JP2002228843A - Optical device and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and integrated optical device which facilitates an alignment with a light receiving and transmitting element, and can easily be made into an airtight structure, and to provide an optical module equipped with the same. SOLUTION: In the optical device, a first multimode optical fiber 2A, a coreless optical fiber 5, a second multimode optical fiber 2B, and a second single mode optical fiber 1B are connected in a line successively to one end of a first single mode optical fiber 1A equipped with a lens part 9 for optically connecting an optical semiconductor device to the other end, and are fixed on a base body. An optical element 4 is arranged in a groove 7 for loading the element formed in the coreless optical fiber 5, and a belt-like body 11 for cementation made of a metal is provided on the outer periphery of the base body 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module having an optical semiconductor element such as a light emitting element or a light receiving element which is suitably used for an optical communication device, a sensor or the like. Further, the present invention relates to an optical device mounted on the optical module and provided with an optical isolator for blocking reflected return light from the outside of the optical module, a wavelength plate for optical sensing and measurement, and the like.

[0002]

2. Description of the Related Art A laser diode (hereinafter, also referred to as an LD) used as a light source for optical communication reflects an emitted light at a certain place and returns to an active layer of the LD again, so that the oscillation state is disturbed and the output power varies. And a wavelength shift, etc., which deteriorates the signal. In particular, analog signals are easily degraded by the above-mentioned reflected return light, and the higher the density of the signal, the more easily the reflected return light is affected. Therefore, with the increase in analog transmission data such as CATV, large capacity, and high speed, Optical isolators have become an essential component.

In order to prevent such a problem of reflected return light, the LD is usually mounted in the same package as an optical isolator that transmits light only in one direction, and constitutes an LD module which is a kind of optical module. ing.

[0004] The general operation of an optical isolator will be briefly described below. As shown in FIG. 8, the optical isolator 4 is configured so that the Faraday rotator 20 is sandwiched between two polarizers 19A and 19B. In such a configuration, the forward light 22 is transmitted as it is, and the backward light 23 is blocked. The Faraday rotator 20 has a Faraday effect by applying a magnetic field from outside, and a Faraday rotator 20 having a Faraday effect without an external magnetic field due to spontaneous magnetization. Is not shown in some cases.

Next, an example of a conventional LD module will be described. As shown in FIG. 11, the LD module J1
Is at least the LD 15 and the lens 6 in the package 18.
A, 6B, the optical isolator 4, one end of the single mode optical fiber 1, and the like are housed. In the figure, reference numeral 16 denotes a light receiving element (hereinafter, also referred to as PD), reference numeral 17 denotes a peltier cooler, and reference numeral 32 denotes a rubber boot for protecting the extra length of the optical fiber.

The light emitted from the LD 15 is transmitted to the lens 6A.
And passes through the optical isolator 4 and the lens 6
The light is condensed by B and is incident on the single mode optical fiber 1. Each optical component is built in the package 18 and the rubber boot 32 in order to shield it from the external environment. In addition, a ball lens, a biconvex lens, an aspheric lens, a graded index lens (hereinafter, referred to as a GRIN lens), or the like is used as the lenses 6A and 6B.

In such an optical module J1, the optical isolator 4, the lenses 6A and 6B, etc. are aligned as independent components after being individually fixed to the holder, so that the number of components is large and adjustment is complicated. There was a problem such as an increase in size.

Further, as shown in FIG. 12, an optical isolator 4 is mounted on a fiber stub using a core-enlarged optical fiber 10 provided with a tip ball 9 in order to reduce the size of the entire optical module and facilitate alignment. A device J2 has also been proposed (see Japanese Patent Application Laid-Open No. H10-68909).

This optical device J2 is a fiber stub type in which an optical isolator 4 is disposed on a ferrule 3 holding a core-enlarged optical fiber 10 formed at the tip of a tip sphere 9 at the center, and is entirely fixed in a sleeve 13. It constitutes an optical device. In the optical device J2, the module with the optical isolator can be assembled with the same man-hour as the module without the optical isolator, and can be manufactured very easily.

Further, since the core-expanded optical fiber is used, the tolerance of defocus (corresponding to the distance between the core-expanded optical fibers in the direction parallel to the optical axis) is large, so that the optical fibers are separated from each other and the Even if an optical element such as an isolator is provided, there is an advantage that coupling loss is small.

