JPH095583A - Package for obliquely cut fiber - Google Patents

Abstract

PURPOSE: To fit the obliquely cut fiber by holding the obliquely cut fiber airtight with simple constitution without deteriorating the efficiency of coupling with the obliquely cut fiber. CONSTITUTION: In a housing 1, a light emitting element 2 brought under the temperature control of a heat sink 14 and a temperature control element 15 is mounted on a substrate 5 across a submount 13. An opening hole 9 is bored in the flank of the housing 1 positioned on the forward output light emission surface side of the light emitting element 2. In the opening hole 9, a holding member 18 is held airtightly which has an optical path correction window 17 for refracting incident light by a specific angle. To the holding member 18, a fiber holder 8 is fixed which holds the obliquely cut fiber 7 so that a ferrule 7a faces the optical path correction window 17. The forward output light from the light emitting element 2 is refracted by the specific angle through the optical path correcting window 17 to reduce return light to the side of the light emitting element 2, and is guided to the obliquely cut fiber 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an obliquely cut fiber whose light incident end face is obliquely cut, and suppresses reflection of light from a light source by a light emitting element such as an LD to optically couple with the obliquely cut fiber. The present invention relates to a package for obliquely cut fiber.

[0002]

2. Description of the Related Art Light emitting devices such as LDs (hereinafter referred to as LDs)
When the light from the light source is coupled to the optical fiber, LD
An optical coupling system with an obliquely cut optical fiber is generally used in order to suppress the reflection of light from the light source, prevent the light interference in the package containing the light source, and stabilize the output light of the LD. .

FIG. 9 shows an example of a conventional package structure using this kind of obliquely cut optical fiber. In this package, an LD 83 mounted on a heat sink 82 via a submount 81 and a light receiving element (hereinafter, referred to as PD) 84 such as a PD for monitoring rear output light from the LD 83 are in a rectangular shape with an open upper surface. It is housed and arranged so as to face the inner casing 85. An opening hole 85a is formed through the side surface of the inner casing 85 from which the front output light is emitted from the LD 83. A flat glass window 86 made of, for example, sapphire glass is fixedly provided in the opening hole 85a. A lid 87 is attached to the upper surface of the inner casing 85 to hermetically seal the inner casing 85 to form a sealed structure. On the outer surface of the inner casing 85 where the glass window 86 is located, the condensing lens 8 is provided on one end side facing the LD 83.
A lens holder 89 to which 8 is fixed is attached. At the other end of the lens holder 89, a fiber holder 91 holding an obliquely cut fiber 90 whose incident end face is obliquely cut is attached. A temperature control element 92 such as a Peltier element is arranged on the lower surface of the inner casing 85. The inner casing 85, the lens holder 89, and the fiber holder 91, which accommodate components such as the LD 83 and the PD 84, are arranged in a state of being accommodated in the outer casing 93.

The package having the above structure has an inner casing 85.
After replacing the inside with dry nitrogen gas having a low dew point, the inner casing 8
The lid 87 is placed on the upper surface of the sheet 5 and is hermetically sealed by seam welding. As a result, the LD 83 can obtain a stable optical output without dew condensation in a predetermined operating temperature range. Then, the front output light of the LD 83 is transmitted through the glass window 8
6 enters the oblique cut fiber 90 through the lens 88, and the LD 83 and the oblique cut fiber 90 are optically coupled. At that time, the rear output light of the LD 83 is P
The monitor light is received by D84.

By the way, in the package configured as described above, for example, the oblique cut fiber 9 in which the incident end face has an inclination angle of 8 ° with respect to a plane orthogonal to the central axis.
In order to perform optical coupling with 0, the light emitted from the LD 83 is approximately half the tilt angle of the oblique cut fiber 90, that is, approximately 4
It is necessary to incline (long wavelength 1300 to 1650 nm) or to obliquely attach the obliquely cut fiber 90 to the package.

Therefore, conventionally, when the light emitted from the LD 83 is tilted by a predetermined angle, a condenser lens (corresponding to the lens 88 in FIG. 9) is arranged between the LD 83 and the oblique cut fiber 90, and The lens was moved on a plane orthogonal to the optical axis of the LD 83.

When the diagonal cut fiber 90 is obliquely attached to the package (inner casing 85),
As shown in FIGS. 10A and 10B, the shape of the fiber holder 91 for holding the obliquely cut fiber 90 has been devised and dealt with.

That is, in the fiber holder 91A shown in FIG. 10A, the mounting surface 94 to the inner casing 85 is a flat surface orthogonal to the central axis, and the through hole 95 is formed obliquely to the central axis. The diagonal cut fiber 90 is inserted into the diagonal through hole 95. Then, the fiber holder 91A is attached to the side surface of the inner casing 85 via the flat attachment surface 94 in a state where the central axis of the oblique cut fiber 90 is inclined with respect to the light emitting surface of the LD 83.

A fiber holder 91B shown in FIG. 10 (b).
The mounting surface 96 to the inner casing 85 is formed obliquely with respect to the central axis, and a through hole 97 is bored along the central axis, and the oblique cut fiber 90 is inserted into the through hole 97. There is. The fiber holder 91B is attached to the side surface of the inner casing 85 via the inclined attachment surface 96 in a state where the central axis of the oblique cut fiber 90 is inclined with respect to the light emitting surface of the LD 83.

