KR101016176B1 - Apparatus for generating multiband mid-infrared laser - Google Patents

Abstract

PURPOSE: An apparatus for generating multi-band mid-infrared laser is provided to countermeasure various kinds of infrared guided missile by simultaneously oscillating multi-band mid-wavelength lasers. CONSTITUTION: A mid-wavelength laser generating apparatus(200) includes a laser oscillating part(210), a wavelength converting part(220), and an optical coupler(230). The laser oscillating part includes a master-oscillator-power-amplifier structure which amplifies seed beam in a multi-stage amplifier. The laser oscillating part uses an entire-optical fiber based structure. Pump laser outputted from the laser oscillating part is inputted into the wavelength converting part. The wavelength converting part oscillates multi-band mid-wavelength infrared laser. The optical coupler matches the radiation directions of a plurality of mid-wavelength infrared lasers.

Description

Multi-band mid-infrared laser generator {APPARATUS FOR GENERATING MULTIBAND MID-INFRARED LASER}

The present invention relates to a mid-infrared laser generating apparatus, and more particularly to a multi-band mid-infrared laser generating apparatus for generating a mid-infrared laser used in directional infrared interference equipment.

Advances in guided missile performance pose a major threat to military equipment such as tanks, transport aircraft, helicopters and warships. The most commonly used guided missile is an infrared guided missile that uses the thermal energy generated by an attack target. Currently, infrared-guided missiles that use a single-pixel infrared detector to track the thermal energy generated by a target are most widely used.

Meanwhile, an infrared countermeasure (IRCM) has been actively developed to protect the military equipment and people of their home against such infrared-guided missile attacks. The IRCM method can be roughly divided into a flare method and a jammer method, and the jammer method can be further divided into an onmi-directional jammer method and a directed jammer method.

The omni-directional jammer method is a method in which a jamming source is fired in an omni-directional direction in preparation for an infrared-guided missile attack, and the directional jammer method is a method in which a jamming source is fired toward an attacking infrared-guided missile. The launched jamming source prevents the infrared detector mounted on the infrared guided missile from detecting the position of the target.

The use of the directional jammer method among the above methods is referred to as a directional infrared countermeasure (Directed IRCM; DIRCM), which has an advantage of higher jamming efficiency than the existing flare method or omnidirectional jammer method.

Meanwhile, a mid-infrared region (2-5 μm) corresponding to a wavelength band used by the detector of the missile is generally used as a jamming source for interfering with the guidance and tracking of the infrared guided missile. Hereinafter, a conventional mid-infrared laser generator for generating such jamming sources will be described with reference to FIG. 1.

1 is a view schematically showing a conventional mid-infrared laser generator. Referring to FIG. 1, the conventional mid-infrared laser generator 100 includes a laser oscillation unit 110 and a wavelength conversion unit 120.

The laser oscillation unit 110 uses a pumping light source to oscillate the laser, and in the method of oscillating the laser, ⅰ) the pumping light source is an Endyag-Nd:YAG (Neodymium-doped yttrium aluminum gamet (Nd:Y ₃ AL) Method of oscillating a diode-pumped solid-state laser (DPSS laser) in a cavity after focusing on a laser crystal (or gain medium) such as ₅ O ₁₂ ))) and ii ) A method of oscillating a bulk-type optical fiber laser in a resonator by inputting a pumping light source to an active optical fiber doped with ytterbium (Yb).

The wavelength converter 120 converts the laser input from the laser oscillation unit 110 to a desired wavelength and outputs it 130. In general, an optical parametric oscillator (OPO) using a nonlinear crystal is mainly used for wavelength conversion because of its high wavelength conversion efficiency to the mid-infrared region and easy wavelength variation.

In order for the mid-infrared laser emitted from the mid-infrared laser generator as described with reference to FIG. 1 to be used as a jamming source for directional interference equipment, the mid-infrared laser generator is ⅰ) the wavelength band of the detector used by the infrared-guided missile. Corresponding to the mid-infrared band corresponding to (2~5μm), i.e., the wavelengths of multiple bands corresponding to Band I, II and IV should be able to oscillate at the same time, and ii) The output of the laser should be stable during the operation of directional infrared interference equipment. .

