A high edge-modulation ratio fiber-coupled pulsed semiconductor laser

Abstract

The application relates to the technical field of semiconductor lasers, in particular to a fiber-coupled pulse semiconductor laser with high side mode suppression ratio, a direct current driving circuit and a coupling output fiber, which provides stable and safe direct current to a semiconductor laser tube, so that the semiconductor laser tube generates continuous laser and the continuous laser is transmitted into the coupling output fiber; the application further comprises the semiconductor laser tube and first fiber type intensity modulation devices, first fiber amplifiers, second fiber type intensity modulation devices and second fiber amplifiers which are sequentially connected on the coupling output fiber; the application further comprises a first driver and a second driver, and the first driver and the second driver respectively provide required driving electric signals for the first fiber type intensity modulation devices and the second fiber type intensity modulation devices. The continuous current is used for driving, so that the excellent spectral characteristics and the high side mode suppression ratio of the laser can be maintained, and the decline of the signal side mode suppression ratio can be prevented.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of semiconductor lasers, in particular to a fiber-coupled pulse semiconductor laser with high side-mode suppression ratio. BACKGROUND

[0002] The fiber-coupled pulse semiconductor laser has a wide application in communication systems, industrial processing and scientific research fields due to its compact size, flexible driving and stable performance, for example, 1310hm and 1550nm waveband products have been used in communication systems for many years, 1550nm waveband products have been applied in laser radars in recent years, and 1064nm waveband products are more applied in industrial lasers, in addition to serving as seed light sources for infrared pulse fiber lasers, the products can also be used for generating green laser and ultraviolet laser through frequency doubling of fiber lasers for more precise processing.

[0003] The fiber-coupled pulse semiconductor laser usually utilizes pulse current to drive a laser tube to generate pulse laser, due to the flexible adjustment of pulse repetition frequency and pulse width of the laser, in combination with the mature fiber master oscillator power amplifier (FMOPA) technology, the average power can be increased to hundreds of watts or even kW level, and the pulse peak power can reach tens to hundreds of kW, so that the needs of applications such as metal marking, metal deep carving and metal cleaning can be met, and the high peak power can also provide high frequency doubling efficiency.

[0004] However, after the semiconductor laser is pulse-modulated, the performance of the semiconductor laser on spectral characteristics is degraded, which is manifested in that the spectral line width is widened, the monochromaticity is deteriorated, and the side-mode suppression ratio (SMSR) is decreased. Referring to the technical data of a commercial 1064nm center wavelength DFB semiconductor laser, the SMSR is 50dB when the average power of continuous light output is 30mW, but when the pulse laser is in a state of 1MHz repetition frequency, 4ns pulse width and 50mW peak power, the SMSR is only 40dB. This is not conducive to many applications that pursue narrow line width and high side-mode suppression ratio, such as fiber sensing, coherent laser radar, optical frequency standard and nonlinear frequency conversion. Especially after one or more stages of fiber amplification, the line width is widened more significantly, and the side-mode suppression ratio is further deteriorated. In view of this, the application provides a fiber-coupled pulse semiconductor laser with high side-mode suppression ratio. SUMMARY

[0005] In order to make up for the above shortcomings, the application provides a fiber-coupled pulse semiconductor laser with high side-mode suppression ratio.

[0006] The technical scheme of the application is as follows:

[0007] A high edge modulation rejection ratio fiber coupled pulsed semiconductor laser comprises:

[0008] A direct current driving circuit and a semiconductor laser tube electrically connected therewith, the direct current driving circuit being used for providing a direct current to the semiconductor laser tube so that the semiconductor laser tube generates continuous laser and the continuous laser is transmitted into a coupling output optical fiber;

[0009] A first fiber type intensity modulation device, a first fiber amplifier, a second fiber type intensity modulation device and a second fiber amplifier connected in sequence through the coupling output optical fiber;

[0010] A first driver and a second driver, the first driver and the second driver being electrically connected with the first fiber type intensity modulation device and the second fiber type intensity modulation device respectively, and the first driver and the second driver providing required driving electrical signals to the first fiber type intensity modulation device and the second fiber type intensity modulation device respectively.

