KR100979018B1 - Fiber based arbitrary pulse laser system for temporal pulse shaping with a high extinction ratio and high resolution - Google Patents

Abstract

The arbitrary pulsed optical fiber laser generation system according to the present invention comprises a pulse programming section for programming pulse information about a preferred pulse, and using the programmed pulse information, a frequency generated from a frequency generator section, an RF associated with the preferred pulse. An arbitrary electrical pulse generator which outputs as a signal and a continuous laser beam input from a continuous wavelength fiber laser source based on the RF signal are discontinuous laser beams. An arbitrary laser pulse controller for converting the signal into an arbitrary laser pulse, and an electro-optic in the arbitrary laser pulse controller if the pulse of the intermittent laser beam does not match the preferred pulse within an acceptable range. a pulse for adjusting the pulse of the intermittent laser beam by inputting a DC bias into a modulator) It characterized by including the government.

Preferred pulse, RF signal, laser diode, DC bias, optical pulse shaping, optical extinction ratio, optical fiber, front-end system, optical amplification

Description

FIBER BASED ARBITRARY PULSE LASER SYSTEM FOR TEMPORAL PULSE SHAPING WITH A HIGH EXTINCTION RATIO AND HIGH RESOLUTION}

The present invention relates to an arbitrary pulsed fiber laser generation system having high extinction ratio and high resolution.

The pulse laser system is applied in various fields such as medical, communication, military, industrial cutting, drilling, welding, cleaning, etc., but there is a problem that the wavelength, intensity, pulse shape, etc. of the laser must be changed according to the use or purpose. .

In order to solve this problem, a tunable laser has emerged, and many pulse laser devices capable of adjusting the laser intensity have been developed and marketed. However, the laser system that can convert the laser pulse shape to the user's desired shape is under study at the world's best research institute.

In particular, the area of greatest interest is the arbitrary pulsed laser system in the front-end system for laser fusion. Laser fusion requires the convergence of tritium and deuterium efficiently by converging several high-intensity laser beams in one place. But among the many variables that cause the laser fusion reaction, an important one is the shape of the laser pulse.

Many pulse forms of theory and simulation results exist to produce laser fusion reactions. However, it is not yet proven which laser pulse shape is the most efficient for fusion reactions. To prove the practicality of laser fusion, the National Institute of Law, Livermore National Laboratory (LLNL) is currently building a National Ignition Facility (NIF). NIF includes high energy laser systems and fusion reactors. Arbitrary pulse generators produce seed laser beams in high-energy laser systems. The arbitrary pulsed laser generation system presented in the form of a paper by NIF has a complicated structure, and has a resolution of 300ps and an extinction ratio of more than 20dB.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and inputs an RF signal output by programming pulse information regarding a preferred pulse to an electrical / optical converter, and receives a continuous laser beam input from a laser source, A high extinction ratio (e.g., by adjusting the pulse of the intermittent laser beam through the adjustment of the DC Bias input to the electrical / optical converter, based on the RF signal, converting to a discontinuous laser beam associated with the preferred pulse). It is an object of the present invention to provide an arbitrary pulsed fiber laser generation system capable of generating an arbitrary laser light pulse desired by a user.

In addition, the present invention is to generate an arbitrary pulsed optical fiber laser having a high extinction ratio (e.g., 26 dB or more) and a high resolution (e.g., 200 ps) and having an adjustable width of, for example, 200 ps to 10 us. The RF signal output from the arbitrary electronic pulse generator is input to one of two electro-optic modulators with DC bias using a Mach-Zehnder interferometer, and the automatic feedback control is performed. It is an object of the present invention to provide an arbitrary pulsed fiber laser generation system capable of generating a stable and high extinction ratio laser light pulse by adjusting the DC bias input to both electric / optical converters through the device.

In order to achieve the object of the present invention as described above, an arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention using a pulse programming unit for programming the pulse information about the preferred pulse, and using the programmed pulse information An arbitrary electrical pulse generator for outputting a frequency generated from the frequency generator as an RF signal associated with the preferred pulse, and a continuous wavelength fiber laser source based on the RF signal. An arbitrary laser pulse controller that converts the incoming continuous laser beam into a discontinuous laser beam, and the pulses of the intermittent laser beam do not coincide with the preferred pulse within an acceptable range. In this case, DC Bias by an electro-optic modulator in the arbitrary laser pulse controller. Input, characterized in that it comprises a pulse adjuster for adjusting the pulse of the intermittent laser beam.

According to the present invention, an RF signal output by programming pulse information relating to a preferred pulse is input to an electric / optical converter, and a continuous laser beam input from a laser source is intermittent laser associated with the preferred pulse based on the RF signal. Converts to a beam, and adjusts the pulse of the intermittent laser beam through the adjustment of the DC bias input to the electrical / optical converter, thereby generating any desired laser light pulse having a high extinction ratio (e.g. It can be generated.