However, the conventional mid-infrared laser generating apparatus oscillates a single wavelength laser by selectively passing only a specific wavelength using one light-mediated oscillator. Therefore, this conventional method does not satisfy the requirements for simultaneous oscillation of multi-band wavelengths required for directional infrared interference equipment, that is, multi-band wavelengths corresponding to Bands I, II, and IV.

In addition, as described above, the DPSS laser generator and the optical fiber laser generator use many optical components for optical path setting, and thus, when external vibration and shock are transmitted to the laser oscillation unit 110, optical axis alignment is affected. And the instability of the laser output.

Accordingly, the present invention provides a method of improving the stability of the laser output by securing structural stability against external impact.

In addition, the present invention provides a method of simultaneously oscillating a multi-band laser.

In addition, the present invention provides a method to precisely match the laser radiation direction by effectively combining the oscillated multi-band laser.

Other objects to be provided in the present invention can be inferred from the following examples and detailed description.

The multi-band mid-infrared laser generating apparatus according to an embodiment of the present invention for achieving the above-described, the optical distributor for distributing the input pump laser into three paths and the distributed pump laser, respectively, of a set wavelength band A wavelength converter having three light-mediated oscillators that converts and outputs to a mid-infrared laser, and reflects lasers corresponding to different specific bands among the mid-infrared lasers output from the wavelength converter, and corresponds to the remaining bands. The laser includes an optical coupling unit having a multi-band optical collimator that outputs to have a set divergence angle by combining three reflecting means for transmitting and lasers output from the three reflecting means, wherein the three light-mediated oscillators include: Periodically polarized inverted lithium niobate (Periodically Poled Lithium Niobate, PPLN), Periodically polarized inverted magnesium added lithium-niobate (Periodically Poled MgO-doped Lithium Niobate, PPMgOLN), Periodically polarized inverted stoichiometric lithium- Periodically Poled Stoichiometric Lithium Niobate (PPsLN), Periodically Polarized Lithium Tantalate (PPLT), Periodically Polarized Inverted Magnesium-Added Lithium Tantalate (Periodically Poled MgO-doped Lithium Tantalate) , PPMgOLT), pseudo of either periodically polarized inverted stoichiometric Lithium Tantalate (PPsLT) and periodically polarized inverted Potassium-Titanyl-Phosphate (Periodically Poled Potassium Titanyl Phosphate, PPKTP) Ferroelectric wave with Qasi-Phase Matching (QPM) structure Use intestinal conversion materials.

The multi-band mid-infrared laser generating apparatus for generating a mid-infrared laser used in a directional infrared interference device according to the present invention has the advantage of being stable to external shock and capable of simultaneously oscillating a multi-band mid-infrared laser. For this reason, there is an advantage of being able to cope with various types of infrared guided missiles using laser detectors in bands I, II and IV.

1 is a view schematically showing a conventional mid-infrared laser generator.
2 is a view schematically showing a mid-infrared laser generating device according to an embodiment of the present invention.
3 is a view showing in more detail the laser oscillation unit according to an embodiment of the present invention.
4 is a diagram showing in more detail a preamplifier according to an embodiment of the present invention.
5 is a view showing in more detail the main amplifier according to an embodiment of the present invention.
6 is a view showing a wavelength converter in more detail according to an embodiment of the present invention.
7 is a view showing a wavelength converter in more detail according to another embodiment of the present invention.
8 is a view showing an optical coupler using a reflector according to an embodiment of the present invention.
9 is a view showing an optical coupler using a medium-infrared optical fiber according to an embodiment of the present invention.
10 is a view showing an optical coupler using a medium-infrared optical fiber according to another embodiment of the present invention.
11 is a conceptual diagram for explaining the effect of the mid-infrared laser generating device according to embodiments of the present invention.

In the following description of the present invention, when it is determined that detailed descriptions of related well-known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view schematically showing a mid-infrared laser generating device according to an embodiment of the present invention.

2, the mid-infrared laser generating apparatus according to an embodiment of the present invention includes a 200, a laser oscillation unit 210, a wavelength converter 220 and an optical coupler 230.

The laser oscillator 210 has a master oscillator power amplifier (MOPA) structure that amplifies the seed beam in a multi-stage amplifier. In addition, the laser oscillation unit 210 adopts an all-fiber type structure in which all optical amplification processes are performed in the optical fiber, and Yb doped optical fiber is used as the optical fiber. do.

