WO2013186834A1 - Olt optical transmitter and temperature control method for olt optical transmitter - Google Patents

Olt optical transmitter and temperature control method for olt optical transmitter Download PDF

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Publication number
WO2013186834A1
WO2013186834A1 PCT/JP2012/064909 JP2012064909W WO2013186834A1 WO 2013186834 A1 WO2013186834 A1 WO 2013186834A1 JP 2012064909 W JP2012064909 W JP 2012064909W WO 2013186834 A1 WO2013186834 A1 WO 2013186834A1
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Prior art keywords
temperature
target value
emitting element
light emitting
optical transmitter
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PCT/JP2012/064909
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French (fr)
Japanese (ja)
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正道 野上
晋 庵原
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三菱電機株式会社
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Priority to PCT/JP2012/064909 priority Critical patent/WO2013186834A1/en
Publication of WO2013186834A1 publication Critical patent/WO2013186834A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H01S5/06804—Stabilisation of laser output parameters by monitoring an external parameter, e.g. temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/024—Arrangements for thermal management
    • H01S5/02407—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling
    • H01S5/02415—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling by using a thermo-electric cooler [TEC], e.g. Peltier element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/0617—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium using memorised or pre-programmed laser characteristics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters

Definitions

  • the present invention relates to an optical communication system, and in particular, an OLT optical transmitter in a station-side terminal device (OLT) of a PON (Passive Optical Network) system, which is one of access optical communication systems, and
  • OLT station-side terminal device
  • PON Passive Optical Network
  • a point-to-multipoint access optical communication system called a PON system has been widely used as a system for realizing a public network using an optical fiber.
  • FIG. 6 is a configuration diagram of a general PON system. As shown in FIG. 6, the PON system is composed of one OLT as a station side device and ONUs (Optical Link Units) as a plurality of subscriber terminal devices connected via an optical star coupler. .
  • OLT optical Local Area Network
  • ONUs Optical Link Units
  • the optical star coupler which is a passive component, has the advantages that it does not require power supply, is easy to install outdoors, and has high reliability. Therefore, in recent years, PON systems have been actively introduced as a trump card for realizing a broadband network.
  • 10G-EPON (10 Gigabit-Ethernet (registered trademark) Passive Optical Network), which is standardized by IEEE 802.3av and capable of communication at a transmission rate of 10 Gbit / s, download from OLT to ONU
  • the 10G signal uses a broadcast communication system based on the 1.58 ⁇ m band.
  • the 10G signal uses the optical wavelength 1.27 ⁇ m band and uses a time division multiplex communication system that controls the transmission timing so that the data of each ONU does not collide.
  • An OLT optical transmitter includes a light emitting element that emits light according to an input current, a cooling element that is controlled so that the light emitting element is within a desired temperature range, and a temperature on the light emitting element side of the cooling element.
  • a first temperature detector that detects the temperature as the internal temperature
  • a second temperature detector that detects the temperature on the opposite side of the light emitting element of the cool / warm element as an external temperature
  • an external temperature detected by the second temperature detector And a target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within a desired temperature range, and the internal temperature detected by the first temperature detector is the target value setting.
  • the temperature control method for an OLT optical transmitter includes a light emitting element that emits light according to an input current, a cooling element that is controlled so that the light emitting element is within a desired temperature range, and a cooling element.
  • a first temperature detector that detects the temperature on the light emitting element side as an internal temperature
  • a second temperature detector that detects a temperature on the opposite side of the light emitting element of the cold element as an external temperature
  • a second temperature detector A target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within a desired temperature range based on the external temperature detected in step 1, and the internal detected by the first temperature detector
  • a temperature control method for an OLT optical transmitter including an ATC circuit that controls the temperature on the light emitting element side of a cool / warm element so that the temperature becomes a target value set by a target value setting circuit, the target value setting As a value according to the external temperature in the circuit As a step of setting a value, when the external temperature is
  • temperature control is performed so that the temperature of the light emitting element matches the external temperature when the ambient temperature (external temperature) of the cold element is in a predetermined range, and constant temperature control is performed outside the predetermined range.
  • the temperature setting is performed so that the wavelength range of the light emitting element falls within a desired wavelength band, and then the cooling element driving circuit consumes.
  • FIG. It is explanatory drawing regarding the temperature control of the light emitting element by the ATC circuit of the conventional OLT optical transmitter. It is explanatory drawing which showed the change of the power consumption at the time of the temperature control of the light emitting element by the ATC circuit of the conventional OLT optical transmitter.
  • FIG. 7 is a configuration diagram of an OLT optical transmitter of a conventional PON system according to Patent Document 1.
  • the conventional OLT optical transmitter shown in FIG. 7 includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC (Auto Power Control) circuit 3, a cooling / heating element (such as Peltier) 4, a first temperature detector 5, And an ATC (Auto Temperature Control) circuit 6.
  • the ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
  • the cool / warm element 4 corresponds to a thermoelectric cooler (TEC).
  • TEC thermoelectric cooler
  • the ATC circuit 6 controls the current flowing through the cool / warm element 4 so that the light-emitting element falls within the wavelength band standard range of, for example, 1.575 ⁇ m to 1.58 ⁇ m as described in the background art. As specific control, the ATC circuit 6 performs control so that the temperature of the light emitting element 1 becomes constant.
  • an output signal (corresponding to a feedback value in temperature control) of the first temperature detector 5 provided on the light emitting element 1 side of the cooling / heating element 4 and a set temperature value Vtld (temperature) are sent to the comparator 61 in the ATC circuit 6. Equivalent to the target value in the control). And the electric current sent through the cool / warm element 4 is controlled by the cool / warm element drive circuit 62 in the ATC circuit 6 so that the difference voltage between them is constant.
  • FIG. 9 is an explanatory diagram showing a change in power consumption when the temperature of the light emitting element 1 is controlled by the ATC circuit 6 of the conventional OLT optical transmitter.
  • the Vtld value is set so that the temperature of the light emitting element 1 is 30 ° C.
  • the temperature Tc on the outside air side of the cooling / heating element 4 is 30 ° C.
  • the cooling / heating element 4 consumes little current.
  • the electric power consumed by the cool / warm element drive circuit 62 becomes a value close to 0 as much as possible.
  • FIG. 1 is a configuration diagram of an OLT optical transmitter applied to the PON system according to Embodiment 1 of the present invention.
  • the OLT optical transmitter includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC circuit 3, a cooling / heating element 4, a first temperature detector 5, an ATC circuit 6, 2 temperature detectors 7 and a temperature-dependent threshold setting circuit 8 (corresponding to a target value setting circuit).
  • the ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
  • FIG. 1 in the first embodiment is different from the configuration of FIG. 7 which is the prior art in that it further includes a second temperature detector 7 and a temperature-dependent threshold setting circuit 8. Yes. Therefore, these differences will be mainly described below.
  • FIG. 2 is an explanatory diagram regarding temperature control of the light emitting element 1 by the ATC circuit 6 of the OLT optical transmitter according to the first embodiment of the present invention. With reference to FIG. 2, the operation and characteristics of the ATC circuit 6 for realizing low power consumption in the first embodiment will be described.