[0010]

However, in the structure for moving the lens described above, the oblique cut fiber 9 is used.
There is a problem that the position where the image is formed is shifted with respect to 0 and the combined state is poor, and not only aberration occurs depending on the position of the lens, but also the position accuracy is required.

Further, the above-mentioned fiber holders 91a, 9a
In any of the configurations of 1b, the oblique cut fiber 9
The through hole 95 for inserting 0 is obliquely drilled, the mounting surface 96 to the inner casing 85 is obliquely polished, and the like, which does not require special processing, but the processing itself is difficult. However, there is also a problem that it is difficult to handle.

Therefore, the present invention has been made in view of the above problems, in which a special processing of a fiber holder for holding an obliquely cut fiber is not required, and an obliquely cut fiber is required with a simple structure without requiring accuracy. It is an object of the present invention to provide a package for a diagonal cut fiber that can be attached and can maintain airtightness without deteriorating the coupling efficiency to the diagonal cut fiber.

[0013]

In order to achieve the above object, a package for obliquely cut fiber according to claim 1 of the present invention has a housing 1 having a through hole 9 for transmitting light and an end face. An oblique cut fiber 7 formed obliquely and an optical path correction window 17 for refracting the light incident on the oblique cut fiber or the light emitted from the oblique cut fiber at a predetermined angle, and the oblique cut in the through hole. An optical path correction member 6 for hermetically maintaining the optical path correction window is provided on the optical axis of the fiber.

According to a second aspect of the present invention, there is provided an oblique cut fiber package in which a light emitting element 2 is housed and a through hole 9 for passing the output light of the light emitting element to the outside is formed. The end face is formed obliquely, and has an oblique cut fiber 7 that receives the output light from the light emitting element, and an optical path correction window 17 that refracts the output light from the light emitting element at a predetermined angle and guides it to the oblique cut fiber, An optical path correction member 6 for hermetically maintaining the optical path correction window on the optical axis between the light emitting element and the obliquely cut fiber in the through hole.
Are provided.

In the oblique cut fiber package of the third aspect, a gas chamber 34 for taking in gas is formed inside, and a through-hole 9 for allowing light to pass therethrough is formed into a case 33 and a case 33, respectively. The light emitting end face is formed obliquely, and the light emitting side oblique cut fiber 7A is formed to enter light into the gas chamber through one of the through holes, and the light incident end face is formed obliquely and is incident from the light emitting side oblique cut fiber. And an optical path correction window 17A for refracting the output light from the light emitting side diagonal cut fiber by a predetermined angle and guiding it to the gas chamber. A light emitting side optical path correcting member 6A for hermetically maintaining the optical path correcting window on the optical axis of the light emitting side oblique cut fiber in the hole, and refracts light passing through the gas chamber by a predetermined angle. An optical path correction window 17B for guiding to the light receiving side oblique cut fiber, and a light receiving side optical path correction member 6B for hermetically maintaining the optical path correction window on the optical axis of the light receiving side oblique cut fiber in the through hole. Is characterized by.

In the oblique cut fiber package according to a fourth aspect of the present invention, there is provided a housing 33 in which a gas chamber 34 for taking in gas is formed, and a through hole 9 for making light incident into the gas chamber is formed. The light emitting end face is formed obliquely, the light emitting side oblique cut fiber 7A for entering light into the gas chamber through the through hole, and the housing facing the through hole on the optical axis of the light emitting side oblique cut fiber. A light receiving element 40 having a light incident end face formed obliquely and receiving light incident from the light emitting side oblique cut fiber and passing through the gas chamber, and output light from the light emitting side oblique cut fiber. Optical path correction window 1 that bends at an angle and leads to the gas chamber
7A, and an optical path correction member 6A for hermetically maintaining the optical path correction window on the optical axis of the light emission side oblique cut fiber in the through hole.

In the oblique cut fiber package according to any one of claims 1 to 4, the optical path correction windows 17, 17A and 17B are:
It is composed of wedge prisms.

In the oblique cut fiber package of the third or fourth aspect, the gas injection port 35 for injecting the gas to be measured into the gas chamber 34, and the gas to be measured injected into the gas chamber to the outside of the housing 1. And a gas discharge port 36 for discharging. Further, as a configuration including a gas injection port 37 for injecting the calibration gas into the gas chamber 34, and sealing members 38, 39 for sealing the calibration gas injected from the gas injection port in the gas chamber Good.

[0019]

In the oblique cut fiber package of claim 1, the optical path correction window 1 is provided on the optical axis of the oblique cut fiber 7 in the through hole 9 for light passage formed in the housing 1.
The optical path correction member 6 having 7 is kept airtight. The light incident on the oblique cut fiber 7 (or the light emitted from the oblique cut fiber 7) is refracted at a predetermined angle by the optical path correction window 17 and output.

In the oblique cut fiber package of the second aspect, the light emitting element 2 is housed inside the housing 1.
The light emitting element 2 and the oblique cut fiber 7 in the through hole 9
An optical path correction member 6 having an optical path correction window 17 is airtightly held on the optical axis between and. Then, the output light from the light emitting element 2 is refracted at a predetermined angle by the optical path correction window 17 and guided to the oblique cut fiber 7, and the light emitting element 2 and the oblique cut fiber 7 are optically coupled.

