JP3276347B2 - Optical / electrical mutual conversion element, optical signal transmitting / receiving device, and optical signal transmitting / receiving system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical / electrical mutual conversion element, an optical signal transmitting / receiving apparatus, and an optical signal transmitting / receiving system, and can be applied to, for example, a system for providing two-way simultaneous communication of signal light.

[0002]

2. Description of the Related Art For example, a base station (Base Station) and a central control station (C) in a mobile communication system.
Research and development have been made to apply two-way simultaneous communication of signal light to communication between the central offices.

FIG. 2 is a block diagram schematically showing a conventional optical signal transmitting / receiving system applicable to two-way simultaneous communication between a base station and a central control station.

In FIG. 2, a central control station 1 includes a semiconductor laser 11 that performs a modulation operation and a semiconductor laser 12 that performs a continuous oscillation operation (CW). From the semiconductor laser 11, light having a wavelength λ3 (for example, 1558 nm) is modulated in accordance with a transmission signal to the base station 2, and a millimeter wave (for example, 59.5)
The signal light S (λ3) converted to the frequency of 1 GHz (GHz) is emitted, and the WDM (wavelength Di) inside the central control station 1 is emitted.
(vision multiplex) coupler 13. Continuous wave light (hereinafter simply referred to as “continuous light”) S (λ4) having a wavelength λ4 (for example, 1537 nm) emitted from the semiconductor laser 12 is incident on the WDM coupler 13.
The signal light S (λ3) and the continuous light S (λ4) are WD
After being wavelength-multiplexed by the M coupler 13, it is transmitted to the base station 2 via an optical waveguide (comprising an optical fiber, an optical amplifier, etc.) 3A connecting the central control station 1 and the base station 2.

In the base station 2, the wavelength multiplexed light from the central control station 1 is converted by the WDM coupler 21 into wavelength components λ3,
λ4. The separated signal light S (λ3) is converted into an electric signal (light / electric conversion) by a photodiode (PD) 22 which is a light receiving element. This electric signal is transmitted by a transmitting unit (concept including modulation configuration and antenna) 23 to a mobile station (Mobile Terminal) (not shown).
It is transmitted to the mobile station as radio waves.

[0006] Information from a mobile station (not shown) is transmitted as radio waves to the base station 2, where the receiving unit (concept including an antenna and a demodulation configuration) 24 captures the electric signal from the receiving unit 24. Is an electroabsorption type optical modulator (E
electro-Absorption Modulat
or: EAM) 25. The continuous light S (λ4) having the wavelength λ4, which is transmitted from the central control station 1 and extracted by the WDM coupler 21, is incident on the electroabsorption optical modulator 25. The continuous light S (λ4) The signal light becomes a millimeter-wave modulated signal light by the electric field applied to the absorption type optical modulator 25. The signal light S (λ4) after the modulation is transmitted to the base station 2
The signal is transmitted to the central control station 1 via an optical waveguide (comprising an optical fiber, an optical amplifier, etc.) 3B connecting the central control station 1 and the central control station 1.

In the central control station 1, the signal light S (λ4)
Is converted into an electric signal (light / electric conversion) by a photodiode (PD) 14 which is a light receiving element.

As described above, the signal light S (λ3) converted from the millimeter wave transmitted from the central control station 1 by the base station 2 is transmitted.
At the same time, the millimeter-wave signal from the mobile station is
(Λ4) and can be transmitted to the central control station 1.

[0009]

However, in the above-described conventional system, the base station 2 needs a component separation structure of the wavelengths .lambda.3 and .lambda.4 from the wavelength-division multiplexed signal. Therefore, two modules of the device 25 are required, and the size of the base station 2 is increased.

In particular, the base station 2 has a narrow radio wave reach,
Since it is assumed that a large number of mobile communication systems are installed, the above-described conventional system has a problem that the entire mobile communication system becomes large.

Such a problem similarly occurs in other optical signal transmitting / receiving systems that provide two-way simultaneous communication of signal light, and optical signal transmitting / receiving apparatuses corresponding to the above-described base stations on the system. .

