JP3891967B2 - Optical communication module and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical communication module, and more particularly to an optical communication module including an optical coupling unit that couples light between a light emitting unit and / or a light receiving unit and an end of an optical fiber. Typically, the optical communication module of the present invention is disposed at the end of an optical fiber constituting an optical communication system such as optical communication in a home or in a vehicle, communication between electronic devices, or a LAN (Local Area Network). .

  Moreover, this invention relates to the manufacturing method of the optical communication module which manufactures such an optical communication module.

  In general, in an optical communication system that transmits signal light through an optical fiber, the light intensity of a light emitting element (for example, a light emitting diode (LED) or a laser diode (LD)) is such that the transmission loss using the longest optical fiber is maximized. Below, the light receiving element (for example, photodiode (PD)) is set so as to obtain a light amount equal to or greater than a light reception amount (minimum light reception amount) that satisfies a predetermined S / N (signal to noise) ratio. The output of the PD is amplified by an iv (current-voltage) conversion amplifier.

  However, in the in-vehicle LAN and the like that are currently in widespread use, the length of the optical fiber used ranges over a wide range such as 1 m at the shortest and 20 m at the longest. Also, in the in-vehicle LAN, the use of plastic optical fiber (POF) is dominant, but POF has a relatively large transmission loss. As a result, in the optical fiber length range of 1 m to 20 m, the transmission loss varies from a minimum of 0.1 dB to a maximum of about 8 dB including the variation of the light source, and the amount of light emitted from the end of the optical fiber varies accordingly. In the case where the automatic power control mechanism does not act on the light emitting element, deterioration with time or the like is further added thereto. For this reason, there is a problem that a receiving system having a considerably large dynamic range must be prepared.

  In order to avoid this, as a method for compensating for the variation in the amount of light, as shown in FIG. 18, a method for adjusting the coupling efficiency with a replaceable filter is known (for example, Patent Document 1 (Japanese Patent Laid-Open No. Sho 59-59)). 28115)). In FIG. 18, 201 is an optical fiber, 206 is an optical coupler, 207 is an optical semiconductor element, 208 is a gradient index lens, 209 is an attenuation filter, 210 is a slide plate for fixing the attenuation filter 209, 211 is A receptacle 212 is a connector plug. When the connector plug 212 is inserted into the receptacle 211 of the optical coupler 206, the light emitted from the optical semiconductor element 207 (LD or LED) is condensed on the end face of the connector plug 212 by the refractive index distribution lens 208 for optical coupling, It is coupled and transported to the optical fiber 201. Here, an attenuation filter 209 for adjusting the amount of light is disposed between the optical semiconductor element 207 and the receptacle 211 outside the refractive index distribution lens 208, and the attenuation filter 209 is inserted from the outside of the optical coupler 206. It is configured to be exchangeable. Therefore, by inserting the attenuation filter 209 that gives an appropriate amount of attenuation according to the loss of the optical transmission system, it is possible to adjust the amount of light within an appropriate operating range of a receiving system (not shown).

  However, the method of adjusting the coupling efficiency with a replaceable attenuation filter as shown in FIG. 18 requires a complicated procedure of attaching an attenuation filter to a minute place → light quantity measurement → removing → attaching another filter → light quantity measurement →. There is a difficulty in automation and mass production. Furthermore, there is a drawback that the size is increased due to the housing for mounting.

  Further, as a method for compensating for the light quantity variation, a method of electrically adjusting a light output amount and a light input amount by attaching a variable resistor to a transmission drive circuit or a reception drive circuit is also known. In FIG. 17, 3 is a light emitting element, 5 is a POF for measuring light output, 7 is a light receiving element for measuring light output, S1 is transmitted light, 41 is a housing, 42 is resin for molding, 43 is a lead frame, 44 Is a transmission element driver IC, 45 is a variable resistor, and 46 is a circuit board. The housing 41 is provided with an optical plug 6 into which the optical fiber 5 is inserted. The light emitted from the light emitting element 3 is taken in through the opposite ends of the optical fiber 5 and emitted from the opposite end of the optical fiber 5. In this method, the variable resistor 45 is adjusted so that the light output S1 becomes a predetermined value while measuring the power of light emitted from the end of the optical fiber 5 with the light receiving element 7. The variable resistor 45 is fixed at the time of original use (communication).

