JPH0663165A - Semiconductor laser stimulator and semiconductor laser therefor - Google Patents

Abstract

PURPOSE:To provide a portable semiconductor laser stimulator which is absolutely safe for the eyes and which has a high degree of treating efficiency, by using high power pulse semiconductor laser having a peak output and a duration time which are specified, for stimulating an affected part or a therapeutic point. CONSTITUTION:When a power source 2 is turned on by manipulating an external switch 1, an oscillator 3 generates reference clock pulses, and a frequency divider 4 lowers the frequency of a reference signal while a gate circuit 5 performs logical computation between the lowered frequency of the reference signal and a source frequency. An input 6 from an external trigger switch is applied to the gate circuit 5, and a laser drive circuit 7 generates a drive current in accordance with the signal, and the semiconductor laser 8 blinks by short pulses. Thus generated laser beam is irradiated to an affected part to be treated through an optical system 9 composed of lenses, optical fibers or the like. This laser stimulator generates a sharp laser beam having a peak value of higher than 1W and a pulse width of less than 100ns. Thereby it is possible to provide a semiconductor laser stimulator having a high safety for the eyes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a therapeutic device using a semiconductor laser. It also relates to the structure of a semiconductor laser used in the therapeutic device.

[0002]

2. Description of the Related Art Recently, it has been known that a therapeutic device using a low-power laser has the same effect as acupuncture and moxibustion in Oriental medicine. In addition, laser treatment in dentistry and oral surgery has been put to practical use and has been effective. An explanatory article is published on page 69 of “O Plus E” December 1988 issue (No. 109). According to this, laser has therapeutic effects such as analgesia, anti-inflammatory and blood circulation improvement, but the mechanism is still unclear. That is, changes in humoral factors due to laser irradiation, increase in blood flow, etc. appear in the same way as with needle stimulation, but whether it is the photochemical action of the laser, the polarization property, the electromagnetic field effect, or the coherence property is involved. There are many unclear points such as whether or not it is there. However, in any case, the greater the irradiation output, the greater the therapeutic effect, and it is a fact that it has been developed into treatments that replace conventional needles, analgesia / anti-inflammatory, dental treatment, and cancer treatment.

A typical treatment method has an output of 20 to 30 mW.
The He-Ne laser or the semiconductor laser having a maximum output of 100 mW or less is continuously irradiated in several times. Further, although pulse irradiation of a semiconductor laser having an output of several W is also a research example, it has not been put to practical use because it is difficult to obtain the semiconductor laser itself.

[0004]

As described above, there is no fixed treatment method in the current laser treatment device, and the irradiation method of the laser is largely dependent on the experience and feeling of the user. In addition, it is difficult to say that the safety when handling the laser is perfect. That is, most of the low-power laser therapy devices currently in use belong to Class 3B of the laser safety standard, and a key switch is required in addition to turning the light on and off. It is necessary to install the safety device. In particular, eye safety measures are important. An object of the present invention is to provide a laser device of class 1 for such a problem, and to realize a semiconductor laser treatment device which is absolutely safe for eyes and has a high therapeutic effect and which is suitable for carrying.

[0005]

DISCLOSURE OF THE INVENTION The present invention is based on a peak output 1W.
As described above, the semiconductor laser treatment device obtains a therapeutic effect by irradiating the affected part or the acupuncture point with the light of a pulsed high-power semiconductor laser having a duration of 100 ns or less. Furthermore, the light source has an oscillation region. It is characterized in that it has a width of 200 μm or more and the active layer is an InGaAsP-based or AlGaAs-based semiconductor laser having a quantum well structure.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows the structure of a semiconductor laser treatment device according to the present invention. When the power supply 2 is turned on by the external switch 1, the oscillator 3 starts transmitting the reference clock. The frequency divider 4 lowers the frequency of this reference signal, and the gate circuit 5 takes a logical operation with the source frequency. Further, an external trigger switch input 6 is added to the gate circuit 5, and as a result, a short pulse has a waveform which lasts periodically for a certain duration. This situation is shown in the time chart of FIG. The laser drive circuit 7 generates a laser drive current by this signal, and the semiconductor laser 8 blinks with a short pulse. The generated laser light is applied to the treatment site through an optical system 9 such as a lens or an optical fiber. FIG. 3 shows a simplified diagram of the state of laser irradiation to this treatment site. FIG. 3A shows a type in which the light emitted from the semiconductor laser 14 is narrowed down by the condenser lens 15 and irradiates the affected area or acupuncture point, and FIG. 3B shows a type in which scattered light is emitted from the probe tip to the skin through the optical fiber 16. is there.