[0011] As a preferred embodiment of the present application, the direct current driving circuit comprises an adjustable precision potentiometer, an overvoltage protection circuit, a precision operational amplifier, an overcurrent protection circuit, an output circuit, a MOS tube and a precision current sampling resistor.

[0012] As a preferred embodiment of the present application, the adjustable precision potentiometer and the inverting input terminal of the precision operational amplifier are connected, the output terminal of the precision operational amplifier and the MOS tube are connected, the non-inverting input terminal of the precision operational amplifier and the precision current sampling resistor are connected, the overvoltage protection circuit is composed of an overvoltage protection chip and a voltage dividing resistor connected with the overvoltage protection chip, the overvoltage protection chip and the adjustable precision potentiometer are electrically connected, the overcurrent protection circuit adopts a self-recovery fuse of SMD0603 series, the fuse and the adjustable precision potentiometer are electrically connected, the output circuit comprises a freewheeling diode, a current source and a switch, the negative electrode of the freewheeling diode is connected with the positive electrode of the current source, the positive electrode is connected with the negative electrode of the current source, the switch and the MOS tube are connected, the adjustable precision potentiometer is used to control the size of the output current, the precision operational amplifier is used to generate a precision voltage value to accurately control the constant current source generated by the MOS tube, the precision current sampling resistor provides negative feedback to the operational amplifier, and the output current value is stabilized in real time, and the overvoltage protection circuit and the overcurrent protection circuit are used to protect the circuit output.

[0013] As a preferred embodiment of the present application, the semiconductor laser tube is selected from one of FP cavity laser, DFB laser, DBR laser, QCL semiconductor laser and VCSEL laser, and the center wavelength includes but is not limited to 650 nm, 808 nm, 880 nm, 915 nm, 940 nm, 974 nm, 976 nm, 1030 nm, 1064 nm, 1310 hm, 1550 nm, 1960 nm and 2100 nm.

[0014] As a preferred embodiment of the present application, the coupling-out fiber is selected from one of polarization maintaining fiber, non-polarization maintaining fiber, single mode fiber and multi-mode fiber, which is used to collect the laser generated by the semiconductor laser tube and transmit the laser in the fiber.

[0015] As a preferred embodiment of the present application, the first fiber type intensity modulator is selected from one of acousto-optic modulator and electro-optic modulator, which modulates the continuous laser coupled into the fiber from the semiconductor laser tube into pulsed laser with specified pulse repetition frequency and specified pulse width under the action of the electrical signal from the first driver.

[0016] As a preferred embodiment of the present application, after receiving the trigger level signal from the system, the first driver extracts the pulse repetition frequency information and pulse width information, and generates corresponding driving electrical signal to provide to the first fiber type intensity modulator, so that the first fiber type intensity modulator generates pulsed laser meeting the requirements.

[0017] As a preferred embodiment of the present application, the first fiber amplifier amplifies the pulsed laser from the first fiber type intensity modulator to compensate the insertion loss of the system due to the application of the first fiber type intensity modulator.

[0018] As a preferred embodiment of the present application, the second fiber type intensity modulator is selected from one of acousto-optic modulator and electro-optic modulator, which modulates the pulsed laser from the first fiber amplifier again under the action of the electrical signal from the second driver, without changing the pulse repetition frequency of the laser, but further shortening the pulse width.

[0019] As a preferred embodiment of the present application, the second fiber amplifier amplifies the pulsed laser from the second fiber type intensity modulator to compensate the insertion loss of the system due to the application of the second fiber type intensity modulator.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] In the present application, the semiconductor laser is driven by continuous current instead of pulsed current, so that the excellent spectral characteristics and high side mode suppression ratio of the laser are maintained, and the decline of the signal side mode suppression ratio is prevented. Then the continuous laser is modulated by the fiber type intensity modulator to form pulsed laser output, which can maintain the linewidth characteristics of the seed laser, and does not produce frequency chirp due to pulse modulation, and still maintains the characteristics of narrow linewidth and high side mode suppression ratio. The fiber amplifier technology is used to compensate the loss of laser average power caused by the fiber intensity modulator, and the laser power is amplified in the fiber amplifier to meet the requirements of subsequent applications. In addition, in the application occasions requiring narrow pulse width, two fiber type intensity modulators are combined to break through the pulse width limit of a single modulator, and super-narrow laser pulses are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Structure diagram of the high side mode rejection ratio fiber coupled pulse semiconductor laser of the present application Figure 1 ;

