US-12619092-B2 - Spectral splitter device

US12619092B2US 12619092 B2US12619092 B2US 12619092B2US-12619092-B2

Abstract

Disclosed is a spectral splitter device for transforming at least one initial light beam coming from a light source into more than two light beams, or vice versa, which includes: a first polarising beam splitter that splits the initial light beam into two orthogonally polarised beams; two optical elements respectively penetrated by the two orthogonally polarised beams; and a second polarising beam splitter and a third polarising beam splitter which split the two orthogonally polarised light beams into four respective output beams. Each of the two optical elements is birefringent and their birefringence depends on wavelength.

Inventors

Carles ORIACH FONT

Assignees

MONOCROM, S.L.

Dates

Publication Date: 20260505
Application Date: 20201229

Claims (19)

1 . A spectral splitter device for transforming an initial light beam from a light source into a pair of light beams by incoherent division, the spectral splitter device comprising: a first polarization beam splitter that splits the initial light beam into the pair of light beams, the pair of light beams orthogonally polarized and incoherent; a pair of optical elements passed through respectively by the pair of light beams; and a second polarization beam splitter and a third polarization beam splitter which in turn split the pair of light beams into four respective output beams, wherein each of said pair of optical elements is birefringent such that the birefringence of the pair of optical elements is dependent on a wavelength of the pair of light beams.
2 . The spectral splitter device of claim 1 , wherein a light from the four respective output beams has different spectral components.
3 . The spectral splitter device of claim 2 , wherein the initial light beam passes through a birefrigent and dispersive optical element prior to passing to said first polarization beam splitter.
4 . The spectral splitter device of claim 2 , wherein the initial light beam passes through a pre-polarization beam splitter prior to passing to said first polarization beam splitter.
5 . The spectral splitter device of claim 3 , wherein the initial light beam passes through a partially reflecting mirror prior to passing to the birefrigent and dispersive optical element.
6 . The spectral splitter device of claim 4 , wherein the initial light beam passes through a partially reflecting mirror prior to passing to the pre-polarization beam splitter.
7 . The spectral splitter device of claim 1 , wherein at least one of the four respective output beams passes through a third optical element, the third optical element being birefrigent.
8 . The spectral splitter device of claim 1 , wherein at least one of the four respective output beams passes through a third optical element, the third optical element being dispersive.
9 . The spectral splitter device of claim 1 , wherein the light source is more than one individual light source that generates a plurality of beams that combine into a single beam when a reverse path is applied to the plurality of beams.
10 . The spectral splitter device of claim 9 , wherein the more than one individual light source obtains the reverse path from a partially reflecting mirror.
11 . The spectral splitter device of claim 1 , wherein further comprising: a controller that controls an optical delay or dispersion of said pair of optical elements.
12 . The spectral splitter device of claim 11 , wherein each of said pair of optical elements comprises birefrigent dispersive crystals of integer multiples of a basic thickness.
13 . The spectral splitter device of claim 12 , wherein each of said pair of optical elements has a phase delay comprising: at least one retarder plate.
14 . The spectral splitter device of claim 12 , wherein each of said pair of optical elements has a phase delay comprising: a support cooperative with each of said pair of optical elements and adapted to tilt the optical element in order to adjust the phase delay.
15 . The spectral splitter device of claim 12 , wherein each of said pair of optical elements has a phase delay comprising: a liquid crystal element having a delay formed therein.
16 . The spectral splitter device of claim 1 , wherein each of said pair of optical elements has at least a pair of parts with a wedge, the wedge adapted to adjust the pair of parts by moving the pair of parts with respect to each other.
17 . The spectral splitter device of claim 1 , wherein the light source is selected from a group consisting of laser diode, a semiconductor laser, a light-emitting diode, a laser bar, a bar stock and combinations thereof.
18 . The spectral splitter device of claim 9 , wherein the more than one individual light source is a matric of light sources.
19 . The spectral splitter device of claim 1 , wherein at least one of said first polarization beam splitter and said second polarization beam splitter is a displacer.

Description

OBJECT OF THE INVENTION The invention, as expressed in the wording of the present description, refers to a spectral splitter device that provides advantages and features, described in detail below, which represent an improvement of the current state of the art within its field of application. More particularly, the object of the invention is centered on a spectral splitter device which, based on the principle of a Lyot filter, allows an increase in the power density of a light source beam, for example a laser, from the linear superposition of two pairs of beams combined by orthogonal polarization, through the use of birefringent and/or dispersive optical elements, for example calcite crystal with the necessary thickness to modify the wavelength in a controlled manner, causing both beams to have the same polarization and thus allowing their linear superposition, which, in turn, allows a cascade repetition of the process, combining again the linearly superimposed beams with other beams subjected to the same effect, and where the equipment comprises an optical assembly plate to be able to accomplish said effect by including additional elements, such as an external resonator that provides a greater cavity and a specific resonance condition, depending on each need, on the output beam obtained. FIELD OF APPLICATION OF THE INVENTION The field of application of the present invention is framed within the sector of the industry dedicated to the manufacture of devices and components for light emitting equipment, for example laser, LED or other technologies. BACKGROUND OF THE INVENTION As is known, when light passes through a birefringent medium, the beam can be broken down into two polarization components with respect to the optical axis of the medium, each of which experiences different refractive indices, resulting in a relative phase shift between the two and thus can induce a change in the polarization state of the light. Since all mediums are dispersive, therefore having different refractive indices for different wavelengths, birefringence is generally also dispersive. Therefore, the change in the polarization state depends on the wavelength. Therefore, it is possible to distinguish, filter, separate or combine different spectral components of light by suitable configurations of birefringent materials and polarization beam splitters. In the simplest case, a birefringent crystal is placed between two polarizers. This filter is known as a Lyot filter. As a phase delay between the polarization states of light is periodic by multiples of π, so is the periodic transmission of the filter with respect to the wavelength. This effect can be very practical for power boosting in certain equipment. For example, laser technology is widely used in industry, usually for use in industrial laser processes, mainly for cutting or welding. Most are made with fiber optic lasers or disk lasers. In any case, what is important in these types of applications is to have energy density that can be concentrated in very small spots. Energy density is achieved by scaling power or decreasing the laser spot size. However, in applications with diodes, all the increase in density is based on the increase in power, since the spot cannot be made smaller owing to the low beam quality in the slow axis, but to date, laser state of the art to increase its power/capacity only allows adding two-diode beams by means of polarization or several per wavelength. Therefore, the development of a new technique that allows an increase in said power by adding more than said two single diodes is desirable, with the aim of the present invention being the development of said new technique that allows an energy density two or four times higher in a simple way. In the current state of the art, to combine two laser beams of two diodes, the two diodes are combined, which are equal and are placed perpendicularly and focused, with different light polarizations (a vertical polarization and another polarization turned horizontally by means of a wave retarder interposed for this purpose), facing a polarization beam splitter, so that they reach the polarization beam splitter and leave united in the same direction, since one passes through the polarization beam splitter and the other is reflected, but maintaining their different polarizations. This means that the combination of both beams cannot be re-combined to increase the power of the output laser, which would be desirable. Each laser consists of a laser active region, also called gain region, in which the energy supplied is converted by stimulated emission into coherent radiation. For this purpose, a laser resonator is needed to ensure that a part of the emerging radiation is returned to the gain region. It therefore contains at least one feedback element, typically a semi-transparent mirror. This resonator determines, by its geometry and physical properties, the feedback characteristics of the laser light, in particular t