JP4446614B2 - Optical device and optical module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical module including an optical semiconductor element such as a light emitting element or a light receiving element that is preferably used in an optical communication device, a sensor, or the like. The present invention also relates to an optical device that is mounted on the optical module and includes an optical isolator, optical sensing, a wavelength plate for measurement, and the like that blocks reflected return light from the outside of the optical module.
[0002]
[Prior art]
Laser diodes (hereinafter also referred to as LDs) used as light sources for optical communication are oscillated when reflected at a location where the emitted light is present and return to the active layer of the LD again. And this degrades the signal. In particular, analog signals are likely to be deteriorated by the reflected return light, and the higher the density of the signal, the more easily affected by the reflected return light. With the increase in analog transmission data such as CATV, increase in capacity, and speed up, Optical isolators have become an essential component.
[0003]
In order to prevent such a problem of reflected return light, the LD is usually mounted in the same package as the optical isolator that transmits light only in one direction, and constitutes an LD module that is a kind of optical module.
[0004]
The general operation of the 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 reverse light 23 is blocked. The Faraday rotator 20 includes a Faraday effect obtained by applying a magnetic field from the outside, and a Faraday rotator 20 having a Faraday effect without an external magnetic field due to spontaneous magnetization. Hereinafter, a magnet for applying a magnetic field for simplicity. May not be shown.
[0005]
Next, an example of a conventional LD module will be described. As shown in FIG. 11, in the LD module J1, at least the LD 15, the lenses 6A and 6B, the optical isolator 4, the one end portion of the single mode optical fiber 1, and the like are accommodated in the package 18. In the figure, 16 is a light receiving element (hereinafter also referred to as PD), 17 is a peltier, and 32 is a rubber boot for protecting the extra length of the optical fiber.
[0006]
The light emitted from the LD 15 is collimated by the lens 6A, passes through the optical isolator 4, is condensed by the lens 6B, and enters the single mode optical fiber 1. Each optical component is built in the package 18 and the rubber boot 32 to be shielded from the external environment. For the lenses 6A and 6B, a ball lens, a biconvex lens, an aspheric lens, a graded index lens (hereinafter referred to as GRIN lens), or the like is used.
[0007]
In such an optical module J1, the optical isolator 4, the lenses 6A, 6B, etc. are aligned as individual components after being separately fixed to the holder, so that the number of components is large and adjustment is complicated and the size is increased. There was a problem.
[0008]
In order to reduce the size of the entire optical module and facilitate alignment, as shown in FIG. 12, an optical device J2 in which an optical isolator 4 is mounted on a fiber stub using a core expansion optical fiber 10 having a tip 9 is also provided. It has been proposed (see Japanese Patent Application Laid-Open No. 10-68909).
[0009]
This optical device J2 is a fiber stub type optical device in which an optical isolator 4 is disposed on a ferrule 3 that is held around a core expansion optical fiber 10 having a tip sphere 9 formed at the tip, and is fixed in a sleeve 13 as a whole. It is composed. In the optical device J2, the module with the optical isolator can be assembled with the same man-hours as the module without the optical isolator, and can be manufactured very easily.
[0010]
In addition, since the core expansion optical fiber is used, the tolerance of defocus (corresponding to the distance between the core expansion optical fibers in the direction parallel to the optical axis) is large. Even if an optical element is installed, there is an advantage that coupling loss is small.
[0011]
Moreover, such a core expansion optical fiber is produced by locally heating a general single mode optical fiber. The single mode optical fiber is heated to diffuse a dopant such as Ge doped in the core, thereby widening the diffusion region of the dopant and reducing the relative refractive index difference.
[0012]
If the core diameter increases without changing the relative refractive index difference between the core and the clad of the optical fiber, the single mode condition is broken and multimode is excited. In the case of an optical fiber with an expanded core, the diffusion of the dopant due to heat causes the expansion of the core and the decrease in the relative refractive index difference at the same time, automatically r × (D) ^1/2 Is 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 clad, and r × (D) ^1/2 Is an amount proportional to the normalized frequency, and if this is constant, the single mode condition is maintained.