[0023] Figure 2 Structure diagram of the high side mode rejection ratio fiber coupled pulse semiconductor laser of the present application Figure 2 ;

[0024] Figure 3 Structure diagram of the DC driving circuit of the present application

[0025] Figure 4 Spectrogram of the high side mode rejection ratio obtained from Example 1

[0026] Figure 5 Laser spectrogram obtained from Example 1 as a comparison using pulse current modulation technique.

[0027] In the drawings:

[0028] DC driving circuit 1, semiconductor laser tube 2, first driver 3, first fiber type intensity modulator 4, first fiber amplifier 5, coupling output fiber 6, second driver 7, second fiber type intensity modulator 8, second fiber amplifier 9

[0029] Adjustable precision potentiometer 01, overvoltage protection circuit 02, precision operational amplifier 03, overcurrent protection circuit 04, output circuit 05, MOS tube 06 and precision current sampling resistor 07. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0031] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0032] Please refer to Figures 1-5 The present application is described in detail by the following examples of the above technical solutions:

[0033] A high edge modulation rejection ratio fiber coupled pulsed semiconductor laser, comprising:

[0034] A direct current driving circuit 1 and a semiconductor laser tube 2 electrically connected therewith, the direct current driving circuit 1 is used to provide direct current to the semiconductor laser tube 2, so that it generates continuous laser, and the laser is transmitted into a coupling output optical fiber 6;

[0035] A first fiber type intensity modulation device 4, a first fiber amplifier 5, a second fiber type intensity modulation device 8 and a second fiber amplifier 9 connected in sequence through the coupling output optical fiber 6;

[0036] A first driver 3 and a second driver 7, the first driver 3 and the second driver 7 are electrically connected with the first fiber type intensity modulation device 4 and the second fiber type intensity modulation device 8 respectively, and the first driver 3 and the second driver 7 provide the required driving electric signal for the first fiber type intensity modulation device 4 and the second fiber type intensity modulation device 8 respectively.

[0037] As a preferred embodiment of the present application, the direct current driving circuit 1 comprises: an adjustable precision potentiometer 01, an overvoltage protection circuit 02, a precision operational amplifier 03, an overcurrent protection circuit 04, an output circuit 05, a MOS tube 06 and a precision current sampling resistor 07.

[0038] As a preferred embodiment of the present application, the adjustable precision potentiometer 01 and the inverting input terminal of the precision operational amplifier 03 are connected, the output terminal of the precision operational amplifier 03 and the MOS tube 06 are connected, and the non-inverting input terminal of the precision operational amplifier 03 and the precision current sampling resistor 07 are connected.

[0039] It should be noted that the overvoltage protection circuit 02 is composed of an overvoltage protection chip and a voltage dividing resistor connected with the overvoltage protection chip, and the overvoltage protection chip and the adjustable precision potentiometer 01 are electrically connected;

[0040] It should be noted that the overcurrent protection circuit 04 adopts a self-recovery fuse of SMD0603 series, and the fuse and the adjustable precision potentiometer 01 are electrically connected;

[0041] It should be noted that the output circuit 05 includes a freewheeling diode, a current source and a switch, the negative electrode of the freewheeling diode is connected to the positive electrode of the current source, the positive electrode is connected to the negative electrode of the current source, and the switch is connected with the MOS tube 06.