When the laser oscillation unit 210 adopts an all-optical fiber-based structure, since the process of absorbing the pump light and emitting the laser is performed inside the optical fiber, it is resistant to external shock, does not require alignment of the optical system, and is not affected by dust, etc. There are advantages. The pump laser output from the laser oscillation unit 210 is input to the wavelength conversion unit 220.

The wavelength converter 220 oscillates a multi-band mid-infrared laser. To this end, the wavelength converter 220 includes three light-mediated oscillators using a ferroelectric wavelength conversion material having a quasi-phase matching (hereinafter referred to as QPM) structure. The pump laser inputted from the laser oscillation unit 210 is distributedly input to three light-mediated oscillators to simultaneously oscillate the mid-infrared lasers in the band I, II, and IV bands.

The QPM structure of the ferroelectric wavelength converting material is periodically polarized inverted lithium niobate (Periodically Poled Lithium Niobate, PPLN), periodically polarized inverted magnesium-added lithium-niobate (Periodically Poled MgO-doped Lithium Niobate, PPMgOLN) , Periodically polarized reversed stoichiometric Lithium-Niobate (PPsLN), Periodically polarized reversed Lithium Tantalate (PPLT), Periodically polarized reversed magnesium-added lithium- Periodically Poled MgO-doped Lithium Tantalate (PPMgOLT), Periodically Polarized Inverted Stoichiometric Lithium Tantalate (PPsLT) and Periodically Polarized Inverted Potassium-Titanyl-Phosphate (Periodically Poled Potassium) Titanyl Phosphate (PPKTP) can be used.

The optical coupler 230 corresponds to any one of the bands of the band I, II, and IV bands by matching the radiation directions of the plurality of mid-infrared lasers output from the wavelength converter 220 and outputting the 240 It delivers the deception effect of directional infrared interference equipment, regardless of the type of infrared-guided missile that uses the mid-infrared detector.

In the above, the concept of the mid-infrared laser generating device according to an embodiment of the present invention was briefly described.

Hereinafter, each component of the mid-infrared laser generating apparatus according to an embodiment of the present invention and the function of each component will be described in more detail with reference to the related drawings.

3 is a view showing in more detail the laser oscillation unit according to an embodiment of the present invention.

Referring to FIG. 3, the laser oscillation unit 210 according to an embodiment of the present invention includes a seed laser diode 211, a preamplifier 212, and a main amplifier 213.

As the seed laser diode 211, a laser diode oscillating a 1064 nm wavelength band is used. The seed laser diode 211 is driven by a direct modulation method by a differential switching method of current, and uses a pulse width control of several tens of nanoseconds. As the seed laser diode 211, any one of a DFB (Distributed FeedBack) laser diode, a DBR (Distributed Bragg Reflector) laser diode, and a FP (Fabry-Perot) laser diode may be used. The seed beam output from the seed laser diode 211 is input to the preamplifier 212.

The preamplifier 212 is composed of a single mode optical fiber amplifier and a single mode double clad optical fiber amplifier, and amplifies the low output optical pulse input from the seed laser diode 211 with high power.

The main amplifier 213 amplifies the primary amplified optical pulse input from the preamplifier 212 with a high output and outputs it 214.

Hereinafter, the structures of the preamplifier and the main amplifier will be described in more detail with reference to the related drawings.

4 is a diagram showing in more detail a preamplifier according to an embodiment of the present invention.

4, the preamplifier 212 according to an embodiment of the present invention, an optical isolator (2121a), a wavelength filter (band pass filter) (2123a), a pump laser diode (2125a), wavelength A single mode optical fiber amplifier composed of a Wavelength Division Multiplexing (WDM) group 2126a and an optical fiber 2128a, an optical isolator 2121b, a wavelength filter 2123b, a pump laser diode 2125b, and a com It includes a single mode double clad optical fiber amplifier composed of a combiner 2126b and an optical fiber 2128b.

The optical isolators 2121a and 2121b block the amplified spontaneous emission (ASE) and reflected light in the reverse direction.

The wavelength filters 2123a and 2123b perform wavelength filtering based on the central wavelength to remove parasitic wavelengths caused by nonlinear phenomena such as the Raman effect.