[0013]
FIG. 9 shows the characteristics of optical coupling using the core expansion optical fiber. The horizontal axis indicates the distance between the optical fibers (opposite spacing: or the width of the element mounting groove formed in the core expansion portion described later), and the vertical axis indicates the coupling loss of light. w represents each mode field diameter (hereinafter abbreviated as MFD), and corresponds to each curve. The wavelength of light is 1.31 μm generally used in optical communication, and the element mounting groove (between optical fibers) is filled with air (refractive index n = 1).
[0014]
When the MFD is 10 μm, the distance between the optical fibers is 70 μm, and there is a loss of 1 dB or more, whereas when the MFD is 40 μm, the loss is 1 dB or less even if the distance between the optical fibers is 800 μm. It can be seen that the binding properties are improved.
[0015]
In addition, an example in which a GI (graded index) fiber, which is a multimode optical fiber, is used as a lens and an optical isolator is installed in a cylindrical member is known (see US Pat. No. 5,325,456). . In this case, GI fibers are installed so as to sandwich both ends of the optical isolator, and optical coupling is achieved.
[0016]
Here, the GI fiber is an optical fiber having an axially symmetric refractive index distribution in which the refractive index gradually decreases from the central axis of the optical fiber, and is generally used for multimode transmission. Most GI fibers have an approximately squared refractive index profile. Since this refractive index distribution has a lens effect similar to that of a GRIN lens, a coupling optical system can be configured by using a GI fiber having an appropriate refractive index distribution with an appropriate length. Parameters indicating the characteristics of the GI fiber include a refractive index difference Δ between the cladding and the core center, a core diameter D, and a convergence parameter A.
[0017]
Furthermore, since the light beam in the GI fiber exhibits the behavior of a sine curve as shown in FIG. 10, the length is represented by the pitch (P) corresponding to the cycle of the light beam behavior. In FIG. 10, the horizontal axis represents the pitch, the vertical axis represents the position of the light beam in the GI fiber, and the portion where the light has spread most is relatively illustrated as 1. Note that P = 1 corresponds to one period (2π) of the sine curve. The light incident from the point light source becomes parallel light at P = 0.25 at the shortest pitch, and P = 0.5 at the shortest pitch again to converge on the point.
[0018]
[Problems to be solved by the invention]
However, there are the following problems when using a core expansion optical fiber.
[0019]
The core expansion optical fiber is manufactured by heating the optical fiber as described above. In order to expand the core to 40 μm or more, heating for several hours to several tens of hours at a temperature of 1000 ° C. or more is required, which is very laborious. Further, a portion where the core diameter is changed from 10 μm to 40 μm requires a tapered portion that gradually increases the core diameter. In order to produce the tapered portion, it is necessary to locally heat the optical fiber by giving a large temperature difference. In addition to simply forming a tapered core, the optical characteristics change greatly depending on the length and angle of the taper portion, so a rapid temperature gradient and delicate control are required.
[0020]
In addition, although the core enlargement portion is several mm, this thermal processing is always required once per device, which is inefficient.
[0021]
Further, an optical system using a GI fiber as a lens has the following problems.
[0022]
A GI fiber, which is a multimode optical fiber, is connected to the tip of a single mode optical fiber and inserted from both ends of the pore. Clearance is required for the pore, and the optical fiber is positioned in μm units Deviations always occur. That is, when an optical fiber is inserted from both ends and hits, an axial deviation always occurs. Moreover, it is impossible to correct the deviation because it is in the pores.
[0023]
Furthermore, since the GI fiber has the same function as the lens, adjustment of the focal length is indispensable. It must be fixed while maintaining an appropriate width. If the optical fiber moves during the fixing operation, there arises a problem that loss increases. Further, when positioning the optical fiber inserted into the pore from both ends against the optical element, it is assumed that the thickness of the optical element is matched to the coupling length of the GI fiber. Further, a loss occurs at the thickness crossing of the optical element. In addition, since the element and the end face of the optical fiber come into contact with each other, there is a problem that it is difficult to fill with a refractive index matching material or the like.