  • FIG. 2 shows the relationship between the LD side temperature Tld of the cooling element 4 with respect to the ambient temperature Tc of the cooling element 4 and Vtld which is a set value (target value) of Tld.
  • the second temperature detector 7 detects the ambient temperature Tc of the cold element 4.
  • the temperature dependent threshold setting circuit 8 sets the threshold setting Vtld of the ATC circuit 6 corresponding to the ambient temperature Tc of the cooling element 4 based on the detection result of the second temperature detector 7 to the temperature characteristic shown in FIG. Generate according to
  • Tc ⁇ 40 ° C. or 100 ° C.
  • the temperature difference between Tld and Tc is reduced from the conventional 70 ° C. to 50 ° C., so that the power consumed by the cool / warm element driving circuit 62 can be reduced. it can.
  • FIG. 3 is an explanatory diagram showing a change in power consumption during temperature control of the light-emitting element 1 by the ATC circuit 6 of the OLT optical transmitter according to Embodiment 1 of the present invention.
  • the power consumption of the cool / warm element driving circuit 62 is about 0.25 W, and the power consumption can be reduced to about 1/4 of the conventional one.
  • the temperature can be set so that the wavelength range of the light emitting element 1 in this operation falls within the 1.575 ⁇ m to 1.58 ⁇ m band.
  • the light emitting element The temperature Tld is controlled to be Tc, and outside the predetermined range, constant temperature control is performed.
  • Tc 10 ° C. to 50 ° C. in the example of FIG. 3
  • FIG. FIG. 4 is a configuration diagram of an OLT optical transmitter applied to the PON system according to Embodiment 2 of the present invention.
  • the OLT optical transmitter according to the second embodiment shown in FIG. 4 includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC circuit 3, a cooling / heating element 4, a first temperature detector 5, an ATC circuit 6, 2 temperature detectors 7 and an MCU (which is an arithmetic circuit and corresponds to a target value setting circuit) 9.
  • the ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
  • FIG. 4 in the second embodiment is different from the configuration of FIG. 1 in the first embodiment in that an MCU 9 is used instead of the temperature-dependent threshold setting circuit 8. Therefore, this difference will be mainly described below.
  • the MCU 9 used in the second embodiment basically performs the same control as the temperature-dependent threshold setting circuit 8 described in the first embodiment. However, the MCU 9 in the second embodiment calculates a set temperature value (target value) Vtld to be given to the ATC circuit 6 based on a table based on the shipping inspection data as a single light emitting element 1.
  • FIG. 5 is a diagram showing shipping inspection data as a single unit of the light emitting element 1 in Embodiment 2 of the present invention and data calculated based on the data.
  • the data (corresponding to the data in the third row in FIG. 5) having a light emission center wavelength of 1575.5 ⁇ m when the light emitting element temperature (Tld) is 30 ° C. corresponds to the shipping inspection data, It is stored in the MCU 9 as data measured in advance. Further, the remaining data (corresponding to data in the first, second, fourth, and fifth lines in FIG. 5) corresponds to data calculated by the MCU 9 based on the shipment inspection data in the third line.
  • a target wavelength range for example, 1.573.5 ⁇ m to 1.577.5 ⁇ m
  • a temperature difference between the outside and the inside satisfying the wavelength range are stored in advance as data.
  • the external temperature corresponds to the temperature Tc on the outside air side of the cooling element 4 detected by the second temperature detector 7, and the internal temperature is detected by the first temperature detector 5. This corresponds to the temperature Tld of the light emitting element 1.
  • the MCU 9 is based on the shipment inspection data, the temperature Tld of the light emitting element 1 detected by the first temperature detector 5, and the temperature Tc on the outside air side of the cold temperature element 4 detected by the second temperature detector 7.
  • the target value Vtld to be given to the ATC circuit 6 is set in the same manner as the temperature dependent threshold value setting circuit 8 in the first embodiment.
  • the temperature difference between Tld and Tc is reduced from the conventional 70 ° C. to 50 ° C.
  • the power consumption can be reduced to about 1/4 of the conventional one.
  • the internal register of the MCU 9 stores only the three values of the emission center wavelength with respect to the temperature of the LD measured in advance and the temperature difference between the outside and inside satisfying the wavelength range obtained by the calculation, so that the amount of memory can be reduced. Become.
  • the temperature Tld of the light emitting element is set to Tc. Control is performed so that constant temperature control is performed outside the predetermined range. As a result, it is possible to reduce the power consumed by the cool / warm element drive circuit after setting the temperature so that the wavelength range of the light-emitting element falls within a desired wavelength band.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)
  • Optical Communication System (AREA)

Abstract

Provided are an OLT optical transmitter and a temperature control method for the OLT optical transmitter such that temperature control is performed in such a manner that when the ambient-side temperature (outside temperature) of a hot/cold element is in a predetermined range, a light-emitting element has the same temperature as the outside temperature, and when the ambient-side temperature is outside the predetermined range, the light-emitting element has a constant temperature. This makes it possible to reduce power consumed by a hot/cold element driving circuit while setting temperature in such a manner that the range of a wavelength of the light-emitting element falls in a desired wavelength band, mainly in a PON system, which is one type of optical communications access system.

Description

ＯＬＴ光送信器およびＯＬＴ光送信器の温度制御方法OLT optical transmitter and temperature control method for OLT optical transmitter
　本発明は、光通信システムに関するものであり、特に、アクセス系光通信システムの一つの方式であるＰＯＮ（Ｐａｓｓｉｖｅ　Ｏｐｔｉｃａｌ　Ｎｅｔｗｏｒｋ）システムの局側終端装置（ＯＬＴ：Ｏｐｔｉｃａｌ　Ｌｉｎｅ　Ｔｅｒｍｉｎａｌ）におけるＯＬＴ光送信器およびＯＬＴ光送信器の温度制御方法に関するものである。 The present invention relates to an optical communication system, and in particular, an OLT optical transmitter in a station-side terminal device (OLT) of a PON (Passive Optical Network) system, which is one of access optical communication systems, and The present invention relates to a temperature control method for an OLT optical transmitter.
　従来、光ファイバを用いた公衆回線網を実現する方式として、ＰＯＮシステムと呼ばれるポイント・トゥ・マルチポイントのアクセス系光通信システムが広く用いられている。 Conventionally, a point-to-multipoint access optical communication system called a PON system has been widely used as a system for realizing a public network using an optical fiber.
　図６は、一般的なＰＯＮシステムの構成図である。ＰＯＮシステムは、この図６に示すように、局側装置である１台のＯＬＴと、光スターカプラを介して接続される複数の加入者端末装置であるＯＮＵ（Ｏｐｔｉｃａｌ　Ｌｉｎｋ　Ｕｎｉｔ）により構成される。 FIG. 6 is a configuration diagram of a general PON system. As shown in FIG. 6, the PON system is composed of one OLT as a station side device and ONUs (Optical Link Units) as a plurality of subscriber terminal devices connected via an optical star coupler. .
