JPH0666721A - Identifying method for substance, sensor using the same and semiconductor laser type substrate identifying sensor - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser type substance identifying sensor which can be applied to a micromachining, has a small size and can be integrated. CONSTITUTION:A semiconductor laser type substance identifying sensor comprises a Fabry-Perot type semiconductor laser 1, a photodiode 2, a photoreceiver 3, a recorder 4 and a driving circuit 6. Liquid 8 to be inspected in contact with a light emitting surface of the laser 1 detects a laser output light P of the laser 1 by the photodiode 2 by utilizing a phenomenon of variation in the light P by varying characteristics of the laser 1, and plots the variation in the light P. The laser 1 and the photodiode 2 can be integrated on the same semiconductor substrate by semiconductor integrating technique with small size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes the fact that the excited state of a semiconductor laser changes depending on the physical properties (characteristics) of a substance such as a liquid contacting the light emitting surface of the semiconductor laser. The present invention relates to a method for identifying physical properties and a semiconductor laser type material identification sensor using the method. In particular, the present invention relates to a sensing unit of a compact and integratable optical sensor suitable for application to FIA (Flow Injection Analysis) or micromachining, and a semiconductor laser type substance identification sensor using the sensing unit.

[0002]

2. Description of the Related Art An optical sensor is known as a sensor for identifying (specifying) a substance, more specifically a liquid (or solution), or verifying the physical properties of the substance of the liquid. Examples of applications of such optical sensors include identification of the type of liquid, measurement of the concentration of sugar in the liquid, measurement of adsorbates such as water on the surface of the substance, or detection of water or oil leaks using optical fibers. .

Among such optical sensors, the optical sensor used for identifying the type of liquid, measuring the concentration of sugar in the liquid, measuring adsorbed substances such as water on the surface of the liquid is usually used for the liquid to be measured. The reflectance, transmittance, or refractive index of light when irradiated with light is measured, and the type of liquid is identified or the physical properties of the liquid are verified from the measurement results.

For various measuring instruments using the FIA or micromachining technology, there is a demand for development of a small and high-performance microsensor or smart sensor due to reasons such as detection environmental conditions and the amount of detection target. Also, from the viewpoint of the detection principle, it is desirable that the sensing unit is particularly small. Further, it is preferable that the size of the entire sensor including the signal processing system is small, and it is desirable to apply the semiconductor technology to integrate the entire sensor.

[0005]

However, in any of the conventionally known photosensors, any of them has a sensing portion, a light emitting diode as a light emitting portion or a semiconductor laser as a simple light emitting means, and a photodetector constituting a light receiving portion. Since it is constructed by combining individual electronic components that are commonly used, such as diodes, we have encountered the problem that the sensing part is relatively large. As a result, the size of the optical sensor is also large. Even if these individual electronic components are formed into an integral structure by applying a normal integration technique, the above requirements required for a sensor cannot be satisfied.

Therefore, in view of the above-mentioned problems, the present invention develops a new practical substance identification method that enables miniaturization and integration of a sensor, and a sensing unit of an optical sensing section using the substance identification method. , And a semiconductor laser type substance identification sensor.

[0007]

Means for Solving the Problems The inventors of the present application have earnestly studied to obtain a sensor in which the sensor itself can be made extremely small and can be integrated in order to achieve the above-mentioned object. Side emission surface (light emission surface)
It has been found that the substance can be identified or the physical property of the substance can be identified by utilizing the principle that the oscillation state of the semiconductor laser itself changes due to the physical property of the contact substance generated when the substance such as liquid contacts. Therefore, according to the present invention, the type or physical property of the contact substance is identified by detecting the change in the oscillation state of the semiconductor laser, which is defined according to the substance in contact with the light emitting portion (light emitting surface) of the semiconductor laser. A method for identifying a substance is provided.

Further, according to the present invention, there is provided an optical sensor characterized in that a semiconductor laser in which the oscillation state of the semiconductor laser changes according to a substance in contact with the light emitting portion is used as a sensing portion of the optical sensor. .

