Tunable UV laser

Abstract

A method, device or system including a UV laser having a first contributing laser part generating a first laser light, a second contributing laser part generating a second laser light and a combined cavity sharing disposed therein at least a portion of shared operable elements of the first and second contributing laser parts, the combined cavity providing for combining the first laser light and the second laser light to generate a third laser light.

Description

Tunable UV Laser BACKGROUND

[0001] The present developments relate to an apparatus and / or method to tunably generate ultra violet (UV) light or laser beams.

[0002] The apparatuses and / or methods that will provide for tunable UV light may be used in a variety of applications including but not limited to scanning, spectroscopy / spectrometry, telecommunication applications, and / or medical applications. UV lasers may be well suited for applications on a micro scale that require high quality results. Moreover, UV lasers may be utilized in a variety of commercial and industrial applications, including, but not limited to: machining on a micro-scale, engraving of precision tools for stamping or micro-spark erosion, marking of glass and synthetics whereby the surface is not changed in structure or chemical composition, drilling of small holes in a variety of materials for example diesel injectors, and precision cleaning of surfaces, such as with artwork. These examples and applications of UV lasers are non-limiting examples, as there are myriad applications and uses of UV lasers.

[0003] Many conventional ultraviolet (UV) continuous wave (CW) lasers are built based on intra-cavity second harmonic generation (SHG) of diode pumped solid state (DPSS) technologies having a range of discrete visible (VIS) wavelengths to choose from. The laser crystals and NLCs (i.e., non-linear crystals) herefor are generally commercially available, however, these types of lasers can typically have what is known as a “green noise” problem (a phenomenon that causes fluctuations in the output of some solid-state lasers caused by competition between modes in the laser's resonant cavity leading to high frequency jitter in the output power; this noise potentially affecting the beam's power and making them less useful). In contrast, an optically pumped semiconductor (OPS) laser has no “green noise” problem. However, only the near infra-red (NIR) region OPS lasers are currently stable for commercial usage. And, conventional UV lasers based on OPS technologies are made of at least two NLCs; which, unfortunately, make them inefficient in UV generation. SUMMARY

[0004] The currently-described developments combine a solid state laser with an semiconductor laser to make a tunable UV laser; typically, combining a DPSS with an OPS, more commonly, a visible light DPSS (VIS DPSS) and a near-infrared OPS (NIR OPS). This may in someimplementations be or involve a DPSS in or as a first part and a MECSEL or VECSEL (MECSEL / VECSEL) in or as a second part to create a hybrid tunable UV laser. MECSEL is an acronym for Membrane External Cavity Surface Emitting Laser(s) (MECSELs) and VECSEL an acronym for Vertical External Cavity Surface Emitting Laser(s) (VECSELs).

[0005] A tunable UV laser formed by combining two laser cavities with either part or all of their cavities shared as a combined cavity. One first cavity is made of or includes a solid state laser crystal which preferably provides photons at a fixed wavelength. The other or second cavity is made of or includes a semiconductor gain media which produces a tunable wavelength. By combining a photon from each of these laser parts inside a nonlinear crystal (NLC) in the shared cavity (shared portion or shared entirety), one higher energy photon is produced in ultraviolet UV wavelengths. The semiconductor gain media provides a range of continuously selectable wavelengths and hence the UV wavelength is tunable. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] For a detailed description of exemplary implementations of the developments, reference will now be made to the accompanying drawings in which:

[0007] Fig.1 provides a schematic view of a laser device, here, a diode pumped solid state (DPSS) laser.

[0008] Fig.2 is a schematic view of a discrete laser device, here, an optically pumped semiconductor (OPS) laser.

[0009] Fig.3 is a schematic view of a two-part laser device having two contributing laser beam-generating parts, inter alia.

[0010] Fig.4 provides a schematic view of an alternative two-part laser device containing two contributing parts and a prism, inter alia.

[0011] Fig.5 is a schematic view of a further alternative two-part laser device.

[0012] Fig.6 is a schematic view of a still further alternative two-part laser device.