[0024]
Furthermore, when an optical module is configured, airtightness is emphasized because moisture or the like does not enter the package from the outside. However, the optical device J2 makes no mention of airtightness or sealing. In order to maintain airtightness in 325 and 456, not only does it require a feedthrough of a metal tube having a complicated shape that is difficult to manufacture, but the number of parts is also complicated.
[0025]
Accordingly, the present invention provides an optical device that solves the above-mentioned problems, is compact and integrated, can be easily aligned with a light emitting / receiving element, and can easily have an airtight structure, and an optical module including the same. With the goal.
[0026]
[Means for Solving the Problems]
In order to achieve the above object, an optical device according to the present invention includes a first multimode optical fiber, a coreless optical fiber at the other end of a first single mode optical fiber having a lens portion for optically connecting an optical semiconductor element at one end. An optical fiber, a second multimode optical fiber, and a second single mode optical fiber are sequentially connected in a row and fixed to a base, and an optical element is disposed in an element mounting groove formed in the coreless optical fiber. In addition, a bonding strip made of metal is provided on the outer periphery of the substrate.
[0027]
For example, specifically, the first multimode optical fiber and the coreless optical fiber second multimode are provided at the other end of the first single mode optical fiber having a lens portion for optically connecting the optical semiconductor element to one end of the optical device. The optical fiber and the second single mode optical fiber are sequentially connected in a row and fixed to the base, and an element mounting groove is formed in the middle of the coreless optical fiber, and the optical element is arranged in the element mounting groove. In the provided optical device, the outer periphery of the base is metallized.
[0028]
The optical device according to the present invention includes a first multimode optical fiber and a second coreless optical fiber at the other end of the first single mode optical fiber having a lens portion for optically connecting the optical semiconductor element at one end. The mode optical fiber and the second single mode optical fiber are sequentially connected in a row and fixed to the base, and an element mounting groove is formed in the middle of the coreless optical fiber, and an optical element is formed in the element mounting groove. In the disposed optical device, the outer periphery of the base is formed in a band shape with a material that can be soldered or welded, and is hermetically bonded at the boundary between the base and the outer peripheral band. To do.
[0029]
Furthermore, the optical device according to the present invention includes a first multimode optical fiber, a coreless optical fiber, a second optical fiber at the other end of the first single mode optical fiber having a lens portion for optically connecting the optical semiconductor element at one end. A multi-mode optical fiber and a second single-mode optical fiber are sequentially connected in a row and fixed to a base, and an element mounting groove is formed in the coreless optical fiber, and an optical element is formed in the element mounting groove. An outer peripheral portion of the base and the portion of the second single mode optical fiber protruding from the base with a covering member made of a solderable or weldable material, and the base and the covering It is characterized in that it is hermetically bonded at the boundary of the member or at the boundary of the second single mode optical fiber and the covering member.
[0030]
The optical device of the present invention is characterized in that in the optical device, the substrate is a ferrule.
[0031]
In the optical module of the present invention, the optical device and an optical semiconductor element optically connected to the lens portion of the first single mode optical fiber of the optical device are disposed, and the optical device and the package are hermetically bonded. It is characterized by doing.
[0032]
The end face of the optical device located on the light emitting / receiving element side of the first single mode optical fiber is processed into a tip to obtain optical coupling with the light emitting / receiving element.
[0033]
Further, in the optical device, the optical element installed in the element mounting groove provided in the middle of the coreless optical fiber is an optical isolator. An optical isolator is formed by integrating a Faraday rotator that rotates a polarization plane by 45 degrees between a pair of polarizers whose polarization planes are inclined by 45 degrees, and the Faraday rotator has spontaneous magnetization. If present, the magnet that applies the magnetic field to the Faraday rotator can be omitted.
