JP2835306B2 - Optical interconnection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a space-parallel optical interconnection device used for wiring between boards of a massively parallel computer, and more particularly to an optical interconnection device in which a planar optical multifunctional element is improved.

[0002]

2. Description of the Related Art In a massively parallel computer in which a large number of processors are simultaneously operated in parallel to dramatically improve the computing capacity, a communication network connecting the processors is enlarged with the increase in the number of processors, and the performance is expected to increase. Not improve
The so-called wiring bottleneck is a problem. As means for solving this problem, attention has been paid to a parallel optical interconnection technology utilizing the high speed and spatial multiplexing of light.

As a configuration of a parallel optical interconnection for connecting a number of boards by using a surface type optical device, an optical signal transmitted from a preceding board is temporarily converted into an electric signal by each board, and the waveform is shaped. After that, a relay method of sending the optical signal to the next board again as an optical signal or a method of relaying the optical signal as it is without converting the optical signal into an electric signal can be considered. In the case of performing multi-stage connection, the former method causes a wiring delay due to electric processing, and thus the latter method of relaying light as it is considered to be advantageous.

[0004] Fig. 3 shows an example of a spatial parallel optical interconnection device of a system for relaying light as it is. In this optical interconnection, an optical interconnection chip 201, 100 processors 2, a memory and peripheral circuits 3, and 100 boards 5 on which electric wiring 4 and the like connecting these are mounted, use a grating lens 6 and the like. They are coupled in a loop by the optical system 7. Chips 201, 2, 3 in the same board are electrically connected by electric wiring 4. Each board 5 is provided with an appropriate cooling system to prevent a rise in temperature. Board spacing is about 3cm on average
It is.

As shown in FIG. 12, each of the interconnection chips 201 has 1,000 surface light emitting elements 20.
Nine and ten thousand surface-type multifunctional elements 210 are mounted. As shown in the figure, the positions of these surface-type optical elements are represented by coordinates (X, Y) (X = 1 to 110, Y = 1 to 100).
It will be specified by. X = 1,12,23,34,4
The surface light emitting element 209 is located at positions 5, 56, 67, 78, 89 and 100, and the surface optical multifunctional element 2 is located at other positions.
10 are arranged.

As shown in FIG. 4, the surface type multifunctional element 210 has a structure in which a light receiving section 11 and an optical amplifying section 12 are integrated. About half of the signal light is received by the light receiving unit 11 by the optical system 7.
The other half is set so as to enter the optical amplification unit 12. The optical amplifying unit 12 has a function of compensating energy lost due to branching to the light receiving unit 11, a boundary portion, reflection / absorption of the electrode 16, and the like, and relaying an optical signal to the next stage.

The optical amplifying unit 12 comprises a Fabry-Perot resonance type surface optical amplifier in which an active region 13 is sandwiched between a reflective film 17 made of a dielectric multilayer film and a reflective film 18 made of a distributed Bragg reflection (DBR) layer. Since it is a resonance type, a gain of 3 dB can be obtained with a current of 10 mA or less. In order to efficiently inject and confine carriers in the active layer 13, the p-cladding layer 14 and the n-cladding layer 15 having a wider bandgap than the active layer 13 have a structure in which the multi-layered active layer 13 is sandwiched. An electrode 16 is provided on the layers 14 and 15.

Since the surface-type optical amplifier has a small one-pass gain, it is necessary to adopt the above-described resonance type configuration in order to reduce the operating current, that is, to reduce the power consumption. However, there is a problem that the operating current can be reduced as the Q value of the resonator is increased, but the wavelength band is narrowed. In order to connect the resonant optical amplifiers having a narrow band in multiple stages, the resonance wavelengths must be strictly aligned. Considering the controllability of the device fabrication process and the fluctuation of the resonance wavelength due to the environment, the multistage connection is extremely severe.

[0010] Of the surface light emitting elements 209, 100 with X = 1 correspond to the outputs from the 100 processors 2 mounted on the board 5. Surface light emitting element 2 at coordinates (1, Y)
The output 09 is connected by the optical system 7 to the planar optical multifunctional element 210 at the coordinates (2, Y) of the next board, and similarly the output of the planar optical multifunctional element 210 at the coordinates (X, Y). Is a surface-type optical multifunctional device 21 arranged at the next stage (X + 1, Y).
Connected to 0.

However, X = 11,22,33,44,5
5, 66, 77, 88, 99 planar optical multifunctional element 210
Does not perform optical relaying, but only performs reception. That is, after electrically shaping the signal waveform deteriorated by ASE noise or the like due to the nine-stage optical amplification relay, X = 12, 23, 34, 45,
X = 13,24,35,4 of the next stage as optical signals again from the surface light emitting elements 209 of 56,67,78,89,100.
6, 57, 68, 79, 90, and 101 to the surface type multifunctional element 210. Surface optical multifunctional device 2 with X = 110
Numeral 10 is for monitoring and performs only reception. X = Receive only
11, 22, 33, 44, 55, 66, 77, 88, 9
9 and 110 may be replaced with a light receiving element.

