JP2018082060A - Optical transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission device including a first light-emitting element, and a second light-emitting element connected in parallel to the first light-emitting element, and arranged so that it is degraded earlier than the first light-emitting element, which is arranged so that the worsening of the uniformity of wavelength spectra accompanying the degradation of the second light-emitting element can be suppressed.SOLUTION: An optical transmission device comprises: a first light-emitting elements 50-1, 50-2, 50-4 operable to emit light; a second light-emitting element 50-3 connected in parallel to the first light-emitting elements 50-1, 50-2, 50-4, arranged so that it is degraded earlier than the first light-emitting elements 50-1, 50-2, 50-4, and having a light-launch opening blocked; and a sensing part operable to sense that the degradation of the second light-emitting element 50-3 is degraded.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical transmission apparatus.

  Patent Document 1 discloses an optical communication system including an optical transmitter having a light emitting element that outputs an optical signal based on input data, and an optical receiver having a light receiving element that receives the transmitted optical signal and converts it into an electrical signal. An output waveform deterioration detection circuit that includes a light receiving element that monitors the output light of the light emitting element of the optical transmitter, detects the rise or fall time of the monitor signal of the light receiving element, and detects the deterioration of the output waveform of the optical transmitter An optical communication system comprising: is disclosed. In the optical communication system disclosed in Patent Document 1, the deterioration of the output waveform is detected before the output waveform of the laser diode, which is the light emitting element of the optical transmitter of the optical communication system, deteriorates to cause a malfunction of the optical receiver. Warning.

JP 2002-368694 A

In order to grasp earlier that the lifetime of the first light emitting element is approaching, for example, a second light emitting element configured to deteriorate faster than the first light emitting element is provided in parallel. A method of determining that the lifetime of the first light emitting element is approaching based on the deterioration state of the light emitting element is conceivable.
The present invention relates to an optical transmission device including a first light emitting element and a second light emitting element connected in parallel with the first light emitting element and configured to deteriorate faster than the first light emitting element. An object of the present invention is to provide an optical transmission device capable of suppressing a decrease in the uniformity of the wavelength spectrum accompanying the deterioration of the second light emitting element.

  In order to achieve the above object, the optical transmission device according to claim 1 is connected to the first light emitting element that emits light in parallel with the first light emitting element, and the first light emitting element. The second light-emitting element is configured to be deteriorated earlier than the element, the light emission port is shielded, and a detection unit that detects that the second light-emitting element has deteriorated.

  According to a second aspect of the present invention, in the first aspect of the present invention, the driving unit that drives the first light emitting element so that the amount of light emitted from the first light emitting element is constant. The detection unit further includes the second unit when a current or voltage value output from the driving unit to the first light emitting element and the second light emitting element is out of a predetermined range. This is to detect that the light emitting element has deteriorated.

  According to a third aspect of the present invention, in the first aspect of the present invention, a light receiving unit that receives light emitted from the first light emitting element, the first light emitting element, and the second light emitting element. A driving unit that drives the element at a constant voltage or a constant current, and the detection unit deteriorates the second light emitting element when the amount of light received by the light receiving unit is out of a predetermined range. Is to detect this.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the number of the first light emitting elements is larger than the number of the second light emitting elements. is there.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the first light emitting element and the second light emitting element have the same shape. An insulating film is provided around each of the insulating films, and the insulating film around the first light emitting element and the insulating film around the second light emitting element are different in at least one of thickness, area, and shape. is there.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the second light emitting element is a heat cloth than any of the first light emitting elements. The talk is arranged at a large position.

  The invention according to claim 7 is the invention according to any one of claims 1 to 5, wherein the first light-emitting element includes a plurality of first light-emitting elements. It is arranged at a position surrounded by the first light emitting element.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the first light emitting element and the second light emitting element have a current confinement structure. The current confinement diameter of the second light emitting element is smaller than the current confinement diameter of the first light emitting element.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the first light emitting element is provided in a plurality, and the plurality of the first light emitting elements are adjacent to each other. The minimum value of the distance between the second light emitting element and one of the first light emitting elements is larger than the maximum value of the distance between the light emitting elements.

  The invention described in claim 10 is notified when the detection unit detects that the second light-emitting element has deteriorated in the invention described in any one of claims 1-9. It has a report part which performs.

  An eleventh aspect of the invention is the invention of the tenth aspect, further comprising an optical transmission line including a core for propagating light, wherein the first light emitting element is more than the second light emitting element. Are also arranged at positions close to the center of the core.

  The invention according to claim 12 is the invention according to claim 11, wherein the first light emitting element is provided in a plurality, and the center of gravity position of the plurality of first light emitting elements is the second light emitting element. It is arranged at a position closer to the center of the core of the optical transmission line than the position of the light emitting element.

  In order to achieve the above object, an optical transmission device according to claim 13 is connected to the first light emitting element that emits light in parallel with the first light emitting element and the first light emitting element. A second light emitting element that emits light, and a detector that detects that the second light emitting element has deteriorated, wherein the first light emitting element The second light emitting element is disposed at a position that does not overlap the core of the optical transmission path, and is disposed at a position that overlaps the core of the transmission path.

  According to the invention described in claim 1 and claim 13, the first light emitting element is connected in parallel with the first light emitting element, and is configured to be deteriorated faster than the first light emitting element. In the optical transmission device including the second light emitting element, there is an effect that an optical transmission device capable of suppressing a decrease in the uniformity of the wavelength spectrum accompanying the deterioration of the second light emitting element is provided.

  According to the second aspect of the invention, even in the APC-driven optical transmission device, there is an effect that the decrease in the uniformity of the wavelength spectrum accompanying the deterioration of the light emitting element is suppressed.

  According to the third aspect of the present invention, even in an optical transmission device driven by constant current driving or constant voltage driving, there is an effect that a decrease in the uniformity of the wavelength spectrum accompanying the deterioration of the light emitting element is suppressed.

  According to the fourth aspect of the present invention, the first light emitting element is detected after it is detected that the second light emitting element is deteriorated as compared with the case where the number of the first light emitting elements is smaller than the number of the second light emitting elements. There is an effect that it takes a long time to reach the lifetime of the light emitting element.

  According to the fifth aspect of the present invention, the first light-emitting element and the second light-emitting element have a life longer than that of the first light-emitting element, as compared with the case where insulating films having the same thickness, area, and shape are used. This also has the effect that the lifetime of the second light emitting element is shortened.

  According to the sixth aspect of the present invention, the lifetime of the first light emitting element is greater than the case where the second light emitting element is disposed at a position not considering the thermal crosstalk from the first light emitting element. In addition, there is an effect that the lifetime of the second light emitting element becomes shorter.

  According to the seventh aspect of the present invention, the lifetime of the first light-emitting element is compared with the case where the second light-emitting element is disposed at a position that does not consider the relationship with the surrounding first light-emitting elements. As a result, the lifetime of the second light emitting element is shortened.

  According to the eighth aspect of the present invention, compared to the case where the current confinement diameter of the first light emitting element is the same as the current confinement diameter of the second light emitting element, the second light emitting element is longer than the lifetime of the first light emitting element. This has the effect of shortening the lifetime of the light emitting element.

  According to the invention described in claim 9, the maximum value of the distance between the adjacent light emitting elements in the first light emitting element, the minimum value of the distance between the second light emitting element and any one of the second light emitting elements, As compared with the case where no consideration is given, the effect of the heat from the second light emitting element on the first light emitting element is further reduced.

  According to the tenth aspect of the invention, there is an effect that it is notified that the life of the first light emitting element is approaching.

  According to the invention of claim 11, the light emitted from the first light emitting element is compared with the configuration in which the first light emitting element and the second light emitting element are at the same distance from the center of the core. There is an effect that it becomes easier to bond to the core.

  According to the twelfth aspect of the present invention, the second light emitting element is positioned closer to the center of the core than the center of gravity of the first light emitting element. There is an effect that light emitted from the light emitting element is more easily coupled to the core.