Pump laser diodes 2125a and 2125b provide a pumping light source. Pump laser diodes 2125a and 2125b use those having an output wavelength of 915 nm or 975 nm. The light output from the pump laser diodes 2125a and 2125b is absorbed by the ytterbium (Yb)-added optical fiber, and the preamplifier 212 emits a pump laser having wavelength variability of several tens of nm or more in the 1 to 1.1 μm band.

The wavelength division multiplexer 2126a and the combiner 2126b combine pumping light and a seed beam.

The optical fibers 2128a, 2128b provide a path of light.

The average power of the seed beam input from the seed laser diode 211 is less than 1 mW, and the primary amplification is performed through a preamplifier composed of two stages of a single mode optical fiber amplifier and a single mode double clad optical fiber amplifier. . At this time, the output of the primary amplified seed beam is 800 mW or more.

The seed beam amplified in the preamplifier is input to the main amplifier to generate a high-power pump laser. The main amplifier will be described below with reference to FIG. 5.

5 is a view showing in more detail the main amplifier according to an embodiment of the present invention.

5, the main amplifier 213 according to an embodiment of the present invention, an optical isolator 2131, a wavelength filter 2132, a pump streamer 2133, an optical fiber 2134, a combiner (2135), a number of pump laser diodes 2136 and a silica end cap (silica end cap) (2137).

The optical isolator 2131 blocks the amplified spontaneous emission (ASE) and reflected light in the reverse direction.

The wavelength filter 2132 removes parasitic wavelengths caused by nonlinear phenomena such as Raman by performing wavelength filtering around the central wavelength.

The pump streamer 2133 prevents unnecessary wavelengths from being excessively pumped.

The optical fiber 2134 provides a path of light.

The combiner 2135 combines the pumped light and the primary amplified seed beam.

The pump laser diode 2136 provides a pumping light source. In one embodiment, six pump laser diodes 2136 are used.

The silica end cap 2137 has a structure in which the output surface is oblique to prevent equipment damage due to high peak output and back reflection of the output. The laser output 214 through the silica end cap 2137 is output through a collimator (not shown).

The main amplifier 213 having the above-described configuration secondarily amplifies the seed beam primarily amplified in the preamplifier 212 to have a high output power of 30 W or more.

The optical fibers used in each of the amplifiers described above with reference to FIGS. 4 and 5 may have different core sizes. Since the loss and reflection of light may occur at the bonding surface when the optical fibers having different core sizes are combined, it is possible to reduce light loss and reflection due to dissimilar optical fiber bonding through appropriate mode matching technology between the heterogeneous optical fibers. .

In addition, in order to increase conversion efficiency in the wavelength converter 220, all components constitute a polarization-maintaining optical fiber amplifier connected with polarization-maintaining optical fibers to maintain the linear polarization characteristics of the seed laser diode 211.

In the above, the structure and function of the laser oscillation unit 210 have been described. Hereinafter, the wavelength converter 220 that receives the light output from the laser oscillator 210 and converts it into a desired wavelength band will be described with reference to the related drawings.

In an embodiment of the present invention, the wavelength converter 220 includes three light-mediated oscillators using a QPM structured ferroelectric wavelength-converting material to oscillate a multi-band mid-infrared laser, and pump light is transmitted to each light-mediated oscillator. The input is distributed to oscillate the mid-infrared laser wavelengths of Band I, II and IV.

At this time, in the configuration of the three optically mediated oscillators, iii) a method of configuring all three optically mediated oscillators in parallel, and ii) two optically mediated oscillators are configured in parallel. A method of configuring the output laser to be input to another light-mediated oscillator can be used.

This is illustrated in FIGS. 6 and 7. Hereinafter, each method will be described with reference to the associated drawings.

6 is a view showing a wavelength converter in more detail according to an embodiment of the present invention.

Referring to FIG. 6, the wavelength converter 220 according to an embodiment of the present invention includes an optical splitter 221 and an optical-mediated oscillator 222, 223, 224.

The optical splitter 221 optically distributes the secondary amplified seed beam (hereinafter, referred to as a pump laser) 214 input from the laser oscillation unit 210 and outputs the light to each light-mediated oscillator 222, 223, 224. .

Each of the light-mediated oscillators 222, 223, and 224 are connected in parallel to each other to receive a pump laser from the light distributor 221.

