WO2000033490A1 - Module emetteur recepteur optique - Google Patents

Module emetteur recepteur optique Download PDF

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Publication number
WO2000033490A1
WO2000033490A1 PCT/JP1998/005384 JP9805384W WO0033490A1 WO 2000033490 A1 WO2000033490 A1 WO 2000033490A1 JP 9805384 W JP9805384 W JP 9805384W WO 0033490 A1 WO0033490 A1 WO 0033490A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
emitting element
circuit
transceiver module
optical transceiver
Prior art date
Application number
PCT/JP1998/005384
Other languages
English (en)
Japanese (ja)
Inventor
Kazuyuki Mori
Tamotsu Akashi
Original Assignee
Fujitsu Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujitsu Limited filed Critical Fujitsu Limited
Priority to PCT/JP1998/005384 priority Critical patent/WO2000033490A1/fr
Publication of WO2000033490A1 publication Critical patent/WO2000033490A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/40—Transceivers

Definitions

  • the present invention relates to crosstalk suppression in an optical transceiver module, and more particularly to a downlink transmission bit rate in an ATM-PON (Passive Optical Ne two rk) described in ITU-T Recommendation G.983.
  • the present invention relates to suppression of electrical crosstalk between transmission and reception in an optical transceiver module suitable for asymmetric transmission of 622 MbZ s and 156 Mb / s upstream transmission.
  • an optical transceiver module in which an optical transmission module and an optical reception module are housed in a single case, a part of the electric signal on the transmission side leaks to the reception side, and electrical crosstalk becomes a problem.
  • a shield structure is employed in which the receiving module is shielded with metal.
  • a transmitter / receiver separation module is used instead of a transceiver structure.
  • An object of the present invention is to provide an inexpensive optical transceiver module capable of suppressing electric crosstalk.
  • a light emitting element a transmitting circuit for driving the light emitting element, a light receiving element, a receiving circuit connected to the light receiving element, and a driving current for the light emitting element are provided between the light emitting element and the transmitting circuit.
  • a low-pass filter that removes high-frequency components of the light-emitting element within a range where the light output from the light-emitting element satisfies a predetermined rule and suppresses crosstalk from the transmission circuit to the reception circuit.
  • An optical transceiver module characterized by the following is provided. BRIEF DESCRIPTION OF THE FIGURES
  • Fig. 1 is a schematic diagram illustrating electrical crosstalk in an optical transceiver module.
  • FIG. 2 is an equivalent circuit diagram of FIG.
  • FIG. 3 is a circuit diagram of the optical transceiver module according to the first embodiment of the present invention.
  • Figures 4A, 4B, 5A and 5B are diagrams illustrating the reduction of crosstalk noise by extending the signal rise / fall time.
  • Figures 6A, 6B and 6C are waveform diagrams illustrating the delay of the optical signal at the beginning of the burst and the improvement.
  • FIG. 7 is a circuit diagram of an optical transceiver module according to a second embodiment of the present invention.
  • FIG. 8 is a circuit diagram of a modification of the circuit of FIG.
  • 9A, 9B and 9C are waveform diagrams illustrating the improvement of the delay at the head of the burst by the circuit of FIG.
  • Figure 10 shows the I-L characteristics of the laser diode at high and low temperatures. It is a graph.
  • FIG. 11 is a principle block diagram of an optical transceiver module according to a third embodiment of the present invention.
  • FIG. 12 is a graph showing the relationship between the reverse bias voltage of the diode and the capacitance.
  • FIG. 13 is a diagram showing a change in voltage at points A to C in FIG. 12 at the time of low drive power and at the time of high drive power.
  • FIG. 14 is a more detailed circuit diagram of FIG.
  • FIG. 15 is a diagram similar to FIG. 13 in which a change in the potential at point C due to a change in data is considered.
  • FIG. 16 is a circuit diagram of a modification of the circuit of FIG.
  • FIG. 17 is a waveform chart for explaining the operation of the circuit of FIG.
  • FIG. 18 is a diagram similar to FIG. 15 in the circuit of FIG. BEST MODE FOR CARRYING OUT THE INVENTION
  • Fig. 1 is a schematic diagram illustrating electrical crosstalk in an optical transceiver module.
  • LD and PD indicate a laser diode and a photo diode for optical transmission and optical reception, respectively.
  • I indicates the drive current of the LD, and R in is the input impedance of the receiving circuit. Since electric crosstalk is capacitive, it is indicated by capacitance Cx.
  • the equivalent circuit of Fig. 1 is shown in Fig. 2.
  • the LD is current-biased to near the light emission threshold, and the equivalent resistance (differential resistance) at that time is indicated by Rd.
  • the impedance of PD is so high that it is omitted.
  • I LD Rd I (R in +).
  • Equation (2) shows that mainly high-frequency components of the components of the drive current I cause crosstalk, and the higher the frequency, the greater the effect of crosstalk.
  • FIG. 3 is a circuit diagram of the optical transceiver module according to the first embodiment of the present invention.
  • a low-pass consisting of a resistor 14 connected in series with the transmission circuit 12 and a capacitor 16 connected in parallel with the transmission circuit 12
  • a filter 18 is provided between the laser diode (LD) 10 for optical transmission and the transmission circuit 12.
  • the low-pass filter 18 removes high-frequency components by extending the rise time and fall time of the drive current of the LD 10, and thereby removes the high-frequency component to the receiving side including the photodiode (PD) 20 and the receiving circuit 22. No electricity Reduces mechanical cross talk.
  • Fig. 4A schematically shows the waveform of the LD drive current in the time domain when the low-pass filter 18 is not provided
  • Fig. 5A shows the LD drive current when the low-pass filter 18 is provided
  • 5 schematically shows a waveform in the time domain.
  • T Indicates the pulse width
  • tr1 and tr2 indicate the rise and fall times of the pulse