Therefore, there is a need for an optical signal transmitting and receiving apparatus and an optical signal system that are simple in configuration and small in size. There is also a need for a component (optical-electrical mutual conversion element) capable of realizing such an optical signal transmitting / receiving device and optical signal transmitting / receiving system.

[0013]

In order to solve this problem, a first optical-electrical mutual conversion element according to the present invention has a wavelength λ1.
And a signal that converts a signal light into an electric signal and passes a continuous light component having a wavelength of λ1.
An electrical converter and an electrical / optical converter that modulates continuous light in accordance with an externally applied electrical signal are optically provided in series on the same semiconductor substrate.

According to a second aspect of the present invention, there is provided an optical / electrical conversion unit which receives a wavelength multiplexed signal of a continuous light having a wavelength λ1 and a signal light having a wavelength λ2, and converts the signal light into an electric signal. continuous light in accordance with an electric signal applied from the outside met the optical signal transmitting and receiving device and an electric / optical conversion section which modulates
An optical / electrical converter and an electrical / optical converter for passing a continuous light component having a wavelength of λ1 are optically provided in series to process a wavelength multiplexed signal without separating it into wavelength components. I do.

Further, according to a third aspect of the present invention, the first station transmits to the second station a wavelength multiplexed signal of continuous light having the wavelength λ1 and signal light having the wavelength λ2. The station has an optical / electrical conversion unit that converts signal light into an electric signal, and an electric / optical conversion unit that modulates continuous light according to an electric signal applied from the outside. An optical signal transmitting and receiving system for transmitting a modulated light to a first station, and the first station receiving the modulated light .
An optical / electrical converter and an electrical / optical converter that allow continuous light components to pass therethrough are optically provided in series to process a wavelength-division multiplexed signal without separating it into wavelength components.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment Hereinafter, an optical / electrical mutual conversion element, an optical signal transmitting / receiving apparatus, and an optical signal transmitting / receiving system according to the present invention will be described in a mobile communication system between a base station and a central control station. The first embodiment applied to this communication will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a main part of an optical signal transmitting / receiving system (mobile communication system) according to the first embodiment.

In FIG. 1, a central control station 4 and a base station 5
Are used for transmitting an optical signal from the central control station 4 to the base station 5, an optical waveguide (comprising an optical fiber or an optical amplifier) 6 </ b> A, and for transmitting an optical signal from the base station 5 to the central control station 4. They are connected by an optical waveguide 6B.

The central control station 4 has two semiconductor lasers 41
And 42, a WDM coupler 43, and a photodiode 44
It has.

The one semiconductor laser 41 oscillates and outputs light having a wavelength of λ1 (for example, 1580 nm), and the emitted light is unmodulated continuous light S (λ1). The other semiconductor laser 42 has a wavelength λ2 (for example, 15
20 nm), and the emitted light is a modulated signal light S (λ2) to be transmitted to the base station 5. In the first embodiment, the wavelength λ2 is shorter than the wavelength λ1. In FIG. 1, the signal light S (λ2)
Is illustrated as being obtained by directly modulating the semiconductor laser 42, but light obtained by modulating light from the semiconductor laser emitting continuous light with an external modulator such as an electroabsorption type optical modulator may be used. It is possible.

The emitted light S from each of the semiconductor lasers 41 and 42
(Λ1) and S (λ2) are each incident on the WDM coupler 43 via, for example, an optical fiber. WDM coupler 4
Reference numeral 3 denotes a wavelength multiplex of these incident lights S (λ1) and S (λ2), and emits the wavelength-multiplexed light to the optical waveguide 6A. That is, the wavelength multiplexed light is transmitted to the base station 5.

The photodiode 44 receives a signal light S (described later) transmitted from the base station 5 via the optical waveguide 6B.
(Λ1) is obtained by photoelectric conversion.