In the oblique cut fiber package of the third aspect, the gas chamber 34 is formed inside the housing 1.
Through holes 9 for allowing light to pass through are formed in the opposing surfaces of the housing 1, and the light emitting side oblique cut fiber 7A and the light receiving side oblique cut fiber 7B are located in the respective through holes 9 on the optical axis. The optical path correction window 17 (17
The optical path correction member 6 (6A, 6B) having A, 17B) is kept airtight. And the light emitting side oblique cut fiber 7
The light emitted from A is refracted at a predetermined angle by the optical path correction window 17A of the light emitting side optical path correction member 6A and guided to the gas chamber 34. After the light having the absorption wavelength of gas is absorbed, the light guided to the gas chamber 34 is refracted at a predetermined angle by the optical path correction window 17B of the light receiving side optical path correcting member 6B and guided to the light receiving side oblique cut fiber 7B. The fibers 7A and 7B are optically coupled.

In the oblique cut fiber package of claim 4, the optical path correction member 6 (6A) having the optical path correction window 17 (17A) is airtightly held on the optical axis of the light emitting side oblique cut fiber 7A in the through hole 9. To be done. In case 1,
The light receiving element 40 is provided so as to face the through hole 9 on the optical axis of the light emitting side diagonal cut fiber 7A. Then, the light emitted from the light emission side oblique cut fiber 7A is refracted at a predetermined angle by the optical path correction window 17A of the light emission side optical path correction member 6A and guided to the gas chamber 34. The light guided to the gas chamber 34 is received by the light receiving element 40 after the light having the absorption wavelength of gas is absorbed.

Thus, the optical path correction window 17 (17A, 17A) having a prism effect for refracting light in an arbitrary direction is provided.
Since B) is provided on the optical path between the oblique cut fiber 7 (7A, 7B) in the through hole 9 of the housing 1, the return light to the light incident side can be reduced and the coupling efficiency for the oblique cut fiber can be reduced. It is possible to form a package excellent in airtightness without deteriorating. Moreover, since no special processing is required as in the past, it is easy to handle, and the work can be performed with the same feeling as coupling with the vertical cut fiber.

In the oblique cut fiber package of each of the above claims, if a wedge prism is used for the optical path correction window 17 (17A, 17B), the refraction angle can be obtained at a constant value within a certain range of the light incident angle, so that it may be a little. Even if there is a displacement, the optical path correction window can be attached to the housing within a certain allowable range without affecting the coupling efficiency.

[0025]

【Example】

(First Embodiment) FIG. 1 is a view showing a first embodiment of an oblique cut fiber package according to the present invention, and FIG. 2 is a partially enlarged sectional view of the same package.

The oblique cut fiber package (hereinafter referred to as a package) according to the first embodiment is a light emitting device such as an LD (hereinafter referred to as an LD) in a case 1 which is hermetically sealed.
2, components such as a light receiving element (hereinafter referred to as PD) 3 such as a PD, a lens 4 for condensing, and the like are mounted on a substrate 5, and the optical path correction is provided on one side surface of the housing 1. The member 6 and the fiber holder 8 holding the diagonal cut fiber 7 are attached in a position adjusted state.

Rectangular housing 1 forming the base of the package
Has an opening 1a formed on its upper surface, and one side surface (right side surface in FIG. 1) has a predetermined shape (for example, a circle).
An opening hole 9 is formed therethrough. A lid 10 for hermetically sealing the housing 1 is attached to the opening 1 a of the housing 1.

A step portion 5a is formed at a right angle in the substantial center of the upper surface of the substrate 5. The right surface of the step portion 5a forms a reference surface that is horizontal with the inner bottom surface 1b of the housing 1, and forms a mounting surface 11 for mounting the LD 2 and the condenser lens 4. Similarly, the left side surface of the step portion 5a also forms a reference surface that is horizontal to the inner bottom surface 1b of the housing 1 and forms a mounting surface 12 for mounting the PD 3.

The LD 2 is formed in a chip shape and has a front surface 2a.
Both of the rear surface 2b and the rear surface 2b form a light emitting surface, and the front output light is emitted from the front surface 2a and the rear output light is emitted from the rear surface 2b as light of a predetermined wavelength. The LD 2 is soldered and fixed to the mounting surface 11 of the substrate 5 via a rectangular chip carrier 13, and the light emitting surface on the front surface 2a side has an oblique cut fiber 7.
It is located higher than the core position.

Between the lower surface of the LD 2 and the chip carrier 13, a heat sink 14 as a heat conductor is closely arranged. The heat sink 14 is a non-conductive heat conductor having good heat conductivity (mainly ceramic, SiC,
It is formed of AlN or the like) and conducts the heat generated in the LD 2 to the substrate 5 side through the chip carrier 13.

The PD 3 receives and monitors the rearward output light from the rear surface 2b of the LD 2, and the light receiving center axis is LD2.
The light emitting surface of the LD 2 is fixed to the mounting surface 12 of the substrate 5 by soldering so as to face the light emitting surface on the rear surface 2b side of the LD 2. The light receiving surface 3a of the PD 3 is a mounting surface 12 that is a reference surface.
A predetermined angle (for example, 10 ° ±
1 °) inclined. This prevents the rear output light from the LD2 from being reflected by the light receiving surface 3a and returning to the LD2 side,
Reciprocal reflection of light between LD2 and PD3 resonates to prevent the oscillation state of LD2 from changing.