According to the present invention, there is also provided for generating an arbitrary pulsed fiber laser having a high extinction ratio (e.g., 26 dB or more) and a high resolution (e.g., 200 ps) and having an adjustable width of, for example, 200 ps to 10 us, The RF signal output from an arbitrary electronic pulse generator with respect to pulse information is input to one of two electro-optic modulators with DC bias using a Mach-Zehnder interferometer, By controlling the DC bias input to both electric / optical converters through an automatic feedback control device, it is possible to generate a stable and high extinction ratio laser light pulse.

Further, according to the present invention, as a seed laser system of a high energy laser system to be used for laser fusion in the future, it may be used in other applications.

Hereinafter, an arbitrary pulsed optical fiber laser generation system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall configuration diagram of an arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention.

The arbitrary pulsed optical fiber laser generation system according to the present invention includes a pulse programming unit 101, a frequency generating unit 102, an arbitrary electric pulse generating unit 103, a laser source 104, an arbitrary laser pulse control unit 105, and an electric machine. It may be configured to include a / light converter (106, 107), a pulse adjusting unit 108, a pulse amplifier 109, a polarizing unit 110, a photodiode 111, and an interface unit (112).

The pulse programming unit 101 functions to program pulse information about a preferred pulse.

An arbitrary electronic waveform generator 103 functions to output the frequency generated from the frequency generator 102 as an RF signal associated with the preferred pulse by using the programmed pulse information.

The pulse programming unit 101 may program pulse information regarding a user's preferred pulse as shown in FIG. 3 (iii), and may transmit the programmed pulse information to an arbitrary electric pulse generator 103. In this case, the pulse information checked at the point K 160 may be output as shown in K 202 of FIG. 2.

In addition, the frequency generator 102 may oscillate a frequency of approximately 10 kHz to the arbitrary electric pulse generator 103, the arbitrary electric pulse generator 103 uses the transmitted pulse information, the frequency, It may output as an RF signal associated with the preferred pulse.

In addition, the arbitrary electric pulse generator 103 may input the output RF signal to the arbitrary laser pulse controller 105 to generate an arbitrary laser pulse based on the RF signal. At this time, the arbitrary electrical pulse generating unit 103 is the second electrical / optical converter when the arbitrary laser pulse controller 105 is composed of the first electrical / light converter 106 and the second electrical / light converter 107 connected in series The output RF signal may be input to the optical converter 107. The arbitrary electric pulse generator 103 may be implemented in the AWG7051 developed by the US Tektronix.

Arbitrary laser pulse controller 105, based on the RF signal, the continuous laser beam input from the continuous wavelength fiber laser source 104, a continuous laser beam Convert to.

The laser source 104 is equipped with a tunable wavelength continuous wavelength diode laser, and the laser source 104 is also an FC / APC (PM) polarization maintaining fiber connected with an arbitrary laser pulse controller 105. As a result, a continuous laser beam having a center wavelength of 1053 nm may be generated through the mounted laser diode. In this case, the continuous laser beam identified at point A 120 may be output as shown in A 201 of FIG. 2.

The arbitrary laser pulse controller 105 may convert the continuous laser beam input through the FC / APC (PM) fiber into an intermittent laser beam based on the RF signal associated with the preferred pulse. That is, the arbitrary laser pulse controller 105 transmits the continuous laser beam to the preferred pulse based on the RF signal through the electrical / optical converters 106 and 107 connected in series with the FC / APC (PM) fiber. Convert to an intermittent laser beam associated with At this time, when the arbitrary laser pulse control unit 105 is composed of the first electrical / optical converter 106 and the second electrical / optical converter 107 connected in series, the second electrical / optical converter to which the RF signal is input ( 107, the continuous laser beam can be converted into an intermittent laser beam associated with the preferred pulse. The intermittent laser beam identified at point B 130 may be output as shown in B 203 of FIG. 2.

The arbitrary laser pulse controller 105 may determine the number of electric / light converters included in consideration of the extinction ratio for the intermittent laser beam or the degree of adjustment for the pulse of the intermittent laser beam.

For example, connecting two electrical / optical converters 106 and 107 in series has the advantage that the extinction ratio is increased, but there is a limitation in that the cost-effectiveness is lowered and the width of an arbitrary laser pulse waveform can only be controlled by about 100 ns.

In addition, when the first electric / light converter 106 is removed and only the second electric / light converter 107 is used, the arbitrary laser pulse width can be further expanded. That is, using one electric / optical converter 107, the width of the arbitrary laser pulse waveform can be controlled by about 10 us.

Therefore, the arbitrary laser pulse controller 105 can adjust the number of electric / optical converters included according to the use and the purpose.