  • Figures 4B and 5B show the spectral envelop in the frequency domain when this pulse is continuous, along with a graph of the crosstalk transfer function. Since the crosstalk noise is the product of the LD drive current and the crosstalk transfer function, the amount of crosstalk can be expressed by the shaded area in Figs. 4B and 5B.
  • the low-pass filter 18 removes the high-frequency components, thereby reducing the crosstalk noise. It is desirable that the low-pass filter 18 be disposed near the transmitting circuit 12.
  • the constant of the low-pass filter 18 must be set so that the light output from the LD 10 satisfies a predetermined mask specification.
  • the transmitting side when the bit rate of the receiving side is higher than that of the transmitting side, such as the subscriber side of the ATM-P0N system, the transmitting side removes high-frequency components that cause crosstalk. Since the bit rate on the transmitting side is lower than that on the receiving side, even if high-frequency components that affect reception are removed on the transmitting side, it is possible to satisfy the specifications of the optical output waveform on the transmitting side
  • the first pulse starts from the state where there is no voltage change in the capacitance of LD 10 and capacitor 16. Therefore, as shown by the solid line in FIG. 6B, the rise of the voltage is delayed by the time required for the charge. Therefore, the light emission of the LD is delayed as shown by the solid line in FIG. 6C, and the mask specification cannot be satisfied.
  • FIG. 7 is a circuit diagram of an optical transceiver module according to a second embodiment of the present invention that solves this problem.
  • the same components as those in FIG. 3 are denoted by the same reference numerals, and the circuit on the receiving side is omitted.
  • a constant voltage is applied to the base terminal of the transistor 24, and plays a role of constantly flowing a constant minute current to the LD 10, as shown by the broken line in FIG. 6A.
  • the capacitance of the LD 10 and the capacitor 16 are charged with the voltage, and the voltage rises with the rise of the signal current as shown by the broken line in FIG.
  • the light emission of LD 10 is not delayed.
  • FIG. 8 shows a modification of the circuit of FIG. In the circuit of Figure 8, the transformer Rather than always flowing a constant bias current, the register 24 follows the control voltage 28 and, as indicated by the dashed line in FIG. 9A, a period beginning at the end prior to the burst transmission and ending at the end of the burst. At, a bias current is supplied to LD.
  • Fig. 10 shows the I-L characteristics of the glue.
  • the higher the temperature of an LD the higher the current threshold value and the lower the luminous efficiency. Therefore, in order to always obtain a constant optical power, the magnitude of the drive current is controlled by monitoring the optical output or the temperature of the LD. As a result, when the LD temperature rises, the drive current I increases accordingly.
  • the cross current I x increases with an increase in the LD drive current I.
  • FIG. 11 is a principle block diagram on the transmitting side of the optical transceiver module according to the third embodiment of the present invention in consideration of the above points.
  • the power controller 30 generates a control voltage such that the optical output from the LD 10 becomes constant according to the output of the temperature sensor or the optical monitor, and sends the control voltage to the LD drive circuit 12.
  • the comparator 32 compares the output of the personal controller 30 with the reference voltages V and e Pl, and provides the comparison result to the diode 34 node.
  • the diode 34 is provided in place of the capacitor 16 in FIG. 3 as a capacitance element whose value changes according to the change of the reverse bias voltage.
  • FIG. 12 shows the relationship between the reverse bias voltage of the diode 34 and the capacitance.
  • Ma FIG. 13 shows the voltages at A to C in FIG. As shown in FIG. 13, when the output of the node controller 30 (point A) indicates a low driving current with small crosstalk, the output voltage of the comparator 32 (point B) becomes a low value. becomes, the reverse bias voltage between the BC becomes V 2. At this time Daio - volume of de 34, as shown in FIG. 12, the removal of high frequency components is not carried out by the low-pass full I filter consisting of a lower value C 2, and the resistors 14 and Daio de 34.
  • the low-pass filter 36 composed of the resistor 14 and the diode 34 in FIG. 11 has variable pass characteristics, and when the LD drive current is large and the crosstalk is large, the high frequency of the drive current is high.
  • the component has a pass characteristic that suppresses crosstalk by removing the component. When the LD drive current is small and the crosstalk is small, the pass characteristic does not remove the high-frequency component of the drive current.
  • FIG. 14 is a circuit diagram showing the circuit of FIG. 11 in more detail.
  • the increase or decrease of the optical output due to the temperature change of the LD is detected by the temperature sensor 38 such as a thermistor for detecting the temperature of the LD or the photo diode 40 for detecting the optical output itself.
  • the voltage is converted into a voltage by the voltage converter 42.
  • Part controller 30 is a controller. It is composed of Laywei 44 and 46 controllers.
  • the comparator 44 compares the output of the current-Z voltage converter 42 with the reference voltage V rep 2 and outputs a comparison signal.
  • the controller 46 generates a control voltage to keep the optical output of the LD 10 constant based on the comparison result of the comparator 44.
  • Fig. 15 is similar to Fig.
  • FIG. 16 is a modification of the circuit of FIG. FIG. 17 shows waveforms at points C to G in FIG. In FIG. 16, the data signal (D) is delayed by delay elements 48 and 50 and supplied to the LD drive circuit 12.
  • the reference value supplied to the comparator 32 is obtained by taking NAND of a data signal that is delayed by a delay time longer than the delay time of the delay elements 48 and 50 (E) and a data signal that is not delayed (F). Generated (G). Therefore, as shown in FIG. 17, the potential at the point G is maintained at the high potential during the period when the potential at the point C changes.
  • the reverse bias voltage of the diode becomes smaller at the change point of the signal where the high frequency component is large and the crosstalk is increased. The crosstalk can be effectively suppressed.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)