Furthermore, according to the present invention, a semiconductor laser,
A semiconductor having means for detecting the operating state of the semiconductor laser, and means for identifying the type or physical property of the substance in contact with the light emitting portion of the semiconductor laser from the operating state of the semiconductor laser detected by the semiconductor laser operating state detecting means. A laser based material identification sensor is provided. Specifically, when the semiconductor laser is energized in a constant current state, the semiconductor laser operating state detecting means is located at a predetermined distance from the other light emitting portion facing the one light emitting portion of the semiconductor laser. It is a light detecting means. Alternatively, when the semiconductor laser is energized in a constant output state, the semiconductor laser operating state detecting means is a current detecting means for detecting the drive current of the semiconductor laser.

The semiconductor laser is preferably a semiconductor laser having a Fabry-Perot resonator or an equivalent semiconductor laser. The semiconductor laser is preferably a distributed feedback semiconductor laser or an equivalent semiconductor laser.

Further, according to the present invention, preferably, the semiconductor laser whose change in operating state is regulated according to the substance in contact with the light emitting portion and one light emitting portion of the semiconductor laser are opposed to each other. There is provided a sensing part of an optical sensor, characterized in that the other light emitting part and a light receiving element located at a predetermined interval are integrally formed on the same semiconductor substrate as an integrated light emitting / light receiving device. Further, there is provided a semiconductor laser type substance identification sensor using the sensing unit. This semiconductor laser type substance identification sensor performs signal processing on a detection signal from the sensing section, a circuit for energizing the semiconductor laser in the sensing section, and a light receiving element in the sensing section, and outputs the signal to a light emitting section of the semiconductor laser. The automatic substance identification means for identifying the type or physical property of the contacted substance and the identification result output means for outputting the identification result identified by the automatic substance identification means.

[0012]

The optical sensor and the semiconductor laser type substance identification sensor according to the present invention have the oscillation state of the semiconductor laser itself which depends on the physical properties of the contact substance when the substance contacts the light emitting surface of the semiconductor laser. By measuring the change in, the type of the contact substance is identified or the physical properties of the substance are verified. That is, when a substance such as a gas or a liquid is brought into contact with the light emitting surface of at least one of the two facing light emitting regions of the semiconductor laser, the reflectance of the light emitting region changes according to the dielectric constant (refractive index) of the contact substance. This change in reflectance causes, for example, a change in reflection loss of a double hetero semiconductor laser formed of a compound semiconductor,
As a result, the oscillation state, that is, the threshold current and the external quantum differential efficiency change. There are two methods for detecting the change in the oscillation state of the semiconductor laser. When the semiconductor laser is driven by a constant current, the change in the oscillation state is detected as a laser output change, or when the constant output is driven. Is detected as a drive current change. The means for identifying the type of the substance or for identifying the physical property of the substance identifies the substance to be detected or the physical property of the substance from the change characteristic of the oscillation state of the semiconductor laser which is determined in advance. .

Since the semiconductor laser type substance identification sensor uses an extremely minute semiconductor laser having several tens of μm to several hundreds of μm in length and width and about 100 μm in thickness as its main components, an extremely minute sensing section is constructed. What you can do
Since the substance in contact with the minute light emitting region of the semiconductor laser can be measured, the substance in the minute region can be identified. In this way, the sensing portion of the optical sensor can be made extremely small, and the semiconductor laser type substance identification sensor using it can also be made small and can be used as a microsensor.

As the semiconductor laser used here,
A semiconductor laser having a Fabry-Perot resonator or an equivalent semiconductor laser is suitable. The reason is that the gain is large, the internal loss is small, the reflection loss is small, and the amplification is easy. A semiconductor laser having a Fabry-Perot resonator is, for example, GaAs, AlGaAs,
It is a double hetero laser or a quantum well laser made of a compound semiconductor such as InGaAs or InGaAsP. Further, as the semiconductor laser, a distributed feedback type semiconductor laser or a traveling wave type semiconductor laser such as DBR or DFB is also suitable.

Photodetection means such as a semiconductor laser and a photodiode can be easily integrated in the forming process, and the sensing portion can be miniaturized as an integrated light emitting / receiving device. When a semiconductor laser energizing circuit, automatic substance identification means, and identification result output means are added to the sensing unit having this integrated light emitting / receiving device,
As a smart sensor, or a semiconductor laser type substance identification sensor which can be suitably applied to FIA or micromachining is configured.