The base station 5 includes a transmission / reception module 51 for transmitting / receiving data to / from the central control station 4, a transmission unit 52 for performing transmission processing to a mobile station (not shown), and a reception unit 53 for performing reception processing of a signal from the mobile station. And Since the transmitting unit 52 and the receiving unit 53 are the same as those in the related art, the description thereof will be omitted.

The transmission / reception module 51 has functions of both a photodiode (optical / electrical conversion element) and an electro-absorption type optical modulator (electrical / optical conversion element). In the case of the first embodiment, the transmission / reception module 51 is composed of one integrated semiconductor element (see FIG. 3), and a photodiode function portion (hereinafter, referred to as a PD portion) is arranged from the incident side. 51a and an electro-absorption type optical modulator function part (hereinafter referred to as E
51b) are connected in series.

The wavelength-division multiplexed light transmitted by the central control station 4 arriving via the optical waveguide 6A is transmitted to the transmitting / receiving module 5
1 is incident.

It is to be noted that a wavelength filter or the like is provided in front of the transmission / reception module 51 to remove unnecessary components, or that an optical direct amplifier is provided to increase the power of wavelength-multiplexed light input to the transmission / reception module 51. May be.

The transmission / reception module 51 receives (optical / electrical conversion) the signal light S (λ2), which is a millimeter wave signal, of the wavelength multiplexed signal in the PD section 51a on the incident side.
A transmitting unit 5 for transmitting the received electric signal I (λ2) to the mobile station;
Give to 2. Further, the transmission / reception module 51 modulates the continuous light S (λ1) of the wavelength multiplexed signal with the electric signal V (λ1) from the mobile station obtained by the reception unit 53 in the EAM part 51b on the emission side, and performs central control. Transmit to station 4.

Here, by properly selecting the wavelengths λ1 and λ2, the absorption loss of the continuous light S (λ1) in the incident PD portion 51a does not increase, and the light can reach the EAM portion 51b on the opposite side. it can. The PD portion 51a has a structure in which the signal light S (λ2) is efficiently absorbed and the continuous light S (λ1) is transmitted. In the first embodiment, for example, λ1 = 1560 nm wavelength, λ2 =
Desired characteristics are obtained by selecting a wavelength around 1520 nm.

Next, the structure of the integrated semiconductor device constituting the transmitting / receiving module 51 will be described with reference to FIG. Here, FIG. 3 is a cross-sectional view showing the structure of the integrated semiconductor device (transmitting / receiving module 51).

In this integrated semiconductor device 51, an optical waveguide structure using InP (n-InP in FIG. 3) as a substrate, similarly to a waveguide structure for light in the wavelength band of 1.5 μm used in ordinary optical communication. Has been applied.

The PD section (light receiving section) 51a and the EAM section (modulation section) 51b have the same structure and composition as a core layer (i layer:
Intrinsic-layer, a layer not intentionally doped with impurities), and has a pin junction structure sandwiched between an n-InP cladding layer and a p-InP cladding layer in the stacking direction. I have. Note that FIG.
Then, the core layer of the PD portion 51a is shown in black, and the EAM
The core layer of the portion 51b is hatched, but this is to make it easy to distinguish between the core layer of the PD portion 51a and the EAM portion 51b.
Have the same structure and composition.

The core layer is made of, for example, an InGaAsP composition or InGaAs (P) / InGaAsP having a band gap wavelength λEg that modulates continuous light S (λ1) and absorbs signal light S (λ2). Of a multiple quantum well structure (MQW). In the first embodiment, the wavelength λ1 = 1580 nm and the wavelength λ2 = 1520 nm
In contrast, by setting the bandgap wavelength λEg to about 1510 nm, desired characteristics are obtained.

The lower n-electrode comprises a PD portion 51a and an EAM
Although common to the portion 51b, the upper p-InGaAs contact layer and the p-electrode are separated so that the PD portion 51a and the EAM portion 51b can be driven independently, and a proper DC bias is applied to each of them. Optical signals can be transmitted and received.

Normally, a DC reverse bias is applied to efficiently operate a photodiode or an electro-absorption optical modulator. FIG. 4 is a graph showing the wavelength dependence of the insertion loss (= optical absorption loss + coupling loss at the incoming (out) emitting end face) depending on the level of the reverse bias applied to the transmitting / receiving module 51.