Further, such a core-expanded optical fiber is
It is made by locally heating a general single mode optical fiber. The single-mode optical fiber is heated to diffuse the dopant such as Ge doped in the core, thereby widening the diffusion region of the dopant and reducing the relative refractive index difference.

If the core diameter is increased without changing the relative refractive index difference between the core and the clad of the optical fiber, the single mode condition is broken and a multimode is excited. In the case of the core-expanded optical fiber, the expansion of the core and the decrease in the relative refractive index difference occur at the same time due to the diffusion of the dopant due to heat, and r × (D) ^1/2 is automatically kept constant. Here, r is the radius of the core of the optical fiber, D is the relative refractive index difference between the core and the cladding, r × (D) ^1/2 is an amount proportional to the normalized frequency, and if this is constant, the single mode condition is Will be kept.

FIG. 9 shows the characteristics of optical coupling using the core-expanded optical fiber. On the horizontal axis, the distance between optical fibers (interval:
Or, the width of the element mounting groove formed in the core enlarged portion described later), and the vertical axis indicates the light coupling loss. w indicates each mode field diameter (hereinafter abbreviated as MFD), and corresponds to each curve. The wavelength of light is 1.31 μm, which is generally used in optical communication, and the groove for mounting the element (between optical fibers)
Is filled with air (refractive index n = 1).

When the MFD is 10 μm, the loss between the optical fibers is 70 μm and the loss is 1 dB or more.
Is 40 μm, the loss is 1 dB or less even when the distance between the optical fibers is 800 μm. Therefore, it can be seen that the coupling characteristics are clearly improved as the MFD increases.

Further, a multimode optical fiber GI
An example in which a (graded index) fiber is used like a lens and an optical isolator is installed in a cylindrical member is known (see US Pat. No. 5,325,456). In this case, G is sandwiched between both ends of the optical isolator.
An I-fiber is installed to achieve optical coupling.

Here, the GI fiber is an optical fiber having an axially symmetric refractive index distribution such that the refractive index gradually decreases from the central axis of the optical fiber, and is generally used for multi-mode transmission. Most GI fibers have an approximately squared index profile. Since this refractive index distribution has a lens effect similarly to the GRIN lens, a coupling optical system can be configured by using a GI fiber having an appropriate refractive index distribution and an appropriate length. Further, parameters indicating the characteristics of the GI fiber include a refractive index difference の between the cladding and the center of the core, a core diameter D, and a convergence parameter A.

Further, since the light beam in the GI fiber exhibits a sine curve behavior as shown in FIG. 10, its length is represented by a pitch (P) corresponding to the period of the light beam behavior.
FIG. 10 shows the pitch on the horizontal axis and the position of the light ray in the GI fiber on the vertical axis. Note that P = 1 corresponds to one cycle (2π) of the sine curve. It is P = 0.25 at the shortest pitch that the light incident from the point light source becomes parallel light, and again, P = 0.5 at the shortest pitch.
It is.

[0018]

However, there are the following problems when using a core-expanded optical fiber.

The core-expanded optical fiber is manufactured by heating the optical fiber as described above. In order to enlarge the core to 40 μm or more, heating at a temperature of 1000 ° C. or more for several hours to several tens of hours is required, which is extremely troublesome. In addition, a portion where the core diameter is changed from 10 μm to 40 μm requires a tapered portion in which the core diameter is gradually increased. In order to produce this tapered portion, a large temperature difference must be applied to the optical fiber to locally heat it. In addition to simply forming a tapered core, the length and angle of the tapered portion greatly change optical characteristics, so that a sharp temperature gradient and delicate control are required.

Although the core enlargement is several millimeters, this thermal processing is required once for each device, which is inefficient.

The optical system using a GI fiber as a lens has the following problems.

A GI fiber, which is a multi-mode optical fiber, is connected to the tip of the single-mode optical fiber and inserted from both ends of the pore. The pore requires a clearance, and the optical fiber has a μm inside the pore. A unit displacement always occurs. That is, when the optical fibers are inserted from both ends and are brought into contact with each other, an axial deviation always occurs. In addition, it is impossible to correct the displacement because it is inside the pore.