When the arbitrary laser pulse controller 105 includes a plurality of electrical / optical converters, the electrical / optical converters 106 and 107 may be connected in series. That is, the first electrical / optical converter 106 and the second electrical / optical converter 107 may be connected in series with the FC / APC (PM) fiber.

At this time, the arbitrary laser pulse control section 105, because the electric / light converters 106, 107 included are very sensitive to noise and heat, making the case a copper plate, so that the noise is reduced and the heat generation is good Can be. Also, for example, the first electrical / optical converter 106 and the second electrical / optical converter 107 may be implemented with a Lithium niobate modulator developed by EO space.

A fiber based pulse amplification system 109 functions to amplify a pulse of the converted intermittent laser beam.

For example, the pulse amplifier 109 may amplify the pulse of the converted intermittent laser beam to be uJ per pulse. Here, the intermittent laser beam identified at point C 140 may be output as shown in C 204 of FIG. 2.

The polarizer 110 functions to polarize the amplified intermittent laser beam.

The polarizer 110 may include a half-wave plate, a first polarizer 1, a Pockels cell, or a second polarizer 2. Here, the polarized intermittent laser beam identified at point D 150 may be output as shown in D 205 of FIG. 2.

In addition, the frequency generator 102 inputs a trigger frequency for synchronization to the arbitrary electric pulse generator 103 and the polarizer 110, thereby inducing them to be synchronized with each other. That is, the frequency generator 102 supplies a frequency (eg, a TTL signal of 10 kHz (f) and 10 Hz (g)) to each of the arbitrary electric pulse generator 103 and the polarizer 110 that polarizes the intermittent laser beam. By generating an electric pulse generator 103 and the polarizer 110.

If the pulse of the intermittent laser beam does not coincide with the preferred pulse within an allowable range, the pulse adjusting unit 108 may include an electro-optic modulator 106 or 107 in the arbitrary laser pulse controller 105. DC Bias is inputted to) to adjust the pulse of the intermittent laser beam.

In this case, when the polarization unit 110 is unable to polarize the intermittent laser beam, the pulse adjusting unit 108 may determine that the pulse of the intermittent laser beam does not coincide with the preferred pulse within an acceptable range. have. In this case, the pulse adjusting unit 108 adjusts the DC bias input to each of the first electric / optical converter 106 and the second electric / optical converter 107, so that the pulse of the intermittent laser beam is allowed with the preferred pulse. Can be adjusted to match within the specified range.

Wherein the DC Bias is an electrical / optical converter (106, 107) that converts a continuous laser beam into an intermittent laser beam associated with a preferred pulse such that an intermittent laser beam is generated that matches the preferred pulse within an acceptable range. , May be an input voltage or current. That is, the pulse adjusting unit 108 may adjust the size of the DC bias so that the pulse of the intermittent laser beam coincides with the preferred pulse within an acceptable range.

A fiber coupled photo diode 111 may visualize the pulse of the amplified intermittent laser beam as shown in C 204 of FIG. 2, and the pulse adjusting unit 108 may be configured to obtain a pulse from the user who responds to the visualized pulse. The size of the DC bias input to the electric / optical converter may be received. The pulse adjusting unit 108 inputs the DC bias of the received magnitude into each of the first electric / optical converter 106 and the second electric / optical converter 107 so that the pulse of the intermittent laser beam is allowed with the preferred pulse. Can be adjusted to match within the specified range.

That is, the pulse adjusting unit 108 may control the photodiode 111 to measure the waveform of an arbitrary laser pulse output from the point C 140 to visualize the measurement result. In addition, as the pulse adjusting unit 108 checks the measurement result, the DC Bias is input through the interface unit 112, and thus the input DC bias is converted into the first electric / optical converter 106 and the second electric / optical light. The pulses of the intermittent laser beam can be adjusted by input to the transducer 107. After the optimization in the manual mode as described above, the measurement result generated in the photodiode 111 is fed back to the pulse adjusting unit 108 to switch to the automatic mode.

Alternatively, the pulse adjusting unit 108 may accumulate the number of times the DC bias is input, and input the DC bias to the electric / optical converters 106 and 107 according to the accumulated number.

2 is a view showing a change in the arbitrary laser pulses for each stage (A, K, B, C, D) in the arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention.

The laser source 104 may generate a continuous laser beam having a center wavelength of 1053 nm through the mounted laser diode as shown in A 201 of FIG. 2.

In addition, the pulse programming unit 101 may program the pulse information regarding the preferred pulse as K 202 of FIG. 2 and transmit the pulse information to the arbitrary electric pulse generator 103.