However, the method of electrically adjusting the light output amount by attaching a variable resistor to the transmission drive circuit as shown in FIG. 17 is an obstacle to miniaturization because the size of the variable resistor itself is large. In addition, when a drive circuit or a variable resistor is sealed in a package or a mold resin in order to ensure reliability, it becomes impossible to adjust the variable resistor after assembly.
JP 59-28115 (2nd page, Fig. 2)

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical communication module that can easily compensate for variations in the amount of light that enters or exits an end of an optical fiber, that is small and can be manufactured at low cost.

  Moreover, the subject of this invention is providing the manufacturing method of the optical communication module which manufactures such an optical communication module.

In order to solve the above problems, an optical communication module according to the present invention includes:
An optical communication module comprising an optical coupling unit for coupling light between a light emitting unit or a light receiving unit or both and an end of an optical fiber,
The optical coupling portion is a semi-fixed light attenuating member made of a film or a pigtail that is irreversibly set to adjust the light transmittance during adjustment after assembling the optical communication module, and the light transmittance is fixed during communication. It is characterized by having.

  Here, the “semi-fixed type in which the light transmittance is set to be variable” means that the light transmittance of a certain light attenuating member is set to be variable at the time of adjustment, and is fixed at the time of original use (during communication). It means that.

In the optical communication module according to the present invention, the light transmittance of the light attenuating member is variably set at the time of adjustment after the assembly of the optical communication module, so that the amount of light incident on or emitted from the end of the optical fiber Can be easily compensated for. There is no need to go through complicated procedures such as replacing the filter as in the conventional example. Therefore, the coupling efficiency of the optical coupling part can be easily kept within a certain range required by the specifications. When the optical communication module is originally used (communication), the light transmittance of the light attenuating member is used in a fixed state. As a result, in an optical communication system to which the optical communication module of the present invention is applied, communication with an optimum light amount is possible. Further, since the change in the light transmittance during adjustment occurs irreversibly, once the light transmittance is set, the light transmittance of the semi-fixed light attenuating member is maintained. Therefore, it is not necessary to provide special means for maintaining the light transmittance of the semi-fixed light attenuating member. Therefore, the configuration of the optical communication module is simplified, and the optical communication module is small and manufactured at low cost.

  As described above, according to the optical communication module of the present invention, variations in the amount of light entering or exiting from the end of the optical fiber can be easily compensated for, and can be manufactured in a small size and at low cost.

In the optical communication module of the present invention, the semi-fixed light attenuating member is a filter or a pigtail . The light transmittance of the semi-fixed light attenuating member can be easily set by adjusting the light transmittance of this filter or pigtail .

  In the optical communication module of one embodiment, the light transmittance of the semi-fixed light attenuating member is continuously variable.

  In the optical communication module of this embodiment, the light transmittance of the semi-fixed light attenuating member can be adjusted with high accuracy.

  In an optical communication module according to an embodiment, the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by a change in characteristics of the material itself forming the member.

  In the optical communication module of this embodiment, the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by the change in the characteristics of the material itself forming the member. Therefore, the configuration of the optical communication module is simplified, and the optical communication module is small and manufactured at low cost.

  In the optical communication module according to one embodiment, the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by heating the material forming the member.

  In the optical communication module according to this embodiment, the light transmittance of the semi-fixed light attenuating member is easily set by adjusting the amount of heating with respect to the material forming the member.

  In the optical communication module of one embodiment, the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by light irradiation to the material forming the member.

  In the optical communication module according to this embodiment, the light transmittance of the semi-fixed light attenuating member is easily set by adjusting the amount of light applied to the material forming the member.

  The wavelength of the light used for the light irradiation may be different from the wavelength of the light used at the time of original use (during communication).

  In the optical communication module of one embodiment, the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by ablation with respect to the material forming the member.

  Here, “ablation” is a phenomenon in which, when a surface of a solid material such as a target is irradiated with a beam having a high energy density such as a laser, the material that has absorbed the beam energy is scattered as a fragment having a large energy.

  In the optical communication module of this embodiment, the light transmittance of the semi-fixed light attenuating member is easily set by adjusting the energy of the ablation beam with respect to the material forming the member.

An optical communication module according to an embodiment
A housing containing the light emitting part or the light receiving part or both,
The housing has an insertion port into which an end of the optical fiber is inserted,
The optical coupling portion is disposed in the housing between the light emitting portion and / or the light receiving portion and the insertion port.