Abstract

Cette invention concerne un module émetteur-récepteur optique conçu pour éliminer le phénomène de diaphonie électrique entre les côtés émission et réception. Un filtre passe-bas constitué par une résistance (14) et un élément capacitif (16) permet de supprimer les composantes haute fréquence du courant de commande d'une diode laser (10) sur le côté émission.
PCT/JP1998/005384 1998-11-30 1998-11-30 Module emetteur recepteur optique WO2000033490A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP1998/005384 WO2000033490A1 (fr) 1998-11-30 1998-11-30 Module emetteur recepteur optique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP1998/005384 WO2000033490A1 (fr) 1998-11-30 1998-11-30 Module emetteur recepteur optique

Publications (1)

Publication Number Publication Date
WO2000033490A1 true WO2000033490A1 (fr) 2000-06-08

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PCT/JP1998/005384 WO2000033490A1 (fr) 1998-11-30 1998-11-30 Module emetteur recepteur optique

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WO (1) WO2000033490A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2386779A (en) * 2002-03-19 2003-09-24 Denselight Semiconductors Pte Multi-channel optical transmitter module
US7720393B2 (en) 2005-01-20 2010-05-18 Fujitsu Limited Optical module

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58111446A (ja) * 1981-12-25 1983-07-02 Canon Inc 光学繊維の送受信モジユ−ル
JPH0368088U (fr) * 1989-11-01 1991-07-03
JPH07162186A (ja) * 1993-12-08 1995-06-23 Fujitsu Ltd 光送受信ユニット
JPH0993221A (ja) * 1995-09-21 1997-04-04 Matsushita Electric Ind Co Ltd 光伝送装置
JPH09214440A (ja) * 1996-02-05 1997-08-15 Kokusai Denshin Denwa Co Ltd <Kdd> パルス情報の双方向伝送方式及び光送受信装置
JPH09275375A (ja) * 1996-04-05 1997-10-21 Toshiba Corp 光通信装置
JPH1091113A (ja) * 1996-09-11 1998-04-10 Pfu Ltd 内部フィルタ選択型表示装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58111446A (ja) * 1981-12-25 1983-07-02 Canon Inc 光学繊維の送受信モジユ−ル
JPH0368088U (fr) * 1989-11-01 1991-07-03
JPH07162186A (ja) * 1993-12-08 1995-06-23 Fujitsu Ltd 光送受信ユニット
JPH0993221A (ja) * 1995-09-21 1997-04-04 Matsushita Electric Ind Co Ltd 光伝送装置
JPH09214440A (ja) * 1996-02-05 1997-08-15 Kokusai Denshin Denwa Co Ltd <Kdd> パルス情報の双方向伝送方式及び光送受信装置
JPH09275375A (ja) * 1996-04-05 1997-10-21 Toshiba Corp 光通信装置
JPH1091113A (ja) * 1996-09-11 1998-04-10 Pfu Ltd 内部フィルタ選択型表示装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2386779A (en) * 2002-03-19 2003-09-24 Denselight Semiconductors Pte Multi-channel optical transmitter module
US7720393B2 (en) 2005-01-20 2010-05-18 Fujitsu Limited Optical module

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