The light-mediated oscillator 222 wavelength-converts the pump laser input from the light splitter 221 and outputs the laser corresponding to the wavelength band of Band I (225).

The light-mediated oscillator 223 wavelength-converts the pump laser input from the light splitter 221 and outputs the laser corresponding to the wavelength band of Band IV (226).

The light-mediated oscillator 224 wavelength-converts the pump laser input from the light splitter 221 and outputs a laser corresponding to the wavelength band of Band II (227).

On the other hand, as described above, instead of connecting all three optically mediated oscillators in parallel, only two optically mediated oscillators are connected in parallel, and a laser output from any one optically mediated oscillator is input to another optically mediated oscillator. It can be configured, which will be described with reference to FIG. 7.

7 is a view showing a wavelength converter in more detail according to another embodiment of the present invention.

Referring to FIG. 7, the wavelength converter 220 according to another exemplary embodiment of the present invention includes an optical splitter 221 and optical intermediate oscillators 222, 223, and 224.

The optical splitter 221 optically distributes the pump laser 214 input from the laser oscillation unit 210 and outputs it to the respective light-mediated oscillators 222 and 223.

The light-mediated oscillator 222 and the light-mag oscillator 223 are connected in parallel to each other to receive a pump laser from the light distributor 221.

The light-mediated oscillator 222 wavelength-converts the input pump laser to generate a laser corresponding to the wavelength band of Band IV. An optical splitter 228 is further installed at the output terminal of the light-mediated oscillator 222, and is distributed to two paths of the laser output from the light-mediated oscillator 222.

One path is a path in which the laser corresponding to the wavelength band of Band IV is output 226 as a first path, and the other path is a path in which the laser is input to the light-mediated oscillator 224.

The optical-mediated oscillator 224 wavelength-converts the laser output from the optical-mediated oscillator 222 and input through the optical splitter 228 to output 224 the laser corresponding to the wavelength band of Band II.

Meanwhile, the light-mediated oscillator 223 wavelength-converts the input pump laser and outputs the laser corresponding to the wavelength band of Band I (225).

In the above, the wavelength converter 220 has been described in detail. Hereinafter, the optical coupler 230 will be described in more detail.

 The optical coupler 230 serves to match the laser emission directions of Bands I, II, and IV output from the wavelength converter 220. In an embodiment of the present invention, the optical coupler 230 uses iii) a structure using a reflector of a mid-infrared region coated with a dielectric material, or ii) a structure in which optical fibers for mid-infrared rays are heterogeneously bonded.

Hereinafter, each embodiment of the optical coupler 230 will be described with reference to the associated drawings.

8 is a view showing an optical coupler using a reflector according to an embodiment of the present invention.

8, the optical coupler 230 according to an embodiment of the present invention includes a plurality of reflecting means (231, 232, 233) and a multi-band optical collimator (234).

The reflecting means 231 includes a reflector reflecting the mid-infrared laser 225 of Band I output from the wavelength converter 220 and a fine adjustment device adjusting the angle of the reflector so that the radiation direction of the output laser coincides. At this time, the reflector provided by the reflecting means 231 is coated to reflect the laser 225 belonging to the medium-infrared band of Band I, and to transmit the lasers 226, 227 belonging to the medium-infrared band of Band II and IV. do.

The reflecting means 232 includes a reflector reflecting the medium-infrared laser 226 of Band IV output from the wavelength converter 220 and a fine adjustment device for adjusting the angle of the reflector so that the radiation direction of the output laser coincides. At this time, the reflector provided by the reflecting means 232 is coated to reflect the laser 226 belonging to the medium-infrared band of Band IV, and to transmit the laser 227 belonging to the medium-infrared band of Band II.

The reflecting means 233 includes a reflector for reflecting the band Ⅱ mid-infrared laser 227 output from the wavelength converter 220 and a fine adjustment device for adjusting the angle of the reflector so that the radiation direction of the output laser coincides. At this time, the reflector included in the reflecting means 233 is coated to reflect the laser 227 belonging to the band Ⅱ mid-infrared band.

On the other hand, as described above, instead of using a reflector, the optical coupler 230 may be configured using optical fibers for mid-infrared rays. This is illustrated in FIGS. 9 and 10.