　多数のＯＮＵに対して、ＯＬＴと伝送路である光ファイバの大部分は共有できるため、運用コストの経済化が期待できる。また、受動部品である光スターカプラには給電が必要なく、屋外設置が容易であり、信頼性も高いという利点がある。このことから、ブロードバンドネットワークを実現する切り札として、近年、活発にＰＯＮシステムの導入が進められている。 For many ONUs, most of the optical fiber, which is the transmission line, can be shared with the OLT. In addition, the optical star coupler, which is a passive component, has the advantages that it does not require power supply, is easy to install outdoors, and has high reliability. Therefore, in recent years, PON systems have been actively introduced as a trump card for realizing a broadband network.
　例えば、ＩＥＥＥ８０２．３ａｖで規格化されている、伝送速度が１０Ｇｂｉｔ／ｓの伝送速度の通信が可能な１０Ｇ－ＥＰＯＮ（１０Ｇｉｇａｂｉｔ　－　Ｅｔｈｅｒｎｅｔ（登録商標）　Ｐａｓｓｉｖｅ　Ｏｐｔｉｃａｌ　Ｎｅｔｗｏｒｋ）においては、ＯＬＴからＯＮＵへの下りにおいて、１０Ｇ信号は、１．５８μｍ帯による同報通信方式を用いている。 For example, in 10G-EPON (10 Gigabit-Ethernet (registered trademark) Passive Optical Network), which is standardized by IEEE 802.3av and capable of communication at a transmission rate of 10 Gbit / s, download from OLT to ONU The 10G signal uses a broadcast communication system based on the 1.58 μm band.
　さらに、各ＯＮＵは、波長分割多重を行うＷＤＭフィルタ（Ｗａｖｅｌｅｎｇｔｈ　Ｄｉｖｉｓｉｏｎ　Ｍｕｌｔｉｐｌｅｘｉｎｇ）により伝送速度を分割するとともに、割り当てられたタイムスロットの自局宛データのみ取り出す。 Further, each ONU divides the transmission rate by a WDM filter (Wavelength Division Multiplexing) that performs wavelength division multiplexing, and extracts only the data addressed to the own station in the assigned time slot.
　一方、各ＯＮＵからＯＬＴへの上りにおいて、１０Ｇ信号は、光波長１．２７μｍ帯を用い、各ＯＮＵのデータが衝突しないように送出タイミングを制御する時分割多重通信方式を用いている。 On the other hand, in the upstream from each ONU to the OLT, the 10G signal uses the optical wavelength 1.27 μm band and uses a time division multiplex communication system that controls the transmission timing so that the data of each ONU does not collide.
　上記のようなＰＯＮシステムの下り方向の通信において、ＯＬＴの１０Ｇ光送信部は、１．５７５μｍ～１．５８μｍ帯の波長帯規格を満足するため、環境温度の変化に対して発光素子（ＬＤ：Ｌａｓｅｒ　Ｄｉｏｄｅ）の温度を一定とする必要がある。そこで、発光素子の温度を一定に保つ従来技術が提案されている（例えば、特許文献１参照）。 In the downstream communication of the PON system as described above, the 10G optical transmission unit of the OLT satisfies the wavelength band standard of 1.575 μm to 1.58 μm band. It is necessary to keep the temperature of Laser Diode) constant. Therefore, a conventional technique for keeping the temperature of the light emitting element constant has been proposed (see, for example, Patent Document 1).
特開２００７－５９５３７号公報JP 2007-59537 A
　しかしながら、従来技術には、以下のような課題がある。
　特許文献１に示された従来技術では、周囲温度が変化した場合において、発振波長を変動させていない。このため、ＬＤ素子温度を一定に保つ冷温素子を備えてはいるものの、素子温度と周囲温度の差が大きくなると、冷温素子を駆動する駆動回路の消費電力が大きくなる問題があった。 However, the prior art has the following problems.
In the prior art disclosed in Patent Document 1, the oscillation wavelength is not changed when the ambient temperature changes. For this reason, although a cooling element that keeps the LD element temperature constant is provided, there is a problem that when the difference between the element temperature and the ambient temperature increases, the power consumption of the drive circuit that drives the cooling element increases.
　本発明は、前記のような課題を解決するためになされたものであり、主にアクセス系光通信システムの一つの方式であるＰＯＮシステムにおいて、発光素子の波長範囲が所望の波長帯に収まるように温度設定を行った上で、冷温素子駆動回路が消費する電力の低減を図ることのできるＯＬＴ光送信器およびＯＬＴ光送信器の温度制御方法を得ることを目的とするものである。 The present invention has been made to solve the above-described problems, and in a PON system, which is mainly one of access-system optical communication systems, the wavelength range of light-emitting elements falls within a desired wavelength band. It is an object of the present invention to obtain an OLT optical transmitter and a temperature control method for the OLT optical transmitter that can reduce the power consumed by the cool / warm element driving circuit after the temperature is set.
　本発明に係るＯＬＴ光送信器は、入力電流に応じた光を発光する発光素子と、発光素子が所望の温度範囲内となるように制御される冷温素子と、冷温素子の発光素子側の温度を内部温度として検出する第１の温度検出器と、冷温素子の発光素子と反対側の温度を外部温度として検出する第２の温度検出器と、第２の温度検出器で検出された外部温度に基づいて、冷温素子の発光素子側の温度を所望の温度範囲内とするための目標値を設定する目標値設定回路と、第１の温度検出器で検出された内部温度が、目標値設定回路で設定された目標値となるように、冷温素子の発光素子側の温度を制御するＡＴＣ回路とを備え、目標値設定回路は、外部温度が、所定の下限温度以上であり、かつ所定の上限温度以下の範囲として規定される所定温度範囲内である場合には、目標値を外部温度と同じ値に設定し、外部温度が、所定の下限温度未満である場合には、目標値を所定の下限温度に設定し、外部温度が、所定の上限温度を越える場合には、目標値を所定の上限温度に設定することで、外部温度に応じた値として目標値を設定するものである。 An OLT optical transmitter according to the present invention includes a light emitting element that emits light according to an input current, a cooling element that is controlled so that the light emitting element is within a desired temperature range, and a temperature on the light emitting element side of the cooling element. A first temperature detector that detects the temperature as the internal temperature, a second temperature detector that detects the temperature on the opposite side of the light emitting element of the cool / warm element as an external temperature, and an external temperature detected by the second temperature detector And a target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within a desired temperature range, and the internal temperature detected by the first temperature detector is the target value setting. An ATC circuit that controls the temperature on the light emitting element side of the cool / warm element so that the target value is set by the circuit, and the target value setting circuit has an external temperature equal to or higher than a predetermined lower limit temperature and a predetermined value Predetermined temperature defined as a range below the upper limit temperature If it is within the range, the target value is set to the same value as the external temperature. If the external temperature is less than the predetermined lower limit temperature, the target value is set to the predetermined lower limit temperature. If the upper limit temperature is exceeded, the target value is set as a value corresponding to the external temperature by setting the target value to a predetermined upper limit temperature.