The first reason that the electric regeneration relay is required every 10 stages is that the ASE (Amplified) of the surface type optical amplifier is used.
This is because, in addition to noise, signal light and ASE light of adjacent channels leak in addition to noise. When such ASE light or crosstalk light accumulates as noise, S
The signal / noise ratio deteriorates, and the total input power of the signal and the noise increases, so that gain saturation is likely to occur. If the signal light power is increased, the S / N ratio can be increased, but gain saturation tends to occur. Therefore, there is a trade-off between improving the S / N ratio and suppressing gain saturation.

The second reason why electrical regeneration relay is required is that the operation of the optical amplifier tends to be unstable due to reflected return light. If there is reflected return light, the optical amplifiers connected in multiple stages form a composite resonator, and unstable operation such as fluctuations in amplification factor and reflectivity depending on the intensity of the return light and the degree of phase overlap. Fall into In particular, as the number of connection stages increases, the mutual relationship becomes complicated, so that even a slight reflection tends to cause instability.

Even if a low reflection coating is applied to the surface of a semiconductor chip or an optical component to prevent unnecessary reflection, return light is generated if the resonant optical amplifier has a reflection gain. The reflectance on the entrance side is R ₁ , and the reflectance on the exit side is R
_2. Assuming that the one-pass gain of the active layer is Gs, it is known that the reflection gain can be made zero by satisfying the relationship of R ₁ = R ₂ Gs ^{2 at} the signal light wavelength. However, it is very difficult to adjust the wavelength to a predetermined value and adjust the one-pass gain and reflectivity of each optical amplifier so as to satisfy this relationship.

The time for the light to travel through the board interval of 3 cm is about 0.
1 ns, and a transmission time of 10 ns is required for 100 stages. Assuming that there is a delay of about 10 ns between the light emission drive unit and the electric regeneration relay, 10 ns × 10 = 100 ns, that is, the total maximum delay time is about 110 ns. The maximum delay time is 100 in the method of electrically regenerative relay in each stage.
Since this time is 0 ns, this method is more excellent in synchronism, but it is still difficult to say that it is sufficiently fast as wiring between boards of a massively parallel processor.

[0015]

As described above, in the conventional spatial parallel optical interconnection apparatus of the type in which the light is relayed as it is, as the scale is increased, signal-to-noise (signal-to-noise) is generated by optical crosstalk between channels or ASE light. (S / N) ratio is degraded and the gain saturation level is lowered. Since the ASE light has lower emission directivity than the signal light, it easily affects adjacent channels. Furthermore, stray light or return light leaking into a distant channel due to reflection or a defect in an optical system or the like easily causes deterioration of the S / N ratio and unstable operation. To eliminate these effects, several steps to 10
It is necessary to carry out electrical regeneration relay once per stage, which causes a problem that the load on the regenerative amplifier circuit increases and the wiring delay time increases. Furthermore, the reproduction amplifier circuit causes electrical crosstalk between array channels.

Another problem with this type of optical interconnection device is that it is necessary to match the wavelength bands of all the resonant optical amplifiers that relay light emitted from one light source. As a practical matter, it is difficult to always adjust the resonance wavelength accurately even if there is a temperature change, and the wavelength adjustment becomes more difficult as the number of connection stages increases.

In addition, in a configuration in which the light receiving unit is integrated outside the optical amplifying unit, the light receiving unit functions as a kind of aperture, so that the power distribution inside the beam cannot be kept constant when connected in multiple stages, and the signal light There is also a problem that quality is deteriorated. Light kicked by a step, an electrode, or the like existing between the light amplification unit and the light receiving unit not only causes a loss but also has a problem that it is reflected and leaks into another channel.

The present invention has been devised in view of the above problems, and has as its object the S / N caused by crosstalk from other channels, ASE noise, reflected return light, and the like.
It is an object of the present invention to provide an optical interconnection device that can eliminate the ratio deterioration, the saturation level decrease, and the operation instability, and can reduce the wiring delay time by increasing the number of optical amplification repeater stages that can be transmitted without electrical regeneration relay.

[0019]

[Means for Solving the Problems]

(Constitution) The gist of the present invention has both an optical receiving function of receiving a part of a transmitted optical signal and an optical amplifying function of compensating for power lost due to reception or the like and relaying the optical signal to the next stage. In an optical interconnection device between boards, in which optical signals are connected in multiple stages by connecting optical interconnection chips in which an array of surface-type optical multifunctional elements are arranged in an array, light leaking from adjacent channels is An object of the present invention is to reduce the influence of the reflected return light from the subsequent stage and increase the number of stages that can be connected without electrical regeneration relay by enabling wavelength adjustment of each stage.

For this purpose, in the optical interconnection device according to the first aspect of the present invention, the optical amplification wavelength band of the optical amplifying unit of each surface type optical multifunctional element is limited to a specific range, and the adjacent surface type The optical multifunctional element is characterized in that it is arranged so that its optical amplification wavelength band is different. This can be realized by setting the reflection characteristics of the input / output surface, the effective cavity length, the gain characteristics of the active region, and the like to values different from those of the adjacent elements. The optical system between the boards is a predetermined surface-type optical element (a surface light-emitting element and a surface-type multifunctional element) whose optical amplification wavelength (and emission wavelength) belong to the same wavelength band.
To join.