[0034]
Further, the optical device and an optical element that receives or emits light are disposed in a package, respectively, and an optical module is formed that is hermetically bonded at a boundary between the optical device and the package.
[0035]
A GI fiber used as a multimode optical fiber and a coreless optical fiber sandwiched between the GI fibers have extremely important roles for adjusting the focal length, preventing misalignment, and simplifying assembly. Originally, it is a single optical fiber, so if it is divided, no axis misalignment will occur in principle.
[0036]
The focal position is precisely determined in advance according to the length of the coreless optical fiber and is guaranteed. No complicated work such as adjustment in the pores is required. The advantages as described above are possible because of the structure that divides the coreless optical fiber.
[0037]
Thereby, a compact optical device in which an optical element such as an optical isolator is mounted in the fiber stub almost without alignment can be configured. In addition, 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 configured. .
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below in detail with reference to the drawings schematically shown. In addition, in each figure, about the same member, the same code | symbol shall be attached | subjected and description shall be abbreviate | omitted.
[0039]
As shown in FIG. 1, the optical device S1 of the present invention includes a first single mode in a ferrule 3 which is a base body in which a metallized layer 11 which is a band-like member made of metal is previously formed in a ring shape on the outer periphery thereof. An optical fiber 1A, a GI fiber 2A that is a first multimode optical fiber, a coreless optical fiber 5 having no core, a GI fiber 2B that is a second multimode optical fiber, and a second single mode optical fiber 1B are sequentially connected in a line. The optical fiber body F is accommodated.
[0040]
One end of the single mode optical fiber protruding from the ferrule 3 has a tip 9 processed to be coupled with an optical semiconductor element (light emitting element or light receiving element), and the other end is polished or single-ended at the end face of the ferrule 3. It is a so-called pigtail shape in which a mode optical fiber is provided with a certain length. The coreless optical fiber 5 divided in the ferrule 3 is optically connected through an optical element (for example, an optical isolator 4) disposed in the element mounting groove 7.
[0041]
The length of the coreless optical fiber 5 is adjusted so that the beam spots by the two GI fibers 2A and 2B coincide at the center. The light propagating through the single mode optical fiber can only have a single mode and maintains a constant MFD. Further, by providing a tip sphere 9 as a lens part for optically connecting the optical semiconductor element to one end of the first single mode optical fiber 1A, the optical semiconductor element and the first single mode optical fiber 1A are optically coupled with high efficiency. However, the relative positional relationship between the ball tip 9 and the optical semiconductor element, that is, the light that propagates through the single mode optical fiber even when the light incident condition changes, and the emitted light is always under 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 tip ball 9 may have any shape as long as it has a lens effect and can be optically connected to the optical semiconductor element.
[0042]
Further, since the GI fiber 2B is a multimode fiber, the emission condition varies greatly depending on the light incident condition. For this reason, the coupling characteristics at the optical element insertion portion cannot be guaranteed. Therefore, by connecting a coreless optical fiber, it is possible to adjust the focal length strictly in advance and to prevent axial misalignment between the optical fibers.
[0043]
Specifically, the optical device S1 is made of chromium / gold, nickel / gold (metal) as a metallized layer 11 in the form of a strip on the outer periphery of a ferrule 3 made of alumina, zirconia, glass or the like having a diameter of 1.25 mm and a length of 12 mm. A film having a structure such as a lower layer / an upper layer of the 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 P (pitch)> 0.25, the beam waist of the light emitted from the first GI fiber 2A, and the exit end face of the second GI fiber 2A The distance is d, the coreless optical fiber 5 having a length of 2d, the second GI fiber 2B having the same length as the first GI fiber 2A, and the second single mode optical fiber 1B are connected in series, and the tip of the first single mode optical fiber 1A is connected. Was processed into a tip 9 to obtain an optical fiber body F. Further, the optical fiber body 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 coreless optical fiber 5 portion.
