting area 62 chip mounting area 63 filter mounting area 65 MEMS base 71 first submount 72 second submount 73 third submount 81 red laser diode 82 green laser diode 83 blue laser diode 91 First lenses 91A, 92A, 93A Lens part 92 Second lens 93 Third lens 97 First filter 98 Second filter 99 Third filter 120 MEMS
121 Mirror 401 First portion 402 Second portion 403 Third portion 404 Fourth portion 405 Joint region 411 First electrodes 411A, 412A Concave portion 412 Second electrode 413 Container 413A Internal space 414 Valve 415 Vacuum pump 416 Pressure gauge

Claims (8)

a light forming part for forming light;
a protective member that defines a first space that accommodates the light forming section and seals the light forming section;
The light forming part is
a laser diode;
a MEMS that includes a mirror that scans the light from the laser diode, and that is arranged such that the mirror is exposed in the first space;
The protection member includes a flat base and a cap,
The cap is
a first part;
a second portion having an annular shape and having one opening closed by the first portion;
a ring-shaped third portion surrounding the other opening of the second portion and connected to cross the second portion;
an annular fourth portion that extends in the thickness direction of the base portion, surrounds the outer periphery of the third portion, and is connected perpendicular to the third portion;
the base and the fourth portion are welded together;
The optical module, wherein the pressure in the first space is lower than atmospheric pressure and equal to or higher than 0.15 atmospheres. 2. The optical module according to claim 1, wherein the pressure in said first space is 0.8 atmospheres or less. 3. The optical module according to claim 1, wherein said laser diode is a semiconductor laser chip. 4. The optical module according to claim 3, wherein the partial pressure of oxygen in said first space is 0.03 atm or more. 5. The optical module according to claim 3, wherein the moisture concentration in said first space is 3000 ppm or less. 6. The optical module according to claim 1, wherein said laser diode emits infrared light. The light forming part is
a plurality of said laser diodes;
7. The optical module according to claim 1, further comprising a filter for combining lights emitted from said plurality of laser diodes. The plurality of laser diodes are
a red laser diode that emits red light;
a green laser diode that emits green light;
and a blue laser diode emitting blue light.

Images