JPH03213833A - Method for predicting device characteristics of integrated optical logic devices - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for predicting device characteristics of integrated optical logic devices.

"Prior Art" As optical input-optical output logic elements necessary in the fields of optical information processing and optical computing, devices using Fabry-Bello resonators, 5EEDs, BILEDs, etc. are known. All of these have the disadvantage that they are difficult to integrate.

Recently, a light-receiving element and a light-emitting element have been combined to provide positive optical feedback from the light-emitting element to the light-receiving element, exhibiting hysteresis characteristics between the input light intensity and the output light intensity, and producing optical switches, optical bistable, optical An optical amplification functional element was proposed as an integrated optical logic element that performs logical operations such as differential gain (A, 5asaki
et al, IEEE Trans, Electron
Devices, 35 (1988) 780).

FIG. 5 shows one example as a sectional view. In the figure, code 51
is an AuZn/Au electrode film, and 52 is (100)P-
InP substrate, code 53 is N-InP block layer, code 5
4 is a P-InP cladding layer, and 55 is an N-InGaA cladding layer.
sP active layer, numeral 56 is an N-InP cladding layer,
Reference numeral 57 is an N-InGaAsP absorption layer, and reference numeral 58 is an N-InGaAsP absorption layer.
InP buffer layer, 59 is N-InP collector layer, 60 is P-InGaAsP base layer, 61 is N-InP emitter layer, 62 is AuGeNi/A
The u electrode layer is shown. Such an optical amplification functional element is
Since it has a simple structure including only a light receiving element and a light emitting element, monolithic integration is easy and array formation is also possible. Furthermore, by changing the voltage and load resistance, it is possible to switch to multiple functions even though it is a single element.

[Problems to be Solved by the Invention] However, with regard to predicting the device characteristics of the above-mentioned optical amplification functional device, that is, predicting the characteristics of each function of the device, so far only diagrammatic solutions have been attempted; Although the operating characteristics are required for the set, the device characteristics when the device parameters change can only be predicted qualitatively.
Furthermore, it was not possible to predict parameter values for achieving desired device characteristics.

For this reason, despite the above-mentioned excellent properties of the optical amplification function element, its design has been extremely troublesome.

The present invention was made in view of the above-mentioned circumstances, and
The purpose of this invention is to provide a method for predicting device characteristics of an integrated optical logic device using an optical amplification function device.

[Means to solve the problem] The present invention will be explained below.

The present invention is "a method for predicting device characteristics of an integrated optical logic element in which a light emitting element and a light receiving element are electrically integrated in series together with a load resistor to provide positive optical feedback from the light emitting element to the light receiving element." It is characterized as follows.

Adjust the bias voltage of the integrated optical logic element to the v1 operating current,
The load resistance is RLq, the resistance of the light receiving element is RP, the input/output light intensity to the integrated optical logic element is P3. ,
,P. . The input light intensity to the light-receiving element is PP0%, the output light intensity from the light-emitting element is PLE%, the positive light feedback rate from the light-emitting element to the light-receiving element is β, and the current-output light intensity characteristic of the light-emitting element is PLE=L( I), (dL/dI≧0), the input light intensity-resistance characteristic of the photodetector is Rpn=H(Pro)-(dH
/dPpn≦O), the following five equations are given between these.

V=I(R,,”RPD) (1
)P, D=P,. +βPLE (2
) Po. , = (l-β)PLE (
3) PL,=L(I) (4
) Rpo=H(Pro) (s
) In these equations (1) to (5), L(I), H
(ppm), equations (1) to (5) are given, and the above V.

A relationship Pi-''g(Pout; V, RL, β) is obtained between Pl, , and p, u, with RL and β as parameters. Then, the device characteristics are predicted based on this relationship.

[Function] FIG. 1 shows an equivalent circuit of an integrated optical logic element to which the present invention is applied. In the figure, numeral 1 indicates a light emitting element, numeral 2 a light receiving element, numeral 3 a load resistor, and numeral 4 a constant voltage power supply. As shown in the figure, the resistance value of load resistor 3 is RL
, the bias voltage from the power supply 4 is set to v1 operating current. Also P. ,P. . , respectively indicate the input/output light intensity to the integrated optical logic element, and ppo and PLE indicate the input/output light intensity to the receiving/emitting element, respectively. Further, β represents a positive light feedback rate from the light emitting element 1 to the light receiving element 2.