By applying a reverse bias of about -1 V to the PD portion 51a, the signal light S having a wavelength λ2 = 1520 nm can be obtained.
(Λ2) results in a loss of about 21 dB. That is, the signal light S (λ2) is almost absorbed by the PD portion 51a, and is efficiently received. On the other hand, continuous light S (λ
1) is the wavelength λ1 = 1580 nm, and the PD portion 51a
In this case, the loss is only about 7 dB. Thus, the continuous light S (λ1) can reach the EAM portion 51b with little absorption in the PD portion 51a.

It should be noted that the signal light S (λ
2) the insertion loss is increased and the continuous light S (λ1)
In order to minimize the insertion loss of the signal light S (λ) when no bias is applied (0 V bias state).
The insertion loss of 2) and the insertion loss of continuous light S (λ1) are 10
Preferably, there is a difference of dB or more.

Since the wavelength dependence of the insertion loss is as shown in FIG. 4, the wavelength λ1 of the continuous light S (λ1) =
Let 1580 nm be the wavelength λ2 = 152 of the signal light S (λ2).
It is longer than 0 nm.

As shown in FIG. 3, in the first embodiment, the continuous light S (λ1) and the signal light S (λ2) enter one transmission / reception module 51 while being wavelength-multiplexed (together). Is done. The signal light S (λ2) is transmitted to the PD portion 51a.
And generate a modulated electric signal I (λ2).
The simultaneously incident continuous light S (λ1) reaches the EAM portion 51b with a small loss as described above. At this stage, the light is in a continuous light (CW) state, and has not been turned into a signal light. Continuous light S reaching the EAM portion 51b
(Λ1) is the modulation voltage V applied to the EAM portion 51b.
The signal light is converted by (λ1), transmitted to the central control station 4 through the optical waveguide 6B, and received by the photodiode 44 of the central control station 4.

Here, the PD portion 51a and the EAM portion 51
By separating the electrodes b, each can be operated simultaneously.

As described above, according to the first embodiment, when two wavelength-division multiplexed lights are incident, the two wavelengths are matched to one transmitting / receiving module without separating the wavelengths. When the light is incident while being left, two-way simultaneous communication becomes possible.

Further, as compared with the conventional method, the configuration of the base station is simplified and the size of the base station can be reduced as much as the wavelength demultiplexing structure is not required. As a result, the whole mobile communication system can be simplified. . Furthermore, since one transmission / reception module has functions of both a photodiode and an electro-absorption optical modulator, the configuration of the base station is also simplified from this point,
The size can be reduced, and as a result, the entire mobile communication system can be simplified.

(B) Second Embodiment Next, an optical / electrical mutual conversion element, an optical signal transmitting / receiving apparatus and an optical signal transmitting / receiving system according to the present invention are used for communication between a base station and a central control station in a mobile communication system. A second embodiment applied will be described in detail with reference to the drawings.

The second embodiment differs from the first embodiment in the detailed configuration of the transmission / reception module in the base station 5.

FIG. 5 is a sectional view showing the structure of a transmitting / receiving module (integrated semiconductor device) 51 according to the second embodiment.

The transmission / reception module (integrated semiconductor device) 51 of the second embodiment is also a PD portion (light receiving portion) 5.
1a and the EAM portion (modulation portion) 51b have the same structure and composition.
-InP substrate, n-InP cladding layer, core layer, p-I
nP cladding layer, p-InGaAs contact layer and p
Consisting of electrodes.

The transmitting / receiving module (integrated semiconductor device) 51 of the second embodiment is different from that of the first embodiment in that, in addition to the PD portion 51a and the EAM portion 51b,
The point is that it has a light guide portion 51c. That is, PD
Between the core layer of the portion 51a and the core layer of the EAM portion 51b,
The point is that a light guide layer is provided to optically cut off the PD portion 51a and the EAM portion 51b. As the light guide layer, for example, an InGaAsP layer having such a composition that waveguide loss with respect to continuous light S (λ1) is small and that the light can be efficiently incident on the EAM portion 51b is applied. As an optical guide layer, for example, I with a band gap λEg = 1200 nm
By inserting the nGaAsP layer into a length of about 1 mm, electrical connection between the PD portion 51a and the EAM portion 51b can be improved.
Optical crosstalk can be significantly reduced.