(A) is sectional drawing which shows an example of a structure of the optical module which concerns on embodiment, (b) is a top view. (A) is a graph which shows the time-dependent change of the light output of the light emission part from which lifetime differs, (b)-(f) is a top view of the optical module by which the light emission part from which lifetime differs is arrange | positioned with various forms. (A) is a circuit diagram which shows the drive part of the optical module which concerns on 1st Embodiment, (b) is a graph which shows a time-dependent change of a drive current. (A) is a flowchart which shows the flow of the initialization process of the optical module which concerns on 1st Embodiment, (b) is a flowchart which shows the flow of a drive control process. (A)-(f) is sectional drawing which shows an example of the manufacturing method of the optical module which concerns on embodiment. (A)-(h) is a figure which shows the variation of the form of arrangement | positioning of a normal light emission part and a monitor light emission part. (A) is a circuit diagram which shows the drive part of the optical module which concerns on 2nd Embodiment, (b) is a graph which shows a time-dependent change of monitor current. (A) is a flowchart which shows the flow of the initialization process of the optical module which concerns on 2nd Embodiment, (b) is a flowchart which shows the flow of a drive control process. (A) is a top view which shows an example of a structure of the optical transmission apparatus which concerns on 3rd Embodiment, (b) is sectional drawing. (A) is a side view which shows the coupling | bonding state of the optical module and optical fiber in the optical transmission apparatus which concerns on 3rd Embodiment, (b) is a top view. (A)-(c) is a figure which shows the variation of the form of arrangement | positioning of a normal light emission part and a monitor light emission part.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
An example of the configuration of the optical module 10 according to the present embodiment will be described with reference to FIG. In the present embodiment, a mode in which a surface emitting semiconductor laser (VCSEL: Vertical Cavity Surface Emitting Laser) array is applied to the optical module according to the present invention will be described as an example. FIG. 1A is a cross-sectional view of the optical module 10 according to the present embodiment, and FIG. 1B is a plan view of the optical module 10. The cross-sectional view shown in FIG. 1A is a cross-sectional view taken along the line AA ′ in the plan view shown in FIG. The optical module 10 according to the present embodiment may include a drive unit that drives the VCSEL array, but FIG. 1 illustrates a configuration that does not include the drive unit. In the present embodiment, a plurality of VCSEL elements constituting the VCSEL array are mainly used for ensuring redundancy of light emitted from the optical module 10. That is, each VCSEL element has a rating capable of outputting the amount of light necessary for communication as a single VCSEL element, and is normal even when one VCSEL element is damaged by an external surge voltage or the like. Redundancy is ensured by constructing a VCSEL array with a plurality of VCSEL elements connected in parallel to each other so that proper communication can be maintained.

  As shown in FIG. 1A, an optical module 10 includes an n-side electrode wiring 30, an n-type lower DBR (Distributed Bragg Reflector) 14 formed on an n-type GaAs (gallium arsenide) substrate 12, an active type The layered structure includes a layer region 16, an oxidized constricting layer 26, a p-type upper DBR 18, an interlayer insulating film 20, and a p-side electrode wiring 22.

  As shown in FIG. 1B, the optical module 10 includes a light emitting region 40 and a p-side electrode pad 28.

  The light emitting region 40 is a region configured as a VCSEL array including a plurality of light emitting units. In the present embodiment, as an example, four light emitting units 50-1, 50-2, 50-3, 50-4 (hereinafter, collectively referred to as “light emitting unit 50”) formed in a mesa shape are included. Since the region except the emission port of each light emitting part is covered with the p-side electrode wiring 22, the light emitting parts are electrically connected to each other in parallel. However, in the optical module 10 according to the present embodiment, the lifetime of at least one of the plurality of light emitting units 50 is set to be shorter than that of the other light emitting units, the light emission port is shielded, and light is emitted. It is not to be done. In the optical module 10, the exit of the light emitting unit 50-3 is shielded, while the exit of the light emitting units 50-1, 50-2, and 50-4 is not shielded. In other words, in the optical module 10, light is emitted from the light emitting units 50-1, 50-2, and 50-4 except the light emitting unit 50-3. In the following, a mesa whose light exit is shielded is also referred to as a “light emitting unit 50” for convenience.

  The p-side electrode pad 28 is configured as a part of the p-side electrode wiring 22, and when connecting a power supply that supplies current to the light emitting region 40 through the p-side electrode wiring 22, a pad that connects a positive electrode of the power supply It is. Note that the negative electrode of the power source is connected to the n-side electrode wiring 30.

  The n-type lower DBR 14 formed on the substrate 12 has a film thickness of 0.25λ / n, where λ is the oscillation wavelength of the optical module 10 and n is the refractive index of the medium (semiconductor layer), and This is a multilayer film reflecting mirror constituted by alternately and repeatedly stacking two semiconductor layers having different refractive indexes.

  The active layer region 16 formed on the lower DBR 14 is a portion that generates light emitted from the light emitting unit 50. The lower spacer 114, the quantum well active layer 116, and the upper spacer formed in this order on the lower DBR 14. 118 (see FIG. 5).

  The quantum well active layer 116 according to the present embodiment may be constituted by, for example, a barrier layer composed of four GaAs layers and a quantum well layer composed of three layers of InGaAs provided therebetween. The lower spacer 114 and the upper spacer 118 are disposed between the quantum well active layer 116 and the lower DBR 14 and between the quantum well active layer 116 and the upper DBR 18 to adjust the length of the resonator. In addition to its function, it also has a function as a cladding layer for confining carriers.

  The p-type oxidized constricting layer 26 provided on the active layer region 16 is a current confining layer, and includes a non-oxidized region 26a and an oxidized region 26b. The current flowing from the p-side electrode pad 28 toward the n-side electrode wiring 30 is restricted by the non-oxidized region 26a.

  The upper DBR 18 formed on the oxidized constricting layer 26 is a multilayer film reflector configured by alternately and repeatedly stacking two semiconductor layers each having a film thickness of 0.25λ / n and having different refractive indexes. .

  On the upper DBR 18 of the light emitting units 50-1, 50-2, and 50-4, an emission surface protection layer 24 that protects the light emission surface is provided. The emission surface protective layer 24 is formed by depositing a silicon nitride film as an example. On the other hand, the upper DBR 18 of the light emitting unit 50-3 is covered with the p-side electrode wiring 22, and the portion corresponding to the emission surface protective layer 24 of the light emitting units 50-1, 50-2, 50-4 is a metal film. It becomes the shielding part 32 by. That is, the light exit of the light emitting unit 50-3 is shielded.

As shown in FIGS. 1A and 1B, an interlayer insulating film 20 as an inorganic insulating film is formed around the semiconductor layer including the mesa of the light emitting unit 50. The interlayer insulating film 20 is disposed below the p-side electrode wiring 22 and the p-side electrode pad 28. As an example, the interlayer insulating film 20 according to the present embodiment is formed of a silicon nitride film (SiN film). The material of the interlayer insulating film 20 is not limited to a silicon nitride film, and may be, for example, a silicon oxide film (SiO ₂ film) or a silicon oxynitride film (SiON film).

  As shown in FIG. 1A, in the light emitting unit 50-1 (the same applies to the light emitting units 50-2 and 50-4), the p-side electrode wiring 22 is connected to the upper DBR 18 through the opening of the interlayer insulating film 20. Has been. A contact layer 124 (see FIG. 5) for connection to the p-side electrode wiring 22 is provided on the uppermost layer of the upper DBR 18, and one end side of the p-side electrode wiring 22 is connected to the upper DBR 18 via the contact layer 124. Connected to form an ohmic contact with the upper DBR 18.

  By the way, the VCSEL that constitutes the light emitting unit 50 (light emitting units 50-1, 50-2, 50-4) of the optical module 10 can extract laser output in a direction perpendicular to the substrate, and is further arrayed by two-dimensional integration. For example, it is suitably used as a light source for optical communication.

  The optical module includes a pair of distributed Bragg reflectors (lower DBR 14 and upper DBR 18) provided on a semiconductor substrate (substrate 12), and an active layer region (active layer region 16) provided between the pair of distributed Bragg reflectors. It is configured with. Then, current is injected into the active layer region by the electrodes (p-side electrode wiring 22 and n-side electrode wiring 30) provided on both sides of the distributed Bragg reflector, thereby causing laser oscillation perpendicular to the substrate surface. The light oscillated from the upper part (the surface side of the emission surface protective layer 24) is emitted.

  In addition, an oxide constriction layer (oxidation constriction layer 26) formed by oxidizing a semiconductor layer containing Al in the composition is provided from the viewpoint of lower threshold current, controllability of the transverse mode, and the like. In order to oxidize the element, the element is etched into a mesa shape and subjected to an oxidation treatment. Thereafter, the mesa-shaped side surfaces exposed by etching and the etched semiconductor surface are generally covered with an insulating material such as a silicon nitride film or a silicon oxide film.