The second object of the present invention for achieving the above object is as follows.
The optical interconnection device according to the invention is characterized in that the optical amplification section of the surface-type optical multifunction element is configured to synchronize with an optical signal and to generate a gain only at a timing different from that of an adjacent surface-type optical multifunction element. This is achieved by modulating the injection current into the optical amplifier.

In each of the first and second cases, it is needless to say that a sufficient bandwidth is required for the modulated optical signal to pass therethrough as an amplification wavelength band. As the definition of the adjacent element,
Only the first adjacent element may be considered, or the range may be extended to the second adjacent element and the third adjacent element.

[0023]

In the optical interconnection device according to a third aspect of the present invention, a heating element for adjusting an optical amplification wavelength band is integrated with each surface-type multifunctional element to constitute one cell. Each cell is characterized in that it is formed on a ternary or more mixed crystal semiconductor layer laminated on a semiconductor substrate and thermally separated from other cells by air, an insulator, or the like. .

It is to be noted that a heating element for mainly adjusting the temperature of the upper reflection film and a heating element for mainly adjusting the temperature of the lower reflection film may be provided in one cell. (Operation) According to the optical interconnection device of the first invention, the signal light and the ASE noise light leaked from the adjacent channel have wavelengths outside the amplification wavelength band of the surface-type multifunctional element of the channel. These are not relayed and accumulated after the next stage. Further, since the number of elements operating at the same wavelength is reduced, the influence of background light and stray light leaking from a distant channel is also reduced.

According to the optical interconnection apparatus of the second invention, the signal light leaked from the adjacent channel or the AS
Since the arrival timing of the E noise light is out of the amplification time of the surface-type optical multifunctional element of the channel, the E noise light is not relayed and accumulated from the next stage. Further, since the number of elements that operate at the same timing is reduced, the influence of background light and stray light leaking from a distant channel is also reduced.

[0027]

According to the optical interconnection device of the third invention, each cell is thermally separated by a material having a high thermal resistivity, such as a mixed crystal semiconductor layer, air, or an insulator, so that it flows to the heating element. The temperature of each cell can be adjusted almost independently by the current. If the volume of the cell (and thus the heat capacity) is reduced, the resonance wavelength can be largely changed by a relatively small change in current, so that the amplification wavelength can be adjusted for each cell. If this method is used, not only can the wavelength of each stage be matched, but also the first invention in which the resonance wavelength is shifted from the adjacent cell can be easily realized.

In the third aspect, if the reflection characteristics of the upper reflection film and the reflection characteristics of the lower reflection film can be controlled separately, the relationship of R ₁ = R ₂ Gs ² with respect to the signal light wavelength is satisfied. As described above, the reflectance on the incident side and the reflectance on the emission side can be finely adjusted, so that the reflection gain which causes unstable operation can be largely suppressed.

As described above, according to the present invention, the effects of crosstalk light, ASE noise, reflected return light, and the like, and the cumulative effect thereof are reduced, and the S / N ratio degradation and gain saturation in a multistage connection are reduced. A reduction in signal input level can be suppressed, or operation instability can be eliminated. In addition, it is easy to match the wavelength and the beam shape of each stage, and multi-stage connection is facilitated. As a result, the number of stages that can be connected without electrical regeneration relay can be increased, and an increase in wiring delay time due to electrical regeneration relay can be significantly suppressed.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. (First Embodiment) FIG. 1 is a view for explaining a spatial arrangement of a surface-type optical multifunctional element and a surface-emitting laser of each wavelength in an interconnection chip of an optical interconnection apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating the arrangement of the optical amplification band and the oscillation wavelength, and FIG. 3 is a diagram illustrating a basic configuration of the entire optical interconnection device according to the first embodiment.

The overall configuration and functions of the optical interconnection device of this embodiment are basically the same as those of the optical interconnection device described in the conventional example. That is, 100 boards 5 on which an optical interconnection chip 1, 100 processors 2, memories and peripheral circuits 3, and electrical wirings 4 for connecting them are mounted, constitute an optical system using an array of grating lenses 6 and the like. 7 form a loop. Chips in the same board are electrically connected by electric wiring 4. Each board 5 is provided with an appropriate cooling system to prevent a rise in temperature. The spacing between the boards is about 3 cm. The signal rate of each channel is 1G
b / s, and the overall throughput by spatial multiplexing is 1
0 Tb / s.

As shown in FIG. 1, each of the optical interconnection chips 1 has 500 surface emitting elements 9 and 10.
000 surface-type multifunctional elements 10 are mounted. As shown in FIG. 1, the positions of these surface-type optical elements 9 and 10 are represented by coordinates (X, Y) (X = 1 to 105, Y = 1 to 100).
It will be specified by. X = 1,22,43,64,8
The surface light emitting element 9 is arranged at the position 5 and the surface optical multifunctional element 10 is arranged at other positions.

As shown in FIGS. 1 and 2, the oscillation wavelength and the optical amplification wavelength of the surface-type optical elements 9a and 10a having odd numbers of X + Y are λ _1.
In the wavelength band centered at 1.29 μm, the oscillation wavelength and the optical amplification wavelength of the planar optical elements 9 b and 10 b having even X + Y are set in the wavelength band centered at λ ₂ = 1.31 μm. .