[0016]

1 is a block diagram of an embodiment of a semiconductor laser type substance identification sensor of the present invention. This semiconductor laser type substance identification sensor includes a semiconductor laser (Fabry-Perot type semiconductor laser) having a Fabry-Perot type resonator, a photodiode such as a silicon photodiode or a PIN photodiode for detecting laser output light of the semiconductor laser, and the like. A light receiving circuit which cooperates with this photodiode to process a detection signal of the photodiode 2, a recorder which plots a characteristic change of the semiconductor laser 1 as a change of laser output light, and a current probe which detects a driving current of the semiconductor laser 1. 5, and a drive circuit 6 for energizing the semiconductor laser 1. As will be described later, either the photodiode 2 and the light receiving circuit 3, or the current probe 5 may be provided. Using this semiconductor laser type substance identification sensor, the pipette 9 is brought into contact with the periphery of the Fabry-Perot type semiconductor laser 1 placed on the sample stage 7, in particular, its reflective surface, according to a detection (identification) operation described later. The type of the liquid 8 to be inspected placed is specified.

FIG. 2 is a perspective view showing a sectional structure as an example of the semiconductor laser 1. This semiconductor laser 1 has, for example, a cavity length L = 300 μm and an electrode width W = 100 μm.
m, height H = 300 μm, that is, its external dimensions are 30
A GaAs / AlGaAs quantum well laser in which a compound semiconductor of 0 × 300 × 100 μm is heterojunction,
As shown in FIG. 1, from both ends, for example, 2.5
It emits (emits) light having a wavelength of about × 10 μm to 200 × 10 μm. The resonator length L defines the length as a Fabry-Perot resonator.

FIG. 3 is a perspective view schematically showing the Fabry-Perot type semiconductor laser 1 shown in FIG. 2 in order to describe the change in operating characteristics of the Fabry-Perot type semiconductor laser 1 shown in FIG. Referring to FIGS. 2 and 3, the Fabry-Perot type semiconductor laser 1 has an active layer defining a quantum well and cladding layers formed on both sides thereof, and a drive current I is applied from a drive circuit 6. Then, the front light FL and the back light RL are emitted from both end surfaces thereof. Inspection target liquid 8
The laser output light when P is not in contact with the light emitting portion is P ₀
And The right end surface of the Fabry-Perot type semiconductor laser 1 is a reflecting surface, and its reflectance is R. When the inspection target liquid 8 having a refractive index n comes into contact with the reflecting surface, the refractive index n
And the reflectance R, the relational expression defined by Expression 1 is established.

[Equation 1]

The laser output light P is also output from the other surface of the Fabry-Perot type semiconductor laser 1 facing the above reflection surface, and the light receiving surface of this laser output light P is, for example, 9 × 9.
It is detected by the photodiode 2 of mm. The laser output light P detected by the photodiode 2 is input to the recorder 4 via the light receiving circuit 3 and the detected value is plotted.

FIG. 4 is a graph showing changes in operating characteristics of the Fabry-Perot type semiconductor laser 1. The laser output light P of the Fabry-Perot type semiconductor laser 1 linearly increases in a small region where the drive current I applied from the drive circuit 6 to the Fabry-Perot type semiconductor laser 1 is less than or equal to the current threshold value I _th. The rate of increase is small. When the drive current I exceeds the current threshold value I _th , the rate of increase of the laser output light P becomes extremely large, and the increase of the drive current I applied from the drive circuit 6 to the Fabry-Perot type semiconductor laser 1 increases the laser output light. P becomes large. When identifying the liquid to be inspected 8,
The drive circuit 6 drives (energizes) the Fabry-Perot type semiconductor laser 1 with a drive current I _{equal to} or higher than the current threshold value I _th .

Equation 2 is the current threshold I _th , the reflectance R of the Fabry-Perot type semiconductor laser 1, the cavity length L, the electrode area S, the internal loss α _i, and the constants β, Γ, I ₀ . Show the relationship.