Further, since the GI fiber has the same function as the lens, it is essential to adjust the focal length. The optical fiber must be fixed while maintaining an appropriate width, and there is a problem that the loss increases if the optical fiber moves during the fixing operation. When positioning the optical fiber inserted into the pore from both ends by pressing the optical fiber against the optical element, it is assumed that the thickness of the optical element is adjusted to the coupling length of the GI fiber. Further, a loss occurs at the intersection of the thickness of the optical element. Also, there is a problem that it is difficult to fill the refractive index matching material or the like because the element and the end face of the optical fiber come into contact with each other.

Further, when an optical module is constructed, airtightness is emphasized in order to prevent moisture or the like from entering the package from the outside. However, in the optical device J2, no mention is made of airtightness or sealing. Patent 5,325,45
In the case of No. 6, not only is it necessary to feed through a metal tube having a complicated and difficult-to-manufacture shape in order to maintain the airtightness, but also the number of parts is complicated.

Therefore, the present invention solves the above-mentioned problems,
It is an object of the present invention to provide an optical device that is compact, integrated, easily aligned with a light receiving and emitting element, and can easily have an airtight structure, and an optical module including the same.

[0026]

To achieve the above object, an optical device according to the present invention comprises a first single mode optical fiber having a lens portion for optically connecting an optical semiconductor element to one end of the first single mode optical fiber. A first multi-mode optical fiber, a coreless optical fiber, a second multi-mode optical fiber, and a second single-mode optical fiber are sequentially connected in a line and fixed to a base, and mounted on the coreless optical fiber. An optical element is provided in the groove, and a bonding strip made of metal is provided on the outer periphery of the base.

For example, specifically, a first device having a lens portion for optically connecting an optical semiconductor element to one end of an optical device is provided.
At the other end of the single-mode optical fiber, the first multi-mode optical fiber and the coreless optical fiber, the second multi-mode optical fiber, and the second single-mode optical fiber are sequentially connected in a line and fixed to the base, In an optical device in which an element mounting groove is formed in the middle of a coreless optical fiber, and an optical element is disposed in the element mounting groove, metallization is applied to an outer periphery of the base.

Further, the optical device of the present invention has a first portion having a lens portion for optically connecting an optical semiconductor element to one end.
At the other end of the single-mode optical fiber, the first multi-mode optical fiber and the coreless optical fiber, the second multi-mode optical fiber, and the second single-mode optical fiber are sequentially connected in a line and fixed to the base, An element mounting groove is formed in the middle of the coreless optical fiber, and in an optical device in which an optical element is disposed in the element mounting groove, an outer peripheral band that covers the outer periphery of the base in a band shape with a material that can be soldered or welded. And is hermetically bonded at a boundary between the base and the outer peripheral band.

Further, the optical device according to the present invention is characterized in that a first multimode optical fiber, a coreless optical fiber, and a first single mode optical fiber having a lens portion for optically connecting an optical semiconductor element at one end. A second multi-mode optical fiber and a second single-mode optical fiber are sequentially connected in a row to be fixed to a base, and a device mounting groove is formed in the middle of the coreless optical fiber, and the device mounting groove is formed. In an optical device in which an optical element is disposed,
An outer periphery of a part of the base and the portion of the second single mode optical fiber protruding from the base is covered with a covering member made of a material that can be soldered or welded, and a boundary between the base and the covering member or the second single mode optical fiber. It is characterized by being hermetically bonded at the boundary between the mode optical fiber and the covering member.

Further, an optical device according to the present invention is characterized in that the base is a ferrule in the above-mentioned optical device.

In the optical module of the present invention, the optical device and an optical semiconductor element optically connected to a lens portion of a first single mode optical fiber of the optical device are provided, respectively, and the optical device and a package are provided. Are hermetically bonded.

Further, the end face of the first single mode optical fiber of the optical device, which is located on the light receiving / emitting element side, is processed to be spherical in order to obtain optical coupling with the light receiving / emitting element.

Further, in the above-mentioned optical device, the optical element installed in the element mounting groove provided in the middle of the coreless optical fiber is an optical isolator.
The optical isolator is configured by disposing a Faraday rotator that rotates the polarization plane by 45 degrees between a pair of polarizers whose polarization planes are inclined by 45 degrees with each other, and the Faraday rotator has spontaneous magnetization. If so, the magnet for applying a magnetic field to the Faraday rotator can be omitted.