[0042] The adjustable precision potentiometer is used to control the size of the output current, the precision operational amplifier is used to generate a precise voltage value to accurately control the constant current source generated by the MOS tube, the precision current sampling resistor provides negative feedback to the operational amplifier, and the output current value is stabilized in real time. The overvoltage protection circuit and the overcurrent protection circuit are used to protect the circuit output, thereby protecting the laser tube, providing stable and safe direct current to the semiconductor laser tube, making it generate continuous laser, and transmitting it to the coupled optical fiber. Only continuous laser can maintain the narrow frequency and high side mode suppression ratio characteristics of the laser.

[0043] As a preferred embodiment of the present application, the semiconductor laser tube 2 is selected from one of FP cavity laser, DFB laser, DBR laser, QCL semiconductor laser, and VCSEL laser, and the center wavelength includes but is not limited to 650nm, 808nm, 880nm, 915nm, 940nm, 974nm, 976nm, 1030nm, 1064nm, 1310hm, 1550nm, 1960nm, and 2100nm.

[0044] As a preferred embodiment of the present application, the coupled output optical fiber 6 is selected from one of polarization maintaining optical fiber, non-polarization maintaining optical fiber, single mode optical fiber, and multi-mode optical fiber, and is used to collect the laser generated by the semiconductor laser tube 2 and make the laser transmit in the optical fiber.

[0045] As a preferred embodiment of the present application, the first optical fiber intensity modulation device 4 is selected from one of acousto-optic modulator and electro-optic modulator, and the first optical fiber intensity modulation device 4 modulates the continuous laser from the semiconductor laser tube 2 into pulsed laser with specified pulse repetition frequency and specified pulse width under the action of the electrical signal from the first driver 3.

[0046] As a preferred embodiment of the present application, after the first driver 3 receives the trigger level signal from the system, the pulse repetition frequency information and the pulse width information are extracted, and the corresponding driving electrical signal is generated and provided to the first optical fiber intensity modulation device 4, so that the pulsed laser meeting the requirements is generated.

[0047] As a preferred embodiment of the present application, the first optical fiber amplifier 5 amplifies the pulsed laser from the first optical fiber intensity modulation device 4 to compensate for the insertion loss of the system due to the application of the first optical fiber intensity modulation device 4.

[0048] As a preferred embodiment of the present application, the second optical fiber intensity modulation device 8 is selected from one of acousto-optic modulator and electro-optic modulator, and the pulsed laser from the first optical fiber amplifier 5 is modulated again under the action of the electrical signal from the second driver 7, without changing the pulse repetition frequency of the laser, but further shortening the pulse width.

[0049] As a preferred embodiment of the present invention, the second fiber amplifier 9 amplifies the power of the pulsed laser from the second fiber intensity modulator 8 to compensate for the insertion loss of the system caused by the application of the second fiber intensity modulator 8.

[0050] It should be added that the pigtail output of the second fiber amplifier 9 is generally connected to an APC connector with an 8-degree angle, or the bare fiber end face is cut at an angle to avoid backlighting during laser output.

[0051] The specific implementation process is as follows: A stable and safe DC current is provided by the DC drive circuit 1 to the semiconductor laser tube 2, causing it to generate continuous laser light, which is then transmitted to the coupled output optical fiber 6. Only continuous laser light can maintain the narrow-band and high side-mode rejection ratio characteristics of the laser. The first driver 3 generates a drive signal, which is provided to the first fiber-optic intensity modulator 4 to modulate the continuous laser light, causing it to generate pulsed laser light with a specified pulse repetition frequency and pulse width. The first fiber amplifier 5 amplifies the power of the pulsed laser light from the first fiber-optic intensity modulator 4, compensating for the insertion loss caused by the application of the first fiber-optic intensity modulator 4 (in some applications, when a single fiber-optic intensity modulator can meet the requirements for laser pulse width, the second driver 7, the second fiber-optic intensity modulator 8, and the second fiber amplifier 9 can be omitted, i.e., ...). Figure 2 The diagram shows a simplified structural schematic of a fiber-coupled pulsed semiconductor laser with high side-mode suppression ratio.