As in the first embodiment, the signal light S (λ2) having a short wavelength is received by the PD portion 51a, and the continuous light S
(Λ1) reaches the EAM portion 51b with little loss.

Here, in the second embodiment, the PD portion 5
Since the light guide portion 51c having the light guide layer having a length of about 1 mm is inserted between the PD portion 51a and the EAM portion 51b, the electric resistance between the PD portion 51a and the EAM portion 51b is high, and the PD portion 51a Even if a part of the signal light S (λ2) that could not be absorbed by the light leaks, it is almost completely removed before reaching the EAM portion 51b because of the light guide layer.

According to the second embodiment, the same effects as in the first embodiment can be obtained. That is,
When two wavelength-multiplexed lights are incident, two-way simultaneous communication becomes possible by inputting two wavelengths to one transmission / reception module without separating the wavelengths without separating the wavelengths. The configuration of the base station is simpler and smaller than that of the above method, and as a result, the entire mobile communication system can be simplified.

In addition to this, according to the second embodiment,
Since there is a light guide section between the PD section and the EAM section of the transmission / reception module, even when the PD section and the EAM section are independently operated at the same time, they hardly interfere with each other, and noise can be reduced due to the interference. Is improved.

In the first embodiment, since the waveguide of the PD portion and the waveguide of the EAM portion are directly joined, the electromotive force modulated by the received light in the PD portion is EA.
It may interfere with the M part and cause noise when the EAM part is driven. Also, the signal light S (λ2) desired to be completely absorbed in the PD part leaks to the EAM part,
In addition to the noise in the AM part, the electric signal for driving the EAM part may also reach the PD part and deteriorate the receiving sensitivity.

(C) Other Embodiments In each of the above embodiments, the case where a millimeter wave and a microwave are transmitted and received from the central control station to the base station has been described. The present invention can be applied to not only the case of transmitting and receiving after conversion but also the case of transmitting and receiving a digital optical signal by intensity modulation. Also, the application target of the optical transmission / reception system of the present invention is not limited to the mobile communication system. Furthermore, in each of the above embodiments, the transmitting and receiving module 51 transmits the modulated continuous light to the source of the continuous light, but transmits the modulated continuous light to a station other than the transmitting source. You may do it.

In each of the above embodiments, in the base station, the transmission / reception module 51 in which the PD section 51a and the EAM section 51b are formed on the same substrate, transmits the signal light S (λ
2), the reception (optical / electrical conversion) and the modulation (electrical / optical conversion) of the continuous light S (λ1) are described. However, the signal light S ( λ2) and continuous light S (λ
Modulation (electric / optical conversion) for 1) may be performed. For example, as shown in FIG. 6, the signal light S (λ2)
A photodiode 51A as an individual module that performs reception (optical / electrical conversion) of light and an electroabsorption optical modulator 51B as an individual module that performs modulation (electrical / optical conversion) on the continuous light S (λ1) are optically connected. You may arrange | position in series and may perform a desired process.

Further, in each of the above embodiments, the structure for receiving (optical / electrical conversion) of the signal light S (λ2) is located on the incident side, and the modulation (electrical / optical conversion) of the continuous light S (λ1) is performed. The configuration that performs is shown after that,
This order may be reversed if the arrangement is optically serial.

Further, in the transmitting / receiving module 51 of each of the above embodiments, the PD section 51a and the EAM section 5
1b has the same structure and composition, but may have a different structure and composition as long as it satisfies the requirement that the absorption loss of the continuous light S (λ1) is small and the signal light S (λ2) can be sufficiently absorbed. .