Further, the optical device and the optical element which receives or emits light are disposed in a package, respectively, and an optical module is formed by hermetically joining at a boundary between the optical device and the package.

The GI fiber used as a multi-mode optical fiber and the coreless optical fiber sandwiched between the GI fibers play a very important role in adjusting the focal length, preventing axial deviation, and simplifying assembly. Since the optical fiber is originally a single optical fiber, no axial deviation occurs in principle when the optical fiber is divided.

The focal position is precisely determined in advance by the length of the coreless optical fiber, and is guaranteed. There is no need for complicated work such as adjustment within the pores. The above-mentioned advantage is made possible only by the structure for dividing the coreless optical fiber.

As a result, a compact optical device in which an optical element such as an optical isolator is mounted in a fiber stub almost free of alignment can be constructed. Further, since the outer peripheral portion of the optical device is metallized or a metal that can be soldered or welded is hermetically bonded, a highly reliable optical module in which the entire package is hermetically sealed with a simple structure can be easily formed. .

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below in detail with reference to the drawings. In the drawings, the same members are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, the optical device S of the present invention
Reference numeral 1 denotes a first single mode optical fiber 1A, a first single mode optical fiber 1A, and a ferrule 3 which is a base on which a metallized layer 11 as a bonding strip made of metal is formed in an annular shape on the outer periphery thereof.
An optical fiber body F in which a GI fiber 2A as a multimode optical fiber, a coreless optical fiber 5 having no core, a GI fiber 2B as a second multimode optical fiber, and a second single mode optical fiber 1B are sequentially connected in a line is housed. Do it.

One end of the single mode optical fiber protruding from the ferrule 3 is formed with a spherical tip 9 for coupling to an optical semiconductor element (light emitting element or light receiving element), and the other end is polished at the end face of the ferrule 3. It has a so-called pigtail shape in which a processed or single mode optical fiber is provided with a fixed length. The coreless optical fiber 5 split in the ferrule 3 is optically connected via an optical element (for example, the optical isolator 4) provided in the element mounting groove 7.

The length of the coreless optical fiber 5 is adjusted so that the beam spots of the two GI fibers 2A and 2B coincide at the center. The light propagating through the single mode optical fiber is capable of only a single mode and maintains a constant MFD. Further, by providing the one-end of the first single-mode optical fiber 1A with the front sphere 9, which is a lens portion for optically connecting the optical semiconductor element, the optical semiconductor element and the first single-mode optical fiber 1A are optically coupled with high efficiency. However, even if the relative positional relationship between the forward sphere 9 and the optical semiconductor element, that is, the light incident condition changes, the light propagates through the single mode optical fiber, and the emitted light always has the same conditions except for the power, Since the light enters the GI fiber 2A having an effect, the optical coupling characteristics are stabilized. The shape of the front sphere 9 is not limited as long as it has a lens effect and can be optically connected to an optical semiconductor element.

Further, since the GI fiber 2B is a multi-mode fiber, the emission condition greatly changes depending on the light incidence condition. For this reason, the coupling characteristics at the optical element insertion portion cannot be guaranteed. Therefore, by connecting the coreless optical fiber, the focal length can be strictly adjusted in advance, and the axial displacement between the optical fibers can be prevented.

More specifically, the optical device S1 is, for example, chromium / gold, nickel / nickel / metallized layer 11 around the ferrule 3 having a diameter of 1.25 mm and a length of 12 mm and made of alumina, zirconia, glass or the like. A film having a structure such as gold (indicated in the order of lower layer / upper layer of the metal film) is formed by vacuum deposition, plating, or the like. Further, the first single mode optical fiber 1A having an MFD of, for example, 10 μm, the first GI fiber 2A having a P (pitch)> 0.25, the beam waist of light emitted from the first GI fiber 2A, and the second G
Assuming that the distance between the output end faces of the I fibers 2A is d, the length 2d
, A second GI fiber 2B and a second single-mode optical fiber 1B having the same length as the first GI fiber 2A are connected in cascade, and the tip of the first single-mode optical fiber 1A is processed into a front sphere 9 to form an optical fiber. Fiber body F was used. Further, the optical fiber F is inserted into the through hole 3a of the ferrule 3 and fixed. Further, an element mounting groove 7 having a width of about 1 mm is formed so as to cross the through hole 3a at the portion of the coreless optical fiber 5.