As shown in FIG. 4, the surface type optical multifunctional device 10 has a structure in which a light receiving element 11 and a surface type optical amplifier 12 are integrated. The average power of the signal light is about 10 μW, and the surface-type optical multifunctional element 10 receives a part (about 5 μW) of the optical signal from the preceding stage by the light receiving element 11 and
The signal light power reduced to μW is again reduced to 1 by the surface type optical amplifier 12.
Amplify to 0 μW and relay to the next stage.

The surface type optical amplifier 12 has a thickness of about 1 μm.
It has a structure in which three GsAsP active layers 13 are sandwiched between a p-cladding layer 14 and an n-cladding layer 15 having a wider bandgap than the active layer 13. A current is injected from the electrode 16 into the active layer 13 via the cladding layers 14 and 15, a stimulated emission gain is generated, and optical amplification is performed. A resonator having an effective cavity length of about 10 μm is formed by the dielectric multilayer film 17 formed above and below and the semiconductor DBR mirror 18, and is set so that only the light in the specific wavelength band is selectively amplified. I have. Here, two kinds of wavelengths are set by changing the Bragg wavelength and the effective cavity length by finely adjusting the thickness of the DBR mirror 18. It is possible to grow the DBR mirrors 18 having different thicknesses by a single epitaxial growth by selectively growing the mask openings having different mask widths or by growing the mesas having different sizes.

At the signal light wavelength (about 1.3 μm), the reflectivity of the dielectric multilayer film 17 is about 86%, and the reflectivity of the DBR mirror 18 is 74%. The surface type optical amplifier 12 is approximately 10 m
A gain of 3 dB is obtained by the current injection of A. The one-pass gain at this time is estimated to be about 0.33 dB, and R ₁ =
The relationship of R ₂ Gs ² is almost satisfied. For this reason, the reflection gain is suppressed to -20 dB or less. The gain wavelength width of the surface-type optical amplifier 12 is as narrow as 1.5 nm or less, and the transmittance of light of an adjacent channel 20 nm away is almost zero. Therefore, crosstalk lambda ₁ channel and lambda ₂ channels is suppressed to a level almost no problem.

100 of the surface light emitting elements 9 where X = 1,
It corresponds to the output from 100 processors 2 mounted on the board 5. Coordinates ( _1, 2Y ₁ -1), (1, 2
The output of the surface light emitting element 9 of Y ₁ ) is output by the optical system 7 to the coordinates (2, 2Y ₁ ), (2, 2Y ₁ −
1), the outputs of the planar optical elements 9 and 10 at coordinates (X ₁ , 2Y ₂ -1) and (X ₁ , 2Y ₂ ) are similarly output to the next stage ( _{X 1 + 1,2Y 2), (} X
₁ + 1, 2y ₂ -1) to disposed the surface optical multifunction element 1
Connected to 0. Here, Y ₁ and Y ₂ are integers of 1 to 50, and X ₁ is ₁ to 20, 22 to 41, 43 to 62, 64.
８３83,85-104. Each surface-type optical multifunctional device 10 receives a part of the optical signal and sends necessary information to the processor 2 in the board.

The surface-type optical multi-function device 10 with X = 21, 42, 63, 84, 105 does not perform optical relaying, but only performs reception.
That is, after electrically shaping the signal waveform deteriorated by the ASE noise due to the 19-stage optical amplification relay, X = 22 and X = 22, respectively.
From the surface light-emitting element 9 having the same Y coordinate of 43, 64, and 85, X = 23, 44, 65, and 86 in the next stage are again converted into optical signals.
To the surface type optical multifunctional element 10 of FIG. Before and after the electric regeneration relay, the wavelength bands λ ₁ and λ ₂ are interchanged. X = 1
The surface-type multifunctional element 10 of 05 is for monitoring and performs only reception. X = 21, 42, 63, 84, 10 for receiving only
5 may be replaced with a light receiving element.

As an example, FIG. 5 shows the flow of signals transmitted from the board (1) between the boards. The element arrangement of each chip 1 is standardized so as to be all the same including the wavelength band. The deflection direction and focus of the grating lens 6 are set so as to realize this signal flow. board
The light sent from (1) is transmitted to the boards (21), (41), (61), (81)
, And return to the board (1). Board (1) to (2
The signal sent at λ ₁ (or λ ₂ ) until ₁ ) is sent to the board (2
1) to (41) and boards (61) to (81) are λ ₂ (λ
₁ ), boards (41) to (61) and boards (81) to (1) are transmitted at λ ₁ (λ ₂ ).

In the optical interconnection device of the present embodiment, since the wavelength of the closest channel is located outside the band of the optical amplifier 12, signal light or ASE noise from an adjacent channel is mixed. Is not amplified and relayed to the next stage. In addition, the number of elements operating in the same wavelength band other than the adjacent channels is reduced by half, and the influence of background noise light due to ASE noise and stray light due to imperfections in the optical system is also reduced to half. Therefore, deterioration of the S / N ratio due to crosstalk and accumulation of noise and reduction of the input level of the gain-saturated signal are suppressed, and it is possible to increase the electrical regeneration relay interval as compared with the related art.