Now, returning to FIG. 1, although the basics of the laser treatment device can be sufficiently achieved by the above-mentioned part, in addition to this, the result from the power monitor 10 of the light source and the display of the timer 11 incorporated in the treatment device, If the display 13 for displaying the cumulative time calculation result 12 of the laser irradiation time and the like is provided, the grasping and reproducibility of the treatment condition can be maintained, and it is very easy to use. A liquid crystal display can be used to easily implement a portable therapy device.

The present invention is to irradiate a sharp laser beam having a peak output of 1 W or more and a pulse width of 100 ns or less with a laser treatment device having such a configuration, and the grounds for this are the safety to the eyes. In consideration of the above, it is intended to obtain the same effect as the conventional treatment device. The description will be given below.

FIG. 4 is a diagram of JIS C6802-1991, "A of Class 1 Visible and Near Infrared Laser Products".
It is a reprint of "EL (exposure emission limit)", but it can be seen that near infrared light, which has a longer wavelength than visible light, is safer. For example, in the visible emission range of 400 nm to 700 nm, where the emission duration is 10 ⁻⁹ to 10 ⁻⁵ s, the upper limit of the emission energy is 2 × 10 ⁻⁷ J. The upper limit of the emission energy is 3.6 × 10 ⁻⁷ , and the output is up to 1.8 times that of visible light. Furthermore, the upper limit is 8 × in the wavelength range of 1400 nm to 10 ⁵ nm.
It will be 10 ^-5 J, and output will be allowed up to 400 times the visible.

On the other hand, when t = 1 is set at a duration of 5 × 10 ^{-5 to} 10 s and the AEL is similarly obtained, a wavelength of 400 is obtained.
At ~ 700 nm, the wavelength is 830 nm for 7 × 10 ^-4 J
Is 1.27 × 10 ⁻³ J and the wavelength is 1400 to 10 ⁵ nm is 4.4 × 10 ⁻³ J, and the ratio to visible light is 1.
8 times and 6.3 times. From the above, it can be seen that the safety is much higher on the long wavelength side even if the output is increased from visible light. Especially, the wavelength exceeds 1.4 μm and the pulse width is 10 ^−5.
It can be seen that there is a two-digit difference below s. Table 1 is shown on the next page for easy understanding.

The pulse width of laser irradiation of 10 W is calculated based on Table 1 and is 20 ns in the visible and the wavelength is 830 nm.
Will be 36 ns. Further, it can be seen that at a wavelength of 1.4 μm or more, a pulse width of 100 ns can be output up to 800 W. On the other hand, assuming that the continuous irradiation of the laser takes 1 second, 0.7 m is obtained for each wavelength described above.
The weak output of W, 1.27 mW, 4.4 mW is obtained, and the therapeutic effect of the laser does not increase so much. This is the reason why the above-mentioned class 1 laser product has not been able to realize a laser therapeutic device having a high therapeutic effect. However, it is pointed out that the therapeutic effect of laser is photochemical or electromagnetic effect rather than thermal effect, and a sufficient therapeutic effect can be obtained by irradiating a laser with a high peak value (1 w or more) for a short time. It is more effective to raise. Also, by doing so, Class 1 is achieved, which is absolutely safe for laser products. Next, some grounds for eye safety are described.

[0012]

[Table 1]

FIG. 5 shows the wavelength of light and the transmittance of the eyeball and the absorption rate of the fundus of the eye. Visible light and near-infrared light pass through the eyeball well, and when the wavelength is 1.4 μm or more, almost no light enters the eye. However, it can be seen that energy is absorbed in the corneal surface layer. Further, it is said that the visible light which passes through the eyeball and focuses on the retina has a light intensity per unit area of 10,000 times on the cornea. This is the reason why there is a large difference in safety with respect to the wavelength of the laser, and the realization of a laser treatment device using a wavelength of 1.4 μm or more is desired.

Then, how can such a long-wavelength laser be realized? A specific example will be described below.

FIG. 6 shows an example of a gain waveguide type stripe structure of an InGaAsP laser having a wavelength of 1 μm band. Basically, AlGaAs, which is most practically used near 800 nm
Since it is the same as the case of the laser, it is good to refer to the manual there as well. InP substrate 61 has a basic structure of 1 μm band
An InGaAsP active layer 63 is formed on top of the
The n-type clad layers 65 and 62 sandwiched are stacked and p- for facilitating the formation of an ohmic electrode.
A cap layer 66 of InGaAsP is overlaid. As the ohmic electrode, Au-Zn is often used for the p-side 68 and Au-Ge-Ni is often used for the n-side 69. Further, SiO ₂ 67 is used for the insulation for forming the electrode into a strip shape. 1.4μ
In the InGaAsP laser with a wavelength of m or more, the third layer In
When the P clad layer is grown as a liquid layer, the active layer is melted back and the interface becomes uneven.
Is GaAsP anti-melt back 64 attached?
The third layer p-InP is grown at a low temperature and a high supercooling temperature. In addition, vapor phase growth methods other than liquid phase growth (MO-CV
In the case of D) or MBE, the AM layer is not necessary because there is no meltback phenomenon. The active layer thickness may be about 0.1 μm to 0.2 μm, and the stripe width may be about 10 μm. Regarding the wavelength, the composition ratio x, y of the In _1-x Ga _x As _y P _1-y active layer was changed from 1.11 μm to 1.
67 μm is obtained.