  The optical communication module according to this embodiment is composed of relatively few members. Therefore, the configuration of the optical communication module is simplified, and the optical communication module is small and manufactured at low cost. Further, in a state where the end of the optical fiber is inserted into the insertion port, the light emitting part and / or the light receiving part and the optical coupling part can be sealed with a housing. Therefore, reliability can be ensured.

An optical communication module manufacturing method of the present invention is an optical communication module manufacturing method for manufacturing the optical communication module described above,
After assembling the above optical communication module, during adjustment,
The signal light generated in the light emitting unit is taken into a predetermined signal observation unit via the optical coupling unit and the optical fiber, and the coupling efficiency of the optical coupling unit is determined while observing the output of the signal observation unit. The light transmittance of the semi-fixed light attenuating member is irreversibly set so as to fall within a predetermined range.

  According to the method for manufacturing an optical communication module of the present invention, an optical communication module is obtained in which the coupling efficiency of the optical coupling portion between the light emitting portion and the opposite end of the optical fiber is within a predetermined range. Further, the method of the present invention can be easily automated, and mass production of optical communication modules becomes possible.

  The optical fiber is preferably a test optical fiber. In the original use (during communication), the test optical fiber is replaced with the original communication optical fiber.

In another aspect, the method for manufacturing an optical communication module of the present invention is a method for manufacturing an optical communication module for manufacturing the optical communication module described above,
After assembling the above optical communication module, during adjustment,
The signal light generated by the predetermined signal generating means is taken into the light receiving unit through the optical fiber and the optical coupling unit, and the coupling efficiency of the optical coupling unit is set to a predetermined value while observing the output of the light receiving unit. The light transmittance of the semi-fixed light attenuating member is irreversibly set so as to fall within the range.

  According to the method for manufacturing an optical communication module of the present invention, an optical communication module is obtained in which the coupling efficiency of the optical coupling portion between the light receiving portion and the opposite end of the optical fiber is within a predetermined range. Further, the method of the present invention can be easily automated, and mass production of optical communication modules becomes possible.

  The optical fiber is preferably a test optical fiber. In the original use (communication), the test optical fiber is replaced with the original optical fiber.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 shows a schematic configuration of an optical communication system (the whole is denoted by reference numeral 10) to which the optical communication module of the present invention is applied. The optical communication system 10 is connected to a plastic optical fiber (hereinafter referred to as “POF”) 1 for transmitting modulated light based on a data signal to be transmitted, and to both ends of the POF 1 so as to be optically coupled. Optical transceivers 2a and 2b. As will be described in detail later, the optical communication module of the present invention is applied to the insertion opening into which the end of the POF 1 of the optical transceivers 2a and 2b is inserted.

  As shown in FIG. 2, the optical transceiver 2a includes a transmission unit 3a and a reception unit 4a, and the optical transceiver 2b includes a transmission unit 3b and a reception unit 4b. POF1 includes two POFs 1a and 1b. The transmission unit 3a is connected to the POF 1a and is connected to the reception unit 4b of the counterpart optical transceiver 2b. The receiving unit 4a is connected to the POF 1b and connected to the transmitting unit 3b of the counterpart optical transceiver.

  In this example, two-way communication is performed using two POFs 1a and 1b, but two-way communication may be performed using one POF. In this example, two-way communication is used. However, for example, a unidirectional communication system including only the transmission unit 3a, the POF 1a, and the reception unit 4b in FIG. 2 may be used.

  Furthermore, the optical communication module of the present invention can also be applied to an optical communication system 10 'as shown in FIG. 4 in which a transmission cable and a reception cable are connected to different transceivers to form a single ring as a whole. . In this example, optical transceivers 31, 32, and 33 are provided in the in-vehicle devices 21, 22, and 23, respectively. The optical transceiver 31 transmits signal light to the optical transceiver 32 via the POF 11, the optical transceiver 32 transmits to the optical transceiver 33 via the POF 12, and the optical transceiver 33 transmits to the optical transceiver 31 via the POF 13.

  When the optical communication system having such a configuration is used as, for example, an in-vehicle LAN, a transmission distance of 20 m at the maximum is necessary in consideration of mounting on a large vehicle and routing, while 1 m as a countermeasure against electromagnetic noise or the like. It may be used at a certain distance. That is, it is necessary to cover the POF from a short distance of 1 m to a long distance of 20 m.