In addition, the frequency generator 102 may oscillate a frequency of approximately 10 kHz to the arbitrary electric pulse generator 103, the arbitrary electric pulse generator 103 uses the transmitted pulse information, the frequency, The signal may be output as an RF signal associated with the preferred pulse and input to the second electrical / optical converter 107 in the arbitrary laser pulse controller 105.

The arbitrary laser pulse controller 105 may convert the continuous laser beam input from the laser source 104 into an intermittent laser beam based on the RF signal associated with the preferred pulse. At this time, when the arbitrary laser pulse control unit 105 is composed of the first electrical / optical converter 106 and the second electrical / optical converter 107 connected in series, the second electrical / optical converter to which the RF signal is input ( 107, the continuous laser beam may be converted, such as B 203 of FIG. 2, into an intermittent laser beam associated with the preferred pulse.

The pulse amplifier 109 may amplify the pulse of the intermittent laser beam as shown in C 204 of FIG.

The amplified intermittent laser beam includes a polarizer 110 including at least one of a half-wave plate, a first polarizer 1, a Pockels cell, and a second polarizer 2. ) May be polarized as shown in D 205 of FIG. 2.

3 is a view showing the input and output results of the arbitrary laser pulse waveform in the arbitrary pulse optical fiber laser generation system according to an embodiment of the present invention.

The arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention may program pulse information regarding a user's preferred pulse as shown in FIG. 3 (iii), based on an RF signal associated with the programmed pulse information. After converting the continuous laser beam generated from the laser source into an intermittent laser beam, amplifying the energy of the converted intermittent laser beam to be uJ per pulse, and performing polarization as shown in FIG. 3 (ii). Any laser pulse can be generated.

According to the present invention, an RF signal related to a preferred pulse can be input to an electric / optical converter to output a laser having a pulse shape similar to the preferred pulse, and through the feedback, DC Bias having a suitable size can be applied to the electric / optical converter. By inputting, the laser having the desired pulse can be optimally induced.

While specific embodiments of the present invention have been described so far, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims and the claims.

1 is an overall configuration diagram of an arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention.

2 is a view showing a change in the arbitrary laser pulses for each stage in the arbitrary pulsed optical fiber laser generation system according to an embodiment of the present invention.

3 is a view showing the input and output results of the arbitrary laser pulse waveform in the arbitrary pulse optical fiber laser generation system according to an embodiment of the present invention.

 <Explanation of symbols for the main parts of the drawings>

101: pulse programming unit

102: frequency generator

103: Arbitrary Electronic Waveform Generator

104: Continuous wavelength fiber laser source

105: Arbitrary laser pulse controller

106: Electro-optic modulator 1

107: second electro-optic modulator 2

108: pulse adjustment unit

109: Fiber based pulse amplification system

110: polarizer

111: fiber coupled photo diode

112: interface unit

Claims (7)

A pulse programming unit for programming pulse information about a preferred pulse; An arbitrary electronic pulse generator for outputting a frequency generated from the frequency generator by using the programmed pulse information as an RF signal associated with the preferred pulse; An arbitrary laser pulse controller for converting a continuous laser beam input from a continuous wavelength fiber laser source into a discontinuous laser beam based on the RF signal; And If the pulse of the intermittent laser beam does not coincide with the preferred pulse within an allowable range, the DC Bias is input to an electro-optic modulator in the arbitrary laser pulse controller to input a pulse of the intermittent laser beam. Pulse adjusting part to adjust Any pulsed optical fiber laser generation system comprising a. The method of claim 1, The arbitrary laser pulse control unit, And a number of electric / optical converters included in consideration of an extinction ratio for the intermittent laser beam or a degree of adjustment for a pulse of the intermittent laser beam. The method of claim 1, The arbitrary laser pulse control unit, And a plurality of electrical / optical converters, wherein the arbitrary pulsed optical fiber laser generation systems are connected in series. The method of claim 1, A pulse amplifier configured to amplify a pulse of the intermittent laser beam; And Polarizer for polarizing the amplified intermittent laser beam More, The pulse adjusting unit, And the polarization of the intermittent laser beam is impossible in the polarizer, and determines that the pulse of the intermittent laser beam does not coincide with the preferred pulse within an acceptable range. The method of claim 4, wherein The frequency generator, And a trigger frequency is inputted to the arbitrary electric pulse generator and the polarizer to cause the arbitrary electric pulse generator and the polarizer to be synchronized with each other. The method of claim 1, Fiber coupled photo diode to visualize the pulse of the intermittent laser beam More, The pulse adjusting unit, And receiving, from the user in response to the visualized pulse, the magnitude of the DC bias to be input to the electrical / optical converter. The method of claim 1, The pulse adjusting unit, 12. The arbitrary pulsed optical fiber laser generation system according to claim 1, further comprising accumulating the number of inputs of the DC bias, and inputting the DC bias to the electric / optical converter according to the accumulated number.

Images