  On the other hand, a light emitting element including a semiconductor laser such as a VCSEL, or generally an LED (Light Emitting Diode) has a unique lifetime. In a device such as an optical communication system using a light emitting element, when the light emitting element is near the end of its life, it must be replaced before a serious failure occurs. Therefore, it is necessary to constantly monitor the light emitting element and detect the deterioration of the light emitting element. The light emitting element may be driven by constant current (or constant voltage drive) in order to make the light output constant. Detection of the deterioration of the light emitting element in such a driving system is performed by, for example, detecting the light output of the light emitting element. Monitoring is performed when the light output becomes less than a predetermined threshold value.

  On the other hand, semiconductor lasers, not limited to VCSELs, may be required to be stabilized so that the optical output does not fluctuate due to temperature fluctuations, power supply fluctuations, and the like. APC (Automatic Power) is one of the stabilization methods. There is a control method. In the APC method, the optical output of the semiconductor laser is detected as a monitor current by a monitor PD (Photo Diode) or the like, the detected monitor current is compared with a reference value, a difference value is obtained, and a drive current is obtained using this difference value. This is a method for performing negative feedback control on the optical output of the semiconductor laser.

  Even if the optical output of the semiconductor laser is controlled to be constant by the APC method, if the semiconductor laser deteriorates with time, the drive current of the semiconductor laser increases and cannot be controlled. Therefore, when the APC control method is used in a device including a light emitting element, for example, the deterioration of the light emitting element is detected when the driving current of the light emitting element exceeds a predetermined threshold.

  Regardless of whether the driving method of the light emitting element is a constant current (constant voltage) driving method or an APC driving method, if the deterioration of the light emitting element is detected, the user of the device on which the light emitting element is mounted is used. On the other hand, it is necessary to promote replacement of parts including the light emitting element. However, in the case of an optical module having a configuration for detecting deterioration of a light emitting element in order to promote replacement, if the deterioration is detected just before the light emitting element becomes unusable, the time until replacement is limited. It is assumed that

  As an optical module corresponding to the above assumption, an optical module according to the following comparative example can be considered. That is, in addition to the first light emitting element having the original light emitting function, the second light emitting element that deteriorates earlier can be connected in parallel with the first light emitting element, and the deterioration of the second light emitting element can be detected. This is an optical module. According to such an optical module, it is configured to detect the deterioration of the second light emitting element and prompt the user to replace it, so that there is a margin in the time until replacement.

  However, in the optical module according to the comparative example, the wavelength spectrum of the second light emitting element varies with the deterioration of the second light emitting element, so that the uniformity of the emission spectrum of the entire optical module decreases. When the uniformity of the wavelength spectrum is reduced, the transmission quality of the optical transmission device using the present optical module is deteriorated as compared with that before the second light emitting element is deteriorated.

  Therefore, in the present embodiment, the light emitting surface of the second light emitting element is shielded. Accordingly, no light is emitted from the optical module even when the second light emitting element is deteriorated, so that a decrease in the uniformity of the wavelength spectrum is suppressed.

  With reference to FIG. 2, a basic concept of detection of deterioration in the optical module 10 according to the present embodiment will be described. The optical module 10 has a plurality of light emitting units 50 including a light emitting unit 50 having a short lifetime. That is, in addition to the light emitting unit 50 that performs a normal light emitting operation in the mounted device (hereinafter, may be referred to as “normal light emitting unit 50n”), the light emission has a shorter lifetime than the normal light emitting unit 50n and monitors the deterioration of the normal light emitting unit 50n. Part 50 (hereinafter, sometimes referred to as “monitor light emitting part 50 m”). In the present embodiment, the monitor light emitting unit 50 m includes the shielding unit 32.

  FIG. 2A shows temporal changes in the light output of the light emitting units A, B, and C, which are three light emitting units having different lifetimes. The lifetimes of the light emitting part A, the light emitting part B, and the light emitting part C are assumed to be long in this order. In FIG. 2A, the change over time in the light output of the light emitting part A is represented by the curve PA, The change is represented by a curve PB, and the change over time of the light output of the light emitting unit C is represented by a curve PC. In FIG. 2A, the initial value of the light output of each light emitting unit is normalized by 1. In the present embodiment, the light emitting unit A is the normal light emitting unit 50n, and the light emitting unit B and the light emitting unit C are the monitor light emitting unit 50m. In addition, the light emission part A which comprises the normal light emission part 50n has the rated output which can output a light output required as the optical module 10 as the single light emission part A or the several light emission part A. FIG.

  Here, when the VCSEL array is configured by only the plurality of light emitting units A, the life of the plurality of light emitting units A comes at the same time, and it becomes difficult to use the optical module 10 any more. Then, even if it is attempted to prompt the user to replace the optical module 10 by detecting deterioration based on the light output indicated by the curve PA, there is a period until it becomes difficult to use when the deterioration of the light emitting unit A is detected. It is short and it is assumed that some users pass over the exchange before it becomes difficult to use.

  Therefore, in the optical module 10 according to the present embodiment, the light emitting unit B and the light emitting unit C having a shorter lifetime than the light emitting unit A are provided as the monitor light emitting unit 50m, and deterioration of the light emitting unit B or the light emitting unit C is detected. Thus, it is grasped that the lifetime as the optical module 10 is approaching. Then, notification that prompts the user to replace the optical module 10 is performed before the lifetime of the optical module 10 is reached (hereinafter, there is a case where “alert is issued”). As shown in FIG. 2A, the light emitting unit B is set to have a shorter lifetime than the light emitting unit A for the period t2, and the light emitting unit C is set to have a shorter lifetime than the light emitting unit B for the period t1. That is, the lifetime of the light emitting unit C is set shorter than that of the light emitting unit A by the period (t1 + t2). The periods t1 and t2 are not particularly limited, but may be set to, for example, about one month to two months because it is sufficient to allow a period until the user replaces the optical module 10. Thus, in the optical module 10 according to the present embodiment, the monitor light emitting unit 50m detects the deterioration earlier than the deterioration of the normal light emitting unit 50n.

  As will be described below, the monitor light emitting unit 50m may include only the light emitting unit B, only the light emitting unit C, or both the light emitting unit B and the light emitting unit C. In addition, a light emitting part having a shorter lifetime than the light emitting part C may be arranged. By arranging the monitor light emitting units 50m having a plurality of lifetimes, a step-by-step alert is issued.

  2B to 2F show an example of the arrangement of the normal light emitting unit 50n and the monitor light emitting unit 50m in the light emitting region 40 of the optical module 10. FIG. In the present embodiment, the arrangement of the normal light emitting unit 50n and the monitor light emitting unit 50m is not particularly limited. However, in FIGS. 2B to 2F, considering application to the optical transmission device 200 described later, An example of the arrangement assuming that the normal light emitting section 50n is coupled to an optical transmission line (such as an optical fiber) is shown. In addition, since the monitor light emission part 50m in this Embodiment does not radiate | emit light, you may arrange | position in any positions fundamentally.

  FIG. 2B shows three light emitting units A (light emitting units 50-1, 50-2, 50-3) which are normal light emitting units 50n, and a light emitting unit B (light emitting unit 50-4) which is a monitor light emitting unit 50m. ), A total of four light emitting portions are arranged. In this embodiment, the light emitting unit 50-4 is shielded from light. In the following, the light emitting parts B and C are shown smaller than the light emitting part A, but this is a schematic representation of the length of the life, and the actual physical size is not necessarily small.

  FIG. 2C shows two light emitting units A (light emitting units 50-1 and 50-4) which are normal light emitting units 50n and one light emitting unit B (light emitting unit 50-2) which is a monitor light emitting unit 50m. In this embodiment, one light emitting unit C (light emitting unit 50-3), which is the monitor light emitting unit 50m, is arranged, for a total of four light emitting units. In this embodiment, the light emitting units 50-2 and 50-3 are shielded from light. According to this arrangement form, since the alert from the light emitting unit B is issued after the alert from the light emitting unit C is issued, the alert is issued step by step. Further, it is easier to determine the deterioration of the optical module 10 when the number of the monitor light emitting units 50m is larger.