  As shown in FIG. 3, POF has a large transmission loss. In this case, it is necessary to expect a transmission loss of 0.15 dB (1 m) to 8 dB (20 m) as the transmission loss. This is a value considering that the wavelength of the LED varies from 630 nm to 680 nm.

  For example, an in-vehicle LAN is currently assumed to have a transmission rate of 50 Mbps and a future transmission speed of 400 Mbps, but if it covers only the range of transmission loss from 0.15 dB to 8 dB, a high-speed PD and preamplifier that can receive up to 400 Mbps Any configured receiving system can receive without problems. However, the amount of signal light coupled from the transmitter to the POF varies by a maximum of 8 dB due to deterioration over time, temperature fluctuation, reflection, production variation, etc., and the coupling efficiency of the signal light amount from the POF to the receiver is also 1. Fluctuates about 5 dB. Generally, the amount of light on the transmission side used in the in-vehicle LAN is -1.5 dBm to -10 dBm, the loss of 0 to 5 dB at two midpoint POF connections, the loss of the POF is 0.15 dB to 8 dB, and other margins are 0. The sum of ˜−2 dB results in a maximum POF light amount of −1.65 dBm and a minimum of −25 dBm. The amount of incident light on the PD is a value that takes into account this value and the reception loss from the POF end to the PD.

  On the other hand, the minimum received light amount of the PD depends on the BER, but is about −26 dBm at a transmission rate of 100 Mbps to 200 Mbps used in POF communication.

Since the POF end minimum light amount is -25 dBm,
−25 − (− 26) = 1 dB
Therefore, the reception loss to the PD needs to be within 1 dB.

Next, the maximum value (overload) of the PD input light amount is −1.65-1−1−2.65 dBm.
Thus, a considerably strong light amount is incident on the PD. Usually, since the reception efficiency itself varies at least 0.5 dB due to tolerances and the like, an overload of -2.15 dBm occurs in the above example.

  If a too large amount of light enters the PD, the rise and fall speed slows down or pulse width distortion occurs, so the maximum amount of incident light allowed by the iv amplifier at the rear stage of the PD is limited to about -5 dBm. . In the case of the above example, the amount of light of -2.15 dBm is too large, and there is a risk of overflow. This comparison is shown in the table of FIG.

  That is, there is a problem that S / N deterioration due to insufficient incident light quantity on the PD and overflow due to excessive incident light quantity on the PD occur in the same system. The present invention was invented to deal with this problem. For example, in the above system example, if the transmitter is a transmitter, the amount of fluctuation due to production variation, device characteristic variation, coupling efficiency variation, etc. is about 3 dB. If there is, it is for improving the fluctuation amount of about 2 dB due to variations in element characteristics and coupling efficiency.

  FIG. 6 shows a state during adjustment of the optical transceiver 2a as the optical communication module of the embodiment.

  The optical transceiver 2 a includes a housing 41 that houses a light emitting element 3 as a light emitting unit and a transmission driver IC 44. The light emitting element 3 and the transmission driver IC 44 are mounted on the lead frame 43 and sealed with a sealing resin 42 having translucency. The housing 41 may contain a light receiving unit and an i-v (current-voltage) conversion amplifier that processes the output in order to perform bidirectional communication. However, in this embodiment, description will be made by paying attention to the optical coupling portion between the light emitting element 3 and the opposite end portion of the optical fiber 5.

  The housing 41 has a cylindrical optical plug 6 as an insertion port into which an end of the optical fiber 5 is inserted at a position facing the light emitting element 3.

  In the optical plug 6, a film 50 as a semi-fixed light attenuating member is disposed at a position between the light emitting element 3 and the opposite end of the optical fiber 5. When the film 50 is exposed to light P1 having a specific wavelength, the film 50 is made of a material whose light transmittance changes with the exposure. At the opposite end of the optical fiber 5, an optical transmitter 51 for changing the characteristics of the substance itself forming the film 50 through a half mirror 52, and a light output measuring light-receiving element 7 as signal observing means. And are arranged.