[0044]
The second single mode optical fiber 1B is polished so that the rear end face 3c of the ferrule 3 coincides, or is made into a pigtail shape having the extra length of the optical fiber as it is. In the element mounting groove 7, the optical isolator 4 manufactured by cutting the polarizers 19 </ b> A and 19 </ b> B and the Faraday rotator 20 after being integrally formed is installed, and the light of the polarizers 19 </ b> A and 19 </ b> B of the optical isolator 4 is installed. A translucent refractive index matching adhesive 8 having a refractive index matched to that of the coreless optical fiber 5 is provided between the input / output surface and one end of the coreless optical fiber 5. As described above, the magnetic field applying means is omitted here. Further, 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.
[0045]
The collimating condition when a point light source is present on the end face of the GI fiber is P = 0.25, but the actual coupling efficiency is highest when the beam waists from the two GI fibers coincide. . At P = 0.25, the beam waist is located just at the exit end face of the GI fiber, and the beam waist does not match when an optical element is sandwiched between the GI fibers. Therefore, in order to form a beam waist at a position away from the emission end face of the GI fiber, the condition of P> 0.25 is required.
[0046]
The light entering from the tip 9 of the first single-mode optical fiber 1A is enlarged in beam diameter by the first GI fiber 2A, passes through the optical isolator 4 as a beam having a beam waist at the center of the coreless optical fiber 5, The light passes through the coreless optical fiber 5 again, is converged to a beam diameter of 10 μm by the second GI fiber 2B, and 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 terminal end.
[0047]
According to the present invention, even if an optical element such as the optical isolator 4 is inserted into the optical transmission line, the alignment becomes almost free. Although the GI fiber is used, its 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, and does not need to be adjusted after the element is mounted. This not only simplifies the process, but also confirms the coupling efficiency defects at the initial stage of the process, that is, before fixing the optical element, etc., so that the total efficiency of the process and damage due to defects can be greatly reduced. become.
[0048]
In this example, the optical isolator 4 is used in the element mounting groove 7 that divides the coreless optical fiber 5, but an optical element such as a wavelength plate or a wavelength filter is also applicable.
[0049]
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 built in the package 18 can be configured. In this manner, by sealing the annular metallized layer (joining band) 11 and the package 18 with the solder 30 on the outer periphery of the optical device S1, a highly reliable airtight structure can be realized easily.
[0050]
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 described above, a metal outer peripheral body (joining belt-like body) 27 covering the outer periphery in a strip shape is joined to the ferrule 3 with a sealing agent 29 such as low melting point glass. To do. As a result, 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.
[0051]
Further, as shown in FIG. 5, in the module M3 in which the optical device S2 and the optical semiconductor element optically coupled to the optical device S2 are built in the package 18, the outer peripheral body 27 of the optical device S2 and the package 18 are hermetically sealed by seam welding. By stopping, it is possible to easily realize a highly reliable airtight structure. The outer peripheral body 27 is preferably an alloy such as SUS or 50 alloy that can be easily welded.
[0052]
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 described above, the outer periphery of the second single mode optical fiber 2B protruding from the ferrule 3 and having a surplus length and the outer periphery of the rear end portion of the ferrule 3 can be soldered or welded. A low-melting-point glass as described above at the boundary between the ferrule 3 and the covering member 28 or at the boundary between the second single mode optical fiber and the covering member 28 by covering the material with a covering member (bonding strip) 28 made of a material. The optical device S3 is configured by performing hermetic bonding with a sealant 26 such as soldering or ultrasonic soldering.
[0053]
Further, as shown in FIG. 7, in the module M3 in which the optical device S3 and an optical semiconductor element optically coupled to the optical device S3 are built in the package 18, the covering member 28 of the optical device S3 and the package 18 are hermetically sealed by seam welding. By stopping, it is possible to easily realize a highly reliable airtight structure.
[0054]
【Example】
Examples in which the present invention is further embodied will be described below.