[0052] However, when a single fiber-optic intensity modulation device cannot meet the requirements for laser pulse width (i.e., as...) Figure 1 As shown, the second driver 7 must generate a driving electrical signal to provide to the second fiber-optic intensity modulator 8 to remodulate the pulsed laser from the first fiber amplifier 5, without changing the pulse repetition frequency, only further shortening the pulse width. The second fiber amplifier 5 amplifies the power of the pulsed laser from the second fiber-optic intensity modulator 8 to compensate for the insertion loss caused by the application of the second fiber-optic intensity modulator 8. Finally, the desired laser parameter characteristics are obtained.

[0053] Example 1, see Figure 2 A semiconductor laser tube 2 with a center wavelength of 1064nm generates a laser with an average power of 340mW under the drive of a 750mA continuous constant current source. After passing through a first fiber-optic intensity modulator 4 (which also has a center wavelength of 1064nm and a rise and fall time of 50ns, in this embodiment, the first fiber-optic intensity modulator 4 is an acousto-optic modulator), a laser pulse with a pulse repetition frequency of 100kHz and a pulse width of 200ns is obtained, and the average power is reduced to 4mW. Then, after passing through a first fiber amplifier 5, with other parameters unchanged, the average power is increased to 250mW. The resulting laser spectrum is shown in [reference needed].Figure 4 , the side mode suppression ratio is 46dBm, while as a contrast, the laser spectrum generated by direct pulse current modulation with the same pulse width is Figure 5 , the side mode suppression ratio is only 35dBm.

[0054] Example 2, see Figure 2 , the semiconductor laser tube 2 with central wavelength 1550nm generates laser with average power 10mW under the drive of 100mA continuous constant current source. After the first fiber type intensity modulation device 4 with the same central wavelength 1550nm (in this example, the first fiber type intensity modulation device 4 is selected as electro-optic modulator), laser pulses with pulse repetition frequency 16Hz and pulse width 100ps are obtained, and the average power is reduced to 0.4mW. After the first fiber amplifier 5, other parameters remain unchanged, and the average power is increased to 100mW.

[0055] Example 3, see Figure 1 , the semiconductor laser tube 2 with central wavelength 1064nm generates laser with average power 340mW under the drive of 750mA continuous constant current source. After the first fiber type intensity modulation device 4 with the same central wavelength 1064nm and rise and fall time 50ns (in this example, the first fiber type intensity modulation device 4 is selected as acousto-optic modulator), laser pulses with pulse repetition frequency 100kHz and pulse width 200ns are obtained, and the average power is reduced to 4mW. After the first fiber amplifier 5, other parameters remain unchanged, and the average power is increased to 250mW. After the second fiber type intensity modulation device 8 with the same parameters (in this example, the second fiber type intensity modulation device 8 is selected as acousto-optic modulator), laser pulses with pulse repetition frequency 100kHz and pulse width 5ns are obtained, and the average power is reduced to 2mW. After the second fiber amplifier 9, other parameters remain unchanged, and the average power is increased to 250mW. In this example, due to the limitation of the properties of rise and fall time, a single acousto-optic modulator cannot generate pulse width less than 50ns, but by using two acousto-optic modulators with the same parameters and controlling the relative delay of their drive signals, pulse width less than 50ns can be achieved. Similarly, for acousto-optic modulators with rise and fall time less than 10ns, the combination of two acousto-optic modulators can achieve laser pulse width in the order of hundreds of picoseconds.

