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KR-102964479-B1 - Interferometric gain laser device

KR102964479B1KR 102964479 B1KR102964479 B1KR 102964479B1KR-102964479-B1

Abstract

A laser device configured to emit coherent optical radiation is described, comprising an optical beam amplifier system (12) comprising a single interferometric optical amplifier array (20), a series of multiple interferometric optical amplifier arrays (20), or multiple interferometric optical amplifier arrays (20), wherein each of the interferometric optical amplifier arrays (20) comprises a Mach-Zehnder type interferometer having an amplification arm (20a) having an active gain region (G) and a passive propagation arm (20b) not having a gain region. The laser device (10) further comprises an optical return path (14) for guiding a beam (B0) coming from the optical beam amplifier system (12) to an input of the optical beam amplifier system to form an optical ring resonance structure, and a radiation output element arranged to extract a portion of the beam coming from the amplifier system and to carry the portion of the extracted beam as output radiation (BL) of the laser device.

Inventors

  • 피치오네, 사라
  • 비아시, 스테파노
  • 파베시, 로렌조
  • 라팔디, 크리스티아노

Assignees

  • 아디제 에스.피.에이.

Dates

Publication Date
20260512
Application Date
20210201
Priority Date
20200131

Claims (12)

  1. A laser device (10) configured to emit coherent optical radiation, wherein the laser device is, - An optical beam amplifier system (12) comprising a single interferometric optical amplification arrangement (20) or a series of multiple interferometric optical amplification arrangements (20, 20', …, 20n) ─ Each interferometric optical amplification arrangement (20) comprises an input beam splitting means (BS) configured to spatially separate an incident optical beam (B i ) into a first beam portion (B1) and a second beam portion (B2), and downstream of the input beam splitting means, an amplification arm (20a) of the first beam portion (B1) comprises an active gain zone (G) capable of emitting photons coherent with the first beam portion, and, meeting at the output of the interferometric optical amplification arrangement (20), an unamplified propagation arm (20b) of the second beam portion (B2) extends ─ ; - A beam combining means (BC) configured to combine the first beam portion (B1), which is different from and amplified by the input beam splitting means (BS), and the second beam portion (B2), which propagates without amplification by the single interferometer optical amplification array (20) or the last interferometer optical amplification array (20'; 20n) among a series of multiple interferometer optical amplification arrays, into the optical beam (B o ) coming from the amplifier system; - A return optical path (14) for a beam (B o ) coming from the amplifier system (12) — the return optical path comprises optical reflector means (M1 to M6) configured to guide the optical beam (B o ) coming from the input section to the amplifier system (12) to form an optical ring resonant structure —; and - Includes a radiation output means (16) arranged to extract a portion of the beam (B o ) coming from the amplifier system (12) and to carry the portion of the beam as radiation (BL) of the laser device (10), And the power of the first beam portion (B1) routed in the amplification arm (20a) is smaller than the power of the second beam portion (B2) routed in the propagation arm (20b) without amplification, A laser device (10) configured to emit coherent optical radiation.
  2. In Article 1, The amplification arm (20a) comprises an active gain region (G) of a semiconductor material capable of emitting coherent photons with the first beam portion (B1) following the achievement of a population inversion condition of charge carriers confined within and a resulting radiative recombination, wherein the active gain region (G) is associated with an electrical excitation system configured to change the thermodynamic equilibrium of populations of charge carriers to determine the inversion condition of the population. A laser device (10) configured to emit coherent optical radiation.
  3. In Article 1 or Article 2, In the above series of interferometric optical amplification arrays (20, 20'; 20, 20', ..., 20 n ), the input beam splitting means (BS i ) is characterized by being configured to spatially separate the interfering first beam portion from the previous interferometric optical amplification array. A laser device (10) configured to emit coherent optical radiation.
  4. In Article 1 or Article 2, In the above series of interferometer optical amplifier arrays (20, 20'; 20, 20', …, 20 n ), each intermediate interferometer optical amplifier array is characterized by having a beam splitter means (BS i ) at its input that is configured to spatially split only the first beam portion of the previous interferometer optical amplifier array and not split the recombined beam of the previous interferometer optical amplifier array. A laser device (10) configured to emit optical radiation.
  5. In Article 1 or Article 2, The portion of the beam (B o ) coming from the amplifier system (12) that is carried as the output radiation (BL) of the laser device (10) is characterized as being a loss beam of the beam combining means (BC) configured to combine the first amplified beam portion (B1) and the second beam portion propagating without amplification (B2) into the optical beam (B o ) coming from the amplifier system (12). A laser device (10) configured to emit coherent optical radiation.
  6. In Article 1, The portion of the beam (B o ) coming from the amplifier system (12) that is carried as the output radiation (B L ) of the laser device (10) is characterized as being a lost beam of one of the optical reflector means (M4) of the return optical path (14). A laser device (10) configured to emit coherent optical radiation.
  7. In Article 1 or Article 2, The amplification arm (20a) comprises optical coupling and collimation means (22, 24) coupled to the active gain zone (G), wherein the optical coupling and collimation means comprise a pair of dioptric systems, each arranged to focus the first beam portion (B1) entering the active gain zone (G) and to collimate the amplified beam portion exiting the active gain zone (G). A laser device (10) configured to emit coherent optical radiation.
  8. In Article 1 or Article 2, The above-mentioned non-amplifying radio wave arm (20b) is characterized by including a reflective system (catopric system) or a refraction system configured to control the addressing or distribution of lateral power of the second beam portion (B2). A laser device (10) configured to emit coherent optical radiation.
  9. In Article 1, The above optical reflector means (M1 to M6) are characterized by comprising a plurality of totally reflective catoptric systems. A laser device (10) configured to emit coherent optical radiation.
  10. In Article 1 or Article 2, The return optical path (14) of the beam (B o ) coming from the amplifier system (12) is characterized by including optical elements configured to shape the distribution of the transverse power of the beam. A laser device (10) configured to emit coherent optical radiation.
  11. In Article 1 or Article 2, The above optical ring resonance structure is characterized by including an optical isolator (26) configured to allow the propagation of a beam in a single predetermined direction. A laser device (10) configured to emit coherent optical radiation.
  12. In Article 1 or Article 2, The optical length of the amplification arm (20a) and the optical length of the radio wave arm (20b) without amplification of each interferometer optical amplification array (20) are the same, characterized by. A laser device (10) configured to emit coherent optical radiation.