The second single mode optical fiber 1B is polished so that the rear end faces 3c of the ferrule 3 coincide with each other, or is made into a pigtail shape having an extra length of the optical fiber as it is. The polarizer 1 is placed in the element mounting groove 7.
9A, 19B and the Faraday rotator 20 are integrally molded, and the optical isolator 4 manufactured by cutting is installed.
Between the light entrance / exit surfaces of the polarizers 19A and 19B of the optical isolator 4 and one end of the coreless optical fiber 5, a transmissive refractive index matching adhesive 8 whose refractive index is matched to the coreless optical fiber 5 is provided. . Note that, as described above, the magnetic field applying unit is omitted here. It is assumed that an antireflection film (not shown) having a reflection amount of 0.2% or less is formed on the surface of the optical isolator 4.

The collimating condition when a point light source is present on the end face of the GI fiber is P = 0.25. However, the coupling efficiency is actually the highest because the beam waists from the two GI fibers coincide with each other. Is the case. P = 0.25
In this case, the beam waist is located exactly at the exit end face of the GI fiber, and the beam waist does not match when the optical element is sandwiched between the GI fibers. Therefore, GI
In order to form a beam waist at a position distant from the emission end face of the fiber, a condition of P> 0.25 is required.

The light entering from the front sphere 9 of the first single-mode optical fiber 1A is expanded in beam diameter by the first GI fiber 2A, and becomes a beam having a beam waist at the center of the coreless optical fiber 5 so as to pass through the optical isolator 4. After passing through the coreless optical fiber 5 again, the beam diameter is converged to 10 μm by the second GI fiber 2B,
The light propagates to the second single mode optical fiber 1B. In the optical device S1, the second single mode fiber 1B has a surplus length of about 1 m on the rear end face 3c, and a connector (not shown) is attached to the end.

According to the present invention, even when an optical element such as the optical isolator 4 is inserted into the optical transmission line, it is almost alignment-free. Although the GI fiber is used, the focal length is adjusted by the length of the coreless optical fiber 5 and is guaranteed at the time of assembling the optical fiber body, so that it is not necessary to adjust after the element is mounted. This is not only a simplification of the process, but also a defect of the coupling efficiency can be confirmed at the initial stage of the process, that is, before fixing the optical element, etc., so that the efficiency of the entire process and the damage due to the defect can be greatly reduced. become.

Although an example in which the optical isolator 4 is particularly used in the element mounting groove 7 for dividing the coreless optical fiber 5 has been described, an optical element such as a wavelength plate or a wavelength filter can also be applied.

Further, in the present invention, as shown in FIG. 3, a module M2 in which the optical device S1 of the present invention and an optical semiconductor element optically coupled to the optical device S1 are incorporated in the package 18 can be formed. In this way, by sealing the annular metallized layer (bonding strip) 11 and the package 18 hermetically with the solder 30 on the outer periphery of the optical device S1, a highly reliable airtight structure can be easily realized.

Further, the optical device of the present invention may be configured as shown in FIG. That is, in the ferrule 3 into which the optical fiber body F is inserted and fixed, the metal outer peripheral body (bonding band) 27 covering the outer circumference in a band shape is joined to the ferrule 3 with the sealing agent 29 such as low melting glass. I do.
Thereby, the high-performance airtightness is maintained at the boundary between the outer peripheral body 27 and the ferrule 3. The sealant used for joining the outer peripheral body 27 and the ferrule 3 may be solder that can be directly joined, such as ultrasonic soldering.

Further, as shown in FIG.
In the module M3 having the package 2 and the optical semiconductor element to be optically coupled with the optical device S2, the outer peripheral body 27 of the optical device S2 and the package 18 are hermetically sealed by seam welding, so that the reliability is easily increased. It is possible to realize a high airtight structure. The outer body 27 is preferably made of an alloy such as SUS or 50 alloy, which can be easily welded.

Further, the optical device of the present invention may be configured as shown in FIG. That is, in the ferrule 3 for inserting and fixing the optical fiber body F, the outer periphery of the second single mode optical fiber 2B protruding from the ferrule 3 and having an extra length and the outer periphery of the rear end of the ferrule 3 can be soldered or welded. A low-melting glass as described above at the boundary between the ferrule 3 and the coating member 28 or at the boundary between the second single-mode optical fiber and the coating member 28 by covering the ferrule 3 and the coating member 28 annularly with a coating member (bonding band-shaped body) 28 made of a material. An optical device S3 is formed by performing airtight bonding with a sealant 26 such as an adhesive or an ultrasonic solder.