　また、本発明に係るＯＬＴ光送信器の温度制御方法は、入力電流に応じた光を発光する発光素子と、発光素子が所望の温度範囲内となるように制御される冷温素子と、冷温素子の発光素子側の温度を内部温度として検出する第１の温度検出器と、冷温素子の発光素子と反対側の温度を外部温度として検出する第２の温度検出器と、第２の温度検出器で検出された外部温度に基づいて、冷温素子の発光素子側の温度を所望の温度範囲内とするための目標値を設定する目標値設定回路と、第１の温度検出器で検出された内部温度が、目標値設定回路で設定された目標値となるように、冷温素子の発光素子側の温度を制御するＡＴＣ回路とを備えたＯＬＴ光送信器の温度制御方法であって、目標値設定回路において、外部温度に応じた値として目標値を設定するステップとして、外部温度が、所定の下限温度以上であり、かつ所定の上限温度以下の範囲として規定される所定温度範囲内である場合には、目標値を外部温度と同じ値に設定するステップと、外部温度が、所定の下限温度未満である場合には、目標値を所定の下限温度に設定するステップと、外部温度が、所定の上限温度を越える場合には、目標値を所定の上限温度に設定するステップとを有するものである。 The temperature control method for an OLT optical transmitter according to the present invention includes a light emitting element that emits light according to an input current, a cooling element that is controlled so that the light emitting element is within a desired temperature range, and a cooling element. A first temperature detector that detects the temperature on the light emitting element side as an internal temperature, a second temperature detector that detects a temperature on the opposite side of the light emitting element of the cold element as an external temperature, and a second temperature detector A target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within a desired temperature range based on the external temperature detected in step 1, and the internal detected by the first temperature detector A temperature control method for an OLT optical transmitter including an ATC circuit that controls the temperature on the light emitting element side of a cool / warm element so that the temperature becomes a target value set by a target value setting circuit, the target value setting As a value according to the external temperature in the circuit As a step of setting a value, when the external temperature is not less than a predetermined lower limit temperature and within a predetermined temperature range defined as a range not more than a predetermined upper limit temperature, the target value is set to the same value as the external temperature Setting the target value when the external temperature is lower than the predetermined lower limit temperature; setting the target value at the predetermined lower limit temperature; and setting the target value when the external temperature exceeds the predetermined upper limit temperature. And a step of setting to a predetermined upper limit temperature.
　本発明によれば、冷温素子の周囲側温度（外部温度）が所定の範囲においては、発光素子の温度を外部温度と一致させるように温度制御し、所定の範囲外においては、一定温度制御を行うことにより、主にアクセス系光通信システムの一つの方式であるＰＯＮシステムにおいて、発光素子の波長範囲が所望の波長帯に収まるように温度設定を行った上で、冷温素子駆動回路が消費する電力の低減を図ることのできるＯＬＴ光送信器およびＯＬＴ光送信器の温度制御方法を得ることができる。 According to the present invention, temperature control is performed so that the temperature of the light emitting element matches the external temperature when the ambient temperature (external temperature) of the cold element is in a predetermined range, and constant temperature control is performed outside the predetermined range. By doing so, in the PON system which is one of the systems of the access optical communication system, the temperature setting is performed so that the wavelength range of the light emitting element falls within a desired wavelength band, and then the cooling element driving circuit consumes. An OLT optical transmitter and a temperature control method for the OLT optical transmitter capable of reducing power can be obtained.
本発明の実施の形態１におけるＰＯＮシステムに適用されるＯＬＴ光送信器の構成図である。It is a block diagram of the OLT optical transmitter applied to the PON system in Embodiment 1 of this invention. 本発明の実施の形態１におけるＯＬＴ光送信器のＡＴＣ回路による発光素子の温度制御に関する説明図である。It is explanatory drawing regarding the temperature control of the light emitting element by the ATC circuit of the OLT optical transmitter in Embodiment 1 of this invention. 本発明の実施の形態１におけるＯＬＴ光送信器のＡＴＣ回路による発光素子の温度制御時における消費電力の変化を示した説明図である。It is explanatory drawing which showed the change of the power consumption at the time of temperature control of the light emitting element by the ATC circuit of the OLT optical transmitter in Embodiment 1 of this invention. 本発明の実施の形態２におけるＰＯＮシステムに適用されるＯＬＴ光送信器の構成図である。It is a block diagram of the OLT optical transmitter applied to the PON system in Embodiment 2 of this invention. 本発明の実施の形態２における発光素子の単体としての出荷検査データおよびそのデータを元に算出されるデータを示した図である。It is the figure which showed the shipping calculation data as a single-piece | unit of the light emitting element in Embodiment 2 of this invention, and the data calculated based on the data. 一般的なＰＯＮシステムの構成図である。It is a block diagram of a general PON system. 特許文献１による従来のＰＯＮシステムのＯＬＴ光送信器の構成図である。It is a block diagram of the OLT optical transmitter of the conventional PON system by patent document 1. FIG. 従来のＯＬＴ光送信器のＡＴＣ回路による発光素子の温度制御に関する説明図である。It is explanatory drawing regarding the temperature control of the light emitting element by the ATC circuit of the conventional OLT optical transmitter. 従来のＯＬＴ光送信器のＡＴＣ回路による発光素子の温度制御時における消費電力の変化を示した説明図である。It is explanatory drawing which showed the change of the power consumption at the time of the temperature control of the light emitting element by the ATC circuit of the conventional OLT optical transmitter.
　以下、本発明のＰＯＮシステムにおけるＯＬＴ光送信器およびＯＬＴ光送信器の温度制御方法の好適な実施の形態につき図面を用いて説明する。 Hereinafter, preferred embodiments of an OLT optical transmitter and a temperature control method of the OLT optical transmitter in the PON system of the present invention will be described with reference to the drawings.
　実施の形態１．
　本発明の説明をする前に、従来技術の問題点に関し、図面を用いて詳しく説明する。図７は、特許文献１による従来のＰＯＮシステムのＯＬＴ光送信器の構成図である。図７に示した従来のＯＬＴ光送信器は、受光素子（ＬＤ）１、モニタ受光素子２、ＡＰＣ（Ａｕｔｏ　Ｐｏｗｅｒ　Ｃｏｎｔｒｏｌ）回路３、冷温素子（ペルチェなど）４、第１の温度検出器５、およびＡＴＣ（Ａｕｔｏ　Ｔｅｍｐｅｒａｔｕｒｅ　Ｃｏｎｔｒｏｌ）回路６を備えて構成されている。また、ＡＴＣ回路６は、比較器６１および冷温素子駆動回路６２を含んで構成されている。 Embodiment 1 FIG.
Before describing the present invention, the problems of the prior art will be described in detail with reference to the drawings. FIG. 7 is a configuration diagram of an OLT optical transmitter of a conventional PON system according to Patent Document 1. In FIG. The conventional OLT optical transmitter shown in FIG. 7 includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC (Auto Power Control) circuit 3, a cooling / heating element (such as Peltier) 4, a first temperature detector 5, And an ATC (Auto Temperature Control) circuit 6. The ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
　ここで、冷温素子４は、熱電クーラ（ＴＥＣ：ＴｈｅｒｍｏＥｌｅｃｔｒｉｃ　Ｃｏｏｌｅｒ）に相当する。そして、後述する図２、３、８、９においては、発光素子１の温度が一定になるように制御を行う状態をＴＥＣ　ＯＮと表記している。 Here, the cool / warm element 4 corresponds to a thermoelectric cooler (TEC). In FIGS. 2, 3, 8, and 9 to be described later, a state in which control is performed so that the temperature of the light emitting element 1 is constant is denoted as TEC ON.