[0055]
[Example 1]
This will be described with reference to FIGS. As shown in FIG. 2A, Δ = 0.85%, the core diameter is 105 μm, and the convergence parameter A = 3.37 × 10 −6 μm− at the tip of the silica-based single mode optical fiber 1A having an MFD of about 10 μm. 2. The GI fiber 2A was fused by electric discharge machining, and the GI fiber 2A was cut so that the pitch P = 0.258 (653 μm).
[0056]
If the surrounding medium is n = 1.46 (corresponding to the refractive index of the coreless optical fiber 5), the distance from the end face 15 of the GI fiber 2A to the beam waist of the emitted light formed by the GI fiber 2A is 550 μm. It becomes.
[0057]
Next, as shown in FIG. 2B, the coreless optical fiber 5 having a refractive index of n = 1.46 was fused to the GI fiber 2A by electric discharge machining and cut to a length of 1100 μm. Then, as shown in FIG. 2 (c), the GI fiber 2B and the single mode optical fiber 1B having the same configuration as the GI fiber 2A are fused and connected in this order, and finally the single mode optical fiber as shown in FIG. 2 (d). A tip sphere 9 of R = 5 μm was formed on one end of 1A by polishing to obtain an optical fiber body F.
[0058]
Next, as shown in FIG. 2 (e), a molybdenum-manganese layer having a thickness of 20 to 30 μm is formed on the outer periphery, and nickel is electroplated to a thickness of about 3 μm and gold is further 0.1 μm in thickness, and the width is 2 mm. The metallized layer 11 was inserted and fixed in the through hole 3a of the zirconia ferrule 3 having a diameter of 1.25 mm and a length of 12 mm. For fixing, a thermosetting epoxy adhesive Epotec 353ND manufactured by Epoxy Technology Co., Ltd. was used. In order to improve hermeticity, low melting point glass or solder may be used. Further, an element mounting groove 7 having a width of 1 mm was formed so as to cross the through hole 3a at the coreless optical fiber 5 portion. A DISCO dicer blade SDC320R10MB01 was used for this processing.
[0059]
Then, as shown in FIG. 2 (f), the optical isolator 4 produced by integrally forming the polarizers 19 </ b> A and 19 </ b> B and the Faraday rotator 20 in the element mounting groove 7 and then cutting it was installed. Here, an ultraviolet curable adhesive or a thermosetting adhesive 8 whose refractive index is matched with that of the coreless optical fiber 5 (for example, an ultraviolet curable epoxy adhesive # 9539 manufactured by NTT Advanced Technology, Inc., an ultraviolet curable manufactured by Daikin Industries, Ltd.) The optical device S1 was configured by filling and bonding between the optical isolator 4 and the coreless optical fiber 5 using a mold adhesive optodyne or a thermosetting adhesive Epoch 353ND manufactured by Epoxy Technology.
[0060]
The optical isolator 4 includes polarizers 19A and 19B (thickness: 200 μm, refractive index: 1.5) and a Faraday rotator 20 (magnetic garnet, thickness: 350 μm, refractive index: 2.2). After the prevention film is formed, it is bonded with an epoxy-based translucent adhesive (for example, a thermosetting adhesive EPOTECH 353ND manufactured by Epoxy Technology). The optical isolator 4 is cut into 400 μm square after performing batch alignment and bonding with a large element of 10 mm square or more. The thickness is 750 μm. Here, since a spontaneous magnetization type garnet is used, no magnet is required.
[0061]
In the optical device of the present invention, when mounted on the LD module, the end surface of the core-side optical fiber on the LD side is the leading ball 9 in order to prevent reflection and simultaneously improve the coupling efficiency. Depending on the case, a lens may be provided.
[0062]
FIG. 3 shows an example in which the LD module M1 is configured using the optical device S1 of the present invention. The first single mode optical fiber 1A of the optical device S1 whose tip end surface on the LD side was processed into a spherical shape was fixed in a V-shaped groove of the substrate. The PD 16 monitors the light of the LD 15 in order to stabilize the light intensity. The optical device S1 was sealed with the solder 30 at the opening 18a of the package 18 to configure a highly airtight LD module M1.