[0013] Fig.7 is a schematic view of a yet still further alternative two-part laser device. DESCRIPTION

[0014] The following discussion is directed to various implementations of the developments hereof. Although one or more of these implementations may be preferred, theimplementations disclosed should not be interpreted, or otherwise used, as or for limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad applications, and the discussion of any implementation is meant only to exemplary of that implementation and is not intended to intimate that the scope of the disclosure, including the claims, is limited to that exemplary implementation.

[0015] A tunable UV laser shown and described herein as formed by combining two laser cavities with either part or all of their cavities shared. Herein, a combined cavity refers to any and either of a single cavity as an entirety shared by two or more lasers, and / or a shared portion of two (or more) otherwise discrete cavities, discrete to the two (or more) contributing lasers hereof. When a combined cavity is an entirety of its own, though shared, it may be either a combined cavity that includes disposed therewithin all of the elements of the two (or more) contributing lasers or contributing parts; or the combined cavity as an entirety may be disposed to contain only the shared elements, here described generally including a mirror and an NLC, as further described below. A first contributing laser or part hereof is made of or includes a solid state laser crystal, frequently a DPSS. The second laser or second part hereof is made of or includes a semiconductor gain media frequently in or as part of an OPS. The first laser or part typically provides photons at a fixed wavelength, in many examples a wavelength shorter than 721nm, and the second part typically produces a tunable wavelength. By combining a photon from each laser or part hereof inside a shared nonlinear crystal (NLC) in the shared cavity (shared portion or shared entirety), one higher energy photon is produced and the wavelength here generated is shorter than 400nm, i.e. ultraviolet UV wavelengths. In the chosen examples here, the semiconductor gain media provides a range of continuously selectable wavelengths and hence the UV wavelength is tunable. This type of combined two-part laser is capable of operating in continuous wave (CW), mode-locking, and Q-switch mode as described further below. In many implementations, these may particularly include and / or be directed to methods, systems and / or devices which may use a MECSEL or a VECSEL having no “green noise” and using only one NLC downstream of the MECSEL or VECSEL.

[0016] Various example implementations are directed to UV lasers, and more particularly to UV lasers that may provide for the efficient and tunable generation of UV light by using a combined laser cavity, or at least two cavities that include a shared or combined cavity portionfor combining light of discrete wavelengths to generate UV light. The specification first turns to a high-level overview of two lasers used in example systems (see e.g., Figs.1 and 2).

[0017] Fig.1 shows a diode pumped solid state laser (DPSS) 100. This laser 100 is shown including or within a DPSS cavity 101 containing two cavity mirrors 102, 103 and a crystal 104 also known as an NLC (or non linear crystal) 104. The crystal 104 can establish a laser beam 105 between cavity mirrors 102 and 103 with a wavelength λ1of light 105; typically, as with a DPSS example as here, resulting in visible (VIS) light 105. A pump source 106 which may be a laser diode 106 can be used to provide excitation to the laser crystal 104. The crystal 104 may in some implementations be praseodymium doped yttrium lithium fluoride (Pr:YLF), inter alia, and the pump source 106 may be such as a 444nm laser diode 106. Here also shown, a lens 107 may be used to shape / reshape the diode laser light into an appropriate operable size inside the laser crystal 104. A further mirror 108 is also shown, which may be used as shown to direct the light 105 and / or as further described below.

[0018] Fig.2 shows a second or alternative laser device 200, here an optically pumped semiconductor (OPS) laser 200. Device 200 has or is disposed within or as part of a cavity 201 containing a MECSEL or VECSEL 202 as the gain media with a cavity mirror (not separately shown) being part of / within the MECSEL / VECSEL 202 and another mirror 203 spaced apart therefrom (in some understood conventionally operable but non-limiting implementations / dimensions, frequently about or at least about a few centimeters away). Between mirror elements 202 and 203, a laser beam 205 is established. The MECSEL / VECSEL 202 may frequently be selected as having a central emission wavelength at around or about infra-red or near infra-red 1060nm by design. In some examples, a laser diode 206, such as an 808nm laser diode 206, in an example, may be used as an excitation source. An optional lens 207 can be used to shape / reshape the diode laser beam into an appropriate operable mode size on / in one or both elements 202 and / or 204. A wavelength selecting element 204 is here shown also located inside the cavity 201 to set the wavelength, λ2. A further mirror 208 is also shown, which may be used as shown to direct the laser beam 205 and / or as described further below.