[Equation 2] Further, the relationship between the current threshold value I _th and the laser output light P when the inspection target liquid 8 is not in contact with the Fabry-Perot type semiconductor laser 1 is shown in Expression 3.

[Equation 3] In Equation 3, h is Planck's constant, ν is the oscillation laser beam frequency, q is the charge of injected electrons, η _d is the external differential quantum efficiency, and I is the drive current.

The solid line in FIG. 4 shows a characteristic curve in which the liquid 8 to be inspected does not come into contact with the reflecting surface of the Fabry-Perot type semiconductor laser 1. When the inspection target liquid 8 comes into contact with the reflection surface of the Fabry-Perot type semiconductor laser 1, as shown by the broken line in FIG.
The characteristics of the laser output light P change. The current threshold I _th becomes large, and the increase rate of the laser output light P becomes small at the drive current I equal to or larger than the current threshold I _th . This change in the operating characteristics is caused by the change in the oscillation state of the Fabry-Perot type semiconductor laser 1 due to the inspection target liquid 8 coming into contact with the light emitting surface of the Fabry-Perot type semiconductor laser 1. Therefore, if the recorder 4 records and analyzes the change in the operating characteristics of the Fabry-Perot type semiconductor laser 1, the inspection target liquid 8 in contact with the reflective surface of the Fabry-Perot type semiconductor laser 1 can be identified.

The identification principle will be described in more detail. Figure 5
6 is a graph showing the behavior of the laser output light P detected by the silicon photodiode 2 with respect to the passage of time when benzene as the inspection target liquid 8 is brought into contact with the reflective surface of the Fabry-Perot type semiconductor laser 1 with a pipette 9. The laser output light P is about 270 mW before the liquid 8 to be inspected comes into contact with the reflection surface of the Fabry-Perot type semiconductor laser 1.
₀ indicates that when the liquid to be inspected 8 comes into contact with the light emitting surface of the Fabry-Perot type semiconductor laser 1 at time 0 seconds, it sharply drops to about 100 mW as shown by a trace ab, and the laser output light P is almost constant during the period c. It is maintained at 100 mW. After that, the laser output light P ₀ begins to rise from the period d toward the original laser output light P ₀ , and after a transient state, the laser output light sharply drops at the time point e and then returns to the original laser output light P ₀ again. To do. Laser output light P in period c
The decrease value of is changed according to the type of the liquid 8 to be inspected. Therefore, if the decrease value is checked in advance, the type of the liquid 8 to be inspected can be specified by recording the laser output light P detected through the photodiode 2 with the recorder 4. Further, as shown in FIG. 5, when the inspection target liquid 8 comes into contact with the light emitting surface of the Fabry-Perot type semiconductor laser 1, a rapid change in the laser output light P occurs, so that the inspection target liquid 8 can be quickly identified. In other words, the detection time is very fast.

As described above, according to the semiconductor laser type substance identification sensor shown in FIG. 1, the liquid 8 to be inspected can be identified in a very short time due to its detection principle. However, the Fabry-Perot type semiconductor laser 1 can be identified by the pipette 9. When the liquid 8 to be inspected is dropped onto the surface of the Fabry-Perot type semiconductor laser 1, it is found that the reproducibility is not high in the period c shown in FIG. 5 due to the instability of the contact state of the liquid 8 to be inspected. It was Therefore, focusing on the characteristic change in the period e shown in FIG. 5, the stability of the characteristic change was verified. Figure 6
[Fig. 4] is a graph plotting measured data showing a change in laser light output P with respect to time when a drive current is changed. As shown in FIG. 6, the characteristic of the period e in FIG. 5 is stable and has high reproducibility. Therefore, in the identification method using the pipette 9 shown in FIG. 1, the characteristic in the period e shown in FIG. It is preferable to detect the change and identify the liquid 8 to be inspected for highly reliable identification.