  At the time of adjustment, the light emitting element 3 in the optical transceiver 2a is driven, and the signal light S1 from the light emitting element 3 is taken in from the opposite end of the optical fiber 5 and emitted from the opposite end. The signal light S1 is received by the light output measuring light-receiving element 7 via the half mirror 52, and the light output is monitored. The optical transmitter 51 emits light P1 having a wavelength that changes the film 50 to be opaque. As a result, as shown in FIG. 7, an opaque portion 53 is formed in the film 50 with the irradiation of the light P1. Therefore, as the transmittance of the film 50 decreases, the power of the signal light S1 decreases. Thus, the output of the signal light S1 can be variably set to a predetermined value.

  In this case, it is possible to easily compensate for variations in the amount of light that enters or exits the end of the optical fiber 5. There is no need to go through complicated procedures such as replacing the filter as in the conventional example. In the original use, the test optical fiber 5 is replaced with the original communication optical fiber, and the light transmittance of the film 50 is used in a fixed state. As a result, in an optical communication system to which the optical transceiver 2a is applied, communication with an optimum light amount is possible.

  In the adjustment method described above, since the opaque portion 53 is generated by the light P1 that has passed through the optical fiber 5, an effect of automatically aligning with the optical fiber 5 is also obtained. It should be noted that the material of the film 50 is changed in color by light P1 having a wavelength other than that for signal transmission, and is not changed by light S1 having a wavelength for signal transmission.

  For example, an organic material that exhibits colorability when irradiated with ultraviolet rays is effective as the material for the film. FIG. 8 shows the relationship between the exposure time and the absorbance when a material introduced as a film for checking the accumulation of ultraviolet rays is exposed to ultraviolet rays (see JP-A-6-32940). In any of the materials A, B, C, and D, the absorbance increases as the exposure time increases. As the absorbance increases, the transmittance decreases. In this publication, a change in absorbance in the visible wavelength region of 666 nm is observed using ultraviolet rays having a wavelength of 366 nm, and the cumulative exposure amount of ultraviolet rays is obtained from this change in absorbance (that is, the degree of coloring).

  Usually, a wavelength of 650 nm is used for optical transmission by POF. Therefore, in the present invention, the light output of the optical transmission by POF is adjusted by using a light attenuation filter made of a photosensitive material whose light transmittance is changed by ultraviolet rays by using the above phenomenon in reverse. Since the system may fail if it returns to the original transmittance again during use, it is necessary that the filter characteristics be semi-fixed (variable only during initial adjustment and not variable during use). Further, since the example of FIG. 8 takes too much time, it is desirable to adjust the transmittance in a short time by changing the UV intensity instead of the time or using a sensitizer.

  As a specific photosensitive material, one having the composition shown in FIG. 9 can be used (see JP-A-6-32940). In FIG. 9, X means an oxygen or sulfur atom. Y represents oxygen, sulfur, -NH- group, or methylene group. R1 is alkyl having 1 to 6 carbon atoms, substituted alkyl (the substituents are phenyl, hydroxy, alkoxy, halogen, sulfonyl, amino, carboxyl, nitro, each group), phenyl, or substituted phenyl (same as the substituents) ). R2 and R2 'may be the same or different and each represents hydroxyl, amino, or a mono- or dialkylamino group having 1 to 6 carbon atoms. R3 and R3 'may be the same or different and each represents hydrogen or alkyl having 1 to 6 carbon atoms. R3 and R3 'may share one atom (oxygen or sulfur) to form a ring. R4R4 'may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms or a halogen group.

  In addition, examples of materials that are irreversibly colored by ultraviolet rays are also introduced in Japanese Patent Application Laid-Open No. 57-194031. Any material exhibiting similar characteristics can be used in the present invention.

  In the above example, the film 50 as the semi-fixed light attenuating member is provided at a position between the light emitting element 3 and the opposite end of the optical fiber 5, but the present invention is not limited to this. The surface 61 (shown in FIG. 7) of the light emitting point of the light emitting element 3 through which the signal light for transmission passes and the surface 62 of the sealing resin 42 are exposed to ultraviolet rays or the like (light having a wavelength not in the wavelength band used for transmission). A material whose transmittance in the wavelength band used for transmission is reduced by irradiation may be attached. As will be described later, when an optical waveguide for relay, a light guide, an optical fiber for relay, or the like is provided between the optical transceiver 2a and the optical fiber for transmission, ultraviolet light is applied to the end face of the optical waveguide for relay, etc. Etc. (light having a wavelength other than the wavelength band used for transmission) may be attached so that a material whose transmittance in the wavelength band used for transmission decreases is irradiated.