[0019] Fig.3 shows a laser device 300 having two contributing laser beam-generating parts 100a and 200a, parts 100a and 200a being not unlike respective lasers 100 and 200 of corresponding Figs.1 and 2. I.e., first and second lasers 100 and 200 of Figs.1 and 2 may beeffectively considered as two first and second parts combined into and making the combined two-part device 300. In the shown example, the sole difference is in the shared or combined cavity 301, as described herein. Fig.3 shows that two first and second cavities 101, 201 are combined to be the combined cavity 301 noting this may be a single cavity 301 or a shared portion 301 (same element reference numeral for sufficiently similar structure or sub-part structure) of the otherwise discrete but at least partially combined cavities 101, 201. In some implementations, all of the elements shown in Fig.3 might be disposed in the combined cavity or shared portion 301; or only limited parts, as for example maybe at least only mirror 303 and NLC 304, described below, may be the elements disposed in the shared / combined cavity. Typically though non-limitatively, also disposed in cavity 301 might be the mirrors 108 and 208 as these are disposed in Fig.3, also, so that beam 305 would emanate from combined cavity or shared portion 301. On the other hand, the discrete other elements might also be disposed within combined cavity or shared portion 301, or might otherwise be disposed in discrete cavities 101 and 201. Thus, the elements 102, 104, 106, 107 might be disposed in the discrete portion of a cavity 101, or otherwise all or some of these elements 102, 104, 106, 107 might be disposed in cavity or shared portion 301. The elements 202, 204, 206, 207 might similarly be separately disposed in a discrete portion of a cavity 201, or otherwise all or some of elements 202, 204, 206, 207 might be disposed in combined cavity or shared portion 301. Hereafter, element 301 will frequently be referred to as a combined cavity 301 which herein includes both options of an entirely combined cavity (with all operative elements therein) or the alternative portionally shared cavity (with only some portion of all the operative elements therein), shared by first and second cavities 101 and 201.

[0020] A mirror 303 and an NLC 304 are shown in Fig.3 disposed inside the combined cavity 301 or the shared section 301 of both cavities to serve as a λ3 generator. The first laser beam 105 and the second laser beam 205 should be wellto each other for best overlapping within the shared section 301. In this configuration mirror 303 is in combined cavity 301 or in the shared portion 301 between the two cavities 101, 201 and has a coating covering the reflective range of the first laser mirror 103 (Fig.1) and the second laser mirror 203 (Fig.2). The mirror 108 is used here to separate the second laser beam 205 apart from the first laser beam105. The mirror 208 is used to separate the UV light output beam 305 apart from the second laser beam 205.

[0021] According to the implementation of Fig.3, a UV photon (not discretely shown, though see beam 305) is generated by combining two photons (not discretely shown, though see beams 105 and 205, respectively) of different wavelengths inside an NLC, here shown in Fig.3 for example, as NLC 304. In an exemplar implementation, one of the photons, see beam 105, e.g., may have a wavelength(λ1) shorter than 721nm which is available from a few solid state laser using crystals, as element 104 of first part 100a, such as praseodymium doped yttrium lithium fluoride (Pr:YLF), praseodymium doped lithium lutetium fluoride (Pr:LLF), or Terbium doped lithium lutetium fluoride (Tb:LLF). The other photon, see beam 205, e.g., having wavelength (λ2) comes from a semiconductor material, as from element 202 of second contributing part 200a, which has more than 20nm of selectable range. By combining inside the NLC 304, one each photon 105, 205 from each otherwise discrete laser 100a, 200a, an output resulting UV photon, see beam 305, e.g., of wavelength (λ3) is generated. The relation between these three wavelengths, λ1, λ2, and λ3, is λ3-1= λ1-1+ λ2-1where λ1is the fixed wavelength depending on the solid state crystal 104 of part 100a with corresponding cavity mirror coating; λ2is the selectable or tunable wavelength coming from semiconductor material 202 of part 200a with wavelength selecting element 204. The wavelength λ3 derived from this process is shorter than 400nm, i.e., UV, and is changeable or tunable.