9 is a view showing an optical coupler using a medium-infrared optical fiber according to an embodiment of the present invention.

Referring to Figure 9, the optical coupler 230 using an optical fiber according to an embodiment of the present invention, the optical focus collimator 235, the optical fiber for transmission 236, the optical coupling optical fiber 237 and multi-band And an optical collimator 234.

The optical focus collimator 235 focuses the mid-infrared lasers of Band I, II, and IV bands output from the wavelength converter 220 to the optical fiber 236 for transmission.

The optical fiber 236 for transmission is fused to one strand of optically coupled optical fibers 237 by heterojunction technology of the optical fibers.

In the optically coupled optical fiber 237, the mid-infrared lasers of Band I, II, and IV bands input from the optical fiber 236 for transmission are transmitted. The optically coupled optical fiber 237 is set to have a predetermined length or more so that the radiation directions of the multi-band mid-infrared laser coincide.

The multi-band light collimator 234 allows the combined lasers of the three wavelengths to be radiated with a specific divergence angle required by directional infrared interference equipment.

In FIG. 9, a structure in which three optical fibers having the same diameter are fused to one optical fiber having a larger diameter than the three optical fibers is illustrated and described.

Alternatively, a structure in which three strands of the same diameter of the infrared rays are stretched to make the diameter of one end smaller and one end of the reduced diameter optical fibers are fused to another optical fiber having the same diameter can be used. There is shown in Figure 10. Each component illustrated in FIG. 10 has the same function as that of each component illustrated in FIG. 9, which has the same reference numerals, and a detailed description thereof will be omitted.

According to the embodiments of the present invention as described above, irrespective of the type of infrared guided missile using the laser detectors of Band I, II and IV bands, the deception effect of the directional infrared interference device can be transmitted. This effect will be described with reference to FIG. 11.

11(a) shows a case where the laser emission ranges of the respective wavelength bands do not match. In (a) of FIG. 11, it is assumed that the region 300 is the laser emission range of Band I, the region 301 is the laser emission range of Band II, and the region 302 is the laser emission range of Band IV. The guided missile 330 is only transmitting the laser of Band II, and if the detector of the guided missile 330 is using the Band IV region, the deception effect on the guided missile 330 cannot be expected.

On the other hand, Figure 11 (b) is a case where the radiation direction of the multi-band laser coincides (303), in this case, regardless of the type of detector used by the guided missile 330, the deception effect on the guided missile 330 I can expect.

According to embodiments of the present invention, as shown in (b) of FIG. 11, it is possible to improve the performance of the directional infrared interference device by matching the emission region of the multi-band laser.

Meanwhile, in the above, preferred embodiments of the present invention have been illustrated and described, but the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. In addition, various modifications can be carried out by a person having ordinary knowledge in the course, and these modifications should not be individually understood from the technical idea or prospect of the present invention.

Claims (7)

In the multi-band mid-infrared laser generating device,
A wavelength converting unit including an optical splitter that distributes the input pump laser into three paths, and three optically mediated oscillators that receive each of the distributed pump lasers and convert and output them to mid-infrared lasers in a set wavelength band,
Of the mid-infrared lasers output from the wavelength converter, the lasers corresponding to different specific bands are respectively reflected, and the lasers corresponding to the other bands are transmitted by combining three reflection means and lasers output from the three reflection means. Including a light coupling unit having a multi-band optical collimator outputting to have a set divergence angle,
The three light-mediated oscillators, Periodically Polarized Lithium Niobate (PPLN), Periodically Polarized Inverted Magnesium Lithium Niobate (Periodically Poled MgO-doped Lithium Niobate, PPMgOLN), Periodic Periodically Poled Stoichiometric Lithium Niobate (PPsLN), Periodically Polarized Lithium Tantalate (PPLT), Periodically Polarized Inverted Magnesium Added Lithium-Tantalate (Periodically Poled MgO-doped Lithium Tantalate, PPMgOLT), Periodically Polarized Stoichiometric Lithium Tantalate (PPsLT) and Periodically Polarized Inverted Potassium-Titanyl-Phosphate (Periodically Poled Potassium Titanyl Phosphate) , PPKTP), a multi-band mid-infrared laser generator using a ferroelectric wavelength converting material of any one of quasi-phase matching (QPM) structures. delete delete delete delete delete delete

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