  FIG. 2D shows two light emitting units A (light emitting units 50-3 and 50-4) that are normal light emitting units 50n and one light emitting unit B (light emitting unit 50-2) that is a monitor light emitting unit 50m. In this embodiment, one light emitting unit C (light emitting unit 50-1), which is the monitor light emitting unit 50m, is arranged, for a total of four light emitting units. In this embodiment, the light emitting units 50-1 and 50-2 are shielded from light. According to this arrangement form, alerts are issued in stages.

  FIG. 2E shows four light emitting units A (light emitting units 50-1, 50-2, 50-3, and 50-4) that are normal light emitting units 50n, and a light emitting unit B (light emitting unit) that is a monitor light emitting unit 50m. One unit 50-5) is arranged in a total of five light emitting units. In this embodiment, the light emitting unit 50-5 is shielded from light. According to this arrangement form, the monitor light emitting unit 50m is surrounded by the normal light emitting unit 50n, and therefore the monitor light emitting unit 50m is arranged at a position that is susceptible to thermal interference from the normal light emitting unit 50n (a position where thermal crosstalk is large). Has been. Therefore, the lifetime of the monitor light emitting unit 50m is shortened compared to the normal light emitting unit 50n.

  FIG. 2 (f) shows three light emitting units A (light emitting units 50-2, 50-3, 50-4) which are normal light emitting units 50n, and a light emitting unit C (light emitting unit 50-1) which is a monitor light emitting unit 50m. ), A total of four light emitting portions are arranged. In this embodiment, the light emitting unit 50-1 is shielded from light. According to this arrangement form, since the life of the light emitting unit C is shorter than the life of the light emitting unit B, an alert is issued earlier than the optical module shown in FIG. Thus, according to the present embodiment, the alert emission timing is made different by selecting the monitor light emitting unit 50m to be used in consideration of the lifetime.

  In the above embodiment, there is no particular limitation on the relationship between the number of normal light emitting units 50n and the number of monitor light emitting units 50m. However, by increasing the number of normal light emitting units 50n to the number of monitor light emitting units 50m, Compared with the case where the number of 50n is smaller than the number of the monitor light emitting units 50m, the time until the life of the normal light emitting unit 50n is reached after the deterioration of the monitor light emitting unit 50m is detected (until the life of the light emitting module is reached). Time). That is, in the APC control method, after the monitor light emitting unit 50m reaches the end of its life, only the remaining normal light emitting unit 50n emits the same amount of light. Therefore, the larger the number of normal light emitting units 50n, the normal light emission. The increase in the amount of light per unit 50n is small. Therefore, as the number of normal light emitting units 50n increases, heat generation due to the increase in the amount of light is suppressed, and the time until the normal light emitting unit 50n reaches the lifetime becomes longer. As a result, a margin is created between the time until the life of the light emitting module is reached after the notification for prompting replacement, that is, the grace period until replacement.

  Next, a method for detecting deterioration in the optical module 10 according to the present embodiment will be described with reference to FIGS. In the optical module 10 according to the present embodiment, APC driving is adopted as the driving method of the light emitting region 40.

  FIG. 3A shows a circuit diagram of an optical module 10 a according to the present embodiment, which is configured by adding a drive circuit for the light emitting region 40 to the optical module 10. As shown in FIG. 3A, the optical module 10a includes a light emitting area 40a including a normal light emitting unit 50n and a monitor light emitting unit 50m as the optical module 10, a monitor PD 62, and an APC driving unit 60. . The anode (p-side electrode pad 28) of the normal light emitting unit 50n, the anode (p-side electrode pad 28) of the monitor light emitting unit 50m, and the cathode of the monitor PD 62 are connected to the power supply VDD. The APC drive unit 60 may be monolithically integrated with the optical module 10 or may be formed of a semiconductor element different from the optical module 10 and connected to each other by a bonding wire or the like. .

  The light emitting area 40a of the optical module 10a employs the same configuration as the light emitting area 40 shown in FIG. That is, three light emitting portions A as normal light emitting portions 50n (only one representative is shown in FIG. 3A) and one light emitting portion C as a monitor light emitting portion 50m are arranged. ing. In the present embodiment, the number of each of the normal light emitting unit 50n and the monitor light emitting unit 50m is not particularly limited, and at least one each may be disposed.

  The APC drive unit 60 is a drive circuit that drives the light emitting region 40a by the APC method. That is, the light output Po emitted from the light emitting region 40a (normal light emitting unit 50n) is received by the monitor PD 62, and the monitor current Im generated by the monitor PD 62 according to the light output Po is input to the APC driving unit 60. The APC drive unit 60 converts the monitor current Im into a voltage signal, and controls the drive current Id that flows through the light emitting region 40a based on the difference between the voltage signal and a reference voltage that indicates the target value of the optical output Po.

  As shown in FIG. 3A, in the optical module 10a, the normal light emitting unit 50n and the monitor light emitting unit 50m constituting the light emitting region 40a are connected in parallel, and the drive current Id is collectively applied to the four light emitting units 50 in total. Is flowing. However, in the optical module 10a according to the present embodiment, the monitor light emitting unit 50m shields light, so that the monitor PD 62 emits light from the three light emitting units A (light emitting units 50-2, 50-3, and 50-4). The light output Po obtained by combining the emitted light is received. The APC driving unit 60 also receives a modulation signal (not shown; for example, a transmission data signal of an optical transmission device to be described later) that modulates the optical output Po of the optical module 10a. This is the sum of the bias current for biasing 40a and the current of the transmission data signal.

  FIG. 3B shows the change with time of the drive current Id of the optical module 10a. As shown in FIG. 3C, the drive current Id of the optical module 10a starts from the drive current initial value Idi and shows a substantially constant value for a fixed period. However, the drive current Id fluctuates in order to keep the light output Po constant with the deterioration of the light emitting region 40a. Although the deterioration of the light emitting region 40a may be caused by the deterioration of the normal light emitting unit 50n, it is mainly caused by the deterioration of the monitor light emitting unit 50m.

  The drive current Id varies with the deterioration of the light emitting region 40a for the following reason. That is, in the light emitting region 40a according to the present embodiment, three light emitting units A and one light emitting unit C are connected in parallel. As shown in FIG. 2A, the light emitting part C deteriorates earlier than the light emitting part A, but the impedance of the light emitting part C changes with the deterioration. When the impedance of the light emitting unit C changes, the parallel impedance of the three light emitting units A and one light emitting unit C changes, so the magnitude of the driving current Id controlled by APC also changes.

  For example, when the impedance of the light emitting unit C increases, the current flowing through the light emitting unit A by APC control is constant, so the drive current Id decreases, and when the impedance of the light emitting unit C decreases, the drive current Id increases. In the optical module 10a, the deterioration of the light emitting region 40a is monitored by monitoring the fluctuation of the drive current Id. The direction of change in the impedance of the light emitting unit C (whether the impedance increases or decreases) differs depending on the deterioration mode, and the direction of change in the drive current Id corresponding to the change mode also varies. An example in which the value increases will be described.

  As shown in FIG. 3B, a drive current lower limit value Idmin and a drive current upper limit value Idmax indicating an allowable fluctuation range are set in advance with respect to the drive current initial value Idi. Of course, any one of the drive current lower limit value Idmin and the drive current upper limit value Idmax may be set. The setting of the drive current lower limit value Idmin and the drive current upper limit value Idmax may be performed in advance by experiment, simulation, or the like. Then, an alert is issued when the driving current lower limit value Idmin or the driving current upper limit value Idmax is deviated in the operating state of the optical module 10a. In the example shown in FIG. 3B, an alert is issued at time ta when the drive current Id exceeds the drive current upper limit value Idmax.

  Since the alert at time ta is from the light emitting unit C, which is the monitor light emitting unit 50m, in the optical module 10a, the monitor light emitting unit 50m gives an indication of deterioration before it becomes difficult to use the optical module 10a due to deterioration of the normal light emitting unit 50n. Detected and alerted. This increases the time margin for replacement by the user. In the optical module 10a according to the present embodiment, the monitor light emitting unit 50m is further shielded from light, so that the emitted light from the monitor light emitting unit 50m is not emitted from the optical module 10a. Therefore, it is suppressed that the uniformity of the spectrum decreases between the normal light emitting unit 50n and the monitor light emitting unit 50m due to the deterioration of the monitor light emitting unit 50m. As a result, for example, when the optical module 10a is applied to an optical transmission device, the quality of the transmission signal is suppressed from being deteriorated compared to before the deterioration of the monitor light emitting unit 50m.