[0063]
[Example 2]
As shown in FIG. 4, an outer peripheral band 27 on the ring was installed on the outer periphery of the zirconia ferrule 3 having a diameter of 1.25 mm and a length of 12 mm, and hermetically bonded with a sealant 26 such as 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 where the optical fiber body F is assembled. The procedure for fixing the optical isolator 4 by inserting and fixing the optical fiber body F to the ferrule 3 and forming an element mounting groove is the same as in the first embodiment. Thereby, it is possible to obtain an optical device S2 in which a module that can be hermetically sealed with a simple configuration can be easily configured. In the figure, reference numeral 24 denotes a jacket for covering the fiber strand.
[0064]
Further, as shown in FIG. 5, the LD module M2 is configured by using the optical device S2. The first single-mode optical fiber 1A of the optical device S2 having a tip end processed on the LD side was fixed to a V-shaped groove of the substrate 14. The PD 16 monitors the light of the LD 15 in order to stabilize the light intensity. The optical device S1 is seam welded to the ring 29 at the opening 18a of the package 18 by a YAG laser, and the ring 29 is welded to the package 18 by the same YAG laser. The ring 29 is provided to adjust the position with respect to the package 18 so that the first single mode optical fiber 1A does not bend greatly. Thereby, LD module M2 with high airtightness was constituted.
[0065]
[Example 3]
As shown in FIG. 6, a covering member 28 having a shape covering the outer periphery of the rear end of the zirconia ferrule 3 having a diameter of 1.25 mm and a length of 12 mm and a part of the second single mode optical fiber 1B is installed and sealed. The agent 26 was airtightly joined. 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 where the optical fiber body F is assembled. The procedure for fixing the optical isolator 4 by inserting and fixing the optical fiber body F to the ferrule 3 and forming an element mounting groove is the same as in the first embodiment.
[0066]
The sealing joint portion has higher airtightness when the cross-sectional area of the sealing agent at the boundary portion inside and outside the package is smaller. Therefore, sealing in the outer periphery of the optical fiber is superior to sealing in the outer periphery of the ferrule 3 as in Example 1 and Example 2. Thereby, it can be set as optical module S3 in which a further structure can be hermetically sealed with a simple configuration. Reference numeral 24 denotes a jacket for covering the fiber strand.
[0067]
Further, as shown in FIG. 7, an LD module M3 is configured using the optical device S2. The first single-mode optical fiber 1A of the optical device S2 having a tip end processed on the LD side was fixed to a V-shaped groove of the substrate 14. The PD 16 monitors the light of the LD 15 in order to stabilize the light intensity. In the optical device S1, a ring 29 was seam welded to the ring 29 at the opening 18a of the package 18, and the ring 29 was also welded to the package 18 by the YAG laser. The ring 29 is provided to adjust the position relative to the package 18 so that the first single mode optical fiber does not bend greatly. Thereby, it was possible to obtain a highly airtight LD module M3.
[0068]
【The invention's effect】
As described above in detail, according to the optical device and the optical module of the present invention, the following remarkable effects can be obtained.
[0069]
Since no lens is used, it can be manufactured inexpensively with a simple configuration.
[0070]
An optical fiber body in which a plurality of basic optical fibers are connected in a line only needs to be adjusted in the connection portion between a multimode optical fiber (for example, GI fiber) and a coreless optical fiber, and has few adjustment axes and is easy to assemble. The coreless optical fiber sandwiched between two multimode optical fibers has the roles of focal length adjustment, prevention of misalignment, and simplification of assembly. Does not occur.
[0071]
Further, for example, a complicated operation such as adjustment in the pore when inserting the optical fiber body from both ends of the ferrule pore is unnecessary.