Between the substrate 5 and the inner bottom surface 1b of the housing 1,
A temperature control element 15 such as a Peltier element is arranged in close contact. The polarity of the temperature control element 15 is controlled by a control signal from a temperature control unit (not shown),
Perform cooling or heating operation according to the heat generation temperature of LD2, and
D2 is kept at a predetermined constant temperature (for example, 25 ° C.).

The lens 4 collects the forward output light from the LD 2 on the incident end face of the oblique cut fiber 7 described later and forms an image. For example, the distance to the image forming point is set to 10 mm, and the lens 4 has a cylindrical shape. It is fixed to the hollow portion 16a of the lens holder 16. Lens holder 16 to which the lens 4 is fixed
After the LD 2 is caused to emit light to perform alignment, the positions of the optical path correction member 6 and the fiber holder 8 are adjusted, and then the LD 2 is fixed to the mounting surface 12 of the substrate 5 on the front surface 2a side.

The optical path correcting member 6 comprises an optical path correcting window 17 and a window holder 18 for holding the optical path correcting window 17. The window holder 18 is, for example, mainly Fe-Ni-C.
It is composed of a hollow pipe material made of o alloy. A small diameter portion 18a that fits into the opening 1a of the housing 1 is formed on one end side of the window holder 18. Window holder 18
A mounting hole 18c having a diameter larger than the diameter of the hollow portion 18b is formed in communication with the hollow portion 18b, and the optical path correction window 17 is mounted in the mounting hole 18c. Window holder 18
One end side of, for example, Ag is used, and is fixed to the housing 1 by brazing all around or at a plurality of points.

On the other end side of the window holder 18, for example, SUS
The welding ring 19 made of material is brazed by, for example, Ag brazing. The welding ring 19 is formed to have substantially the same diameter as the window holder 18 and melts when the fiber holder 8 is coaxially positionally adjusted with respect to the window holder 18,
The fiber holder 8 is fixed to the window holder 18 with a part of the ferrule 7a of the oblique cut fiber 7 being inserted into the hollow portion 18b.

The optical path correction window 17 is for refracting the front output light from the LD 2 and refracting it in an arbitrary direction without splitting it, and angling it. It has a glass plate of a predetermined thickness and an apex angle a as shown in FIG. It is composed of a glass wedge prism having a triangular cross section. The optical path correction window 17 is fixed in the hollow portion 18b of the window holder 18 on the side of the small diameter portion 18a. As a material of the optical path correction window 17, a material having a small dispersion is preferable, and a pipe material for holding the optical path correction window 17 (the window holder 1
It is general to match the thermal expansion coefficient with that of 8), but if an appropriate solder such as Au-Sn solder or low melting point glass is used as the solder, it should be fixed to the window holder 18 without cracking. You can In some cases, it is not necessary to intentionally apply heat, and an adhesive may be used.

The optical path correction window 17 is arranged obliquely with respect to the light emitting surface of the LD2, and the influence of the reflection of light on the LD2 side is extremely small, but an AR coat is applied to the surface on the LD2 side. If applied, the reflection of light to the LD2 side can be further suppressed. The optical path correction window 17 may have various shapes such as a circular shape, a polygonal shape such as a triangle or a quadrangle, or the like.

Here, FIG. 3A is a view showing a cross-sectional shape of a wedge prism as the optical path correction window 17, and FIG.
Is a diagram showing the light incident angle-refraction angle characteristics with respect to the apex angle when a wedge prism is used, and the refractive index n is 1.5.

In FIG. 3B, the apex angle of the wedge prism is a (°), the light incident angle is t (°), and the refraction angle is D.
When (°) is set, the refraction angle D is given by a / 2 when the light incident angle is t = 0 °. When the apex angle a is changed in the range of 2 to 10 °, for example, the refraction angle D does not change so much and shows a constant value up to the light incident angle t = 30 ° in any state. , D = a / 2 is satisfied. From this, the light incident angle t = 0 to 30 ° is set as the allowable range, and the optical path correction member 6 can be attached to the housing 1 without requiring the extra position (angle) accuracy.

The fiber holder 8 has a cylindrical shape with a through hole 20 formed along the central axis. The diameter of the through hole 20 is formed to be slightly larger than the outer diameter of the ferrule 7a of the oblique cut fiber 7, and the ferrule 7a of the oblique cut fiber 7 is inserted into the through hole 20. One end of the fiber holder 8 forms a mounting surface 8a whose outer diameter is substantially the same as the outer diameter of the end surface of the optical path correction member 6.

The oblique cut fiber 7 is composed of the ferrule 7a.
The inclined surface 7 that is polished by cutting the front end surface of the optical disk, that is, the light incident end surface obliquely at a predetermined angle with respect to the surface orthogonal to the optical axis.
b is formed. The inclined surface 7b prevents the front output light from the LD2 from reflecting and returning to the LD2 side.
The oscillation state of the LD 2 is prevented from changing due to the resonance caused by the repeated reflection of light between the obliquely cut fiber 7 and the oblique cut fiber 7.