RP is the resistance characteristic of the light receiving element 2 against the input light intensity.
Assuming that D, the above equation (1) is an expression of Kirchhoff's law in this equivalent circuit.

Equation (2) represents the input light intensity P, to the light receiving element 2. This indicates that a part of the optical output of the light emitting element 1 is incident with an optical feedback rate β (0≦β≦1).

Equation (3) indicates that the total output PLE from the light emitting element 1 minus βPLE which is optically fed back to the light receiving element 2 becomes the optical output from the integrated optical logic element.

Equation (4) shows that the total output PLE of the light emitting device 1 is a function of the operating current . This means that the light emitting element 1 is regarded as a "conversion element that converts current into light."

Equation (5) expresses that the resistance Rr'D of the light receiving element 2 is a function of the input light intensity PPD. This means that the light receiving element 2 is regarded as a "resistance that changes depending on the intensity of input light."

The functions L(I) and H( in equations (4) and (5)
Pro), equations (1) to (5) become P,. and P. . It can be solved as a simultaneous equation for , P,
The relationship between n and P o u L is expressed as V, R,, P, with β as a parameter.・g(P..t:V+RL+β
)(6).

Given the parameters V, RL, and β, p, , and P
The relationship between o u L is determined.

P j n and P. The relationship between , , and can be roughly divided into Figure 2 (
The result will be as shown in I) to (IV). The element characteristic in (I) in the same figure is a differential gain function, the function in (II) in the figure is a limiter function, the function (III) is an optical bistable function, (
Function IV) is a light switch function. Parameter V
By selecting IRLIβ, one of these functions can be selected as the function of the integrated optical logic element.

At the stage where equation (6) is given, a desired function from among the above functions can be selected by proceeding with the following procedure.

That is, for the differential gain function, for a function g, the conditions g'(Pp.,)>0 and g(Pp.,)>o
(7) is weighted.

For the optical bistable function, the condition g' (
P. , )〈O and g(P,,,,)>0 and g(
P7. . ) > O(8).

For the light switch function, the condition g' (P, .,)〈0 and g(P, , ,)>0 for the function g.
and g(P, , , )<0
(9) is weighted.

Furthermore, for the limiter function, the condition (g(P,,,+.)<0 and g(P-1,)<O and g'(p,.,)<0) for the function g. or (g'(Pp.,)
〉0 and g(P,,t)〈O) (10).

In each of the above equations, "g'" is the variable P of the function g. "PP.," means the differentiation by 5°, and "PP.," refers to the function g as the variable P.

. , the result of dividing 2 same planes gives 0. , t, i.e., P at the inflection point of the function g. . , are the coordinates.

Also, rpm, g, 'Pm1nJ are the functions g
Variable P that gives the local maximum value and local minimum value. is the value of U.

When these conditions (7) to (10) are used, the following equations (11) to (15) are obtained as boundary conditions and quadruple point conditions in which each function cannot be distinguished.

Between optical bistable and optical switch: g (P, .) - 〇 and g' (P, .,)
<0(11) Between optical switch and limiter: g(P,,,,)=O and g'(Pp.i)<
0 (12) Between limiter and differential gain: g (Pp.,) - 〇 and g' (Pp.,) > 0
(13) Differential gain-optical bistable: g' (P, .,)=O and g(Pp.,)>O
(14) 4 points: g(PP.t)=g'(Pp.,)=O(15) The above boundary conditions (11) to (14) express the constraint conditions of the parameters on the boundaries of each function. give. Therefore, when these constraints are plotted for independent parameters, we get
A diagram of the distribution state of functions regarding these parameters, that is, a functional diagram can be obtained.

In this functional diagram, the above (11) to (14) are placed around the four points.
) will expand into four functional areas separated by the boundary conditions. By overlapping the definition range of each parameter on the above functional diagram, the range of parameters for realizing each function is determined. In particular, since the four functions are in contact around the four points, if the four points exist within the definition range of the parameters, it is possible to realize all of the above four functions by partially changing the parameters.