  If the optical module 10a continues to operate even after an alert is issued at time ta, the drive current Id starts to increase due to the deterioration of the light emitting unit A after a certain time has elapsed. Therefore, an upper limit value of the drive current Id corresponding to the deterioration of the light emitting unit A may be further set, and for this upper limit value, for example, notification for requesting replacement to the user may be performed.

  Next, a drive control method for the optical module 10a will be described with reference to FIG. FIG. 4A shows a flow of an initial value setting process for setting a drive current initial value Idi that is an initial value of the drive current Id of the optical module 10a and a monitor current initial value Imi that is an initial value of the monitor current Im. For example, it is executed in advance by a manufacturer before shipment of a product. FIG. 4B is a flowchart showing a flow of a drive control process for controlling the drive current in the operating state of the optical module 10a, and is a process mainly executed during a period in which the user is using the optical module 10a.

  With reference to FIG. 4A, an initial value setting process according to the present embodiment will be described.

  First, in step S100, the drive current Id is supplied to the light emitting region 40a (normal light emitting unit 50n, monitor light emitting unit 50m) of the optical module 10a.

  In the next step S102, it is determined whether or not the optical output Po is within a specified value range, that is, whether or not the optical output Po is within an initial set value range. The initial setting value is set from, for example, the design conditions of the optical module 10a. If the determination is affirmative, the process proceeds to step S106. If the determination is negative, the process proceeds to step S104.

  In step S104, after adjusting the drive current Id so that the light output Po falls within the range of the specified value, the process returns to step S102 to determine again whether or not the light output Po is within the range of the specified value.

  In step S106, the drive current Id at that time is set as the drive current initial value Idi, and is stored in storage means such as a RAM (Random Access Memory) provided in the control unit 70. Further, the monitor current Im at that time is stored in the storage means as the monitor current initial value Imi. Thereafter, the initial value setting process ends.

  Next, with reference to FIG. 4B, a drive control process until an alert is issued in the optical module 10a will be described.

  First, in step S200, the drive current initial value Idi set in the initial value setting process is supplied as the drive current Id to the light emitting region 40a (normal light emitting unit 50n, monitor light emitting unit 50m) of the optical module 10a.

  In the next step S202, it is determined whether or not the monitor current Im is within a specified value range, more specifically, whether or not the monitor current Im is within a predetermined range centered on the monitor current initial value Imi. If the determination is negative, the process proceeds to step S204, the drive current Id is adjusted so that the monitor current Im is within the specified value range, and then the process returns to step S102, where the monitor current Im is set to the specified value again. It is determined whether it is within the range. The loop of steps S202 and S204 indicates APC control according to the present embodiment.

  On the other hand, when an affirmative determination is made in step S202, the process proceeds to step S206, and whether or not the drive current Id is within a specified value range, that is, the drive current Id is not less than the drive current lower limit value Idmin and not more than the drive current upper limit value Idmax It is determined whether it is within the range. For example, when the monitor light emitting unit 50m deteriorates and the impedance of the monitor light emitting unit 50m increases, the entire drive current Id supplied to the optical module 10a becomes smaller than the initial state. On the other hand, when the monitor light emitting unit 50m is deteriorated and the impedance of the monitor light emitting unit 50m is lowered, the entire drive current Id supplied to the optical module 10a is reduced to the initial state. Therefore, the deterioration state of the monitor light emitting unit 50m is determined by setting the drive current lower limit value Idmin and the drive current upper limit value Idmax.

  If the determination in step S206 is affirmative, the process returns to step S202, and it is determined again whether the monitor current Im is within the specified value range.

  On the other hand, if the determination in step S206 is negative, the process proceeds to step S208, where an alert is issued when the monitor current Im is outside the allowable range, and then the drive control process is terminated. Note that light emission from the optical module 10a is maintained by continuing APC control even after issuing an alert.

  The drive control in FIG. 4B is executed by the control unit 70 controlling the ACP drive unit 60 and the like. Further, the drive current lower limit value Idmin and the drive current upper limit value Idmax in step S206 are determined in advance by a manufacturer or the like, and the determination in step S206 is performed by hardware or software configuring the control unit 70. In the case of determination by hardware, a voltage signal representing the magnitude of the drive current Id from the power monitor unit 68 and a reference voltage value corresponding to the drive current lower limit value Idmin and the drive current upper limit value Idmax are compared by a comparator or the like. Judge by comparing with the circuit. On the other hand, when the determination is made by software, a processor such as a CPU for operating the software is provided, and a voltage signal indicating the magnitude of the drive current Id converted into a digital signal and a RAM provided in the control unit 70 are stored in advance. The stored drive current lower limit value Idmin and drive current upper limit value Idmax are compared and determined on software. That is, the control unit 70 functions as a detection unit that, together with the power monitor unit 68, detects that the monitor light emitting unit 50m has deteriorated.

  In the optical module 10a according to the present embodiment, an example in which the alert is issued by setting the drive current lower limit value Idmin and the drive current upper limit value Idmax with respect to the drive current Id has been described, but the current values are different. A plurality of drive current lower limit values Idmin and drive current upper limit values Idmax may be set, and alert notification contents and notification methods may be varied step by step for each upper limit value and lower limit value. For example, as the deterioration progresses, the user may be notified of a message or the like that more strongly requests replacement.

  Next, with reference to FIG. 5, the manufacturing method of the optical module 10 which concerns on this Embodiment is demonstrated. The optical module 10 includes four light emitting units 50 as shown in FIG. 1B. However, since the manufacturing process is the same except for the formation of the shielding unit 32, one of them will be described below. The light emitting unit 50 will be illustrated and described. In addition, the structure of the same name in FIG. 5 from which the code | symbol differs from FIG. 1 has the same function.

First, as shown in FIG. 5A, the film thickness of AlAs and GaAs on the substrate 110 made of n-type GaAs is changed to the in-medium wavelength λ ′ (= λ) by metal organic chemical vapor deposition (MOCVD). N-type lower DBR112 having a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ , lower spacer 114 made of undoped Al _0.22 Ga _0.78 As, and undoped quantum. The thickness of the well active layer 116 (consisting of three 80 nm thick InGaAs quantum well layers and four 150 nm thick GaAs barrier layers) and the upper spacer 118 made of undoped Al _0.22 Ga _0.78 As is the medium. 'active layer region 130 serving as, on its carrier concentration 1 × 10 ¹⁸ cm ^-3, thickness medium wavelength lambda' inner wavelength lambda p-type AlAs layer 120 which is 1/4 of, a thereon _0.9 Ga _0.1 As and a carrier concentration each film thickness and GaAs were alternately 22 periodically laminated so that 1/4 of the medium wavelength ^{λ '1 × 10 18 cm -3} , the total film thickness of about 2μm A p-type upper DBR 122 and a p-type GaAs contact layer 124 with a film thickness of 1 × 10 ¹⁹ cm ⁻³ and an in-medium wavelength λ ′ are sequentially stacked thereon.

  The source gas is trimethylgallium, trimethylaluminum, trimethylindium, arsine, the dopant material is cyclopentadinium magnesium for p-type and silane for n-type, the substrate temperature during growth is 750 ° C., and vacuum is used. Without breaking, the source gas was changed sequentially, and the film was formed continuously.

  Next, as shown in FIG. 5B, the laminated film is etched partway through the lower DBR 112 to form a mesa 126 to expose the side surface of the AlAs layer 120. In order to process the mesa shape, a resist mask R was formed on the crystal growth layer by photolithography, and reactive ion etching using carbon tetrachloride as an etching gas was used.

  Thereafter, the resist mask R is removed, and as shown in FIG. 5C, only the AlAs layer 120 is oxidized from the side by water vapor in a furnace at about 400 ° C. to increase the resistance, and the oxidized region 132 and the non-oxidized region 120a. The diameter of the non-oxidized region 120a is about 3 μm as an example. This non-oxidized region 120a becomes a current injection region.

  Thereafter, as shown in FIGS. 5D and 5E, an interlayer insulating film 134 made of SiN is vapor-deposited except for the upper surface of the mesa 126, and the resist mask R is used to remove the emission port 140 and start from Ti / Au. A p-side electrode wiring 136 is formed. At this time, the resist mask R is not formed for the mesa 126 which is the monitor light emitting unit 50m, and the shielding unit 32 made of Ti / Au is formed. Further, Au / Ge is vapor-deposited as the n-side electrode wiring 138 on the back surface of the substrate 110. In this way, the optical module 10 shown in FIG. 5F is completed. In this embodiment mode, an example in which the current confinement structure is formed by oxidation has been described as an example. However, the present invention is not limited to this, and the current confinement structure may be formed by ion implantation.