[0022] A few UV wavelength generation examples are provided for illustration. For the following parts of this paragraph, a MECSEL is used for element 202. If, in a first implementation, λ1 is chosen to be 639.8nm from Pr:YLF 104 and λ2 is selected to be 1064nm from the MECSEL 202, then λ3 is 399.5nm. If, in a second implementation, λ1 is chosen to be 522.6nm and λ2 is selected to be 1064nm, then λ3 is 350.5nm. A typical MECSEL 202 centered at about 1064nm has a tunable range of from about 1044nm to about 1084nm, allowing this configuration 301 to provide a range of UV emission 305 from about 348nm to about 352nm. A MECSEL 202 with tuning range of 880nm to 920nm, would produce UV light 305 from this arrangement 301 from about 328nm to about 333nm. It is possible to generate a UV photon, see beam 305, e.g., shorter than about 300nm when λ1 is 479nm and λ2 is shorter than 800nm, based on this architecture 301.

[0023] Several optional implementations or parts of implementations are apparent. In Fig.3, for example, what is shown is a tunable UV laser 300, here a two-part laser 300, made of two contributing parts 100a, 200a either with the options of one combined cavity as an entirety wholly, or of two independent cavities with one or more shared sections or portions; either and both of which being referred to herewithin as a combined cavity. One part 100a may have a partially separate cavity 101, or a shared combination cavity 301, this first part 100a containing a solid state laser gain material to provide a photon wavelength(λ1), that in some implementations is shorter than 721nm. The other part, second part 200a, also sometimes referred to as a broadband part 200a, contains either in its own partially separate cavity 201, or within a shared totality combined cavity 301, a semiconductor material 202 and a wavelength selection element 204 to set the desired wavelength(λ2) to provide a broadband wavelength 205. In the shared section 301 of both cavities, or the single combined cavity 301, the NLC 304 is utilized to convert the photons from both parts into one higher energy photon(λ3). The three wavelengths, λ1, λ2, and λ3, may be disposed to follow the relationship of λ3-1= λ1-1+ λ2-1.

[0024] Furthermore, more specifically, in optional alternatives description, the first part laser 100a contains at least one laser crystal that frequently may include crystal material chosen as made of one of the solid state laser crystals which have emission wavelengths shorter than 721nm and typically or preferably in a green wavelength or a shorter wavelength. Suitable alternative crystals may be Pr:YLF, Pr:LLF having emission alternatives of 479nm, 522.6nm, 607nm, 640nm, 698nm, 720.9nm; or Tb:LiLuF4having emission alternatives of 543nm, 587nm. Also, cavity mirrors would be made of substrates with corresponding coatings suitable for reflecting the desired wavelength with high reflectivity. The reflectivity would preferably, but non-limitingly be 99% or higher. The coating would frequently be chosen / disposed to ensure only one desired wavelength is established and is amplified during the laser operation.

[0025] As a further optionally more specific implementation, the second contributing laser part 200a contains at least one semiconductor gain material 202 which can be a VECSEL or a MECSEL that can include semiconductor material, for example, of any of GaAlAs / GaAs material systems, InGaAs / GaAs material systems, GaInNAs / GaAs material systems, InGaAsP / InP material systems, and GaInAsSb / GaSb material systems. A recent list of available or alternative material systems may be found in the publication “Vertical External Cavity Surface Emitting LasersVECSEL Technology and Applications”, Wiley-VCH 2022. The wavelength selection optics, e.g., but not limited to element 204, can be a birefringent filter plate (BFP), a grating, an optical prism, an etalon, a Volume Bragg grating (VBG), or any optically dispersive element. The cavity mirrors may be made of substrates with corresponding coating suitable for reflecting the desired wavelength with high reflectivity. The reflectivity is preferably 99% or higher. In order to cover the complete operable and / or desirable tuning range of the wavelength, the high reflecting coating would in many implementations preferably cover the full tuning range.