Conversely, when focusing on a specific function, the area of that function in the functional diagram defines the conditions that the parameters must satisfy in order to realize that function.

[Example] Hereinafter, description will be given based on specific examples.

Example 1 A case where an integrated optical logic element is constructed by combining a light emitting diode as a light emitting element and a phototransistor as a light receiving element.

In a light emitting diode, the operating current ■ and the output light intensity P
In the operating region where a linear relationship holds between LH and LH, the function L(I) in the equation (4) is expressed as L(I) with the proportional coefficient A.
=A·I (4-1) can be given.

On the other hand, for a phototransistor as a light-receiving element, there is a well-known relationship between the emitter-grounded current gain hFE and the collector current gain, as 11FEcc■'-''', where n is the emitter-base distance. pn
It is an ideal factor for bonding.

Optical gain Go p L of phototransistor, resistance RP
D, operating current, Gop between the above hFEs, t=(■/e)/(ppo/h・ν)CX:r/
pr'.

The following relationship holds true: Rpo=VpO/I Q:1/I. Here, e represents the charge of the electron, h represents the blank constant, and ν represents the wavelength of the incident light.

From the above relationship, between RPD and PPD R11r) Engineering PiB holds true.

Even in the limit where ppo is 0, the actual Rp n ′! J<(
1), so Pl. - Let the resistance value at 〇 be R8.

Also, since RI'D does not become O even when ppo→ω, if the resistance value in this case is R■, the relationship RPD=Rω+Ro/ (1+(ppo/pc)") holds. Therefore, as the function H(PPD) in the equation %formula%(5), H(PPD)-R■+Ro/(1+(PPD/Pc)'
) (5-1) can be given. Here P. The RPD is Rp o -R.

and R8oCP; is the value of the input light intensity at the boundary of 8.

In this way, the above equations (1) to (5) are concretely determined, so Plo and P. . , we find the function g that gives the relationship between P, with sufficiently high precision.・g(P.

. ,) Pc[((Ro/(Rt+Rω))+11((P...,
/((1-β)Pl"))-1)/(1-(P..,/
((1-βOkiTji))]-””+(β/(1-β))
・P. 5. It can be approximated as (6-1).

In the formula (6-1), P'-A-V/(Rt, +R■).

The boundary conditions between functions are written down according to equations (11) to (14) as follows.

Between optical bistable and optical switch: β”=2n(1+R♂)””-(R:(n-1)-3
)”'/[(Ro(n+1)+S)”・(Rro(n-1
)+2n-3)] (11-1) Optical switch-limiter=βm, 2n(1+R: )l+1/+1
, (R3(n-1)+S) l/n/[(R
o(n+1)-3)""(Ro(n-1)+2n-3)
] (12-1) Between limiter and differential gain: β-=2n(nl)I/n, (1+R)l+I/n/[(n+1)''(Ro(
n-1)+2n)] (13-
1) Differential gain - optical bistable: β" = (4/ R11,)n (n-1) -1
+ I / n (1+ R, 11) I + l /
n ・(1+n)-1-17n
(14-1). Here, R3=Ro/(Rt, +RC13), β"・β・P
7'B''/Pc.

S= o,)-n-R,"n+R,"n2)
It is. Pl''=AV/(RL+Rco).

In this example, the independent parameters are β', RO', and n. Also, the conditions for the four points are β"・((n+1)/(n-1))"" and R♂=4n
/(n-1)2, , , , , , , (15-1)
It is.

The boundary (11
If a functional diagram is drawn according to -1) to (14-1) and four points (15-1), it will be as shown in Fig. 3.

Based on this functional diagram, it is possible to find the region of parameters β", R3 to realize each element characteristic. Also, by solving β", Ro", n for V, β, RL, these parameters V , β+RL and the relationship with each element characteristic can be known.

Example 2 Consider a light emitting diode as a light emitting element.