  In the above example, as the material of the light attenuating film 50, a material whose transmittance in the wavelength band used for transmission is reduced by irradiation with ultraviolet rays or the like (light having a wavelength other than the wavelength band used for transmission) is used. However, it is not limited to this. A material whose transmittance is changed by heating, for example, a novolak photoresist or the like, may be locally heated to reduce the transmittance. In this case, the material of the light attenuation film 50 is a material whose transmittance is changed by heating. The microheater for locally heating the film is preferably arranged in the housing 41 at a place where it does not hinder optical transmission. There is no particular problem as a material whose transmittance is changed by heating as long as the final coloring degree is irreversibly stable and does not cause a temporal variation of the light transmission amount.

In the above example, the light transmittance of the material substance itself of the light attenuation film 50 is changed by heating. However, the present invention is not limited to this. The shape of the light attenuating film 50 may be changed by heating, and as a result, the coupling efficiency of the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5 may be changed. Further, in this example, the micro heater incorporated in the housing 41 is described as the heating means, but local heating by a CO ₂ laser or the like may be used. Furthermore, as described above, the shape of the light attenuating film 50 may be changed by heating. However, laser ablation can be used as means for changing the shape.

  Further, as shown in FIG. 10, an opening 54 is provided in the side surface of the cylindrical optical plug 6 of the housing 41, and a reaction gas or the like is temporarily injected from the outside through the opening 54 to seal the sealing resin 42. Among them, the state of the surface through which the signal light for optical transmission passes may be changed. In this case, the surface of the sealing resin 42 functions as a light attenuating member, and the coupling efficiency of the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5 is set variably.

  Further, as shown in FIG. 11, foreign matter may be attached to the surface of the sealing resin 42 through which the signal light for optical transmission passes through the opening 54 from the outside. Also in this case, the surface of the sealing resin 42 functions as a light attenuating member, and the coupling efficiency of the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5 is set variably.

  In addition, the coupling efficiency of the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5 is a semi-fixed mechanical shutter or aperture having a variable aperture, and a semi-fixed filter having a variable transmittance. It may be variably set using. In particular, as shown in FIG. 12, two polarizing films 57a and 57b are accommodated in a cylindrical optical plug 6, and the angle formed by the polarizing axes of the two polarizing films 57a and 57b is adjusted. good. Thereby, the coupling efficiency of the optical coupling part between the light emitting element 3 and the opposing end surface of the optical fiber 5 can be easily varied and set. In this case, it is desirable that the rotation angle of the polarizing film be adjusted from the outside of the housing.

  In each of the above-described examples, the coupling efficiency between the light emitting element 3 and the opposite end face of the optical fiber 5 is easily maintained once set.

  According to each of the above-described examples, the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5 is configured with relatively few members. Therefore, the configuration of the optical transceiver 2a is simplified, and the optical transceiver 2a is small and manufactured at low cost. In addition, in a state where the end of the optical fiber is inserted into the optical plug 6, the components of the optical transceiver 2 a can be sealed with the housing 41. Therefore, reliability can be ensured.

  The above-described examples all adjust the coupling efficiency of the optical coupling portion between the light emitting element 3 and the opposite end face of the optical fiber 5, but are not limited to this, and the light reception that constitutes the optical transceiver 2a. You may adjust the coupling efficiency of the optical coupling part between the element 4a (refer FIG. 2) and the end surface which the optical fiber 5 opposes.

  Specifically, after assembling the optical transceiver 2a, the signal light generated by the predetermined signal generating means is taken into the light receiving element 4a through the optical fiber 5 and the optical coupling unit, and the output of the light receiving element 4a is observed. However, the light transmittance of the semi-fixed light attenuating member is variably set. In this case, an optical communication module is obtained in which the coupling efficiency of the optical coupling portion between the light receiving element 4a and the opposite end portion of the optical fiber 5 is within a predetermined range.

  The adjustment method described above can be easily automated, enabling mass production of optical communication modules.

(Second Embodiment)
As an optical communication module, there is a type in which an optical transceiver is connected to an original transmission optical fiber by a relay optical fiber. Such an optical fiber for relay is called an optical waveguide, a light guide, or a pigtail.