Further, the transmission / reception module 51 in each of the above embodiments is a novel invention itself, and its application is not limited to the optical signal transmission / reception system as in the above embodiments.

[0057]

As described above, according to the optical-electrical mutual conversion element of the first aspect of the present invention, the optical-electrical conversion unit for converting the signal light having the wavelength λ2 in the input wavelength-division multiplexed signal into the electric signal. And the wavelength λ1 in the input wavelength multiplexed signal.
And an electrical / optical conversion unit that modulates continuous light having an external optical signal according to an externally applied electrical signal is optically provided in series on the same semiconductor substrate. The configuration of the optical signal transmitting and receiving system can be made simple and small.

According to the optical signal transmitting / receiving apparatus of the second aspect of the present invention, the optical / electrical converter for converting the signal light having the wavelength λ2 in the input wavelength multiplex signal into an electric signal, Electric / modulation of continuous light having a wavelength λ1 in a signal in accordance with an externally applied electric signal;
Since the optical converter and the optical converter are optically provided in series, the wavelength multiplexed signal can be processed without being separated into each wavelength component, and the configuration of the optical signal transmitting / receiving apparatus can be made simple and small.

Further, according to the optical signal transmission / reception system of the third aspect of the present invention, the second station converts the signal light having the wavelength λ2 in the wavelength multiplexed signal from the first station into an electric / electrical signal. A conversion unit, and an electric / optical conversion unit that modulates continuous light having a wavelength λ1 in the wavelength multiplexed signal from the first station according to an externally applied electric signal to obtain modulated light to be transmitted to the first station. Are optically provided in series, so that the second station can process the wavelength multiplexed signal without separating it into each wavelength component, and can simplify the configuration of the optical signal transmitting / receiving system, particularly the second station. , And can be small.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical transmission and reception system according to a first embodiment.

FIG. 2 is a block diagram illustrating a configuration of a conventional optical transmission / reception system.

FIG. 3 is a cross-sectional view illustrating a structure of a transmission / reception module (optical / electrical mutual conversion element) according to the first embodiment.

FIG. 4 is a graph showing the relationship between the wavelength and the insertion loss of the transmission / reception module (optical-electrical mutual conversion element) in the first embodiment, using an applied bias as a parameter.

FIG. 5 is a cross-sectional view illustrating a structure of a transmission / reception module (optical / electrical mutual conversion element) according to a second embodiment.

FIG. 6 is a block diagram illustrating a configuration example of an optical / electrical converter and an electrical / optical converter in another embodiment.

[Explanation of symbols]

4: Central control station (first station) 5: Base station (second station) 51: Transceiver module (optical / electrical mutual conversion element) 51a: PD part (photodiode function part; optical / electrical conversion part) ), 51b ... EAM part (electric absorption type optical modulator function part; electric / optical conversion part), 51c ... light guide part (passive waveguide), 51A ... photodiode (light / electric conversion part), 51B ... electric absorption type Optical modulator (electric / optical converter).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Nakamura, Inventor 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Naoyuki Mineo 1-7-112, Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Yoshiki Shibuya 1-7-1 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Kiyoshi Nagai 1-7-1, Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Takashi Ushikubo 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Toshiaki Kuri 4-2-1 Kitanikitamachi, Koganei-shi, Tokyo (56) References JP-A-9-121043 (JP, A) JP-A-53-41104 (JP, A) JP-A-3-160833 (JP, A) JP-A-4- 139924 (JP, A) (58) key Field (Int.Cl. ⁷ , DB name) H01L 31/00-31/12

Claims (15)