FIG. 7 shows changes in laser output light P of benzene, trichlene, i-butanol and methyl ethyl ketone (MEK) indicated by black circles having a refractive index n shown on the horizontal axis, and benzene indicated by white circles. Trichlene, i-
3 is a graph showing changes in the current threshold value I _th of butanol and methyl ethyl ketone (MEK) plotted in the recorder 4. This measurement is a result of driving the Fabry-Perot type semiconductor laser 1 from the drive circuit 6 with a pulse current having a peak value of 700 mA, a pulse width of 0.1 μs, and a pulse interval of 10 μs. Thus, the laser output light P in the atmosphere
It is understood that the difference between the laser output light P when the liquid 8 to be inspected comes into contact with the light emitting surface of the semiconductor laser 1 by ₀ and the pipette 9 changes according to the refractive index n of the liquid. Therefore, as described above, when the photodiode 2 detects a change in the laser output light P and the recorder 4 plots the characteristic thereof, the type of the inspection target liquid 8 can be specified. When the physical properties of the liquid 8 to be inspected are to be analyzed, the physical properties of the liquid can be known by detecting the laser output light P by the photodiode 2 and plotting the detected values by the recorder 4. As a result of this identification, it was verified that the laser output was sufficiently changed according to the refractive index of the liquid, and that the liquid could be sufficiently identified by using the semiconductor laser type substance identification sensor to be practically used.

FIG. 8 shows the value of the laser output light P (black circle) of benzene, trichlene, i-butanol and methyl ethyl ketone and the value of the current threshold value I _th (white circle) when the reflectance R is plotted on the horizontal axis. Show. The characteristics shown in FIG. 7 and the characteristics shown in FIG. 8 are related using Expressions 1 to 3.

In the above example, the photodiode 2 is used to detect a change in the laser output light P of the Fabry-Perot type semiconductor laser 1 to specify the liquid 8 to be inspected, or to analyze the physical properties of the liquid 8 to be inspected. As mentioned above, FIG. 7 and FIG.
In place of monitoring the laser output light P in the photodiode 2, the current probe 5 detects the change in the current threshold I _th of the current applied from the drive circuit 6 to the Fabry-Perot type semiconductor laser 1 as described above. Similarly, the liquid to be inspected 8
It is shown that the physical property of the liquid 8 to be identified or to be inspected can be analyzed. In other words, Fabry-Perot type semiconductor laser 1
When energizing the diode in a constant current state, the photodiode 2
A light detecting means for detecting the output light of the semiconductor laser, such as, may be used. When energizing the Fabry-Perot type semiconductor laser 1 in a constant output state, current detection for detecting the drive current of the semiconductor laser such as the current probe 5 is performed. Means may be used.

FIG. 9 shows a container 27 of the semiconductor laser type object identification sensor of the present invention described above as the second embodiment of the present invention.
A configuration diagram in which the sensing unit is immersed in the inspection target liquid 28 in order to identify the inspection target liquid 28 stored in FIG. The sensing portion of the semiconductor laser type object identification sensor has an electrode portion 11c of the semiconductor laser, a monitoring laser output light emitting surface 11a, and a laser output light reflecting surface 11b, and a predetermined gap with the monitoring laser output light emitting surface 11a. A photodiode 12 arranged with a gap of 30 is integrally configured on a conductive base 21 which also functions as a counter electrode of the electrode portion 11c and a heat sink. Since the Fabry-Perot type semiconductor laser 11 generates heat due to its excitation, it is efficiently cooled by the base 21 which also functions as a heat sink. The sensing unit is provided with circuits corresponding to the above-described light receiving circuit 3, recorder 4, and drive circuit 6, but these circuits are not shown in FIG. The photodiode 12 is connected to the light receiving circuit 3 and the recorder 4 via cables 31 and 32, and the electrode portion 11c of the semiconductor laser 11 and the base 21 are connected to each other.
Is connected to the drive circuit 6 via cables 33 and 34.