Here, the inclined surface 7 of the oblique cut fiber 7
The inclination angle of b is set to an angle at which the return loss desired by the user is obtained. And, for example, the inclined surface 7b is 8
In the case where the LD 2 is polished at a temperature of 63 °, the optical axis of the LD 2 is designed to be located 63 μm above the optical axis of the oblique cut fiber 7. When the optical axis of the LD 2 is located below the optical axis of the oblique cut fiber 7, the inclined surface 7b of the oblique cut fiber 7 is in the opposite direction to that of FIG. 1, that is, orthogonal to the optical axis of the oblique cut fiber 7. It will tilt upward with respect to the plane.

Next, a method for assembling the package configured as described above will be described. First, the inner bottom surface 1 of the housing 1
The temperature control element 15 is soldered and fixed to b. Further, the chip carrier 13 on which the LD 2 is mounted, the lens holder 16 on which the LD 2, PD 3 and the lens 4 are fixedly mounted are solder-fixed to the respective mounting surfaces 11 and 12 of the substrate 5, and the substrate 5 of the temperature control element 15 is fixed. Fix with solder on the surface. At the same time, the window holder 18 to which the optical path correction window 17 is fixed is fixed to the opening hole 9 of the housing 1 by brazing. At that time, the fiber holder 8 is movably attached to the window holder 18 in a state where the tip end of the ferrule 7b of the oblique cut fiber 7 is inserted into the hollow portion 18b. After that, LD2, PD
Predetermined wiring is applied to each component such as 3.

After the above assembly is completed, the LD 2 is caused to emit light to align the lens 4 fixed to the lens holder 16. Here, in aligning the optical axis of the lens 4, first, as shown in FIGS.
The inner surface of the chip carrier 13 on which the LD 2 is mounted is brought into contact with a pair of abutment blocks 31 that are fixed on the substrate 5 so as to face each other at right angles to the optical axis of 2. In this state, the chip carrier 13 is fixed to the substrate 5 by soldering. Next, lens 4
The lens holder 16 in which is fixed is held by a clamper 32, and is moved on a plane orthogonal to the optical axis of the LD 2 to set L
Align with D2. Then, as shown in FIGS. 4C and 4D, the inner surface of the lens holder 16 is abutted to the abutment block 3
The lens holder 16 and the abutment block 31 are fixed to each other by YAG welding while being in contact with the lens 1.

Next, the fiber holder 8 is placed on the plane orthogonal to the optical axis of the LD2 while the front output light from the LD2 is received by the oblique cut fiber 7 so that the fiber holder 8 is positioned coaxially with the window holder 18. Use to move and adjust.
At this time, adjustment of the LD 2 with respect to the optical axis direction is performed by moving the ferrule 7a inserted into the fiber holder 8.
When these adjustments are completed, the ferrule 7a of the oblique cut fiber 7 is fixed to the fiber holder 8 by soldering, and then the welding ring 19 is melted to fix the fiber holder 8 to the window holder 18
Weld to. Next, the lens holder 16 having the lens 4 fixed thereto is fixed to the substrate 5 by, for example, YAG laser welding. In this state, the inside of the housing 1 has a low dew point (for example, 213
Replace with dry nitrogen gas or the like. After that, the lid 10 is placed on the opening 1a of the housing 1, seam welding is performed over the entire circumference of the lid 10, and the lid 10 is fixed to the housing 1 and hermetically sealed.

Therefore, according to the above-described embodiment, the optical path correcting member 6 having the prism effect of refracting the incident light in an arbitrary direction is provided with the opening hole of the housing 1 on the optical path between the oblique cut fiber 7. Since it is airtightly attached to the diagonal cut fiber 9, it is possible to reduce the reflection of light returning to the LD 2 side and angle the diagonal cut fiber 7 without degrading the coupling efficiency with respect to the diagonal cut fiber 7. In addition, since the fiber holder 8 for holding the oblique cut fiber 7 does not require any special processing as in the past, it is easy to handle and the work can be performed with the same feeling as coupling with the vertical cut fiber.

Since the wedge prism is used as the optical path correction window 17, the light incident angle within a predetermined range (specifically,
As shown in FIG. 3B, the refraction angle is obtained at a constant value in the range of 0 to 30 °, and even if some positional deviation occurs, the coupling efficiency with respect to the oblique cut fiber 7 is not affected. , With a certain degree of positional accuracy,
The wedge prism can be attached to the opening hole 9 of the housing 1 while keeping airtightness.

Next, FIG. 5A is a view showing a second embodiment of the package according to the present invention, and FIG. 5B is a view showing a third embodiment of the same package. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

(Second Embodiment) In a package according to the second embodiment, the inside of a rectangular casing 33 forms a gas chamber 34 to form a gas cell. In FIG. 5A, the housing 3
A tubular gas injection port 35 for injecting the measured gas WA into the gas chamber 34 is formed on the left side of the upper surface of 3. In addition, since the measurement optical path length is long when measuring the concentration of the gas to be measured WA, the housing 3 positioned symmetrically to the gas injection port 35.
A tubular gas exhaust port 36 for exhausting the gas under measurement WA injected into the gas chamber 34 is formed on the right side of the lower surface of 3, so that the entire gas chamber 34 is filled with gas. As the measured gas WA injected into the gas chamber 34,
There are gases such as methane, carbon dioxide, acetylene, and ammonia. Opening holes 33a formed on both sides of the housing 33,
33b includes the optical path correction member 6 (6) described in the first embodiment.
(A, 6B) are attached to face each other. A fiber holder 8 in which the oblique cut fiber 7 is inserted is attached to each window holder 18 (18A, 18B). Although not shown, one oblique cut fiber 7 (7A) is connected to the light source section, and the other oblique cut fiber 7 (7B) is connected to the light receiving section.