(57) [Claims] 1. A wavelength-division multiplexed signal of a continuous light having a wavelength λ1 and a signal light having a wavelength λ2 is inputted, wherein the signal light is converted into an electric signal and the wavelength λ1 is converted into an electric signal .
An optical / electrical conversion unit for passing a continuous light component, and an electric / electrical converter for modulating the continuous light in accordance with an externally applied electric signal.
An optical-electrical mutual conversion element, wherein a light conversion part is provided optically in series on the same semiconductor substrate. 2. The optical / electrical converter according to claim 1 , wherein the signal having a wavelength of λ2 is provided.
2. The light according to claim 1, wherein the insertion loss of the optical component is high , the optical / optical conversion unit is located on the incident side of the wavelength division multiplexed signal, and is located at a subsequent stage on the optical path.・
Electric interconversion element. 3. The optical device according to claim 1, wherein the wavelength λ1 of the continuous light is longer than the wavelength λ2 of the signal light.
Electric interconversion element. 4. The optical / electrical mutual conversion element according to claim 1, wherein both the optical / electrical converter and the electrical / optical converter have a waveguide structure. 5. The optical / electrical mutual conversion element according to claim 1, wherein said optical / electrical converter and said electrical / optical converter have the same composition and the same structure. 6. The composition and structure of the light-to-electricity conversion part and the light-to-electricity conversion part are such that a wavelength λ2
6. The optical-electrical mutual conversion device according to claim 5, wherein the insertion loss for the light having the wavelength of? 1 is greater than the insertion loss for the light having the wavelength? 1 by 10 dB or more. 7. A passive waveguide having a composition whose band gap is larger than that of said optical / electrical converter and said electric / optical converter is inserted between said optical / electrical converter and said electric / optical converter.
7. The optical-electrical mutual conversion element according to any one of claims 6 to 6. 8. An optical / electrical conversion unit that receives a wavelength multiplexed signal of a continuous light having a wavelength λ1 and a signal light having a wavelength λ2, converts the signal light into an electric signal, and converts the continuous light from outside. the optical signal transmission and reception apparatus having an electrical / optical conversion section which modulates in response to applied electrical signals, and said optical / electrical converter for passing the continuous light component of the wavelength .lambda.1, and the electrical / optical conversion part Are optically provided in series,
An optical signal transmitting / receiving apparatus for processing a wavelength multiplexed signal without separating it into wavelength components. 9. The optical / electrical conversion unit according to claim 1 , wherein the signal of wavelength λ2 is
9. The light according to claim 8, wherein the insertion loss of a light component is high , the light / light conversion part is located on the incident side of the wavelength multiplexed signal, and the electric / light conversion part is located at a subsequent stage on the light path. Signal transmitting and receiving device. 10. The wavelength λ1 of the continuous light is equal to the wavelength λ2 of the signal light.
The optical signal transmitting / receiving device according to claim 8, wherein the optical signal transmitting / receiving device is longer. 11. The optical / electrical conversion unit according to claim 1, wherein the optical / electrical conversion unit and the electric / optical conversion unit are configured as described above. An optical signal transmitting / receiving device according to claim 8. 12. A first station transmits a wavelength multiplexed signal of a continuous light having a wavelength λ1 and a signal light having a wavelength λ2 to a second station, and the second station multiplexes the signal light. An optical / electrical conversion unit for converting the continuous light into an electric signal; and an electric / optical conversion unit for modulating the continuous light according to an electric signal applied from the outside. transmitted to the first station, the first station an optical signal transmitting and receiving system for receiving the modulated light, and have contact with the second station, of passing the continuous light component of the wavelength λ1
And said optical / electrical converter for, and the electrical / optical conversion part optically arranged in series, the optical signal transmission and reception system, characterized in that the processing without separating the wavelength-multiplexed signal to each wavelength component. 13. The second station, wherein the optical / electrical conversion unit has a high insertion loss of a signal light component having a wavelength λ2.
The optical signal transmission / reception system according to claim 12, wherein the optical / optical conversion unit is located on the incident side of the wavelength multiplexed signal, and is located downstream of the optical path. 14. The wavelength λ1 of the continuous light is equal to the wavelength λ2 of the signal light.
14. The optical signal transmitting and receiving system according to claim 12, wherein the optical signal transmitting and receiving system is longer. 15. The configuration of the optical / electrical conversion unit and the electric / optical conversion unit in the second station,
13. The optical signal transmission / reception system according to claim 12, wherein the optical / electrical mutual conversion element according to any one of claims 7 to 7 is applied.