　次に、図７に示した従来のＯＬＴ光送信器の動作について説明する。ＡＴＣ回路６は、冷温素子４に流す電流を制御することで、背景技術で記載のとおり、発光素子が、例えば、１．５７５μｍ～１．５８μｍ帯の波長帯規格範囲内に収まるようにする。具体的な制御として、ＡＴＣ回路６は、発光素子１の温度が一定になるように制御を行う。 Next, the operation of the conventional OLT optical transmitter shown in FIG. 7 will be described. The ATC circuit 6 controls the current flowing through the cool / warm element 4 so that the light-emitting element falls within the wavelength band standard range of, for example, 1.575 μm to 1.58 μm as described in the background art. As specific control, the ATC circuit 6 performs control so that the temperature of the light emitting element 1 becomes constant.
　まず、ＡＴＣ回路６内の比較器６１に、冷温素子４の発光素子１側に設けた第１の温度検出器５の出力信号（温度制御におけるフィードバック値に相当）と、設定温度値Ｖｔｌｄ（温度制御における目標値に相当）とが入力される。そして、両者の差電圧が一定となるように、ＡＴＣ回路６内の冷温素子駆動回路６２により、冷温素子４に流す電流を制御する。 First, an output signal (corresponding to a feedback value in temperature control) of the first temperature detector 5 provided on the light emitting element 1 side of the cooling / heating element 4 and a set temperature value Vtld (temperature) are sent to the comparator 61 in the ATC circuit 6. Equivalent to the target value in the control). And the electric current sent through the cool / warm element 4 is controlled by the cool / warm element drive circuit 62 in the ATC circuit 6 so that the difference voltage between them is constant.
　図８は、従来のＯＬＴ光送信器のＡＴＣ回路６による発光素子１の温度制御に関する説明図である。この図８に示すように、ＡＴＣ回路６は、周囲温度Ｔｃ（冷温素子４の、発光素子１が実装された面とは反対側の面の温度であり、外部温度に相当）の変化には依存せずに、発光素子１の温度（Ｔｌｄ）の一定制御を行う。 FIG. 8 is an explanatory diagram regarding temperature control of the light-emitting element 1 by the ATC circuit 6 of the conventional OLT optical transmitter. As shown in FIG. 8, the ATC circuit 6 has a change in the ambient temperature Tc (the temperature of the cold element 4 on the side opposite to the surface on which the light emitting element 1 is mounted, corresponding to the external temperature). Regardless of the dependency, the temperature (Tld) of the light emitting element 1 is controlled to be constant.
　次に、ＡＴＣ回路６による温度制御を行う際の消費電力の変化について説明する。図９は、従来のＯＬＴ光送信器のＡＴＣ回路６による発光素子１の温度制御時における消費電力の変化を示した説明図である。例えば、発光素子１の温度を３０℃とするようにＶｔｌｄ値を設定した場合、冷温素子４の外気側の温度Ｔｃが３０℃の時には、冷温素子４はほとんど電流を消費しない。このため、冷温素子駆動回路６２が消費する電力は、限りなく０に近い値となる。 Next, a change in power consumption when performing temperature control by the ATC circuit 6 will be described. FIG. 9 is an explanatory diagram showing a change in power consumption when the temperature of the light emitting element 1 is controlled by the ATC circuit 6 of the conventional OLT optical transmitter. For example, when the Vtld value is set so that the temperature of the light emitting element 1 is 30 ° C., when the temperature Tc on the outside air side of the cooling / heating element 4 is 30 ° C., the cooling / heating element 4 consumes little current. For this reason, the electric power consumed by the cool / warm element drive circuit 62 becomes a value close to 0 as much as possible.
　一方、冷温素子４の外気側の温度Ｔｃが、１００℃あるいは－４０℃になった場合（３０℃±７０℃に相当する場合）を考えると、冷温素子４にて発光素子１側の温度を下げるため、大きな電流が必要となる。この結果、冷温素子駆動回路６２は、一般的には、１Ｗ近い電力が必要になるという問題がある。 On the other hand, when the temperature Tc on the outside air side of the cooling / heating element 4 becomes 100 ° C. or −40 ° C. (corresponding to 30 ° C. ± 70 ° C.), the temperature on the light emitting element 1 side is set by the cooling / heating element 4. A large current is required to reduce the voltage. As a result, there is a problem that the cool / warm element drive circuit 62 generally requires electric power close to 1 W.
　そこで、このような問題を解決するための、本発明によるＯＬＴ光送信器の温度制御方法について、次に説明する。図１は、本発明の実施の形態１におけるＰＯＮシステムに適用されるＯＬＴ光送信器の構成図である。 Therefore, the temperature control method of the OLT optical transmitter according to the present invention for solving such a problem will be described next. FIG. 1 is a configuration diagram of an OLT optical transmitter applied to the PON system according to Embodiment 1 of the present invention.
　図１に示した本実施の形態１におけるＯＬＴ光送信器は、受光素子（ＬＤ）１、モニタ受光素子２、ＡＰＣ回路３、冷温素子４、第１の温度検出器５、ＡＴＣ回路６、第２の温度検出器７、および温度依存閾値設定回路８（目標値設定回路に相当）を備えて構成されている。また、ＡＴＣ回路６は、比較器６１および冷温素子駆動回路６２を含んで構成されている。 The OLT optical transmitter according to the first embodiment shown in FIG. 1 includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC circuit 3, a cooling / heating element 4, a first temperature detector 5, an ATC circuit 6, 2 temperature detectors 7 and a temperature-dependent threshold setting circuit 8 (corresponding to a target value setting circuit). The ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
　本実施の形態１における図１の構成は、従来技術である先の図７の構成と比較すると、第２の温度検出器７、および温度依存閾値設定回路８をさらに備えている点が異なっている。そこで、これらの相違点を中心に、以下に説明する。 The configuration of FIG. 1 in the first embodiment is different from the configuration of FIG. 7 which is the prior art in that it further includes a second temperature detector 7 and a temperature-dependent threshold setting circuit 8. Yes. Therefore, these differences will be mainly described below.
　図２は、本発明の実施の形態１におけるＯＬＴ光送信器のＡＴＣ回路６による発光素子１の温度制御に関する説明図である。この図２を用いて、本実施の形態１において、低電力化を実現するＡＴＣ回路６の動作、および特徴について説明する。 FIG. 2 is an explanatory diagram regarding temperature control of the light emitting element 1 by the ATC circuit 6 of the OLT optical transmitter according to the first embodiment of the present invention. With reference to FIG. 2, the operation and characteristics of the ATC circuit 6 for realizing low power consumption in the first embodiment will be described.