Assuming that the average optical path length between the boards is 3 cm,
A transmission time of 10 ns is required for 100 stages. The delay time due to the light emission drive unit and the electric regeneration relay is set to 10
Assuming ns, a total delay of 10 ns × 5 = 50 ns is added. As a result, the maximum delay time of the whole becomes about 60 ns, which is about a half compared with 110 ns of the conventional example. As described above, according to the present embodiment, in the optical interconnection device using the surface-type optical multifunctional element, the wiring delay time can be significantly reduced. Also, the number of circuits required for regenerative relay can be reduced.

FIG. 6 is a view for explaining the arrangement of chip wavelengths and the flow of information between boards in an optical interconnection device according to a modification of the first embodiment. In this variation,
The wavelengths are set to be different up to the second proximity, and four wavelength bands are used. In the optical connection between the boards, the Y coordinate does not change and the X coordinate changes by two. That is, the light transmitted from the surface light emitting element 9 of X = 1 on a certain board (referred to as a board (1)) is equal to the X = X on the board (2), (3), (4),.
Amplified and relayed by 3, 5, 7,... 49 surface-type optical multifunction elements 10 and X = 51 surface-type optical multifunction elements 10 on the board (26).
Received at. The received signal is waveform-shaped by the board (26), transmitted from the surface light emitting element 9 of X = 53, and optically amplified and relayed by the surface optical multifunctional element 10 of the board on the way, while the board (51). )) X = 103 area type optical multifunctional element 1
It is transmitted to 0. The signal received at X = 103 is subjected to waveform shaping, and then transmitted from the surface light emitting element 9 at X = 104 on the board (51).

Similarly, this signal is output to the board (76) (X = 5
4, X = 52), and is relayed and transmitted to the surface-type multifunctional element 10 at X = 2 on the board (1). A signal transmitted at a wavelength λ ₁ (λ ₂ ) between X = 1 to 103 propagates at a wavelength λ ₃ (λ ₄ ) between X = 104 and 2.

In this modification, the influence of crosstalk from the second adjacent channel is also eliminated. Further, since the number of elements operating in the same wavelength band is reduced to 1/4, the influence of background noise and stray light can be suppressed to a small level. For this reason, it is possible to further increase the reproduction relay interval.

The present invention is not limited to the above embodiments and modified examples, but various wavelength arrangements are possible. Modifications of the wavelength arrangement are shown in FIGS. FIG. 8 shows another method of changing the wavelength of each surface type optical element. For example, the resonance wavelength may be actively changed by temperature control or the like using a micro heater 41 or the like (FIG. 8A), or DB
The period of the R layer 18 may be fixed, and the effective resonance wavelength may be changed depending on the presence or absence of the selective etching layer 42 inserted between the DBR layers 18 (FIG. 8B). Alternatively, the transmission path may be inclined to change the optical path length of the resonator. Even if the refractive index is changed by changing the internal carrier density by light excitation or injection current, the resonance wavelength can be changed. In addition, the operating wavelength can be changed by various methods such as a combination of a traveling wave type surface optical amplifier and a wavelength selection filter film.

From the standpoint of standardization and expandability, it is preferable that the wavelength arrangement of the surface emitting element and the surface-type optical multifunctional element be the same for all chips, but a method of alternately using two patterns having the opposite wavelength arrangements is also available. Conceivable. (Second Embodiment) Next, an optical interconnection device according to a second embodiment of the present invention will be described with reference to FIG. The configuration of the entire device and the structure of the planar optical multifunctional element are almost the same as those of the optical interconnection device of the first embodiment (FIGS. 3 and 4). There are 100 boards,
A total of 10,000 processors 2 are connected. All surface type optical elements operate in the same wavelength band. The operation rate of one channel is 1 Gb / s, and the total throughput by spatial multiplexing is 10 Tb / s.

As shown in FIG. 9, each of the interconnection chips 21 has 500 surface-emitting elements 29 and 1.
0000 surface-type optical multifunctional elements 30 and 500 light-receiving elements 31 are mounted. These planar optical elements 29, 3
The positions of 0 and 31 are represented by coordinates (X, Y) of (X, Y) as shown in FIG.
= 1 to 21, Y = 1 to 500).
The surface light emitting element 29 is arranged at X = 1, the surface optical multifunctional element 30 is arranged at X = 2 to 20, and the light receiving element 31 is arranged at X = 21.

Those of the surface light emitting elements 29 where Y = 1 to 100 are driven by the output signal of the processor 2 of the board. Y = 101 to 200, 201 to 30
0,301 to 400,401 to 500 surface light emitting elements 29
Are Y = 1-100, 101-200, 201, respectively.
The light receiving elements 31 are driven by electric signals obtained by reproducing the outputs of the light receiving elements 31 to 300 and 301 to 400. Y =
The light receiving elements 31 of 401 to 500 are for monitoring.