In the second embodiment, from the light source portion (not shown), the absorption wavelength of the gas to be measured WA injected into the gas chamber 34 in the housing 33 through the gas inlet 35 (for example, 1.65 μm for methane, Light having a wavelength including 1.44 μm for carbon dioxide and 1.53 μm for acetylene) is incident on the inside of the gas chamber 34 via the one oblique cut fiber 7A.
The light that has passed through the measurement gas atmosphere in the gas chamber 34 is absorbed by the light having the absorption wavelength of the measurement gas WA,
The light is incident on the other diagonal cut fiber 7B and is received by a light receiving unit (not shown). Then, the basic phase sensitive detection signal and the second harmonic phase sensitive detection signal are detected from the output signal of the received light, and the concentration of the gas to be measured WA is measured from the ratio of these signals.

(Third Embodiment) The package according to the third embodiment is the same as the package of the second embodiment except that the optical path correcting member 6 is used.
5B is attached to both side surfaces of the housing 33, the optical path correction member 6 (6A) is attached only to the opening hole 33a on the left side surface of the housing 33 on the light emitting side in FIG. 5B. The opening hole 3 on the right side of the housing 33 on the light receiving side.
A light receiving element (hereinafter referred to as PD) 40 is fixedly provided on 3b. Although not shown, the diagonal cut fiber 7
(7A) is connected to the light source unit.

In the third embodiment, the light incident on the gas chamber 34 from the light source section (not shown) through the oblique cut fiber 7A is the light having the absorption wavelength of the gas to be measured WA in the atmosphere to be measured. After being absorbed, the light receiving surface 40a is directly received by the PD 40 which is inclined by a predetermined angle.

By the way, the gas concentration detection value obtained by the measurement has a property that it changes depending on the length of the set optical path between the light source section and the light receiving section and the amount of light from the light source section when the measurement system is constructed or before the measurement is started. Therefore, it is necessary to periodically calibrate the detected gas concentration.

Therefore, FIGS. 6 (a) and 6 (b) show a package used when calibrating the above gas concentration.
FIG. 6A shows a fourth embodiment of the package according to the present invention, and FIG. 6B shows a fifth embodiment of the same package.
The same components as those in the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted.

(Fourth Embodiment) In the package of the fourth embodiment, a gas injection hole for injecting the calibration gas WB into the gas chamber 34 inside the casing 33 is provided on the upper surface of the rectangular casing 33. 37 is formed. A sealing plug 38 for sealing the calibration gas WB in the gas chamber 34 is fitted into the gas injection hole 37 while the calibration gas WB having a predetermined concentration and a predetermined pressure is injected into the gas chamber 34. ing. Sealing plug 3
On the upper part of 8, a lid 39 is fixed by welding in close contact with the upper surface of the sealing plug 38 and the upper surface of the housing 33.
Leakage of the calibration gas WB is prevented. The configuration other than the above is the same as that of the second embodiment.

(Fifth Embodiment) In the package of the fifth embodiment, as in the fourth embodiment, a gas injection hole 37 is formed in the upper surface of a rectangular casing 33, and the gas injection hole 37 is filled with gas. Sealing plug 38 for containing the calibration gas WB in the chamber 34
Is fitted, and a lid 39 for preventing the calibration gas WB from leaking is fixed to the upper portion of the sealing plug 38. The configuration other than the above is the same as that of the third embodiment. As described above, in the fourth and fifth embodiments, the calibration gas cell is prepared by preparing a plurality of packages in which the calibration gas WB at a predetermined concentration (for example, every 1 ppm) and a predetermined pressure is sealed in the gas chamber 34 in advance. Can be configured.

Further, according to the packages of the second to fifth embodiments described above, the optical path correction window 17 for refracting light in a predetermined direction is provided on the optical path between the light emitting section and the light receiving section. Since the optical path correction member 6 is provided, the reflected light to the light incident side can be reduced, and the gas concentration can be measured or calibrated with a smaller error.

Next, FIG. 7 is a block diagram showing an example of a gas concentration measuring device in which the package according to the fourth or fifth embodiment is used, and FIG. 8A is an explanatory view of the wavelength locking operation in the device. , A diagram showing an example of gas absorption characteristics,
FIG. 8B shows a current waveform during the wavelength lock operation and a received light waveform at each wavelength on the absorption line of FIG. 8A.