The semiconductor laser 11 is applied to the electrode portion 11c via the cable 33 and is excited by the drive current I from the drive circuit 6 flowing through the current path returning via the base 21 to emit monitoring laser output light. Light is emitted from both sides of the surface 11a and the laser output light reflection surface 11b. The laser output light reflecting surface 11b comes into contact with the liquid 28 and the operating characteristics of the semiconductor laser 11 are changed. Laser output light emission surface 1 for monitoring
The photodiode 12 arranged facing the 1a with a gap 30 therebetween detects the change in the laser output light P, and the recorder 4 identifies the type of the liquid 28 to be inspected in the same manner as described above. The semiconductor laser type substance identification sensor using the sensing unit immersed in the liquid to be inspected 28 also provided the same results as the identification results shown in FIGS. 7 and 8. In particular, in the identification of the inspection target liquid 28 in the state where the semiconductor laser 11 shown in FIG. 9 is immersed in the inspection target liquid 28, unlike the method using the pipette 9 shown in FIG. The reproducibility was high even in the period c. That is, as in the first embodiment, the liquid 2 to be inspected before the transient state is detected in the period e of FIG.
It turns out that 8 can be identified. Therefore, in the semiconductor laser type substance identification sensor shown in FIG. 9, the type of the inspection target liquid 28 can be identified in a short time with high reliability.

A third embodiment of the semiconductor laser type substance identification sensor of the present invention will be described. FIG. 10 is a cross-sectional perspective view of the sensing unit shown in FIG. 9 integrated and formed on a semiconductor substrate as an integrated light emitting / receiving device. This sensing unit
A semiconductor laser 41 is formed on one side of the semiconductor substrate 40, and a photodiode 42 is formed on the other side facing the semiconductor substrate 41 via the separation groove 43. An electrode 41c is formed on the semiconductor laser 41. As shown in FIG. 9, a light receiving circuit 3, a recorder 4, a current probe 5, a driving circuit 6 and the like are connected to the sensing unit to form a semiconductor laser type substance identification sensor.

A specific example of the sensing unit will be shown. The semiconductor substrate 40 is made of GaAs and has a separation groove 4 with a width of 10 μm.
The semiconductor laser 41 on the right side separated by 3 has a cavity length L =
GaAs / AlG with 300 μm and electrode width W = 100 μm
It is a Fabry-Perot type semiconductor laser of a quantum well crystal having an aAs multiple quantum well structure. The left side of the separation groove 43 is G
It is the photodiode 42 of aAs. The drive circuit 6 sets the Fabry-Perot type semiconductor laser 41 to a peak value of 700
It is driven by a pulse current of mA, pulse width 0.1 μs, and pulse interval 10 μs.

FIG. 11 shows the refractive index n of the substances, benzene, trichlene and methyl ethyl ketone, and the laser of the Fabry-Perot type semiconductor laser 43 in the semiconductor laser type substance identification sensor using the sensing part of the integrated light emitting / receiving device shown in FIG. The change of the output light P is shown. The vertical lines show the variation in the measured values. It can be seen that even if the laser output light P of benzene, trichlene, and methyl ethyl ketone varies, there is a sufficient gap between them and they can be accurately identified. In other words, it was found that even if the sensing unit shown in FIG. 10 is used, the type of the liquid 28 to be inspected can be identified and can be put into practical use.

FIG. 12 is a diagram showing the structure of a semiconductor laser type substance identification sensor as a fourth embodiment of the present invention. The semiconductor laser type substance identification sensor 50 is connected with an integrated light emitting / receiving device 51, a semiconductor laser energizing circuit 52, an automatic substance identifying means 53, and an identification result outputting means 54 as shown in the figure. Integrated light emitting / receiving device 51
Is a sensing unit illustrated in FIG. 10, that is, a semiconductor laser 4 integrated with a semiconductor substrate 40 with a separation groove 43 therebetween.
1 and the photodiode 42. The semiconductor laser energizing circuit 52 is a circuit for energizing the semiconductor laser 41 in the integrated light emitting / receiving device 51 equivalent to the driving circuit 6 described above. The automatic substance identification means 53 is constituted by a microcomputer or the like, and instead of the recorder 4 described above, the inspection target liquid 28 is automatically identified by a program process from the change in the laser output light described above.
The identification result output means 54 includes, for example, a display device such as a liquid crystal, and displays the result identified by the automatic substance identification means 53 in a visually recognizable state. A printer or the like can be added to the identification result output means 54 to enable recording.