　この図２には、冷温素子４の周囲側温度Ｔｃに対する冷温素子４のＬＤ側温度Ｔｌｄ、およびＴｌｄの設定値（目標値）であるＶｔｌｄの関係が示されている。第２の温度検出器７は、冷温素子４の周囲側温度Ｔｃを検出する。そして、温度依存閾値設定回路８は、第２の温度検出器７の検出結果に基づいて、冷温素子４の周囲側温度Ｔｃに対応したＡＴＣ回路６の閾値設定Ｖｔｌｄを、図２に示す温度特性に従って生成する。 FIG. 2 shows the relationship between the LD side temperature Tld of the cooling element 4 with respect to the ambient temperature Tc of the cooling element 4 and Vtld which is a set value (target value) of Tld. The second temperature detector 7 detects the ambient temperature Tc of the cold element 4. Then, the temperature dependent threshold setting circuit 8 sets the threshold setting Vtld of the ATC circuit 6 corresponding to the ambient temperature Tc of the cooling element 4 based on the detection result of the second temperature detector 7 to the temperature characteristic shown in FIG. Generate according to
　この結果、ＡＴＣ回路６は、Ｔｃ＝１０℃～５０℃の範囲においては、Ｔｌｄ＝Ｔｃとなるように、Ｔｃに対し連続的に変化するＴｌｄを用いて発光素子１の温度を制御することができる。一方、ＡＴＣ回路６は、Ｔｃ＜１０℃の範囲においては、目標値としてＴｌｄ＝１０℃を用いて、Ｔｃ＞５０℃の範囲においては、目標値としてＴｌｄ＝５０℃を用いて、発光素子１の一定温度制御を行う。 As a result, in the range of Tc = 10 ° C. to 50 ° C., the ATC circuit 6 can control the temperature of the light emitting element 1 using Tld that continuously changes with respect to Tc so that Tld = Tc. it can. On the other hand, the ATC circuit 6 uses Tld = 10 ° C. as the target value in the range of Tc <10 ° C., and uses Tld = 50 ° C. as the target value in the range of Tc> 50 ° C. The constant temperature control is performed.
　つまり、冷温素子４は、Ｔｃ＝１０℃～５０℃の範囲では、Ｔｌｄ＝Ｔｃの制御が行われるため、ほとんど電流を消費しない。一方、Ｔｃ＝－４０℃、あるいは１００℃の場合には、ＴｌｄとＴｃの温度差が、従来の７０℃から５０℃と小さくなるため、冷温素子駆動回路６２が消費する電力を低減させることができる。 In other words, the cold element 4 consumes little current in the range of Tc = 10 ° C. to 50 ° C. because Tld = Tc is controlled. On the other hand, when Tc = −40 ° C. or 100 ° C., the temperature difference between Tld and Tc is reduced from the conventional 70 ° C. to 50 ° C., so that the power consumed by the cool / warm element driving circuit 62 can be reduced. it can.
　図３は、本発明の実施の形態１におけるＯＬＴ光送信器のＡＴＣ回路６による発光素子１の温度制御時における消費電力の変化を示した説明図である。図３に示すように、冷温素子駆動回路６２の消費電力は、０．２５Ｗ程度となり、従来の約１／４の低消費電力化が可能となる。また、本動作における発光素子１の波長範囲を１．５７５μｍ～１．５８μｍ帯に収まるような温度設定が可能である。 FIG. 3 is an explanatory diagram showing a change in power consumption during temperature control of the light-emitting element 1 by the ATC circuit 6 of the OLT optical transmitter according to Embodiment 1 of the present invention. As shown in FIG. 3, the power consumption of the cool / warm element driving circuit 62 is about 0.25 W, and the power consumption can be reduced to about 1/4 of the conventional one. In addition, the temperature can be set so that the wavelength range of the light emitting element 1 in this operation falls within the 1.575 μm to 1.58 μm band.
　以上のように、実施の形態１によれば、冷温素子の周囲側温度Ｔｃが所定の範囲（先の図３の例では、Ｔｃ＝１０℃～５０℃の範囲に相当）においては、発光素子の温度ＴｌｄをＴｃとするように制御し、所定の範囲外では、一定温度制御を行っている。この結果、発光素子の波長範囲が所望の波長帯に収まるように温度設定を行った上で、冷温素子駆動回路が消費する電力の低減を図ることが可能となる。 As described above, according to the first embodiment, when the ambient temperature Tc of the cold element is in a predetermined range (corresponding to the range of Tc = 10 ° C. to 50 ° C. in the example of FIG. 3), the light emitting element The temperature Tld is controlled to be Tc, and outside the predetermined range, constant temperature control is performed. As a result, it is possible to reduce the power consumed by the cool / warm element driving circuit after setting the temperature so that the wavelength range of the light emitting element falls within a desired wavelength band.
　実施の形態２．
　図４は、本発明の実施の形態２におけるＰＯＮシステムに適用されるＯＬＴ光送信器の構成図である。図４に示した本実施の形態２におけるＯＬＴ光送信器は、受光素子（ＬＤ）１、モニタ受光素子２、ＡＰＣ回路３、冷温素子４、第１の温度検出器５、ＡＴＣ回路６、第２の温度検出器７、およびＭＣＵ（演算回路のことであり、目標値設定回路に相当）９を備えて構成されている。また、ＡＴＣ回路６は、比較器６１および冷温素子駆動回路６２を含んで構成されている。 Embodiment 2. FIG.
FIG. 4 is a configuration diagram of an OLT optical transmitter applied to the PON system according to Embodiment 2 of the present invention. The OLT optical transmitter according to the second embodiment shown in FIG. 4 includes a light receiving element (LD) 1, a monitor light receiving element 2, an APC circuit 3, a cooling / heating element 4, a first temperature detector 5, an ATC circuit 6, 2 temperature detectors 7 and an MCU (which is an arithmetic circuit and corresponds to a target value setting circuit) 9. The ATC circuit 6 includes a comparator 61 and a cool / warm element drive circuit 62.
　本実施の形態２における図４の構成は、先の実施の形態１における図１の構成と比較すると、温度依存閾値設定回路８の代わりにＭＣＵ９が用いられている点が異なっている。そこで、この相違点を中心に、以下に説明する。 The configuration of FIG. 4 in the second embodiment is different from the configuration of FIG. 1 in the first embodiment in that an MCU 9 is used instead of the temperature-dependent threshold setting circuit 8. Therefore, this difference will be mainly described below.
　本実施の形態２で用いられるＭＣＵ９は、基本的には、先の実施の形態１で説明した温度依存閾値設定回路８と同様の制御を行う。ただし、本実施の形態２におけるＭＣＵ９は、発光素子１の単体としての出荷検査データに基づくテーブルに基づいて、ＡＴＣ回路６に与える設定温度値（目標値）Ｖｔｌｄを算出する。 The MCU 9 used in the second embodiment basically performs the same control as the temperature-dependent threshold setting circuit 8 described in the first embodiment. However, the MCU 9 in the second embodiment calculates a set temperature value (target value) Vtld to be given to the ATC circuit 6 based on a table based on the shipping inspection data as a single light emitting element 1.