The LD module 45 in this gas concentration measuring device constitutes a wavelength stabilizing light source, and is an LD 48 arranged on a temperature control element 47 such as a Peltier element which is heated or cooled by a temperature controller 46. And LD48
Calibration gas cell 49 that allows the rear output light from
The calibration light receiver 50 is provided for receiving the light in which the light having the absorption wavelength by the gas absorption line in the calibration gas cell 49 is absorbed. As the calibration gas cell 49, the packages of the above fourth and fifth embodiments are adopted. When the package of the fifth embodiment is adopted, the calibration photodetector 50 is also included in the package and is composed of one module.

In the gas concentration measuring apparatus, the temperature controller 46 controls the heating or cooling of the temperature control element 47 to control the driving of the LD 49 to a temperature at which a predetermined absorption spectrum is obtained. It is extremely difficult to achieve the stability of the system only by the temperature control element 47. Therefore, the rear output light of the LD 48 is detected by the calibration light receiver 50 via the calibration gas cell 49, and the absorption characteristic of the calibration gas cell 49 is used to electrically lock the wavelength of the LD 48 to a constant value. I'm hanging.

More specifically, the signal from the oscillator 53 (for example, 20 kHz) when the switch 51 is switched to the filter 52 side is used as a carrier, and the signal from the current source 54 is superposed on this carrier and the LD 48 has a constant value. When the modulation is applied, the light reception power of the light reception signal by the calibration light receiver 50 increases or decreases according to the wavelength on the absorption line of the gas in the calibration gas cell 49 (state of P1 or P2 in FIG. 8A). At that time, in the state of P0 shown in FIG. 8 (a), its power increases only when it is swung by either arrow A or B in the figure (the received light signal in this state of P0 is called a second harmonic wave). ing). Therefore, the peak value of the absorption line is searched by detecting the doubled wave by the phase detection circuit 55, and the LD
48 is locked at the peak wavelength. The switch 51 supplies a modulated current I1 and an unmodulated current I2 alternately to the LD 48, for example, 125
Switching control is performed at Hz. Then, the current I2
Is supplied, the LD 48 is controlled to a wavelength outside the absorption line of the gas in the calibration gas cell 49.

As described above, the package of the fourth or fifth embodiment is adopted as the calibration gas cell 49 in the LD module 45, and the phase detection circuit 55 is used to detect the second harmonic of the backward output light of the LD 48. The wavelength of the LD 48 is locked by locking the wavelength of the LD 48 at the peak position (P0 in FIG. 8A) of the absorption spectrum at which this second harmonic wave is detected.

When the wavelength stabilization control of the LD 48 is performed, the forward output light from the LD 48 is divided into two by the optical branching device 56. Then, one of the lights is used as a monitor light receiver 57.
The light is received by and is input to the calculator 58 as a monitor signal. The other light passes through the measured portion 61 in which the optical fibers 60 are connected to both ends of the measurement gas cell 59, the light having the absorption wavelength of the measured gas in the measurement gas cell 59 is absorbed, and the measurement light receiver 62 is received. Is received by. After that, arithmetic unit 5
Reference numeral 8 detects the basic phase sensitive detection signal and the second harmonic phase sensitive detection signal from the output signal of the received light, calculates the concentration of the gas to be measured in the measurement gas cell 59 from the ratio of these signals, and outputs the result. Is displayed on the display 63.

The package of the second or third embodiment may be adopted as the measuring gas cell 59 in the above-mentioned gas concentration measuring device. In the case of adopting the package of the third embodiment, the measuring light receiver is used. 62 is also included in the package, and the optical fiber 60 between the measurement gas cell 59 and the measurement light receiver 62 is not required.

By the way, in the above-mentioned first embodiment,
As shown in FIG. 4, if the optical isolator 41 is fixedly provided on the lens holder 16 while being positioned on the optical path between the LD 2 and the oblique cut fiber 7, reflection of light to the LD 2 side can be further suppressed, The influence of reflection can be reduced.

In addition to the LD2 in the first embodiment, the DFB in which the oscillation wavelength sensitively changes with respect to the ambient temperature
(Distributed Feed Back) type or DBR (Distributed B
ragg Reflector type LD, LED, SLD (Super Lum)
(Inescent Diode) or the like can be used, and even in this case, the same effect as the above can be obtained.

[0067]

As described above, according to the package of the present invention, an optical path correcting member having an optical path correcting window having a prism effect for refracting light in an arbitrary direction is provided at an angle in a through hole of a housing. Since it is provided on the optical path between the cut fiber and the cut fiber, it is possible to reduce the return light to the light incident side, and it is possible to configure a package having excellent airtightness without deteriorating the coupling efficiency with the oblique cut fiber. Moreover, since the fiber holder for holding the obliquely cut fiber does not require any special processing as in the conventional case, it is easy to handle, and the work can be performed with the same feeling as coupling with the vertically cut fiber.

According to the package of claim 3 or 4, the reflected light to the light incident side can be reduced, and the gas concentration can be measured or calibrated with a smaller error. In particular, claim 5
According to this package, since a wedge prism that can obtain a constant refraction angle in a certain range of light incident angle is used as the optical path correction window, even if there is some positional deviation, it may affect the coupling efficiency. Instead, the optical path correction window can be attached to the housing in a hermetically sealed manner within a certain allowable range.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a diagonal cut fiber package according to the present invention.

FIG. 2 is a partially enlarged sectional view of the same package.