The board numbers are assigned in the order in which they are connected.
And an integer from 100 to 100. The outputs of the planar optical elements 29 and 30 at the coordinates (X, Y) of the board Z are respectively output by the optical system 7 to the planar optical element 30 at the coordinates (X + 1, Y) of the board Z + 1 (1 when Z = 100). , 31 are connected. The surface emitting element 29 receives a part of the signal power and sends a signal to the processor of the board,
Compensates for the lost optical power and relays the signal to the next board.

As shown in FIG. 10, when the transmission rate is B, one cycle T = 1 / B (1 ns in this example) is set to two operation timings Ta and Tb in the time zone (in this example, 50 times each).
0 ps). Y + Z is an odd surface type optical element 29
a, 30a and 31a become active only in the range of the operation timing Ta, and the surface-type optical elements 29b and
The bias is controlled so that 30b and 31b become active only in the range of the operation timing Tb. Of course, a slight gap may be provided between Ta and Tb. As a result, since the nearest element always becomes active only at a different timing, crosstalk from the nearest element is suppressed.

In addition, since the number of elements that operate at the same timing is reduced by half even when the whole is considered, the influence of background noise light and stray light is also reduced. As a result, optical amplification relay transmission with a high S / N ratio is realized, the number of optical amplification relay stages can be increased, and the number of electrical regenerative relay circuits can be reduced, and the wiring delay time can be reduced.

In the second embodiment, various modifications are possible, such as further dividing the operation timing. A driving method of shifting the operation timing of each element using a bit line and a word line is a matrix type device (memory, C
(For example, a CD imaging device and a display such as a liquid crystal display), which can be easily realized. Although it is necessary to increase the operation speed of the drive circuit, the number of drive circuits can be reduced by changing the operation timing of the bit line and sharing the word line with a plurality of elements. In addition, as a result of the pulse driving, there are effects of reducing power consumption and reducing the influence of heat generation.

Further, by combining the first embodiment and the second embodiment, it is also possible to suppress the influence of ASE noise and crosstalk from peripheral channels. In this case, there are various variations such as a combination in which the operation timing is different in the first proximity in the X direction and the wavelength band is different in the first proximity in the Y direction, or a combination in which the wavelength and the operation timing of the first proximity are simultaneously changed. Is possible. For example, if four kinds of wavelengths and four kinds of operation timings are used, the number of elements operating simultaneously at the same wavelength can be reduced to 1/16, and the influence of background noise can be greatly reduced. If an optical system capable of minimizing the influence of ASE noise is constructed, optical connection without electrical regeneration relay of 100 or more stages is possible. (Third Embodiment) FIG. 11 is a diagram schematically showing a cross-sectional structure of a planar optical multifunctional element which is an element of an optical interconnection device according to a third embodiment of the present invention. The description of the entire apparatus is the same as that of the first and second embodiments, and thus will be omitted.

This surface type optical multifunctional element is made of semi-insulating InP.
Cell 6 having a mesa multilayer structure formed on a substrate (semiconductor substrate) 60 via an n-type InGaAs layer (mixed crystal layer) 61
2. Consisting of holes 63 penetrating to the InGaAs layer 61 formed under the cell 62, the upper part of the cell 62 constitutes a light receiving part 64, and the lower part of the cell constitutes an optical amplifying part 65 from the lower part of the cell to part of the InGaAs layer 61. ing.

The light receiving portion 64 has a three-layer structure of an n-type InP layer 66, an undoped InGaAs light absorbing layer 67 having a thickness of 0.5 μm, and a p-type InGaAsP layer (photoluminescence wavelength 1.1 μm) 68 in order from the top. . Light absorbing layer 6
7 is depleted by a reverse bias applied via an electrode 69 provided on the n-type InP layer 66 and an electrode 70 provided on the p-type InGaAsP layer 68. n-type I
The nP layer 66 and the light absorbing layer 67 are processed into a mesa shape and embedded with polyimide 71, and a non-reflective coating film 72 is formed on the light incident surface. About 50% of the incident light is absorbed by the light absorbing layer 67 and is extracted from the electrodes 69 and 70 as a photocurrent.

The optical amplifying section 65 includes a semiconductor DBR layer 73,
-Type InGaAsP layer (photoluminescence wavelength 1.1)
μm) 74, undoped InGaAsP active layer (photoluminescence wavelength 1.3 μm) 75, n-type InP layer 7
6, n-type InGaAs layer 61, dielectric multilayer reflective film 77,
It comprises an insulating film 78, an ohmic electrode 79 formed on the p-type InGaAsP layer 74, and an ohmic electrode 80 formed on the n-type InGaAs layer 61. The active layer 75 is limited to a 5 μm square area, and has a thickness of about 2 μm. The active layer 75 is buried with the p-type InGaAsP layer 74, and the insulating film 78 is formed on the p-type InGaAsP layer 74 other than the region where the active layer 75 is located so that the current injected from the electrodes 79 and 80 gathers in the active layer 75. And n-type InP layer 76
Is separated.