[0026] Yet further more specific alternative implementations may include both cavities sharing a common optical path and / or common optics. The optical paths of both cavities should or would frequently preferably be overlapping in the common section as robustly as possible. Preferably, the overlapping of beams is better than 50% of the beam diameter. The NLC 304 disposed in the shared section 301 would chosen for ability to convert optical power from both wavelengths (λ1, λ2) into a shorter wavelength (λ3). Putting the NLC 304 inside the shared section 301 of both cavities is to take advantage of the high optical power intensities used for non-linear optical conversion. Because λ1, λ2are from two different lasers and are different in wavelengths, the non-linear process to generate a UV wavelength does not have “green noise” in CW operation. Electrical modulation, see element 204, can be applied to the second contributing laser part 200a (MECSEL / VECSEL) to produce modulated UV output without the relaxation oscillation of a DPSS laser.

[0027] In a further specificity alternative implementation, the optical paths of both cavities can be separated outside of or beyond the shared section. One or more optical elements can be used to separate the optical paths. Such optics may be or include one or both mirrors 108 and / or 208 which may be made of optically transparent substrate such as fused silica, magnesium fluoride, or any suitable material and is coated with dielectric coating to separate λ1 from λ2. Thus, one or both mirrors or optical elements or optics 108, 208 may be disposed within or outside combined cavity 301. Additional optic 208 may be disposed with a dielectric coating to separate shorter wavelength and longer wavelength, optic 208 being placed in the optical path where the UV λ3 light 305 can be extracted.

[0028] Fig.4 shows an alternative configuration of a tunable UV laser 400 with a combined cavity 401 (partial or entire, as above-described combined cavity 301). Elements in Fig.4 havingthe same reference numbers as in previously-described drawings have the same attributes in Fig.4; newly-appearing reference numeral elements are described here. A dispersive optical element such as an optical prism 408 aka a dispersive prism 408 is shown used to separate the NIR 405a, VIS 405b, and UV 405 wavelengths.

[0029] Fig.5 shows a mode locked UV laser 500, with a combined cavity 501 (similar to cavities 301, 401, above). Elements in Fig.5 having the same reference numbers as in previously-described drawings have the same attributes in Fig.5; newly-appearing reference numeral elements are described here. Mode-locked UV laser 500 is based on a Kerr-lens 504. A mode-locked UV laser 500 is created when the second laser part 200a does not have a wavelength selecting element but includes a mode locking device such as a Kerr-lens 504. The Kerr-lens 504 replaces the wavelength selecting element (see element 204 of Figs.2 and 3) in the optical path to generate from the broadband emission 205 from the semiconductor 202 a train of short pulses 505a at a characteristic wavelength here in an example, in near infra-red, NIR 505a. The pulsed NIR 505a and the DPSS light 105, in an example, CW VIS light 105, together generate a short pulse train of pulsed UV wavelength light 505 in the NLC and exit the cavity 501 through the mirror 208. The pulse width in this configuration may be much shorter than 1ns.

[0030] Fig.6 shows a mode locked UV laser 600, with a combined cavity 601 (similar to cavities 301, 401, 501 above). Elements in Fig.6 having the same reference numbers as in previously-described drawings have the same attributes in Fig.6; newly-appearing reference numeral elements are described here. Mode locked UV laser 600 is based on a semiconductor saturable absorber mirror (SESAM) 604. The SESAM 604 serves as one end mirror in the MECSEL / VECSEL cavity (element 202 here being a MECSEL or VECSEL understood to have first and second mirrors (first mirror not separately shown) therewithin or sufficiently associated therewith). The SESAM 604 aligns the starting time of all the wavelengths to generate a train of mode locked NIR pulses 605a in the MECSEL / VECSEL cavity. The mode locking device is the SESAM 604. This train of mode-locked NIR pulse light 605a mixes with CW VIS light 105 inside NLC 304 to generate a train of mode-locked UV pulses 605.

[0031] Fig.7 shows a Q-switched UV laser 700, with a combined cavity 701 (similar to cavities 301, 401, 501, 601 above). Elements in Fig.7 having the same reference numbers as inpreviously-described drawings have the same attributes in Fig.7; newly-appearing reference numeral elements are described here. Q-switched UV laser 700 has added a Q-switch device 704 in the DPSS laser part 100a. The Q-switch 704 allows the DPSS laser cavity 100a to generate a short VIS pulse 705a typically of few nano seconds. The VIS pulse 705a mixes with CW NIR 205 inside NLC 304 to generate UV pulse 705. In this, a Q-switched UV laser 700 may contain a Q- switch device 704 such as a pockels cells, an acoustic optical modulator, or a passive Q-switch 704, see Fig.7. The UV output pulse width from this configuration 700 may be between 1ns to 100ns depending on the DPSS laser.