  FIG. 13 shows a schematic configuration of an optical transceiver 2a ′ as such a relay type optical communication module.

  The optical transceiver 2a ′ includes a housing 41 that houses a light emitting element 3 as a light emitting unit and a transmission driver IC 44, as shown in FIG. The light emitting element 3 and the transmission driver IC 44 are mounted on the lead frame 43 and sealed with a sealing resin 42 having translucency. The housing 41 may contain a light receiving unit and an i-v (current-voltage) conversion amplifier that processes the output in order to perform bidirectional communication.

  The housing 41 has a cylindrical optical plug 6 into which the end of the relay optical fiber 8 is inserted at a position facing the light emitting element 3. The opposite end of the relay optical fiber 8 is inserted into the optical plug 6 ′ of the relay socket 9.

  The relay socket 9 has a cylindrical main body, and has a pair of optical plugs 6 'and 6' on both sides of the main body. The ends of the optical fibers inserted into the optical plugs 6 'and 6', in this example, the end of the relay optical fiber 8 and the end of the transmission (or test) optical fiber 5 are optically coupled to each other. It has become.

  In the optical coupling part between the light emitting element 3 of the optical communication module of this type and the opposite end of the optical fiber for relay 8, and the optical coupling part between the optical fiber for relay 8 and the optical fiber for transmission 5, It is also possible to set the light transmittance variably by providing a semi-fixed light attenuating film or the like as described in the first embodiment. However, in this type, it is effective to variably set the light transmittance of the relay optical fiber 8 by some means (a semi-fixed type). In that case, the relay optical fiber 8 is grasped as a semi-fixed optical attenuation member.

  For example, when POF is used as the material of the relay optical fiber 8, the substance forming POF is often PMMA (polymethyl methacrylate). In this POF made of PMMA, transmission loss increases with the heat treatment time as shown in FIG. 14 (document published by Mitsubishi Rayon, a POF manufacturer). If the characteristics shown in FIG. 14 are used as they are, it takes too much time and cannot be used, but if an accelerated method such as high-temperature heating is employed, it can be used in the present invention.

  Specifically, after the optical transceiver 2a is assembled, the signal light generated in the light emitting element 3 is transmitted to the relay optical fiber 8, the relay socket 9, the test optical fiber 5, and the half mirror 52 (see FIG. 6). The light transmittance of the relay optical fiber 8 is variably set by heating while the light output is received by the light receiving element 7 for light output measurement and the light output is observed. As a result, an optical transceiver 2a ′ in which the coupling efficiency of the relay optical fiber 8 falls within a predetermined range is obtained.

  The adjustment method described above can be easily automated, enabling mass production of optical communication modules.

  In the above example, the light transmittance of the material substance itself of the relay optical fiber 8 is changed by heating. However, the present invention is not limited to this. As shown in FIG. 15, the resin light guide or optical waveguide represented by POF contracts due to an external stress such as a mechanical shutter or a caulking process. 8 ′). In such a case, the coupling efficiency can be adjusted in the same manner as the coupling efficiency is adjusted by changing the cross-sectional area of the optical path by arranging the mechanical shutter and aperture described above.

  Further, in FIG. 16, a distance D1 between the light emitting element 3 and the opposite end of the relay optical fiber 8, a distance D4 between the opposite ends of the relay optical fiber 8 and the transmission optical fiber 5, The axis deviation D2 between the light emitting element 3 and the opposite end of the relay optical fiber 8 or the axis deviation D3 between the opposite ends of the relay optical fiber 8 and the transmission optical fiber 5 is reduced by half. It is also possible to adjust between the light emitting element 3 and the transmission optical fiber 5 by adjusting to a fixed type, that is, by changing and setting the spatial change amount or state of the optical path between the optical transceiver and the optical fiber. The coupling efficiency of can be changed. This also applies to the previous embodiment.

  The present invention is a POF that requires a large aperture as an optical fiber used for a transmission medium, a high degree of freedom in designing an optical communication module connection part, a large transmission loss per unit distance, and a wide dynamic range at a receiver. It is applied more effectively in optical communication using the.