According to the semiconductor laser type substance identification sensor 50, the type of the inspection target liquid 28 can be easily identified automatically. In particular, the automatic substance identification means 53 drives the semiconductor laser energizing circuit 52 a plurality of times, inputs the laser output light P a plurality of times from the photodiode 42 in the integrated light emitting / receiving device 51, and processes the signal a plurality of times. By doing so, it becomes possible to more accurately identify the inspection target liquid 28. Also,
It is also possible to verify the physical properties of the liquid to be inspected 28 by the processing program of the automatic substance identification means 53.

The semiconductor laser type substance identification sensor 50 is suitable for FIA, micromachining and the like. Further, if the current semiconductor integration technology is applied, the automatic substance identification means 53 can be integrated in the integrated light emitting / receiving device 51, and a smart sensor in which a sensing unit and its signal processing unit are integrally configured can be realized.

To realize the sensing portion of the semiconductor laser type substance identification sensor or the optical sensor of the present invention, the present invention is not limited to the above-mentioned embodiments. For example, the semiconductor laser of the present invention is not limited to the semiconductor laser having the Fabry-Perot type resonator described above, but may be another semiconductor laser having the same characteristics as the semiconductor laser having the Fabry-Perot type resonator, for example, an active layer. DBR and D with a diffraction grating
A traveling wave semiconductor laser such as FB can also be used. As the semiconductor laser of the present invention, a distributed feedback semiconductor laser or an equivalent semiconductor laser can be preferably used.

Although the above-mentioned embodiments have been described with respect to the basic constitution for demonstrating the detection principle of the semiconductor laser type substance identification sensor or sensing unit of the present invention, the semiconductor laser type substance identification sensor or sensing unit of the present invention is described. Can be applied to various situations or applications, for example, identification of a liquid to be inspected or analysis of its physical properties in various measuring instruments using FIA or micromachining technology. Although the liquid or the solution has been exemplified as the substance to be inspected, the present invention can be applied to the identification of not only the liquid other than the liquid described above in the present invention but also other substances that change the operation characteristics of the semiconductor laser due to the difference in the refractive index.

[0038]

As described above, according to the present invention, the FIA is based on the principle of utilizing the change of the semiconductor laser itself.
It is possible to configure a minute sensor with high practicability suitable for or micromachining. Since the sensing part of this sensor is composed of a minute semiconductor laser, the sensor system can be miniaturized and integrated. Furthermore, the semiconductor laser type substance identification sensor or sensing unit of the present invention is provided with FIA.
When applied to various measuring instruments that use the micromachining technology, it contributes to downsizing and high performance of the measuring system. The sensing unit of the present invention or the semiconductor laser type substance identification sensor using this sensing unit has a quick response and can quickly identify the substance to be inspected and verify the physical properties of the substance. The sensing unit and the signal processing unit of the present invention can be integrated on a semiconductor substrate to form a smart sensor.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a semiconductor laser type substance identification sensor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a detailed sectional structure of the semiconductor laser shown in FIG.

FIG. 3 is a diagram showing an operating principle of the semiconductor laser shown in FIG.

FIG. 4 shows basic operating characteristics of the semiconductor laser shown in FIG.
6 is a graph showing a change in operating characteristics of the semiconductor laser, which changes depending on the liquid in contact with the reflecting surface of the semiconductor laser 1.

5 is a graph showing changes in the output of the semiconductor laser shown in FIG. 1 over time due to the liquid contacting the semiconductor laser.

6 is a graph showing changes in laser output with time of driving currents of various semiconductor lasers in a period e shown in FIG.

FIG. 7 is a graph showing a laser output change and a current threshold change of the semiconductor laser when the horizontal axis is the refractive index of the substance for identifying the type of liquid by the semiconductor laser type object identification sensor of the present invention. Is.

FIG. 8 is a graph showing a laser output change and a current threshold change of the semiconductor laser when the horizontal axis is the reflectance for identifying the liquid type by the semiconductor laser type object identification sensor of the present invention. .

FIG. 9 is a sectional perspective view of a sensing portion of a semiconductor laser type substance identification sensor as a second embodiment of the present invention.

FIG. 10 is a sectional perspective view in which a sensing portion of an optical sensor as a third embodiment of the present invention is integrated as an integrated light emitting / receiving device.

11 is a graph showing a measurement result of a liquid measured by using the sensing unit shown in FIG.

