JPS5922382A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of an oscillation wavelength in a semiconductor laser element based on an ambient temperature change by providing a heating element heating the laser element at a fixed temperature from an outer circumference. CONSTITUTION:A thermal good conductive material 10 having electric insulating property is arranged on the outside of a cylindrical body 4-4 while being fast stuck and fixed to the cylindrical body, and the heating element 11 is set up fast stuck and fixed on the outside of the thermal good conductive material 10. A self-temperature control heating element manufactured by an equipment such as a positive temperature characteristic thermistor is used as the heating element 11. A heat-insulating material 12 for reducing the inflow of heat from the circumference and the outflow of heat to the circumference is mounted so as to cover all of the heating element 11 and a substrate 4-1. When fixed voltage V0 is applied in a fixed power region in the positive temperature characteristic thermistor, currents I1 flow when an ambient temperature is T1, and power consumption reaches V0XI1. When the ambient temperature rises to T2, currents I0 decrease, power consumption reduces to V0XI0, and the heating element is operated so that the temperature of the device is kept constant automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser generator that generates laser light.

Conventionally, semiconductor laser elements have been widely used as light sources in fields such as optical communications.

In such a case, so-called Auto Power Control is used to maintain the optical output of the semiconductor laser at a constant power.
(hereinafter referred to as APO) is often adopted.

FIG. 1 explains this method, in which the optical output of the semiconductor laser emitted from the semiconductor laser element 1 is received by a photodetector 2, amplified by an amplifier 3, and then a laser drive circuit 4.
The output of the photodetector 2 is controlled so that the output is always constant. This method is widely used as a method for correcting changes in the optical output of a semiconductor laser device due to environmental temperature changes, device deterioration, etc.

However, when a semiconductor laser element is used for image recording or the like, the wavelength dependence of the sensitivity of the photoreceptor used in the device poses a major problem. In devices using a short wavelength laser such as a normal He-Ne laser, the spectral sensitivity of the photoreceptor near the laser wavelength is often flat, and the conventional A
It is also possible to adopt the PO method.

On the other hand, a semiconductor laser has a wavelength of around 8000λ, which is in the near-infrared region compared to an eNe laser, so the sensitivity of a commonly used photoreceptor is low. For this reason, when a semiconductor radar is used in such an image recording apparatus, the photoreceptor is often sensitized. However, even with sensitization, it is not possible to flatten the spectral sensitivity even in the semiconductor laser wavelength range due to image quality stability, photoreceptor durability, etc., and the spectral sensitivity is dependent on wavelength 9 as shown in Figure 2a.

Therefore, it is necessary to control the amount of light depending on the wavelength of the semiconductor laser element used, and if wavelength fluctuations occur during operation of the semiconductor laser, good images cannot be obtained with the conventional APO method.

To give an example, a semiconductor laser has a wavelength temperature coefficient of 2.5 to 3.0^, and if there is a temperature change of 30°C, M a
x, a wavelength change of 90λ occurs. Therefore, the higher the wavelength dependence of the sensitivity of the photoreceptor, the worse the obtained image becomes.

In order to prevent the laser oscillation wavelength from shifting due to changes in the ambient temperature of the semiconductor laser element, the present invention uses a heating element that heats the semiconductor laser element to a constant temperature to control the temperature itself by applying a constant voltage. By using a self-temperature-controlled heating element, the above-mentioned drawbacks of the conventional method are eliminated.

The present invention will be explained below based on Examples.

FIG. 3 shows an embodiment of the present invention, in which a laser beam emitted from a semiconductor laser device 9 is collimated by a collimator lens 5, reflected by a rotating polygon mirror 6,
The image is formed by the imaging lens 7 and scanned on the photosensitive drum 8. At this time, an image is formed on the photosensitive drum 8 by applying current modulation to the semiconductor laser element in the semiconductor laser device.

FIG. 4 shows a cross-sectional view of a semiconductor laser device according to the present invention. 4-1 is a disk-shaped metal board, and on this metal board 4-1 is a metal block 4- made of a good heat conductor such as copper.
2 is fixed, and a semiconductor laser device 4-3 is fixed to the end of this metal block.The metal block 4-2 and the semiconductor laser device are connected to a bottom plate 4-5 and a cylindrical body 4- 4, and by closely fixing the sealed container and the substrate 4-1,
The semiconductor laser element 4-3 is isolated from the external environment.

A window 4-6 made of a translucent material such as glass is provided in a part of the bottom plate 4-5 and fixed in an airtight manner to the bottom plate 4-5 and C, so that the laser emitted from the semiconductor radar element 4-3 can be passed through the container. It is something that is derived outside.

A thermally conductive material 10 having electrical insulation properties is disposed on the outside of the cylindrical body 4-4 in close contact with the cylindrical body. and heat generating element 11.
establish. The heating element 11 is a self-temperature-controlled heating element made of, for example, a positive temperature coefficient thermistor. Reference numeral 12 denotes a heat insulating material for reducing the inflow of heat from the surroundings and the outflow of heat to the surroundings, and is provided so as to completely cover the heat generating element 11 and the front base layer 4-1. 13 is the heat generating element -
This is a power supply for applying a constant voltage. In a positive temperature characteristic thermistor, in a constant power region, when a constant voltage Vo is applied, a current of ■1 flows when the ambient temperature is T1, and the power consumption becomes ■XI. Ambient temperature T.

When the temperature increases, the current decreases, power consumption decreases, and the temperature automatically becomes constant.

If configured as described above, even if the ambient temperature changes by 30°C, the area around the semiconductor laser element can change by about 5°C.Thereby, the spectral sensitivity characteristics shown in Figure 2 can be changed. Conventionally, even in the case of the drum, wavelength shift between colors occurs, but wavelength shift occurs between chairs, and the amount of change in spectral sensitivity becomes small.

In this manner, the present invention makes it possible to always emit high-quality laser beams ζb4 regardless of the environmental temperature in order to prevent wavelength shift due to temperature changes in the semiconductor laser element. In the above embodiment, the heat insulating material 12 is not necessarily required and can be omitted if necessary.

[Brief explanation of the drawing]

Fig. 1 is a light amount control circuit diagram of a conventional semiconductor laser device, Fig. 2 is a wavelength dependence characteristic diagram of a photoreceptor, Fig. 3 is a perspective view of an image recording device, and Fig. 4 is a cross-sectional view of the semiconductor laser device. . Here, 4-1 is a substrate, 4-3 is a semiconductor laser element, and 4-
4 is a cylindrical body, 4-5 is a bottom plate, 4-6 is a window, and 11 is a heat generating element. Figure 1 Figure 2 Figure 3 Figure 2654

Claims (1)

[Scope of Claims] 1. A semiconductor laser device characterized in that a case for protecting a semiconductor laser element is provided, a heat generating element is fixed to the outer periphery of the case, and the semiconductor laser element is heated by the heat generating element. 2. A semiconductor laser device according to claim 1, wherein the heating element is a self-temperature-controlled heating element. 3. A semiconductor laser device according to claim ¥iSI, characterized in that the heat generating element is wrapped in a heat insulating member.