Description

Interferometric gain laser device The present invention relates to laser devices, particularly, but not exclusively, semiconductor laser devices. One of the main limitations of this particular class of lasers is the impossibility of achieving high optical power higher than tens of watts, for example, approximately kilowatts or more, from a single laser diode. Such power is essential in specific industrial processes, for example, in the industrial processing of materials, metal plates, and profiles, where lasers are used as thermal tools for a wide variety of applications that depend on the interaction parameters between the material being processed and the laser beam, specifically the energy density per unit volume of the incident laser beam on the material and the interaction time interval. For example, a hardening process is executed by directing a low energy density (approximately tens of W per mm² of surface) onto a metallic material for an extended period (approximately a few seconds), whereas a photo-ablation process is executed by directing a high energy density (approximately tens of MW per mm² of surface) onto the same metallic material for a period of approximately femtoseconds or picoseconds. Control of these parameters in the intermediate range of increasing energy density and decreasing processing time allows welding, cutting, drilling, engraving, and marking processes to be executed. A laser device is also used in additive processes where the material is supplied, for example, in the form of a filament or in the form of a powder emitted by a nozzle, or alternatively, the material may exist in the form of a powder bed and thus, melted by laser radiation, followed by the re-solidification of the material to obtain a three-dimensional print. In conventional technology, a combination of different laser beams is used to obtain optical power tens of times higher than the above-mentioned levels. Different laser beams can be combined through different techniques based on the individual associations of laser emitting devices, such as combining beams that are incoherent to each other (incoherent combination), combining beams at different wavelengths, and combining beams that are coherent to each other (coherent combination). Disadvantageously, through a non-coherent beam combination, a total beam is acquired, and the radiance of this total beam (the extent of which considers both total optical power and resulting beam quality) does not exceed the radiance of a single laser. Furthermore, in non-coherent combination techniques, there is no relationship between the accompanying beams (no phase or spectrum), and thus, optical power increases with increasing number of accompanying laser-emitting devices at the expense of the quality of the total beam acquired. Through wavelength beam combination or coherent beam combination, it is possible to increase the emitted optical power while maintaining the quality of the resulting beam without alteration, and the radiant brightness increases linearly with the number of combined laser-emitting devices. In particular, in wavelength beam combination technology, each laser-emitting device operates at a different wavelength, and the use of dispersive optical elements allows for the overlap of the beams to be combined. Consequently, an increase in power is achieved at the expense of the beam's spectral quality. On the other hand, in an architecture for coherent beam combinations, all laser-emitting devices operate at the same wavelength, and since a specific phase relationship exists, constructive interference can occur between individual beams. The use of one of the mentioned technologies depends on applications requiring high optical power. For example, to generate high-intensity sources of the type used for laser processing of materials, it is necessary to adopt architectures for wavelength or coherent beam combinations. Among these, the former is currently the most frequent solution, and the main reason can be attributed to its greater ease of implementation. In fact, since these are techniques for combining different laser beams—that is, beams carried by different laser-emitting devices—the main difficulty in generating architectures for coherent beam combinations lies in the active control of the phase relationships essential to obtain constructive interference between the various accompanying beams. These difficulties become even greater for semiconductor laser devices, where thermal instabilities and nonlinear phenomena can significantly alter the phase of the beam. Further features and advantages of the present invention will be presented in more detail in the following detailed description of embodiments given as non-limiting examples with reference to the accompanying drawings. Figure 1 is a general diagram of a laser device according to the present invention. FIG. 2 is a first schematic embodiment of a laser device according to the present invention having a s