As a light receiving element, the function H(Ppn) is H(PpoCRoexp(-γPpl))+RO)-R
Consider a virtual light receiving element given by pn (5-2). However, the resistance monotonically decreases as the input light intensity ppo increases, which is the same as in a normal light receiving element.

The characteristics of each element of an integrated optical logic device that combines these light-receiving elements and light-emitting elements will be considered.

The function L(I) is the function form (4-1) in Example 1.
) can be used.

As in Example 1, Ro and Rω have a PPD of 0.
and represents the RPD when +ω. These Nikki R8>
>Rω. Further, γ represents the attenuation rate of the resistance with respect to the input light PPD.

In this case, the relationship between R8,, and P out is P,,
=(1/γ) 10g[(RO/(RL+R■))・(
1/((Pken”/P..,)・(l−β)−1))]−
(]βbal−β)P. ,.

・g(P.,,) (6-2
). Here p=x "A 'V/ (RL"R
Co).

The boundary conditions between functions are written down according to equations (11) to (14) as follows.

Between optical bistable and optical switch: 10gRo"2β"(1+T)-1og(1+T
)+log(1-T) (11-2) Between optical switch and limiter: logR,"=2β"(1-T)+log(1+T
)-1og(1-T) (12-2) Between limiter and differential gain: logR,"=2β"
(13-2) Differential gain between 7 optical bistables: β”=1 (14-
1). Here, R3・Ro/(Rt+R■), β′=4β・γ, pn+
Bx In this example, there are two independent parameters, β' and R. Further, the conditions for the quadruple point are β''=1 and R:=e2(15-1).

The boundary (1
If a functional diagram is drawn according to 1-1) to (14-1) and 4 points (15-1), it will become as shown in FIG.

Parameter β1 for realizing each element characteristic based on this functional diagram. The area of R♂ can be found. Furthermore, by solving β'', R♂ for V, β, and RL, it is possible to know the relationship between these parameters V and β+RL and the characteristics of each element.

What can be used as a light emitting element is not only the light emitting diode that has a linear relationship between current and output light intensity as discussed in Example 1.2, but also a laser diode that has a nonlinear relationship between current and output light intensity. In addition, the light receiving element is not limited to a phototransistor, but a photoconductor or a photodiode can be used, or a combination of these and a FET can be considered as one light receiving element and the device characteristic prediction method of the present invention can be applied. be.

In order to actually set the functions of the integrated optical logic device, it is necessary to know the values of each of the above parameters.

Among these parameters, V and Rt can be determined during operation, but β* RO + Rco, A, n, and PCoγ are determined individually for each specific device after device fabrication, and must be determined by some method. . A specific example of a method for determining these parameters and setting the functions of the element will be described below.

In this method, parameters such as β, R8, and R■ are determined based on the current-output light intensity characteristics and current-voltage-human power light intensity characteristics of the integrated optical logic element, and the function settings are performed based on the results. .

The flow diagram in Figure 6 (III) roughly shows the steps of this method, which includes the step of measuring the device characteristics, the step of determining each parameter by fitting based on the results, and the step of determining the device function based on the functional diagram. It consists of the process of setting.

First, to explain the measurement of device characteristics, the current-output light intensity characteristics of the integrated optical logic device are measured as shown in FIG. 6(I).

That is, a current is applied from a constant current source 14 to the integrated optical logic element 10 via a resistor 12, and the output light intensity of the element 10 is measured by changing the current value. The output light intensity is measured by condensing the light output from the element 10 onto the light receiving element 18 using the condenser lens 16.

In this manner, the current-output light intensity characteristics of the integrated optical logic device 10 are measured.

The current-voltage-human power light intensity characteristics of integrated optical logic elements are as follows.
This is carried out as shown in Figure (II).

A resistor 11, a constant voltage power supply 17, an ammeter 13, and a voltmeter 15 are connected to the integrated optical logic element lO as shown in the figure, and the light from a light emitting element 20 such as a laser diode is focused by a condensing lens 19 and integrated. The light is irradiated onto the optical logic element 10 for input.

By changing the input light intensity and measuring the accompanying changes in the values of the ammeter 13 and voltmeter 15, the current-voltage-manual light intensity characteristic can be measured.