Although not shown in the figure, this mesa multilayer cell 6
A heat sink is provided on the upper part of the second and the lower part of the substrate 60. The upper heat sink is provided separately for each cell, and the thermal resistivity between the cell and the substrate 60 is about 2 mm.
Since the InGaAs layer 61 is separated by a relatively high 1 K · cm / W (about 14 times that of the InP substrate), the temperature interference between cells is small. For thermal isolation between cells, it is not limited to InGaAs. In general, it is advantageous to use a ternary or higher mixed crystal semiconductor layer because its thermal resistance is high.

A transparent metal resistive film 83 (micro heater) is formed on the dielectric multilayer reflective film 77 so as to be inserted between the two low-resistance electrodes 81 and 82. , The temperature of the dielectric multilayer reflective film 77 rises. When a voltage is applied between the electrode 79 and the electrode 70 to flow a current through the semiconductor DBR layer 73, the semiconductor DBR
Heat is generated by the resistance of the layer 73, and the surrounding temperature increases. These function as heat generating elements integrated in the semiconductor optical multifunctional element. Dielectric multilayer reflective film 77 and semiconductor D
Most of the portion between the BR layers 73 is an insulating film 78 having a high thermal resistance.
, The two temperatures can be controlled almost independently.

The resonance wavelength is determined by the two heating elements 73 and 8.
3, heat generation due to the current injected into the active layer 75,
And the temperature of the upper and lower heat sinks. Therefore, by adjusting the heat generated by the two reflection films 73 and 77, it is possible to simultaneously control the resonance wavelength and finely adjust the reflectance balance between the upper and lower reflection films. Here, the resonance wavelength control is performed so that the resonance wavelength is shifted from the adjacent element by 10 nm, and the resonance wavelength is matched in one line, and the relationship of R ₁ = R ₂ Gs ² is approximately established. It is assumed that the balance between the two heating elements is adjusted. As a result, similarly to the first embodiment, the crosstalk light from the adjacent channel and the ASE background noise are reduced, and the S / N ratio is improved.

By injecting a current of about 6 mA from the electrodes 79 and 80, a gain of about 3 dB is generated in the optical amplifier 65, and the one-pass gain at this time is about 0.2 dB.
For example, the reflectivity of the DBR film 73 is about 89%, and the dielectric multilayer reflective film 7 has a relation of R ₁ = R ₂ Gs ^2.
7 is controlled to be about 81%. As a result, 6 dB due to two passes through the light absorbing layer 71
In addition, the reflection gain is suppressed to -30 dB or less, and the operational instability due to the reflected return light can be suppressed even when multi-stage connection is performed. Although the reflection gain with respect to the adjacent channel wavelength cannot be suppressed by making the reflectivity asymmetric, the light absorption layer 7
One reduces at least 6 dB.

Further, according to the configuration in which the light receiving section 64 is integrated with the optical amplifying section 65 in the direction perpendicular to the substrate as shown in FIG. The change in beam power distribution due to the aperture effect, the generation of reflected noise light due to kicking, and the power loss can also be avoided.

The present invention is not limited to the above embodiments. In any of the embodiments, the number of boards, the number of elements, and the like can be appropriately changed according to specifications. The present invention can be applied not only to a loop type optical interconnection device but also to a bus type or star type optical interconnection device. The electronic elements to be connected are not limited to the processor, and can be applied to optical interconnection between boards, frames, and multichip modules on which various elements are mounted. It is not always necessary that the correspondence between the electronic element and the surface optical element is 1: 1. A plurality of electronic elements may correspond to one surface optical element.

The optical coupling between the boards is not limited to the grating lens array, and various methods such as a selfoc lens, an optical fiber array, various light guides, holography, and a combination thereof can be used. The optical system may be provided with another means (such as an aperture) for reducing background noise, reflected light, and stray light. It is not necessary for one guide system to correspond to each surface light element, and a plurality of surface light elements and a plurality of corresponding surface light elements of another board are connected by one lens. It does not matter. The intervals between the boards need not be constant, and the intervals between the elements arranged in parallel need not be constant.

The semiconductor material is also made of AlGaAs, InGa
P-based, InGaAlAsSb-based, AlGaInN-based, M
Various types such as a gZnCdSeS type are conceivable and can be applied to various wavelength bands accordingly. A quantum well structure may be used for the active layer. Further, the optical interconnection chip and the electronic element may be integrated, or a plurality of optical interconnection chips may be mounted on one board. For example, it is possible to use a chip made of a different material for the light receiving element and make a modification such as integration with an electronic device. As the light emitting element, an edge-emitter type semiconductor laser array can be used instead of the surface emitting laser. Of course, even without separately preparing a light-emitting element, it is also possible to use a surface-type optical multifunctional element whose reflectivity is appropriately designed to oscillate by applying a large current.

The surface optical multifunctional device is not an integrated device of a light receiving device and a surface optical amplifier, but may be a device in which the surface optical amplifier itself has a light receiving function due to a change in terminal voltage or the like. I do not care. Further, in addition to the light receiving function and the amplifying and relaying function, other functions such as an optical gate / modulating function, an optical deflecting / branching function, etc. may be provided. In addition, various modifications can be made without departing from the spirit of the present invention.