FIG. 7 shows the structure of a typical refractive index guided stripe laser having a wavelength band of 1 μm. In the refractive index guided type, a waveguide having a refractive index distribution is formed in a localized gain region, which serves as a waveguide region and determines a horizontal transverse mode. The waveguide width W is about 2 μm. From the relationship with the current injection stripe width S, the rib waveguide type of S> W and S = W
BH (embedded) type can be roughly divided into two. The figure shows the former type. Generally, in the refractive index guided stripe structure, the horizontal and transverse modes are stable, and the longitudinal modes are easily unified. In addition, it is also characterized in that optical damage is unlikely to occur and operation at high light output density is possible.

The InGaAsP-based laser is popular mainly for optical communication, and a laser having a CW output of several 10 mW and a pulse of several 100 mW is obtained. However, in order to obtain a pulsed laser with an output of 1 W or more and several tens of W required for the present invention, the following improvements are needed based on the above laser.

FIG. 8 shows a new laser according to the present invention in which the active layer has a multiple quantum well structure. The structure has many points in common with the above-mentioned gain waveguide type. That is, an n-type InP clad layer 82 is grown on an n-InP substrate 81, an active layer 83In _1-x Ga _x As _y P _1-y having a quantum well structure is stacked on the clad layer 82, and p-InP It is sandwiched by the clad layers 84 to form a sandwich structure. At this time, MOCVD or MBE method is used to form the quantum well and the like, and the composition x is 0.7.
Fix at 6 or 0.65. Regarding the y composition, the upper limit of y is set to 0.4 to 0.9, and the bottom of y is set to 0.1.
Shake to Furthermore, the well width at this time is 100
The barrier width is set to about 70 angstroms or less, and wells are periodically formed. After forming the active layer in this way, a cap layer 85p-InGaAsP for obtaining an ohmic contact is grown, and an unnecessary portion is insulated with SiO ₂ 86, and then the stripe width of the p electrode 87 is broadened to 200 μm or more. Resonator length is 4
It is from 00 to 500 μm. By doing so, a giant pulse semiconductor laser having an oscillation wavelength of 1.4 μm to 1.6 μm, an output of 10 W and a pulse width of 100 ns or less can be obtained by increasing the area of the laser oscillation region. This is a one-digit to two-digit increase in output compared to the conventional type, so the ability as a laser treatment device is greatly increased. Further, as mentioned above, the wavelength range has no effect on the eyes, so that the safety is extremely high.

The quantum well structure laser has several features. First, a low threshold current is possible. This is convenient for lowering the power of the device and making it battery-operated. The second feature is that the oscillation wavelength can be changed only by changing the width of the quantum well. This means that the parameter that controls the wavelength can change the width of the well as well as change the material composition.
The degree of freedom is extremely high. The third feature is that the temperature dependence of the threshold current is smaller than that of the double hetero laser. This is very convenient in practice, and a device having little temperature dependence can be realized. The fourth characteristic is that the high speed modulation characteristic is superior to that of the double hetero laser. This is also an important factor for a laser treatment device that uses pulsed light. By making it possible to use the quantum well laser in this manner, a number of good results are obtained for practical machines.

Other than the above-mentioned InGaAsP system, there is a possibility that a semiconductor laser having a wavelength of 1.4 μm or more can be realized, and InGa near 2 μm and in the range of 3 to 4 μm.
AsSb system, InAsPSb system in 1 to 6 μm band, 4 to
PbSSe system in the 8 μm band, PbS in the 6 to 28 μm band
There are nTe system and PbSnSe system. However, in general, when the oscillation wavelength becomes long, an alloy having a small band-to-band energy is used, so that electrons and holes are easily excited by thermal energy and a pn junction is not formed. Further, the higher the temperature, the shorter the life of these charges. Therefore, a cooler is required to prevent this. Therefore, the miniaturization of the device, which is another object of the present invention, may be conflicting.
Caution must be taken.