  Next, a method for manufacturing the monitor light emitting unit 50m in the present embodiment will be described. In the present embodiment, the normal light emitting portion 50n is manufactured by the normal manufacturing process described above. On the other hand, the monitor light emitting unit 50m uses any one of the following methods 1 to 5 or a method in which a plurality of methods 1 to 5 are selected and combined, and the life of the normal light emitting unit 50n is reduced. Is manufactured so as to shorten the length.

  Method 1: The oxidized aperture diameter (current constriction diameter) in the normal light emitting portion 50n is varied. The oxidized aperture diameter is the diameter of the non-oxidized region 26a (non-oxidized region 120a) that is substantially circular. The diameter of the oxidized aperture is usually about 3 to 10 μm, but the diameter of the oxidized aperture is about 2 μm smaller than this diameter. The smaller the aperture diameter, the shorter the life. This is because the resistance to the current flowing through the non-oxidized region 26a increases, so that heat generation in the monitor light emitting unit 50m increases, and the junction temperature of the monitor light emitting unit 50m increases.

  Method 2: The stress applied to the light emitting part is made different from that of the normal light emitting part 50n. As a specific method for making the stress relating to the light emitting portion different, for example, at least one of the thickness, area, and shape of the interlayer insulating film 20 (interlayer insulating film 134) may be different. At that time, it is preferable that the shape of the normal light-emitting portion 50n and the shape of the monitor light-emitting portion 50m are the same in order to easily manage the difference in stress. Here, “same” is a concept including variations such as manufacturing variations. According to the method 2, even if the normal light emitting unit 50n and the monitor light emitting unit 50m have the same oxidized aperture diameter, the lifetimes are different. Note that the specific thickness, area, and shape are determined by experiments, simulations, or the like after determining how short the lifetime of the monitor light emitting unit 50m is to be set compared to the normal light emitting unit 50n. That's fine.

  Method 3: The monitor light emitting unit 50m is arranged at a position where the thermal crosstalk is larger than any of the normal light emitting units 50n. This method will be described with reference to FIGS. FIG. 6 is a diagram showing the p-side electrode wiring 22, the normal light emitting unit 50 n, and the monitor light emitting unit 50 m that form the light emitting region 40. The position where the thermal crosstalk is large refers to a position where the monitor light emitting unit 50m receives a large thermal stress from the normal light emitting unit 50n. More specifically, as shown in FIG. 6A, the monitor light emitting unit 50m is sandwiched between the normal light emitting units 50n. As shown in FIGS. 6B and 6C, the monitor light emitting unit 50m The form which arrange | positions the normal light emission part 50n around is mentioned.

  Method 4: The monitor light emitting unit 50m is arranged at a position surrounded by the normal light emitting unit 50n.

  Method 5: Arrangement is made such that the minimum value of the distance between the monitor light emitting unit 50m and one of the normal light emitting units 50n is larger than the maximum value of the distance between adjacent light emitting units in the normal light emitting unit 50n. Since the monitor light emitting unit 50m does not emit light, it is not necessary to arrange the monitor light emitting unit 50m at a position where it is optically coupled to the outside like the normal light emitting unit 50n. Conversely, if the monitor light emitting unit 50m is arranged at a position where it is optically coupled to the outside, the temperature rise of the normal light emitting unit 50n is promoted. Therefore, the monitor light emitting unit 50m is arranged apart from the normal light emitting unit 50n. In this case, the direction of separation may be any direction. Specific arrangements include arrangements as shown in FIGS. 6D and 6E. Circles indicated by reference symbol C in FIGS. 6D and 6E indicate positions of a core 302 of an optical fiber 300 described later.

  FIG. 6D shows an example in which two normal light emitting units 50 n and one monitor light emitting unit 50 m are arranged apart from each other in the extending direction of the p-side electrode wiring 22. As shown in FIG. 6D, in this example, the normal light emitting part 50n is arranged so as to be positioned at the approximate center of the core, and the monitor light emitting part 50m is shifted in the extending direction of the p-side electrode wiring 22 so as to be separated from the core. Yes. FIG. 6E shows an example in which three normal light emitting units 50n and one monitor light emitting unit 50m are arranged in the same way of thinking.

[Second Embodiment]
With reference to FIG. 7 and FIG. 8, the optical module 10b which concerns on this Embodiment is demonstrated. While the optical module 10a according to the above embodiment employs the APC driving method, the optical module 10b employs a constant current driving method. In this embodiment, a constant voltage driving method may be used instead of the constant current driving method.

  FIG. 7A shows an optical module 10b including a drive circuit for the light emitting region 40a. As shown in FIG. 7A, the optical module 10b includes a light emitting region 40a, a monitor PD 62, a constant current drive unit 64, and a power monitor unit 66. Since the light emitting area 40a is the same as the light emitting area 40a of the optical module 10a according to the above embodiment, the description thereof is omitted.

  The constant current driver 64 is a part that drives the light emitting region 40a with a constant current by a constant current source (not shown). A signal for modulating the light output Po emitted from the light emitting region 40a, for example, a transmission data signal, is input to the constant current driver 64, but is not shown in FIG. 7A. The drive current Id is a current obtained by adding the bias current and the current due to the transmission data signal. The constant current drive unit 64 according to the optical module 10b controls the optical output Po while keeping the bias current constant.

  The power monitor unit 66 includes, for example, a current-voltage conversion circuit, and converts the monitor current Im generated in the monitor PD 62 into a voltage signal in accordance with the light output Po of the light emitting region 40a, whereby the light output of the light emitting region 40a. Monitor Po.

  As in the first embodiment, the control unit 72 is configured by hardware or software, and detects deterioration of the optical module 10b based on a voltage signal representing the magnitude of the monitor current Im. That is, the control unit 72 functions as a detection unit that detects the deterioration of the monitor light emitting unit 50m included in the optical module 10b together with the power monitoring unit 66.

  FIG. 7B shows a change with time of the monitor current Im. As shown in FIG. 7B, the monitor current Im changes at the monitor current initial value Imi for a certain period after the operation start of the optical module 10b, and fluctuates with deterioration of the light emitting unit 50 included in the light emitting region 40a. In the optical module 10b, the light emitting area 40a is monitored by the fluctuation of the monitor current Im to detect deterioration.

  The reason why the monitor current Im varies in the optical module 10b shown in FIG. 7A is that the impedance of the monitor light emitting unit 50m changes with the deterioration of the monitor light emitting unit 50m. The direction in which the impedance of the monitor light emitting unit 50m changes (whether the impedance increases or decreases) differs depending on the deterioration mode. For example, when the impedance of the monitor light emitting unit 50m increases with the deterioration of the monitor light emitting unit 50m, the value of the drive current Id is constant, so that the current flowing through the normal light emitting unit 50n increases. Then, since the light output Po from the normal light emitting unit 50n increases, the monitor current Im increases.

  FIG. 7B shows a change with time of the monitor current Im when the monitor current Im increases with the deterioration of the monitor light emitting unit 50m. In the present embodiment, two types of threshold values are set as threshold values for determining the fluctuation of the monitor current Im. That is, the first monitor current minimum value Immin1 and the first monitor current maximum value Immax1 indicating the first fluctuation range, the second monitor current minimum value Immin2 and the second monitor current maximum value Immax1 indicating the fluctuation range larger than the first fluctuation range. This is the monitor current maximum value Immax2. In the example shown in FIG. 7B, the first alert is issued when the first monitor current maximum value Immax1 is exceeded at time ta1, and the second monitor current maximum value Immax2 is exceeded at time ta2. A second alert is issued. The second alert is, for example, notification of a message or the like that requests replacement more strongly than the first alert. In the present embodiment, an alert due to deterioration of the monitor light emitting unit 50m is generated before the deterioration of the normal light emitting unit 50n is detected, so that a grace period until replacement by the user is secured and the monitor light emitting unit 50m is shielded from light. Therefore, a decrease in the uniformity of the wavelength spectrum of the optical module 10b is suppressed.