Next, the determination of each parameter by fitting will be explained. This determination step is performed in the procedure shown in FIG. 6 (IV).

Parameter A is determined by the current-output light intensity characteristic measured as described above (see equation (4-I) above).

In addition, by performing nonlinear optimization from the current-voltage-manual light intensity characteristics and the characteristics determined by experiment, parameters specific to the element; β, Ro, RωHn+Pc, and γ can be determined. That is, the peak value of the voltage with respect to the input light intensity in the current-voltage-human power light intensity characteristic, that is, the voltage value when the voltage reaches the maximum by changing the current, is measured, and this curve is compared with the curve predicted from the model. This is a method of adapting the

Rω can be determined from the current-voltage relationship when the input light is sufficiently strong and the integrated optical logic element is turned on. Furthermore, one parameter can be deleted from the case where the input light intensity is 0. If the input light intensity is not O, the remaining parameters are determined by fitting.

If the parameters are determined little by little in this way, the parameters can be determined more easily than if all the parameters are determined at once.

Once the device-specific parameters have been determined in this manner, the function settings are performed in accordance with the procedure shown in FIG. 6(V).

That is, by changing V and V with respect to the element-specific parameters determined as above, the functional diagram (see Fig. 3-4) is prepared.
If you plot above, the locus of the plot points will be drawn. When this locus is within the region representing the desired function, ■ and Rt give the bias voltage and load resistance that should be set in order to realize the desired function.

[Effects of the Invention] As described above, according to the present invention, a method for predicting device characteristics of an integrated optical logic device can be provided.

According to this method, when designing an integrated optical logic device, it is possible to quantitatively predict the range of parameters and conditions between parameters to obtain desired device characteristics.
Design of integrated optical logic devices becomes extremely easy. Further, it can be applied to various specific elements as light emitting elements and light receiving elements.

Since the function of an integrated optical logic device can be known only from the characteristics and optical feedback rate of each constituent element, it is extremely suitable for designing integrated devices.

When actually implementing the present invention, the above-mentioned procedure is programmed so that when L (I) and H (PPD) are input, a functional diagram is automatically drawn and the relationship between parameters and element characteristics is calculated. It is better to

[Brief explanation of drawings]

FIG. 1 is a diagram showing an equivalent circuit of an integrated optical logic device, FIG. 2 is a diagram explaining four element functions of an integrated optical logic circuit, and FIGS. 3 and 4 are diagrams for explaining an embodiment. FIG. 5 is a diagram showing an example of the structure of an integrated optical logic element, and FIG. 6 is a diagram for explaining an example of a specific function setting method. 1100 light emitting element, 200. Light receiving element, 300. Load resistance, 4°6. constant voltage power supply

Claims (1)

[Claims] Predicting device characteristics of an integrated optical logic device in which a light emitting element and a light receiving element are electrically integrated in series together with a load resistor to provide positive optical feedback from the light emitting element to the light receiving element. A method in which the bias voltage is V, the operating current is I, the load resistance is R_L,
The resistance of the light receiving element is R_P_D, and the input and output light intensities to the integrated optical logic element are P_i_n and P_o_u_, respectively.
t, the input light intensity to the light receiving element is P_P_D, the output light intensity from the light emitting element is P_L_E, the positive light feedback rate from the light emitting element to the light receiving element is β, the current-output light intensity characteristic of the light emitting element is P_L_E=L (I), (dL/dI≧0), R_P_D=H(P_P_
D), when (dH/dP_P_D≦0), V=I
(R_L+R_P_D) (1) P_P_D=P_i_n+βP_L_E (2) P_o_
u_t=(1-β)P_L_E(3)P_L_E=L(
I) (4) R_P_D=H(P_P_D) (5) In equations (1) to (5), L(I), H(P_
P_D), solve equations (1) to (5) above, and calculate P_D with the above V, R_L, and β as parameters.
Relationship between i_n and P_o_u_t P_i_n=g(P_o
___u_t; V, R_L, β), and based on this relationship,
A method for predicting device characteristics of an integrated optical logic device, characterized by predicting device characteristics.