It is a figure which shows schematic structure of the optical communication system to which the optical communication module of this invention was applied. It is a figure which shows the structure of the optical communication system of FIG. 1 in detail. It is a figure which shows an example of the loss characteristic of the optical fiber depending on the wavelength of a light source. It is a figure which shows schematic structure of the optical communication system which can apply the optical communication module of this invention. FIG. 5 shows a loss estimation when the present invention is not applied in the optical communication system of FIG. It is a figure which shows the state at the time of adjustment of the optical transceiver of 1st Embodiment to which the optical communication module of this invention is applied. It is a figure which shows the aspect which the state of the semi-fixed optical attenuation filter changed by the time of adjustment of the optical transceiver of FIG. It is a graph which shows the permeation | transmission characteristic of the light of the wavelength used for transmission by irradiation of the ultraviolet-ray (light of the wavelength which is not used for transmission) of the material applicable to this invention. It is a figure which shows an example of chemical formula of the material which has the characteristic of FIG. It is a figure which shows the modification of the optical transceiver to which the optical communication module of this invention is applied. It is a figure which shows another modification of the optical transceiver to which the optical communication module of this invention is applied. It is a figure which shows another modification of the optical transceiver to which the optical communication module of this invention is applied. It is a figure which shows the structure of the optical transceiver of 2nd Embodiment to which the optical communication module of this invention is applied. It is a graph which shows the transmission loss increase amount of POF by heat processing. It is a figure which illustrates the state where the optical fiber for relay was changed. It is a figure which shows another modification of the optical transceiver to which the optical communication module of this invention is applied. It is a figure which shows the conventional optical communication module which adjusts an optical output with an electric circuit using semi-fixed resistance. It is explanatory drawing which shows the structure of the conventional optical communication system of the type which replaces | exchanges a filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b Optical fiber 2, 2a, 2b Optical transceiver 3, 3a, 3b Light emitting element 4, 4a, 4b Light receiving element 5 Optical output measuring optical fiber 6 Optical plug 7 Measuring optical receiver 8 Repeating optical fiber 8 'Optical fiber attenuating part for relay 9 Relay socket 10 Optical communication system 10' Optical communication system with various transmission distances 41 Housing 42 Mold resin 43 Lead frame 44 Driver IC for transmission
50 Semi-fixed optical attenuator

Claims (9)

An optical communication module comprising an optical coupling unit for coupling light between a light emitting unit or a light receiving unit or both and an end of an optical fiber,
The optical coupling portion is a semi-fixed light attenuating member made of a film or a pigtail that is irreversibly set to adjust the light transmittance during adjustment after assembling the optical communication module, and the light transmittance is fixed during communication. An optical communication module comprising: The optical communication module according to claim 1,
An optical communication module, wherein the light transmittance of the semi-fixed light attenuating member is continuously variable. The optical communication module according to claim 1 or 2,
An optical communication module, wherein the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by a change in the characteristics of the substance itself forming the member. The optical communication module according to claim 3,
An optical communication module, wherein the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by heating the material forming the member. The optical communication module according to claim 3,
The optical communication module according to claim 1, wherein the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by light irradiation to the material forming the member. The optical communication module according to claim 3,
An optical communication module characterized in that the irreversible change in the light transmittance of the semi-fixed light attenuating member is caused by ablation with respect to the material forming the member. The optical communication module according to any one of claims 1 to 6 ,
A housing containing the light emitting part or the light receiving part or both,
The housing has an insertion port into which an end of the optical fiber is inserted,
The optical communication module, wherein the optical coupling part is disposed in the housing between the light emitting part and / or the light receiving part and the insertion port. An optical communication module manufacturing method for manufacturing the optical communication module according to any one of claims 1 to 7 ,
After assembling the above optical communication module, during adjustment,
The signal light generated in the light emitting unit is taken into a predetermined signal observation unit via the optical coupling unit and the optical fiber, and the coupling efficiency of the optical coupling unit is determined while observing the output of the signal observation unit. A method for manufacturing an optical communication module, wherein the light transmittance of the semi-fixed light attenuating member is irreversibly set so as to fall within a predetermined range. An optical communication module manufacturing method for manufacturing the optical communication module according to any one of claims 1 to 7 ,
After assembling the above optical communication module, during adjustment,
The signal light generated by the predetermined signal generating means is taken into the light receiving unit through the optical fiber and the optical coupling unit, and the coupling efficiency of the optical coupling unit is set to a predetermined value while observing the output of the light receiving unit. A method of manufacturing an optical communication module, wherein the light transmittance of the semi-fixed light attenuating member is irreversibly set so as to fall within a range.

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