Further, as shown in FIG.
In the module M3 in which the package 3 and the optical semiconductor element to be optically coupled to the optical device S3 are incorporated in the package 18, the covering member 28 of the optical device S3 and the package 18 are hermetically sealed by seam welding, so that the reliability can be easily reduced. It is possible to realize a high airtight structure.

[0054]

Embodiments of the present invention will be described below.

Example 1 This will be described with reference to FIGS. As shown in FIG. 2A, at the tip of a silica-based single mode optical fiber 1A having an MFD of about 10 μm, △ =
0.85%, core diameter 105 μm, convergence parameter A =
3.37 × 10 −6 μm−2, the GI fiber 2A was fused by electric discharge machining, and the pitch P = 0.258 (653 μm).
m), the GI fiber 2A was cut.

If the surrounding medium is n = 1.46 (corresponding to the refractive index of the coreless optical fiber 5), the GI fiber 2A
From the end face 15 to the beam waist of the emitted light formed by the GI fiber 2A is 550 μm.

Next, as shown in FIG. 2B, n = 1.
The coreless optical fiber 5 having a refractive index of 46 was fused to the GI fiber 2A by electric discharge machining and cut into a length of 1100 μm. Then, as shown in FIG. 2C, the GI fiber 2B and the single mode optical fiber 1B having the same configuration as the GI fiber 2A are fusion-spliced in this order.
As shown in (d), an end fiber 9 of R = 5 μm was formed on one end of the single-mode optical fiber 1A by polishing to obtain an optical fiber body F.

Next, as shown in FIG.
A molybdenum-manganese layer is formed with a thickness of about 30 μm, nickel is further plated thereon by a thickness of about 3 μm, and gold is further electrolytically plated with a thickness of 0.1 μm to form a metallized layer 11 having a width of 2 mm. The zirconia ferrule 3 was inserted and fixed in the through hole 3a. EPOTECH 35, a thermosetting epoxy adhesive manufactured by Epoxy Technology
3ND was used. Low-melting glass or solder may be used to improve airtightness. Further, an element mounting groove 7 having a width of 1 mm was formed so as to cross the through-hole 3a at the portion of the coreless optical fiber 5. In this process, a DISCO dicer blade SDC320R10MB01 was used.

Then, as shown in FIG. 2F, an optical isolator 4 formed by integrally molding the polarizers 19A and 19B and the Faraday rotator 20 in the groove 7 for mounting the element and cutting the same is set. . Here, an ultraviolet-curing adhesive or a thermosetting adhesive 8 whose refractive index is matched with that of the coreless optical fiber 5 (for example, an ultraviolet-curing epoxy adhesive # 9539 manufactured by NTT Advanced Technology, an ultraviolet-curing epoxy manufactured by Daikin Industries, Ltd.) Adhesive optodyne or EPOTECH 353, a thermosetting adhesive manufactured by Epoxy Technology
The optical device S1 was formed by filling and bonding between the optical isolator 4 and the coreless optical fiber 5 using ND or the like.

The optical isolator 4 includes polarizers 19A and 19
B (thickness 200 μm, refractive index 1.5), Faraday rotator 20 (magnetic garnet, thickness 350 μm, refractive index 2.
After forming an anti-reflection film on each light transmitting surface, an epoxy-based light-transmitting adhesive (for example, a thermosetting adhesive EPOTECH 353N manufactured by Epoxy Technology Co., Ltd.)
D). In addition, the optical isolator 4 is 10
It is cut into 400 μm squares after performing collective alignment and bonding with a large element of mm square or more. Thickness 75
0 μm. Further, since a spontaneously magnetized garnet is used here, no magnet is required.

In the optical device of the present invention, L
When the optical fiber is mounted on the D module, the end surface of the core-enlarged optical fiber on the LD side is formed as a spherical tip 9 in order to prevent reflection and simultaneously improve coupling efficiency. However, depending on the design of the optical module, a lens may be provided.