  Note that specific values of the first monitor current minimum value Immin1 and the first monitor current maximum value Immax1 are, for example, within a range of variation of ± 10% from the monitor current initial value Imi, and the second monitor current minimum value Immin2 The specific value of the second monitor current maximum value Immax2 may be set, for example, as a range of variation ± 50% from the monitor current initial value Imi.

  Next, a drive control method for the optical module 10b will be described with reference to FIG. FIG. 8A shows a drive current initial value Idi and a monitor current initial value Imi, which are initial values of the drive current Id of the optical module 10b, and the first monitor current minimum value Immin1 and the first monitor current. It is a flowchart which shows the flow of the initial value setting process for setting maximum value Immax1, 2nd monitor current minimum value Immin2, and 2nd monitor current maximum value Immax2. On the other hand, FIG. 8B is a flowchart showing the flow of the drive control process for controlling the drive current in the operating state of the optical module 10b.

  As shown in FIG. 8A, the initial value setting process of the optical module 10b is the same as the initial value setting process of the optical module 10a according to the embodiment shown in FIG. 4 from step S100 to step S106. Therefore, the same reference numerals are given to the steps of the same processing, and the description is omitted.

  In the subsequent step S108, the first monitor current minimum value Immin1, the first monitor current maximum value Immax1, the second monitor current minimum value Immin2, the second monitor current based on the monitor current initial value Imi set in step S106. The maximum value Immax2 is calculated and stored in the storage means provided in the control unit 72. The first monitor current minimum value Immin1, the first monitor current maximum value Immax1, the second monitor current minimum value Immin2, and the second monitor current maximum value Immax2 are set by the experiment, simulation, or the like. Alternatively, a coefficient indicating the ratio to the above may be obtained and set by multiplying the set monitor current initial value Imi by the coefficient.

  Next, with reference to FIG. 8B, a drive control process until an alert is issued in the optical module 10b will be described.

  First, in step S300, the drive current Id is set to the drive current initial value Idi set in the initial value setting process.

  In the next step S302, it is determined whether or not the monitor current Im is in the range of the first monitor current minimum value Immin1 or more and the first monitor current maximum value Immax1 or less. If the determination is affirmative, step S302 is looped and the operation of the optical module 10b is continued.

  On the other hand, if a negative determination is made in step S302, the process proceeds to step S304.

  In step S304, the first alert is issued when the monitor current Im is out of the range of the first monitor current minimum value Immin1 or more and the first monitor current maximum value Immax1 or less. For example, the user is requested to replace the optical module 10b (notifies the life of the optical module 10b).

  In the next step S306, it is determined whether or not the monitor current Im is in the range of the second monitor current minimum value Immin2 or more and the second monitor current maximum value Immax2 or less. If the determination is affirmative, only the first alert is issued and the operation of the optical module 10b is continued.

  On the other hand, if a negative determination is made in step S306, the process proceeds to step S308, and a second alert is issued. The second alert is, for example, notification of a message or the like that requests replacement more strongly than the first alert. And while continuing operation | movement of the optical module 10b, the drive control process for issuing the alert which concerns on this Embodiment is complete | finished.

[Third Embodiment]
With reference to FIG. 9 and FIG. 10, an optical transmission apparatus 200 according to the present embodiment will be described. The optical transmission apparatus 200 is an apparatus that constitutes an optical transmission unit of a communication apparatus that performs optical communication with each other via an optical fiber. The optical transmission apparatus 200 includes the optical modules (optical modules 10, 10a, and 10b) according to the above embodiments. Yes. In the present embodiment, a mode in which the optical module 10 is mounted will be described below as an example.

  FIG. 9A is a plan view of the optical transmission apparatus 200, and FIG. 9B is a cross-sectional view. As shown in FIGS. 9A and 9B, the optical transmission apparatus 200 includes the optical module 10, the monitor PD 62, the submount 214, and a package on which these configurations are mounted. The package of the optical transmission device 200 includes a stem 202, a cap 204, a cathode terminal 216, anode terminals 218 and 219 (not hidden by the anode terminal 218 in FIG. 9B), and a cathode terminal 220. Yes.

  The submount 214 is a substrate on which the optical module 10, the monitor PD 62, and the like are mounted, and is configured by, for example, a semiconductor substrate. Further, an n-side wiring 212 is formed of a metal film or the like on the mounting surface side of the submount 214 such as the optical module 10 and the n-side electrode wiring 30 of the optical module 10 is connected.

  The stem 202 is a metal base on which the submount 214 is mounted, and holds a cathode terminal 216, anode terminals 218 and 219, and a cathode terminal 220. The cathode terminal 216 and the anode terminals 218 and 219 are held on the stem through necessary insulating portions, but the cathode terminal 220 is directly brazed to the stem 202 (at the same potential).

  As shown in FIG. 9A, the p-side electrode pad 28 of the optical module 10 is connected to the anode electrode 208 by a bonding wire, and is connected to the outside (driving power source or the like) via the anode terminal 218. On the other hand, the n-side electrode wiring 30 of the optical module 10 is connected to the cathode electrode 210 via the n-side wiring 212 and the bonding wire, and is connected to the outside (drive power supply etc.) via the cathode terminal 216.

  The anode of the monitor PD 62 is connected to the anode electrode 206 via a bonding wire, and is connected to the outside (drive power supply etc.) via the anode terminal 219. On the other hand, the cathode of the monitor PD 62 is connected to the stem 202 by a bonding wire, and is connected to the outside (driving power source or the like) via the cathode terminal 220.

  The cap 204 hermetically seals a semiconductor element or the like mounted on the submount 214, and is formed of metal in this embodiment. The cap 204 is formed with an opening through which the optical output Po from the optical module 10 passes, and the partial reflection mirror 222 is attached to the opening. Most of the light output Po passes through the partial reflection mirror 222 and is output to the outside (an optical fiber described later in the present embodiment), but a part (for example, about 10%) is reflected by the partial reflection mirror 222. Then, it enters the monitor PD 62 as monitor light Pm. The monitor current Im described above is generated by the monitor light Pm.

  The semiconductor elements constituting the control unit 70, the APC driving unit 60, the constant current driving unit 64, the power monitoring unit 66, etc., and necessary passive components such as resistors and capacitors are connected via the cathode terminal 216 and the anode terminals 218 and 219. Are mounted on a control board 74 connected to the optical module 10 and the monitor PD 62 to constitute the optical transmission device 200. The control unit 70, the APC drive unit 60, and the like may be mounted on the submount 214.

  In addition, the optical transmission device 200 includes display means such as a display 76 and a warning light that function as a notification unit, and notifies the user that an alert has been issued based on an instruction from the control unit 70. In addition, as long as the configuration has a function of notifying the user, other configurations such as audio means may be used.

  Next, the coupling between the optical module 10 and the optical fiber 300 will be described with reference to FIG. FIG. 10A is a cross-sectional view showing a coupling state between the optical module 10 and the optical fiber 300, and FIG. 10B is a plan view. As the optical fiber 300 according to the present embodiment, a single mode fiber, a multimode fiber, a plastic fiber, or the like is used without particular limitation, but in this embodiment, a multimode fiber is used.

  As shown in FIG. 10A, the optical fiber 300 includes a core 302 and a clad 304. As shown in FIGS. 10A and 10B, the light emitting unit 50 of the optical module 10 is arranged so that the light output Po is incident on the core 302 of the optical fiber 300. In the present embodiment, no lens is used for coupling the optical module 10 and the optical fiber 300. However, the present invention is not limited to this, and the optical module 10 and the optical fiber 300 may be coupled using a lens.

  Here, in the above embodiment, the optical transmission device 200 mounted in a can-type package has been described as an example. However, the present invention is not limited to this, and an optical transmission device mounted in a flat package may be used.

  In the optical modules 10, 10 a, 10 b and the optical transmission device 200 according to the above-described embodiment, the monitor light emitting unit 50 m is shielded in order to suppress a decrease in spectral uniformity in the optical output Po from the optical module, and the monitor light emitting unit The light was not emitted from 50 m. Since the monitor light emitting unit 50m from which light is not emitted does not need to be coupled to the optical fiber 300, the optical transmission apparatus may be configured in consideration of only the position of the normal light emitting unit 50n without considering the position of the monitor light emitting unit 50m. Conceivable. Hereinafter, the arrangement form according to this configuration method will be described as a method for manufacturing the optical transmission device and the monitor light emitting unit 50m according to the present embodiment. Since the optical transmission apparatus according to the present embodiment is the same as the optical transmission apparatus 200 except for the arrangement of the monitor light emitting unit 50m, the illustration will be omitted with reference to FIGS.