FIG. 12 is a configuration diagram of a semiconductor laser type substance identification sensor as a fourth embodiment of the present invention.

[Explanation of symbols]

1 ・ ・ Semiconductor laser (Fabry-Perot type semiconductor laser) 2 ・ ・ Photodiode 3 ・ ・ Photodetector circuit 4 ・ ・ Recorder 5 ・ ・ Current probe 6 ・ ・ Drive circuit 7 ・ ・ Sample stage 8 ・ ・ Inspected liquid 9 ・ ・Pipette 11 ... Semiconductor laser (Fabry-Perot type semiconductor laser) 11a ... Laser output light emitting surface for monitoring 11b ... Laser output light reflecting surface 11c ... Electrode part 12 ... Photodiode 21 ... Base 27 ... Container 28 .. Liquid to be inspected 30 .. Gap 31-34 .. Cable 40 .. Semiconductor substrate 41 .. Semiconductor laser 41c .. Electrode 42 .. Photodiode 43 .. Separation groove 50 .. Semiconductor laser type substance identification sensor 51. ..Integrated light emitting / light receiving device 52..Semiconductor laser energizing circuit 53..Automatic substance identification means 54..Identification result output means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Karubu 1-3-16 Higashiarima, Miyamae-ku, Kawasaki-shi, Kanagawa (72) Inventor Yasuki Karita 4-3-1 Tsujido Shinmachi, Fujisawa-shi, Kanagawa NOK Co., Ltd. (72) Inventor Masao Nishioka 2-30-19-204 Hasune, Itabashi-ku, Tokyo

Claims (11)

[Claims] 1. A substance identification method for identifying the type or physical property of the contact substance by detecting a change in the oscillation state of the semiconductor laser, which is defined according to the substance in contact with the light emitting portion of the semiconductor laser. 2. An optical sensor, wherein a semiconductor laser, in which the oscillation state of the semiconductor laser changes depending on a substance in contact with the light emitting portion, is used as a sensing portion of the optical sensor. 3. A semiconductor laser, a means for detecting the operating state of the semiconductor laser, and a substance which comes into contact with the light emitting portion of the semiconductor laser from the operating state of the semiconductor laser detected by the semiconductor laser operating state outputting means. Alternatively, a semiconductor laser type substance identification sensor having means for identifying physical properties. 4. When the semiconductor laser is energized in a constant current state, the semiconductor laser operating state detecting means is separated from the other light emitting portion of the semiconductor laser by a predetermined distance. 4. The light detecting means located at
The semiconductor laser type substance identification sensor described. 5. The semiconductor laser type material according to claim 3, wherein when the semiconductor laser is energized in a constant output state, the semiconductor laser operating state detecting means is a current detecting means for detecting a drive current of the semiconductor laser. Identification sensor. 6. The semiconductor laser type substance identification sensor according to claim 3, wherein the semiconductor laser is a semiconductor laser having a Fabry-Perot resonator or an equivalent semiconductor laser. 7. The semiconductor laser type substance identification sensor according to claim 3, wherein the semiconductor laser is a distributed feedback semiconductor laser or an equivalent semiconductor laser. 8. A semiconductor laser in which a change in its operating state is regulated according to a substance in contact with the light emitting portion, and a predetermined light emitting portion that opposes the one light emitting portion of the semiconductor laser. A sensing part of an optical sensor, characterized in that a light-receiving element located at a distance is integrally formed on the same semiconductor substrate as a light-emitting / light-receiving device. 9. A sensing unit, a circuit for energizing a semiconductor laser in the sensing unit, and a detection signal from a light receiving element in the sensing unit for signal processing to detect a substance in contact with a light emitting unit of the semiconductor laser. 9. The semiconductor laser type substance identification sensor according to claim 8, further comprising: an automatic substance identification means for identifying a type or a physical property; and an identification result output means for outputting an identification result identified by the automatic substance identification means. 10. The semiconductor laser type substance identification sensor according to claim 8, wherein the semiconductor laser is a semiconductor laser having a Fabry-Perot resonator or an equivalent semiconductor laser. 11. The semiconductor laser is a distributed feedback semiconductor laser or an equivalent semiconductor laser.
The semiconductor laser type substance identification sensor described.