FIG. 3 shows an example in which an LD module M1 is constructed using the optical device S1 of the present invention. An optical device S1 in which a V-shaped groove of the substrate 14 is spherically processed at the LD-side end surface.
The first single mode optical fiber 1A was fixed. PD
Reference numeral 16 monitors the light of the LD 15 to stabilize the light intensity. The optical device S1 is connected to the opening 18 of the package 18.
a, the LD module M1 sealed with the solder 30 and having high airtightness was formed.

[Example 2] As shown in FIG. 4, the diameter is 1.25 m.
An outer peripheral band 27 on the ring was set around the outer periphery of the zirconia ferrule 3 having a length of 12 mm and a length of 12 mm, and was hermetically bonded with a sealant 26 such as a low-melting glass. Here, the manufacturing procedure of the optical fiber body F in the ferrule 3 is the same as that of the first embodiment, and the optical characteristics are guaranteed at the stage when the optical fiber body F is assembled. The procedure for inserting and fixing the optical fiber body F into the ferrule 3, forming the element mounting groove, and fixing the optical isolator 4 is the same as that in the first embodiment. Thus, the optical device S2 can be easily configured as a module that can be hermetically sealed with a simple configuration. In the figure, reference numeral 24 denotes a jacket for covering the fiber strand.

As shown in FIG. 5, the optical device S2
Was used to form an LD module M2. V of substrate 14
The first single-mode optical fiber 1A of the optical device S2 having the LD-side end face processed to be spherical is fixed to the groove of the mold. PD1
Numeral 6 monitors the light of the LD 15 to stabilize the light intensity. The optical device S1 has an opening 18a of the package 18.
The ring 29 is subjected to seam welding by a YAG laser, and the ring 29 is welded to the package 18 by the YAG laser. The ring 29 is provided for adjusting the position with respect to the package 18 so that the first single mode optical fiber 1A does not bend greatly. Thereby, a highly airtight LD module M2 was configured.

Example 3 As shown in FIG.
A covering member 28 shaped so as to cover the outer periphery of the rear end of the zirconia ferrule 3 having a length of 12 mm and a length of 12 mm and a part of the second single mode optical fiber 1 </ b> B was installed, and hermetically bonded with a sealant 26. The procedure for manufacturing the optical fiber body F in the ferrule 3 is the same as that in the first embodiment, and the optical characteristics are guaranteed at the stage when the optical fiber body F is assembled. The procedure for inserting and fixing the optical fiber body F into the ferrule 3 and forming the element mounting groove to fix the optical isolator 4 is the same as in the first embodiment.

The smaller the cross-sectional area of the sealing agent at the boundary between the inside and outside of the package, the higher the airtightness of the sealing joint. Therefore, the hermeticity is better when sealed around the optical fiber than when sealed around the ferrule 3 as in Examples 1 and 2. Thus, an optical module S3 capable of performing a more advanced hermetic sealing with a simple configuration can be obtained. Reference numeral 24 denotes a jacket for covering the fiber.

As shown in FIG. 7, the optical device S2
Was used to constitute an LD module M3. V of substrate 14
The first single-mode optical fiber 1A of the optical device S2 having the LD-side end face processed to be spherical is fixed to the groove of the mold. PD1
Numeral 6 monitors the light of the LD 15 to stabilize the light intensity. The optical device S1 has an opening 18a of the package 18.
The ring 29 was subjected to seam welding using a YAG laser, and the ring 29 was similarly welded to the package 18 using a YAG laser. The ring 29 is provided for adjusting the position with respect to the package 18 so that the first single mode optical fiber is not largely bent. As a result, a highly airtight LD module M3 was obtained.

[0068]

As described above, according to the optical device and the optical module of the present invention, the following remarkable effects can be obtained.

Since no lens is used, it can be manufactured at a low cost with a simple configuration.

An optical fiber body in which a plurality of basic optical fibers are connected in a line only needs to adjust the connection between a multimode optical fiber (for example, a GI fiber) and a coreless optical fiber. is there. A coreless optical fiber sandwiched between two multi-mode optical fibers has the role of adjusting the focal length, preventing axial misalignment, and simplifying assembly. Since it is originally a single optical fiber, the splitting of the optical fiber is essentially the same. Does not occur.

In addition, for example, when the optical fiber is inserted from both ends of the fine hole of the ferrule, a complicated operation such as adjustment in the fine hole is unnecessary.