[0056] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A fiber-coupled pulsed semiconductor laser with high side-mode suppression ratio, characterized in that, include: A DC drive circuit (1) and a semiconductor laser tube (2) electrically connected thereto. The DC drive circuit (1) is used to provide DC current to the semiconductor laser tube (2) so that it generates continuous laser light and transmits it to the coupled output optical fiber (6). The first fiber-optic intensity modulator (4), the first fiber-optic amplifier (5), the second fiber-optic intensity modulator (8), and the second fiber-optic amplifier (9) are sequentially connected through the coupling output fiber (6). The first driver (3) and the second driver (7) are electrically connected to the first fiber optic intensity modulator (4) and the second fiber optic intensity modulator (8), respectively. The first driver (3) and the second driver (7) provide the required driving electrical signals to the first fiber optic intensity modulator (4) and the second fiber optic intensity modulator (8), respectively. The DC drive circuit (1) includes: an adjustable precision potentiometer (01), an overvoltage protection circuit (02), a precision operational amplifier (03), an overcurrent protection circuit (04), an output circuit (05), a MOSFET (06), and a precision current sampling resistor (07); the adjustable precision potentiometer (01) is connected to the inverting input terminal of the precision operational amplifier (03), the output terminal of the precision operational amplifier (03) is connected to the MOSFET (06), and the non-inverting input terminal of the precision operational amplifier (03) is connected to the precision current sampling resistor (07). The overvoltage protection circuit (02) consists of an overvoltage protection chip and a voltage divider resistor connected to the overvoltage protection chip. The overvoltage protection chip and the adjustable precision potentiometer (01) are connected to the MOSFET (06), the output terminal of the precision operational amplifier (03), and the non-inverting input terminal of the precision operational amplifier (03) are connected to the precision current sampling resistor (07). The potentiometer (01) is electrically connected to the overcurrent protection circuit (04), which uses an SMD0603 series self-resetting fuse. The fuse and the adjustable precision potentiometer (01) are electrically connected. The output circuit (05) includes a freewheeling diode, a current source, and a switch. The negative terminal of the freewheeling diode is connected to the positive terminal of the current source, and the positive terminal is connected to the negative terminal of the current source. The switch and the MOSFET (06) are connected. The adjustable precision potentiometer (01) is used to control the magnitude of the output current. The precision operational amplifier (03) is used to generate a precision voltage value to accurately control the constant current source generated by the MOSFET (06). The precision current sampling resistor (07) provides negative feedback to the operational amplifier (03) to stabilize the output current value in real time. The overvoltage protection circuit ( 02) and overcurrent protection circuit (04) are used to protect the circuit output; the first fiber-optic intensity modulator (4) is selected from one of acousto-optic modulator and electro-optic modulator. Under the action of the electrical signal given by the first driver (3), the first fiber-optic intensity modulator (4) modulates the continuous laser from the semiconductor laser tube (2) coupled into the optical fiber into a pulsed laser with a specified pulse repetition frequency and a specified pulse width; after receiving the trigger level signal sent by the system, the first driver (3) extracts the pulse repetition frequency information and pulse width information, and generates the corresponding driving electrical signal, which is provided to the first fiber-optic intensity modulator (4) to generate a pulsed laser that meets the requirements; the first fiber amplifier (5) The pulsed laser from the first fiber intensity modulator (4) is amplified to compensate for the insertion loss caused by the application of the first fiber intensity modulator (4). The second fiber intensity modulator (8) is selected from either an acousto-optic modulator or an electro-optic modulator. Under the action of the electrical signal given by the second driver (7), the pulsed laser from the first fiber amplifier (5) is re-modulated without changing the pulse repetition frequency of the laser, but the pulse width is further shortened. The second fiber amplifier (9) amplifies the pulsed laser from the second fiber intensity modulator (8) to compensate for the insertion loss caused by the application of the second fiber intensity modulator (8).

2. The fiber-coupled pulsed semiconductor laser with high side-mode suppression ratio as described in claim 1, characterized in that: The semiconductor laser tube (2) is selected from one of the following: FP cavity laser, DFB laser, DBR laser, QCL semiconductor laser, and VCSEL laser, and its center wavelength includes 650nm, 808nm, 880nm, 915nm, 940nm, 974nm, 976nm, 1030nm, 1064nm, 1310nm, 1550nm, 1960nm, and 2100nm.

3. The fiber-coupled pulsed semiconductor laser with high side-mode suppression ratio as described in claim 1, characterized in that: The coupling output fiber (6) is selected from one of polarization-maintaining fiber, non-polarization-maintaining fiber, single-mode fiber, and multimode fiber, and is used to collect the laser generated by the semiconductor laser tube (2) and transmit the laser in the fiber.

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