　図５は、本発明の実施の形態２における発光素子１の単体としての出荷検査データおよびそのデータを元に算出されるデータを示した図である。具体的には、発光素子温度（Ｔｌｄ）が３０℃のときの発光中心波長が１５７５．５μｍとなっているデータ（図５における３行目のデータに相当）が、出荷検査データに相当し、あらかじめ測定されたデータとしてＭＣＵ９内に記憶されている。また、残りのデータ（図５における１、２、４、５行目のデータに相当）は、３行目の出荷検査データに基づいてＭＣＵ９が算出するデータに相当する。 FIG. 5 is a diagram showing shipping inspection data as a single unit of the light emitting element 1 in Embodiment 2 of the present invention and data calculated based on the data. Specifically, the data (corresponding to the data in the third row in FIG. 5) having a light emission center wavelength of 1575.5 μm when the light emitting element temperature (Tld) is 30 ° C. corresponds to the shipping inspection data, It is stored in the MCU 9 as data measured in advance. Further, the remaining data (corresponding to data in the first, second, fourth, and fifth lines in FIG. 5) corresponds to data calculated by the MCU 9 based on the shipment inspection data in the third line.
　さらに、ＭＣＵ９内には、目的の波長範囲（例えば、１．５７３．５μｍ～１．５７７．５μｍ）、およびその波長範囲を満たす外部と内部の温度差が、データとしてあらかじめ記憶されている。ここで、外部の温度とは、第２の温度検出器７で検出される冷温素子４の外気側の温度Ｔｃに相当し、内部の温度とは、第１の温度検出器５で検出される発光素子１の温度Ｔｌｄに相当する。 Further, in the MCU 9, a target wavelength range (for example, 1.573.5 μm to 1.577.5 μm) and a temperature difference between the outside and the inside satisfying the wavelength range are stored in advance as data. Here, the external temperature corresponds to the temperature Tc on the outside air side of the cooling element 4 detected by the second temperature detector 7, and the internal temperature is detected by the first temperature detector 5. This corresponds to the temperature Tld of the light emitting element 1.
　そして、ＭＣＵ９は、出荷検査データ、第１の温度検出器５で検出された発光素子１の温度Ｔｌｄ、および第２の温度検出器７で検出された冷温素子４の外気側の温度Ｔｃに基づいて、演算を行い、先の実施の形態１における温度依存閾値設定回路８と同様に、ＡＴＣ回路６に与える目標値Ｖｔｌｄを設定する。 Then, the MCU 9 is based on the shipment inspection data, the temperature Tld of the light emitting element 1 detected by the first temperature detector 5, and the temperature Tc on the outside air side of the cold temperature element 4 detected by the second temperature detector 7. Thus, the target value Vtld to be given to the ATC circuit 6 is set in the same manner as the temperature dependent threshold value setting circuit 8 in the first embodiment.
　より具体的には、ＭＣＵ９は、あらかじめ記憶された出荷検査データ（図５の例では、Ｔｌｄ＝３０℃、波長＝１５７５．５μｍに相当）を読み出し、目的の波長範囲（例えば、１．５７３．５μｍ～１．５７７．５μｍ）に収まる温度を算出する関数により、高温側（例えば、Ｔｌｄ＝５０℃）および低温側（例えば、Ｔｌｄ＝１０℃）の一定温度制御点を、Ｔｌｄ＝３０℃のＬＤ波長データ、および発光素子１の温度Ｔｌｄと冷温素子４の外気側の温度Ｔｃとの温度差に基づいて、周期的な逐次計算を行うことにより求める。 More specifically, the MCU 9 reads out shipping inspection data stored in advance (corresponding to Tld = 30 ° C. and wavelength = 1575.5 μm in the example of FIG. 5), and the target wavelength range (for example, 1.573. A constant temperature control point on the high temperature side (for example, Tld = 50 ° C.) and low temperature side (for example, Tld = 10 ° C.) is calculated by the function for calculating the temperature within 5 μm to 1.577.5 μm. It is obtained by performing periodic sequential calculation based on the LD wavelength data and the temperature difference between the temperature Tld of the light emitting element 1 and the temperature Tc on the outside air side of the cool element 4.
　そして、ＡＴＣ回路６は、逐次演算によりＭＣＵ９で求めた高温側（５０℃）および低温側（１０℃）の一定温度制御点に基づいて、Ｔｃ＝１０℃～５０℃時にはＴｌｄ＝Ｔｃとなるように、Ｔｃに対し連続的にＴｌｄを制御する。また、ＡＴＣ回路６は、Ｔｃ＜１０℃ではＴｌｄ＝１０℃に、Ｔｃ＞５０℃ではＴｌｄ＝５０℃に一定温度の制御を行う。 Then, the ATC circuit 6 makes Tld = Tc when Tc = 10 ° C. to 50 ° C. based on the constant temperature control points on the high temperature side (50 ° C.) and the low temperature side (10 ° C.) obtained by the MCU 9 by sequential calculation. In addition, Tld is continuously controlled with respect to Tc. The ATC circuit 6 controls the constant temperature at Tld = 10 ° C. when Tc <10 ° C., and at Tld = 50 ° C. when Tc> 50 ° C.
　このようにして、先の実施の形態１における温度依存閾値設定回路８と同様の制御を、ＭＣＵ９を用いて行うことにより、発光素子１の発光中心波長バラツキを適用システムの波長範囲に納めることができる。さらに、ＡＴＣ回路６は、Ｔｃ＝１０℃～５０℃の範囲では、Ｔｌｄ＝Ｔｃとして制御を行う。つまり、冷温素子４は、Ｔｃ＝１０℃～５０℃の範囲においては、Ｔｌｄ＝Ｔｃの制御が行われるため、ほとんど電流を消費しないこととなる。 In this way, by performing the same control as the temperature-dependent threshold setting circuit 8 in the first embodiment using the MCU 9, the emission center wavelength variation of the light emitting element 1 can be kept within the wavelength range of the application system. it can. Further, the ATC circuit 6 performs control with Tld = Tc in the range of Tc = 10 ° C. to 50 ° C. In other words, the temperature / temperature element 4 consumes little current because Tld = Tc is controlled in the range of Tc = 10 ° C. to 50 ° C.
　一方、Ｔｃ＝－４０℃、あるいはＴｃ＝１００℃のときには、ＴｌｄとＴｃの温度差が従来の７０℃から５０℃と小さくなる。このため、先の実施の形態１と同様に、従来の約１／４の低消費電力化が可能になる。さらに、ＭＣＵ９の内部レジスタは、あらかじめ測定したＬＤの温度に対する発光中心波長と、演算で求めた波長範囲を満たす外部と内部の温度差の３値のみを記憶するため、メモリ量の削減が可能となる。 On the other hand, when Tc = −40 ° C. or Tc = 100 ° C., the temperature difference between Tld and Tc is reduced from the conventional 70 ° C. to 50 ° C. For this reason, as in the first embodiment, the power consumption can be reduced to about 1/4 of the conventional one. Furthermore, the internal register of the MCU 9 stores only the three values of the emission center wavelength with respect to the temperature of the LD measured in advance and the temperature difference between the outside and inside satisfying the wavelength range obtained by the calculation, so that the amount of memory can be reduced. Become.