When an optical element is inserted into the optical fiber, an element mounting groove may be formed in the coreless optical fiber portion. Even if the groove position for mounting the element is shifted within the range of the coreless optical fiber, no problem occurs at all, so that it is extremely easy to manufacture. Further, the insertion of an optical element, for example, an optical isolator can be performed almost alignment-free.

Although an optical system using an optical fiber is used, it is not necessary to use a core-enlarged optical fiber which is troublesome to manufacture and difficult to control.

An optical device in which an optical fiber body is housed in a ferrule is small and has high stability.

Further, since the bonding strip made of metal is provided on the outer periphery of the base, it is possible to easily adopt a solder sealing structure with the package, and it is possible to easily form a module having high sealing performance. .

Further, it is possible to perform laser welding of the bonding strip and the package. Laser welding is a simpler and shorter process than solder encapsulation, and heat is generated only locally, affecting the optical elements built into optical devices and the optical semiconductor elements in the laser module. Less is.

Further, by adopting a configuration in which the rear end of the optical device is covered with a metal covering member (bonding band), the optical fiber and the covering member can be sealed with solder, and the optical fiber can be used as a substrate. In addition to the case in which the optical device is supported only by itself, the encapsulation property of the optical device itself is improved because the encapsulation path is longer, and the encapsulation bonding to the package is easy.

Further, when the base is made of a ferrule,
Since the optical fiber is fixed with high precision to the center axis of the ferrule, alignment of the optical semiconductor element with the lens portion (front spherical portion) formed at one end of the first single mode optical fiber becomes easy, for example. It has high durability and can be made compact.

By using such an optical device, the optical device is small, easy to manufacture, inexpensive, has little change over time,
An optical module with excellent airtightness can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating an optical device according to the present invention.

FIGS. 2A to 2F are cross-sectional views schematically illustrating a process of manufacturing an optical device according to the present invention.

FIG. 3 is a cross-sectional view schematically showing an optical module according to the present invention.

FIG. 4 is a cross-sectional view schematically showing an optical device according to the present invention.

FIG. 5 is a cross-sectional view for schematically explaining an optical module according to the present invention.

FIG. 6 is a sectional view schematically showing an optical device according to the present invention.

FIG. 7 is a sectional view schematically illustrating an optical module according to the present invention.

FIG. 8 is a perspective view schematically showing an operation of the optical isolator.

FIG. 9 is a graph showing a relationship between a coupling interval of a core-enlarged optical fiber and a diffraction loss.

FIG. 10 is a schematic diagram illustrating behavior of light in a GI fiber (multi-mode optical fiber).

FIG. 11 is a partial cross-sectional view illustrating a conventional optical module.

FIG. 12 is a cross-sectional view illustrating a device in which an optical isolator is mounted on a conventional core-enlarged optical fiber.

[Explanation of symbols]

 1, 1A, 1B: Single mode optical fiber 2A, 2B: GI fiber (multimode optical fiber) 3: Ferrule (base) 3a: Through hole 4: Optical isolator 5: Coreless optical fiber 6A, 6B: Lens 7: Device mounting Groove 8: refractive index matching adhesive 9: tip sphere (lens portion) 10: core enlarged optical fiber 11: metallized layer (bonding band) 12: V groove 13: sleeve 14: substrate 15: LD (light emitting element: 16: PD (light receiving element: optical semiconductor element) 17: Peltier cooler 18: package 18a: package opening 19A, 19B: polarizer 20: Faraday rotator 22: forward incident light 23: reverse incident light 24: Fiber jacket 26: Sealant 27: Outer body (Bonding for joining) 28: Coating member (Bonding for joining) 29: Re 30: Solder 32: Rubber boot J1: Optical module J2: Optical device M1, M2, M3: Optical module S1, S2, S3: Optical device F: Optical fiber body

Claims (2)

[Claims] 1. A first multi-mode optical fiber, a coreless optical fiber, a second multi-mode optical fiber, and a first single-mode optical fiber having a lens portion for optically connecting an optical semiconductor element at one end. And the second single mode optical fibers are sequentially connected in a row to be fixed to the base, an optical element is disposed in the element mounting groove formed in the coreless optical fiber, and the outer periphery of the base is made of metal. An optical device comprising a bonding strip. 2. An optical module comprising: a substrate; and the optical device and an optical semiconductor element optically connected to a lens portion of a first single mode optical fiber of the optical device.