[0072]
In addition, when an optical element is inserted into the optical fiber body, an element mounting groove may be formed in the coreless optical fiber portion. Even if the element mounting groove position is within the range of the coreless optical fiber, no problem occurs even if it is shifted. Further, for example, an optical isolator which is an optical element can be inserted almost without alignment.
[0073]
Further, although the optical system uses an optical fiber, it is not necessary to use a core-expanded optical fiber that is troublesome to manufacture and difficult to control.
[0074]
An optical device in which an optical fiber body is housed in a ferrule is small and highly stable.
[0075]
In addition, since a bonding strip made of metal is provided on the outer periphery of the base body, it is possible to easily take a solder sealing structure with the package, and a module with high sealing performance can be easily obtained.
[0076]
Further, it is possible to laser weld the joining strip and the package. Laser welding is a simpler and shorter process than solder sealing, and heat is generated only locally, so it has an effect on optical elements built in optical devices and optical semiconductor elements in laser modules. Less is.
[0077]
In addition, by adopting a configuration in which the rear end of the optical device is covered with a metal covering member (joint band), the optical fiber and the covering member can be solder-sealed, and the optical fiber is supported only by the substrate. In addition to this, since the sealing path becomes longer, the sealing property of the optical device itself is improved, and the sealing and joining to the package is easy.
[0078]
Further, when the base is composed of a ferrule, the optical fiber is fixed with high accuracy with respect to the central axis of the ferrule. For example, a lens portion (tip ball portion) formed at one end of the first single mode optical fiber, an optical semiconductor element, Alignment becomes easy, and the durability is high, and the size can be reduced.
[0079]
By using such an optical device, it is possible to provide an optical module that is small and easy to manufacture, inexpensive, has little change over time, and has excellent airtightness.
[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 manufacturing process of 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 cross-sectional view schematically showing an optical device according to the present invention.
FIG. 7 is a cross-sectional view for schematically explaining an optical module according to the present invention.
FIG. 8 is a perspective view schematically showing the operation of the optical isolator.
FIG. 9 is a graph showing the relationship between the coupling interval of the core-enlarged optical fiber and the diffraction loss.
FIG. 10 is a schematic diagram illustrating the behavior of light in a GI fiber (multimode 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 expansion 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: Groove for element mounting
8: Refractive index matching adhesive
9: tip ball (lens part)
10: Core expansion optical fiber
11: Metallized layer (band for bonding)
12: V groove
13: Sleeve
14: Substrate
15: LD (light emitting element: optical semiconductor element)
16: PD (light receiving element: optical semiconductor element)
17: Peltier Eculer
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: Peripheral body (band for bonding)
28: Cover member (band for joining)
29: Ring
30: Solder
32: Rubber boots
J1: Optical module
J2: Optical device
M1, M2, M3: Optical module
S1, S2, S3: Optical devices
F: Optical fiber body

Claims (1)

A first multimode optical fiber, a graded index fiber, a coreless optical fiber, and a second multimode optical fiber are connected to the other end of the first single mode optical fiber having a lens portion for optically connecting an optical semiconductor element to one end. An optical fiber body in which graded index fibers and second single mode optical fibers are sequentially connected in a row,
A through hole is formed in the axial direction, and the base body is housed in the through hole in the base body in which the outer peripheral portion is formed of a metal and has a bonding strip for airtight bonding to the opening of the package. and a step of fixing the,
The graded index fiber that is the first multimode optical fiber and the graded index fiber that is the second multimode optical fiber are both longer than 0.25 pitch, and
The length of the coreless optical fiber is such that the beam waist from the graded index fiber that is the first multimode optical fiber and the beam waist from the graded index fiber that is the second multimode optical fiber are at the center. The length adjusted to match,
Forming an element mounting groove across the through hole in the base and the coreless optical fiber so as to divide the coreless optical fiber at an arbitrary position;
The device mounting groove, a manufacturing method of an optical device, characterized by further comprising the step of disposing an optical element for connection the coreless optical fiber and the optical dividing by the device mounting groove.

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