[0032] A tunable UV laser may thus be formed by combining two laser cavities and / or parts of their cavities shared. A first cavity may be or include a solid state laser crystal which provides one or more photons at a fixed wavelength, for example a wavelength shorter than 721nm. The other cavity may be or include a semiconductor gain media which produces a tunable wavelength. By combining a photon from each cavity inside a nonlinear crystal (NLC), one higher energy photon is produced and the wavelength is shorter than 400nm. The semiconductor gain media may provide a range of continuously selectable wavelength and hence the UV wavelength is tunable. This type of laser may be capable of operating in continuous wave (CW), mode-locking, and Q-switch mode.

[0033] The above discussion is meant to be illustrative of the principles and various implementations of the presently-described developments, invention and / or inventions. Numerous variations, ramifications, and modifications of the basic concepts which have not been described may become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that all such ramifications and variations be included within the scope of the appended claims and their legal equivalents, and the scope of the invention or inventions not be limited by the examples given, or the claims hereof.

Claims

CLAIMS What is claimed is:

1. A method, device or system as described herein.

2. A method, device or system according to claim 1; including a UV laser comprising: a first contributing laser part generating a first laser light; and a second contributing laser part generating a second laser light; and a combined cavity sharing disposed therein at least a portion of shared operable elements of the first and second contributing laser parts, the combined cavity providing for combining the first laser light and the second laser light to generate a third laser light.

3. A method, device or system according to claims 1 or 2; the combined cavity being one of: an entirety wholly comprising all the operable elements of the first and second contributing laser parts, or a shared portion of two independent cavities, each sharing a respective section or portion thereof to define the combined cavity, the two independent cavities being first and second cavities of the corresponding first and second contributing laser parts.

4. A method, device or system according to claims 1-3; the combined cavity comprising disposed therewithin one or both: a combined cavity nonlinear crystal (NLC); and a combined cavity mirror.

5. A method, device or system according to claims 1-4; the combined cavity having a common optics path disposed therewithin, with one or both of first and second separation optical devices disposed one or both: within the combined cavity; or outside the combined cavity.

6. A method, device or system according to claims 1-5; further including one or more of: the first contributing laser part being a solid state diode pumped (SSDP) laser; and the second contributing laser part being an optically pumped semiconductor (OPS) laser.

7. A method, device or system according to claims 1-6; further including one or more of: the first contributing laser part comprises a laser gain material to provide a wavelength (λ1); and, the second contributing laser part comprises a laser gain material to provide a wavelength (λ2).

8. A method, device or system according to claim 7; further including: the output wavelength being λ3, and, the wavelengths being disposed to follow the relationship of λ3-1= λ1-1+ λ2-1.

9. A method, device or system according to claims 1-8; further including one or more of: λ1 being shorter than about 721nm; λ2being broadband wavelength; λ2 being a variable or tunable wavelength; and λ3 being an ultraviolet (UV) wavelength.

10. A method, device or system according to claim 9; the second contributing laser part further comprising a wavelength selection element to set the wavelength λ2.

11. A method, device or system according to claims 4-10; further including one or more of: the combined cavity NLC being disposed to one or both combine and convert the first and second laser light into the third laser light, the third laser light being a higher energy wavelength λ3.

12. A method, device or system according to claims 1-11; further including one or more of: the first contributing laser part comprising at least one laser crystal; andthe second contributing laser part comprising at least one semiconductor gain material; the second contributing laser part comprising at least one semiconductor gain material that is one of a VECSEL or a MECSEL.

13. A method, device or system according to claim 12; further including one or more of: the crystal material being a solid state laser crystal; and, the semiconductor material being one of: a GaAlAs / GaAs material system, an InGaAs / GaAs material system, a GaInNAs / GaAs material system, an InGaAsP / InP material system, and a GaInAsSb / GaSb material system.