FIG. 9 shows a semiconductor laser having a wavelength of 850 nm in the near infrared, which is also an AlGaAs system and similarly has an active layer of a quantum well type. n-type AlGa on n-GaAs substrate 91
A clad layer 92 of As is grown, and an active layer 93Al _x Ga _1-x As having a quantum well structure is stacked on the clad layer 92.
It is sandwiched between p-AlGaAs cladding layers 84 to form a sandwich structure. At this time, the MOCVD or MBE method is used for forming the quantum well and the like as in the previous example, and the upper limit of the composition x is set to 0.22 to 0.20 and the bottom of x is set to 0. Further, at this time, the well width is set to 100 angstroms or less and the barrier width is set to about 70 angstroms. After forming the active layer in this way, a contact layer 95p-GaAs for obtaining ohmic contact is formed.
Is grown and the unnecessary portion is insulated with SiO ₂ 96, and then the stripe width of the p-electrode 97 is broadened to 200 μm or more. The resonator length is 400 to 500 μm. By doing so, a giant pulse semiconductor laser having an oscillation wavelength of about 850 nm, an output number of 10 W and a pulse width of 100 ns or less can be obtained by increasing the area of the laser oscillation region. This near-infrared semiconductor laser has a pulse width of several tens of nanometers as shown in Table 1.
If s is set, it is possible to make a laser product of class 1 even if the peak output is 10 W class.

[0022]

As described above, according to the present invention, a high-power pulsed semiconductor laser is used as a light source to irradiate an affected area or an acupuncture point requiring treatment. Therefore, the semiconductor laser therapeutic apparatus is compact and highly safe for the eyes. Was realized. Also,
With an InGaAsP-based semiconductor laser incorporating a quantum well structure in the active layer, a pulse laser having a wavelength of 1.4 μm to 1.7 μm, a duration of several ns to 100 ns, and a peak value of several tens W can be realized, and it is small and has a therapeutic effect. A high-performance device can be realized. In addition, near-infrared AlGaAs having a wavelength near 850 nm
Also for the semiconductor laser, a similar high-power pulse laser can be realized, and a class 1 laser treatment device that is easy to handle can be provided. As described above, the present invention can improve the conventional laser treatment device of class 3B to a device of class 1 which is highly safe for the eyes and has no problem for anyone to use, so that the laser treatment device can be widely popularized. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor laser treatment device according to the present invention.

FIG. 2 is a signal waveform time chart of the laser treatment device according to the present invention.

FIG. 3 is a schematic view of the state of light irradiation of the laser treatment device according to the present invention.

FIG. 4 AEL for Class 1 visible and near infrared laser products
The standard diagram showing.

FIG. 5 is a measurement diagram showing light wavelength, eyeball transmittance, and fundus absorptivity.

FIG. 6 is a schematic configuration diagram of a gain waveguide type stripe structure of an InGaAsP laser.

FIG. 7 is a configuration diagram of a refractive index guided stripe structure of an InGaAsP laser.

FIG. 8 is a schematic configuration diagram of an InGaAsP multiple quantum well laser according to the present invention.

FIG. 9 is a schematic configuration diagram of an AlGaAs multiple quantum well laser according to the present invention.

[Explanation of symbols]

 1 power switch 2 power source 3 oscillator 4 frequency divider circuit 5 gate circuit 6 external trigger switch 7 laser drive circuit 8 laser light source 9 optical system 10 optical power monitor 11 timer 12 irradiation accumulated time 13 liquid crystal display 61 n-InP substrate 62 n-InP 63 InGaAsP active layer 64 InGaAsP AM layer 65 p-InP 66 p-InGaAsP 67 SiO2 68 p-electrode 69 n-electrode 81 n-InP substrate 82 n-InP 83 InGaAsP active layer 84 p-InP 85 p-InGaAsP 86 SiO2 87 p-electrode 88 n-electrode 91 n-GaAs substrate 92 n-AlGaAs 93 AlGaAs active layer 94 p-AlGaAs 95 p-GaAs 96 SiO2 97 p-electrode 98 n-electrode

Claims (4)

[Claims] 1. A peak output of 1 W or more and a duration of 100 ns
The affected part of the following pulsed high-power semiconductor laser light,
Alternatively, a semiconductor laser treatment device characterized in that a therapeutic effect is obtained by irradiating acupuncture points. 2. The oscillation region width is 200 μm or more, and
The semiconductor laser for a semiconductor laser therapeutic device according to claim 1, wherein the active layer has a quantum well structure. 3. The semiconductor laser for a semiconductor laser therapeutic device according to claim 2, wherein the semiconductor laser is an InGaAsP-based semiconductor laser having an oscillation wavelength of 1.4 μm to 1.7 μm. 4. The semiconductor laser for a semiconductor laser therapeutic device according to claim 2, which is an AlGaAs semiconductor laser having an oscillation wavelength near 850 nm in the near infrared.