Method 6: The normal light emitting unit 50n is disposed closer to the center of the core than the monitor light emitting unit 50m. FIG. 11A shows a form in which the normal light emitting unit 50n and the monitor light emitting unit 50m are arranged by this method. As shown in FIG. 11A, in the present embodiment, the normal light emitting unit 50n is arranged at the approximate center of the core, whereas the monitor light emitting unit 50m is arranged at a position shifted from the center. In this way, if the normal light emitting unit 50n is arranged closer to the center of the core considering only the position of the normal light emitting unit 50n, the normal light emitting unit 50n and the monitor light emitting unit 50m are located at the center of the core. On the other hand, the light emitted from the optical module is easily coupled to the core of the optical fiber as compared with the configuration having the same distance.
Method 7: The position of the center of gravity G of the plurality of normal light emitting units 50n is arranged closer to the center of the core of the optical transmission path than the position of the monitor light emitting unit 50m. FIGS. 11B and 11C show examples of the light emitting region 40 arranged by this method. As described above, when there are a plurality of normal light emitting units 50n, the center of gravity is arranged closer to the center of the optical fiber core than the monitor light emitting unit 50m, thereby including both the normal light emitting unit 50n and the monitor light emitting unit 50m. Compared with a configuration in which the center of gravity of the light emitting portion is arranged at the center of the core of the optical fiber, the light emitted from the optical module is easily coupled to the core of the optical fiber.

[Fourth Embodiment]
Hereinafter, the optical transmission apparatus according to the present embodiment will be described. In the optical modules 10, 10 a, 10 b and the optical transmission device 200 according to the above-described embodiment, the monitor light emitting unit 50 m is shielded in order to suppress a decrease in spectral uniformity in the optical output Po from the optical module, and the monitor light emitting unit The light was not emitted from 50 m. In this embodiment, the emission port of the monitor light emitting unit 50m is not shielded, and instead of shielding the monitor light emitting unit 50m, the arrangement is considered so that the emitted light from the monitor light emitting unit 50m is not easily coupled to the optical fiber. It is a form. Accordingly, the following description will be made as an embodiment of a method for manufacturing the monitor light emitting unit 50m according to the present invention. The optical transmission apparatus 200a according to the present embodiment is the same as the optical transmission apparatus 200 except for the arrangement and structure of the monitor light emitting unit 50m. Omitted.

  Method 8: The normal light emitting unit 50n is arranged so that the light emitted from the normal light emitting unit 50n is incident on the core of the optical fiber 300, and the monitor light emitting unit 50m is arranged to receive the light emitted from the monitor light emitting unit 50m. It arrange | positions in the position which is not incident on the core of the optical fiber 300. FIG. Specifically, for example, as shown in FIGS. 6D and 6E, the monitor light emitting unit 50m is arranged at a position that does not overlap with the core of the optical fiber. In this way, compared with the configuration in which the monitor light emitting unit 50m is positioned so as to overlap the core of the optical fiber, the emitted light from the monitor light emitting unit 50m is less likely to be coupled to the optical fiber. As a result, even if the emission port of the monitor light emitting unit 50m is not shielded, the change in the spectrum of light coupled to the optical fiber when the spectrum of the monitor light emitting unit 50m changes is suppressed.

  As described above, the optical transmission apparatus according to the present embodiment also ensures a grace period until the user replaces the optical module, and suppresses a decrease in the uniformity of the wavelength spectrum of the optical module.

  In each of the above-described embodiments, the embodiment using the light emitting element array in which each light emitting portion is formed monolithically has been described as an example. However, the present invention is not limited to this, and the embodiment using individual light emitting elements as each light emitting portion. It is good.

10, 10a, 10b Optical module 12 Substrate 14 Lower DBR
16 Active layer region 18 Upper DBR
20 Interlayer insulating film 22 P-side electrode wiring 24 Emission surface protective layer 26 Oxide constriction layer 26a Non-oxidized region 26b Oxidized region 28 p-side electrode pad 30 n-side electrode wiring 32 Shielding portion 40, 40a Light emitting region 50, 50-1, 50 -2, 50-3, 50-4 Light emitting part 50n Normal light emitting part 50m Monitor light emitting part 60 APC driving part 62 Monitor PD
64 Constant current drive units 66, 68 Power monitor units 70, 72 Control unit 74 Control board 76 Display 90 Optical module 110 Substrate 112 Lower DBR
114 Lower spacer 116 Quantum well active layer 118 Upper spacer 120 AlAs layer 120a Non-oxidized region 122 Upper DBR
124 Contact layer 126 Mesa 130 Active layer region 132 Oxidized region 134 Interlayer insulating film 136 P-side electrode wiring 138 n-side electrode wiring 140 Outgoing port 200, 200a Optical transmission device 202 Stem 204 Cap 206, 208 Anode electrode 210 Cathode electrode 212 n-side Wiring 214 Submount 216 Cathode terminal 218, 219 Anode terminal 220 Cathode terminal 222 Partial reflection mirror 300 Optical fiber 302 Core 304 Clad C Core position G Center of gravity Id Driving current Idmin Driving current lower limit Idmax Driving current upper limit Idi Driving current initial value Im Monitor current Imi Monitor current initial value Immin1 First monitor current minimum value Immax1 First monitor current maximum value Immin2 Second monitor current minimum value Immax2 Second monitor current maximum value PA , PB, PC Light output Po Light output Pm Monitor light R Resist mask VDD Power supply

Claims (13)

A first light emitting element that emits light;
A second light-emitting element connected in parallel with the first light-emitting element and configured to be deteriorated earlier than the first light-emitting element, wherein the light emission port is shielded;
A detection unit for detecting that the second light emitting element has deteriorated;
An optical transmission device comprising: A drive unit that drives the first light emitting element so that the amount of light emitted from the first light emitting element is constant;
In the detection unit, the second light emitting element deteriorates when a value of a current or a voltage output from the driving unit to the first light emitting element and the second light emitting element is out of a predetermined range. The optical transmission device according to claim 1, wherein the optical transmission device is detected. A light receiving portion for receiving light emitted from the first light emitting element;
A driving unit that drives the first light emitting element and the second light emitting element at a constant voltage or a constant current;
The optical transmission device according to claim 1, wherein the detection unit detects that the second light emitting element has deteriorated when the amount of light received by the light receiving unit is out of a predetermined range. The optical transmission device according to claim 1, wherein the number of the first light emitting elements is larger than the number of the second light emitting elements. The first light emitting element and the second light emitting element have the same shape and an insulating film is provided around each of them.
The at least one of thickness, area, and shape differs between the insulating film around the first light emitting element and the insulating film around the second light emitting element. An optical transmission device according to 1. The optical transmission device according to any one of claims 1 to 5, wherein the second light emitting element is disposed at a position where thermal crosstalk is larger than any of the first light emitting elements. A plurality of the first light emitting elements;
The optical transmission device according to any one of claims 1 to 5, wherein the second light emitting element is disposed at a position surrounded by the plurality of first light emitting elements. The first light emitting element and the second light emitting element have a current confinement structure,
The optical transmission device according to claim 1, wherein the current confinement diameter of the second light emitting element is smaller than the current confinement diameter of the first light emitting element. A plurality of the first light emitting elements;
The minimum value of the distance between the second light emitting element and one of the first light emitting elements is larger than the maximum value of the distance between adjacent light emitting elements in the plurality of first light emitting elements. The optical transmission device according to claim 8.   10. The optical transmission device according to claim 1, further comprising: a notification unit that performs notification when the detection unit detects that the second light emitting element is deteriorated. 11. Having an optical transmission line including a core that propagates light;
The optical transmission device according to claim 10, wherein the first light emitting element is disposed closer to the center of the core than the second light emitting element. A plurality of the first light emitting elements;
The optical transmission device according to claim 11, wherein the center of gravity of the plurality of first light emitting elements is disposed closer to the center of the core of the optical transmission path than the position of the second light emitting element. . A first light emitting element that emits light;
A second light emitting element that emits light, connected in parallel with the first light emitting element and configured to degrade faster than the first light emitting element;
A detection unit that detects that the second light emitting element has deteriorated,
The first light emitting element is disposed at a position overlapping with the core of the optical transmission path, and the second light emitting element is disposed at a position not overlapping with the core of the optical transmission path.