14. A method, device or system according to claim 12; further including one or more of: the crystal material being a solid state laser crystal having an emission wavelength that is: shorter than 721nm, a green wavelength or a wavelength shorter than a green wavelength; and, the crystal material being made of one of the following solid state laser crystals: Pr:YLF, Pr:LLF having an emission wavelength of one of 479nm, 522.6nm, 607nm, 640nm, 698nm, 720.9nm, and, Tb:LiLuF4 having an emission wavelength of one of 543nm, 587nm.

15. A method, device or system according to claims 12-14; further comprising: a wavelength selection device cooperatively disposed relative to the semiconductor gain material in the second contributing laser part to provide tunable output for the second laser.

16. A method, device or system according to claim 15; further including one or more of:a wavelength selection device comprising wavelength selection optics that are one or more of: a birefringent filter plate(BFP), a grating, an optical prism, an etalon, a Volume Bragg grating (VBG), or any optically dispersive element.

17. A method, device or system according to claims 1-16; further including one or more of: the first contributing laser part generating a first laser light further comprising one or more of: a first part laser diode; a first part lens; a first part NLC; a first part upstream mirror upstream of the NLC; and, a first part downstream mirror downstream of the NLC; ; and a second contributing laser part generating a second laser light; and a second part laser diode; a second part lens; an OPS semiconductor device; and a second part mirror downstream of the OPS; 18. A method, device or system according to claim 17; further including: the wavelength selection device cooperatively disposed relative to the OPS semiconductor device to tune the second laser output therefrom.

19. A method, device or system according to claims 4-18; further including: the combined cavity having disposed therein a common optical path and common optics; the common optics being: the combined cavity nonlinear crystal (NLC); and the combined cavity mirror. .

20. A method, device or system according to claims 4-19; further including one or more of: the optical paths of first and second lasers are overlapping in the combined cavity;the optical paths of first and second lasers overlap in the combined cavity at more than 50% of the beam diameter of one or both the first and second lasers; the NLC in the combined cavity converts optical power from both wavelengths(λ1, λ2) into a shorter wavelength (λ3); the NLC inside the combined cavity uses the high optical power intensities for non-linear optical conversion; “green noise” is eliminated in CW operation because λ1, λ2being different from two different laser and are different in wavelengths, the non-linear process to generate UV wavelength λ3does not have green noise; electrical modulation can be applied to the second part laser (MECSEL / VECSEL) to produce modulated UV output without the relaxation oscillation of a DPSS laser.

21. A method, device or system according to claims 4-20; further including one or more of: the optical paths of both first and second and third lasers are separated outside and beyond the combined cavity; an optical element is used to separate the optical paths of the first, second and third lasers; this optical element being made of optically transparent substrate such as fused silica, magnesium fluoride, or any suitable material and is coated with dielectric coating to separate λ1 from λ2; the optical element having a dielectric coating to separate shorter wavelength and longer wavelength is placed in the optical path where the UV λ3 light can be extracted.

22. A method, device or system according to claims 1-21; further including one or more of: any one or more laser mirrors being made of substrates with corresponding coating suitable for reflecting the desired wavelength with high reflectivity; the reflectivity is preferably 99% or higher; to cover the complete tuning range of the wavelength, the high reflecting coating will cover the full tuning range; and, the coating ensures only one desired wavelength is amplified and is established during the laser operation.

23. A method, device or system according to claims 1-22; including one or more of: a dispersive optical element or an optical prism.

24. A method, device or system according to claims 23; the dispersive optical element or optical prism being disposed as one or more of: instead of any downstream mirrors; and, to separate the optical paths of VIS, NIR, and UV.

25. A method, device or system according to claims 1-24; further including one or more of: creating a mode-locked UV laser using instead of a wavelength selecting element in the second part, rather a mode locking device of one or more of: a Kerr-lens; and, a SESAM.

26. A method, device or system according to claim 25; further including one or more of: a broadband emission from the semiconductor and a mode locking device creating a train of short pulses at the characteristic wavelength; a short pulse light and a DPSS light mix in the NLC to generate a short pulse train of UV wavelength; a pulse width in this configuration is shorter than 1ns.

27. A method, device or system according to claims 1-24; further including one or more of: creating a Q-switched UV laser comprising: a Q-switch device of a pockels cells, an acoustic optical modulator, or a passive Q-switch; and the UV output pulse width from this configuration is between 1ns to 100ns depending on the DPSS laser.

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