FIG. 3A is a side view of a wedge prism used as an optical path correcting member of the package. FIG. 3B is a diagram showing characteristics of a light incident angle and a refraction angle with respect to a prism apex angle when the wedge prism is used.

FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are operation diagrams when the optical axes of the lenses in the same package are aligned.

FIG. 5 (a) is a view showing a second embodiment of the oblique cut fiber package according to the present invention. (B) is a view showing a third embodiment of the oblique cut fiber package according to the present invention.

FIG. 6 (a) is a view showing a fourth embodiment of the oblique cut fiber package according to the present invention. FIG. 6 (b) is a view showing a fifth embodiment of the oblique cut fiber package according to the present invention.

FIG. 7 is a block diagram showing an example of a gas concentration measuring device in which the oblique cut fiber package according to the present invention is used.

8 (a) is an explanatory diagram of a wavelength locking operation in the gas concentration measuring device of FIG. 7, showing an example of gas absorption characteristics. (B) Current waveform during wavelength locking operation and FIG.
The figure which shows the received light waveform in each wavelength on the absorption line of (a).

FIG. 9 is a configuration diagram showing an example of a conventional diagonal cut fiber package.

10A and 10B are configuration diagrams of a fiber holder used in a conventional diagonal cut fiber package.

[Explanation of symbols]

1, 33 ... Casing, 2 ... LD (light emitting element), 6 ... Optical path correction member, 7 (7A, 7B) ... Oblique cut fiber, 9 ... Open hole (through hole), 17 (17A, 17B) ... Optical path correction Window, 34 ... Gas chamber, 35 ... Gas inlet, 36 ... Gas outlet, 37 ... Gas inlet, WA ... Measured gas, WB ... Calibration gas.

Claims (7)

[Claims] 1. A housing (1) having a through hole (9) for allowing light to pass therethrough, an obliquely cut fiber (7) having an end face obliquely formed, and incident on the obliquely cut fiber. An optical path correction member having an optical path correction window (17) for refracting light or light emitted from the oblique cut fiber at a predetermined angle, and hermetically maintaining the optical path correction window on the optical axis of the oblique cut fiber in the through hole. (6) An oblique cut fiber package comprising: 2. A through hole (9) for accommodating a light emitting element (2) inside and allowing the output light of the light emitting element to pass to the outside.
A housing (1) formed with the light, an obliquely cut fiber (7) having a light incident end surface formed obliquely and receiving output light from the light emitting element, and refracting output light from the light emitting element at a predetermined angle. An optical path correction window (17) for guiding the optical path correction window to the oblique cut fiber, and an optical path correction member (6) for hermetically maintaining the optical path correction window on the optical axis between the light emitting element and the oblique cut fiber in the through hole. And a diagonal cut fiber package. 3. A housing (33) in which a gas chamber (34) for taking in gas is formed, and through holes (9) for passing light are formed respectively on the opposite surfaces, and a light emitting part. A light-emitting side oblique cut fiber (7A) whose end face is formed obliquely and allows light to enter the gas chamber through one of the through holes, and a light incident end face which is formed obliquely and which is incident from the light-emitting side oblique cut fiber It has a light receiving side oblique cut fiber (7B) for receiving the light passing through the gas chamber, and an optical path correction window (17A) for refracting the output light from the light emitting side oblique cut fiber at a predetermined angle and guiding it to the gas chamber. A light emitting side optical path correcting member (6A) for hermetically maintaining the optical path correcting window on the optical axis of the light emitting side oblique cut fiber in the through hole; and a light receiving side for refracting light passing through the gas chamber by a predetermined angle. Has an optical path correction window (17B) for guiding in order cut fibers,
A package for a diagonal cut fiber, comprising: a light receiving side optical path correcting member (6B) that hermetically holds the optical path correcting window on the optical axis of the light receiving side oblique cutting fiber in the through hole. 4. A housing (33) in which a gas chamber (34) for taking in gas is formed, and a through hole (9) for allowing light to enter the gas chamber, and a light emitting end face. Is obliquely formed, and the light emitting side oblique cut fiber (7A) is configured to allow light to enter the gas chamber through the through hole.
And is provided in the housing so as to face the through hole on the optical axis of the light emitting side obliquely cut fiber, has a light incident end face formed obliquely, and is incident from the light emitting side obliquely cut fiber to enter the gas chamber. The light receiving element (40) for receiving the light passing therethrough, and the light path correction window (17A) for refracting the output light from the light emitting side oblique cut fiber at a predetermined angle and guiding it to the gas chamber, the light emission in the through hole An oblique cut fiber package comprising an optical path correction member (6A) for hermetically maintaining the optical path correction window on the optical axis of the side oblique cut fiber. 5. The optical path correction window (17, 17A, 17)
The oblique cut fiber package according to any one of claims 1 to 4, wherein B) is a wedge prism. 6. A gas inlet (35) for injecting a measured gas into the gas chamber (34), and a gas for discharging the measured gas injected into the gas chamber to the outside of the casing (33). The oblique cut fiber package according to claim 3 or 4, further comprising a discharge port (36). 7. A gas inlet (37) for injecting a calibration gas into the gas chamber (34), and a sealing member for sealing the calibration gas injected from the gas inlet into the gas chamber ( Three
8, 39), and the package for obliquely cut fibers according to claim 3 or 4.