　以上のように、実施の形態２によれば、ＭＣＵを用いて、先の実施の形態１と同様に、冷温素子の周囲側温度Ｔｃが所定の範囲においては、発光素子の温度ＴｌｄをＴｃとするように制御し、所定の範囲外では、一定温度制御を行っている。この結果、発光素子の波長範囲を所望の波長帯に収まるような温度設定を行った上で、冷温素子駆動回路が消費する電力の低減を図ることが可能となる。 As described above, according to the second embodiment, using the MCU, similarly to the first embodiment, when the ambient temperature Tc of the cool / warm element is within a predetermined range, the temperature Tld of the light emitting element is set to Tc. Control is performed so that constant temperature control is performed outside the predetermined range. As a result, it is possible to reduce the power consumed by the cool / warm element drive circuit after setting the temperature so that the wavelength range of the light-emitting element falls within a desired wavelength band.

Claims (3)

  1. 　入力電流に応じた光を発光する発光素子と、
    　前記発光素子が所望の温度範囲内となるように制御される冷温素子と、
    　前記冷温素子の前記発光素子側の温度を内部温度として検出する第１の温度検出器と、
    　前記冷温素子の前記発光素子と反対側の温度を外部温度として検出する第２の温度検出器と、
    　前記第２の温度検出器で検出された前記外部温度に基づいて、前記冷温素子の前記発光素子側の温度を前記所望の温度範囲内とするための目標値を設定する目標値設定回路と、
    　前記第１の温度検出器で検出された前記内部温度が、前記目標値設定回路で設定された前記目標値となるように、前記冷温素子の前記発光素子側の温度を制御するＡＴＣ回路と
    　を備え、
    　前記目標値設定回路は、前記外部温度が、所定の下限温度以上であり、かつ所定の上限温度以下の範囲として規定される所定温度範囲内である場合には、前記目標値を前記外部温度と同じ値に設定し、前記外部温度が、前記所定の下限温度未満である場合には、前記目標値を前記所定の下限温度に設定し、前記外部温度が、前記所定の上限温度を越える場合には、前記目標値を前記所定の上限温度に設定することで、前記外部温度に応じた値として前記目標値を設定する
    　ＯＬＴ光送信器。     A light emitting element that emits light according to an input current;
    A cooling / heating element controlled so that the light emitting element is within a desired temperature range;
    A first temperature detector for detecting the temperature on the light emitting element side of the cold element as an internal temperature;
    A second temperature detector for detecting the temperature of the cold element opposite to the light emitting element as an external temperature;
    A target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within the desired temperature range based on the external temperature detected by the second temperature detector;
    An ATC circuit that controls the temperature on the light emitting element side of the cool / warm element so that the internal temperature detected by the first temperature detector becomes the target value set by the target value setting circuit; Prepared,
    The target value setting circuit sets the target value as the external temperature when the external temperature is equal to or higher than a predetermined lower limit temperature and within a predetermined temperature range defined as a range equal to or lower than a predetermined upper limit temperature. When the external temperature is less than the predetermined lower limit temperature, the target value is set to the predetermined lower limit temperature, and the external temperature exceeds the predetermined upper limit temperature. The OLT optical transmitter sets the target value as a value corresponding to the external temperature by setting the target value to the predetermined upper limit temperature.
  2. 　請求項１に記載のＯＬＴ光送信器において、
    　前記目標値設定回路は、前記発光素子の基準温度、前記基準温度における発光中心波長、目標の波長範囲、および前記目標の波長範囲を満たすための外部温度と内部温度との温度差に関する各データをあらかじめ記憶する記憶部を有し、前記第２の温度検出器で検出された前記外部温度に加え、前記第１の温度検出器で検出された前記内部温度を読み込み、読み込んだ温度データおよび前記記憶部に記憶されている各データに基づいて、前記所定の下限温度および前記所定の上限温度を算出し、前記外部温度に応じた値として前記目標値を設定する
    　ＯＬＴ光送信器。     The OLT optical transmitter according to claim 1, wherein
    The target value setting circuit includes each data relating to a reference temperature of the light emitting element, a light emission center wavelength at the reference temperature, a target wavelength range, and a temperature difference between an external temperature and an internal temperature to satisfy the target wavelength range. A storage unit for storing in advance, in addition to the external temperature detected by the second temperature detector, the internal temperature detected by the first temperature detector is read, the read temperature data and the storage An OLT optical transmitter that calculates the predetermined lower limit temperature and the predetermined upper limit temperature based on each data stored in the unit, and sets the target value as a value according to the external temperature.
  3. 　入力電流に応じた光を発光する発光素子と、
    　前記発光素子が所望の温度範囲内となるように制御される冷温素子と、
    　前記冷温素子の前記発光素子側の温度を内部温度として検出する第１の温度検出器と、
    　前記冷温素子の前記発光素子と反対側の温度を外部温度として検出する第２の温度検出器と、
    　前記第２の温度検出器で検出された前記外部温度に基づいて、前記冷温素子の前記発光素子側の温度を前記所望の温度範囲内とするための目標値を設定する目標値設定回路と、
    　前記第１の温度検出器で検出された前記内部温度が、前記目標値設定回路で設定された前記目標値となるように、前記冷温素子の前記発光素子側の温度を制御するＡＴＣ回路と
    　を備えたＯＬＴ光送信器の温度制御方法であって、
    　前記目標値設定回路において、前記外部温度に応じた値として前記目標値を設定するステップとして、
    　　前記外部温度が、所定の下限温度以上であり、かつ所定の上限温度以下の範囲として規定される所定温度範囲内である場合には、前記目標値を前記外部温度と同じ値に設定するステップと、
    　　前記外部温度が、前記所定の下限温度未満である場合には、前記目標値を前記所定の下限温度に設定するステップと、
    　　前記外部温度が、前記所定の上限温度を越える場合には、前記目標値を前記所定の上限温度に設定するステップと
    　を有する
    　ＯＬＴ光送信器の温度制御方法。     A light emitting element that emits light according to an input current;
    A cooling / heating element controlled so that the light emitting element is within a desired temperature range;
    A first temperature detector for detecting the temperature on the light emitting element side of the cold element as an internal temperature;
    A second temperature detector for detecting the temperature of the cold element opposite to the light emitting element as an external temperature;
    A target value setting circuit for setting a target value for setting the temperature on the light emitting element side of the cool / warm element within the desired temperature range based on the external temperature detected by the second temperature detector;
    An ATC circuit that controls the temperature on the light emitting element side of the cool / warm element so that the internal temperature detected by the first temperature detector becomes the target value set by the target value setting circuit; A temperature control method for an OLT optical transmitter comprising:
    In the target value setting circuit, as the step of setting the target value as a value according to the external temperature,
    When the external temperature is equal to or higher than a predetermined lower limit temperature and within a predetermined temperature range defined as a range equal to or lower than a predetermined upper limit temperature, the target value is set to the same value as the external temperature; ,
    When the external temperature is less than the predetermined lower limit temperature, setting the target value to the predetermined lower limit temperature;
    A temperature control method for an OLT optical transmitter, comprising: setting the target value to the predetermined upper limit temperature when the external temperature exceeds the predetermined upper limit temperature.
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