[0067]

As described above, according to the present invention, even when multi-stage connection is performed, the effects of crosstalk and ASE noise from peripheral channels and the effects of reflected return light are suppressed, so The number of stages that can be connected only by optical amplification relay without regeneratively relaying increases. Therefore, the number of circuits required for the electrical regeneration relay is reduced, and the wiring delay time is reduced. As a result, a low-cost, high-speed, flexible and highly reliable optical interconnection device is realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a spatial arrangement of a surface-type multifunctional element and a surface-emitting laser in an optical interconnection chip of an optical interconnection device according to a first embodiment.

FIG. 2 is a diagram showing an arrangement of an optical amplification band and an oscillation wavelength in the optical interconnection chip of FIG. 1;

FIG. 3 is a diagram schematically showing a basic configuration of the entire optical interconnection device.

FIG. 4 is a diagram schematically illustrating a cross-sectional structure of a surface-type optical multifunctional element mounted on the optical interconnection chip of FIG. 1;

FIG. 5 is a diagram showing a flow of an optical signal between boards in the first embodiment.

FIG. 6 is a diagram showing a modification of the wavelength arrangement and the flow of information between boards in the first embodiment.

FIG. 7 is a diagram showing another modification of the wavelength arrangement in the first embodiment.

FIG. 8 is a diagram illustrating an example of a method of integrating planar optical elements having different resonance wavelengths.

FIG. 9 is a diagram showing an element arrangement of a chip in the optical interconnection device according to the second embodiment.

FIG. 10 is a diagram showing operation timings of elements according to the second embodiment.

FIG. 11 is a view showing a cross-sectional structure of an optical multifunctional element of an optical interconnection device according to a third embodiment.

FIG. 12 is a view showing a spatial arrangement of a surface-type optical multifunctional element and a surface-emitting laser in a conventional optical interconnection device.

[Explanation of symbols]

 1, 2, 201 ... Optical interconnection chip 2 ... Processor 3 ... Memory and peripheral circuit 4 ... Electrical wiring 5 ... Board 6 ... Grating lens 7 ... Optical system 9, 29, 209 ... Surface light emitting device 10, 30, 210 ... Surface type optical multifunctional element 11, 64 ... Light receiving element part 12, 65 ... Surface type optical amplifier part 13, 75 ... Active layer 14, 15 ... Cladding layer 17, 18, 73, 77 ... Resonator mirror 31 ... Light receiving element 41 83, micro heater 42, semiconductor selective etching layer 60, semi-insulating InP substrate (semiconductor substrate) 61, n-type InGaAs layer (mixed crystal layer) 62, mesa structure cell 78, insulating film

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Nunoue 1 Toshiba R & D Center, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture (56) References JP-A-5-152608 (JP, A) JP-A-3-200228 (JP, A) JP-A-6-37299 (JP, A) JP-A-9-5580 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 27/14-27/15 H04B 10/00-10/28

Claims (4)

(57) [Claims] 1. A surface-type light comprising an integrated light receiving section for receiving a part of a transmitted optical signal and an optical amplifier for relaying the optical signal to the next stage by compensating for the power lost by receiving light and the like. An optical interconnection chip in which a plurality of multi-function elements are arranged to constitute an optical interconnection chip, the chips are arranged in multiple stages, and optical signals are coupled in a multi-stage parallel manner by connecting each chip with an optical system. Wherein the optical amplification wavelength band of the optical amplification unit of each surface type optical multifunctional element is set so as not to overlap with the optical amplification wavelength band of the optical amplification unit of the adjacent surface optical multifunction element. Optical interconnection device. 2. A planar light in which a light receiving portion for receiving a part of a transmitted optical signal and an optical amplifying portion for compensating power lost due to light reception and relaying the optical signal to the next stage are integrated. An optical interconnection chip in which a plurality of multi-function elements are arranged to constitute an optical interconnection chip, the chips are arranged in multiple stages, and optical signals are coupled in a multi-stage parallel manner by connecting each chip with an optical system. The optical amplifying part of each surface type optical multifunctional device in
An optical interconnection device, wherein the optical interconnection device is modulated so as to synchronize with an input optical signal and to generate a gain at a timing different from that of an optical amplifier of an adjacent surface-type optical multifunctional element. 3. A planar light in which a light receiving portion for receiving a part of a transmitted optical signal and an optical amplifying portion for compensating power lost due to light reception and relaying the optical signal to the next stage are integrated. An optical interconnection chip is configured by arranging a plurality of multi-functional elements, and the chips are arranged in multiple stages, and optical signals are coupled by an optical system to perform multi-stage parallel relay of optical signals. The multi-functional optical device has a heat generating element for adjusting the optical amplification wavelength band of the optical amplifying unit integrated therein to constitute one cell, and each cell is composed of three or more elements stacked on a semiconductor substrate. An optical interconnection device, which is formed on the mixed crystal semiconductor layer of (1) and thermally separated from other cells. 4. The optical amplification section of each surface-type optical multifunctional device is a Fabry-Perot resonance type surface-type optical amplifier in which the upper and lower sides of an active region are sandwiched between reflection films, and the heating element mainly controls the temperature of the upper reflection film. 4. The optical interconnection device according to claim 3 , wherein at least two heating elements for adjusting the temperature and at least two heating elements for adjusting the temperature of the lower reflective film are provided.