An all-fiber white light laser for laser display

Abstract

The application provides a full-fiber white light laser for laser display, comprising a blue light pumping source; the blue light pumping source is connected with a resonant cavity assembly through a multimode tail fiber; a gain fiber is arranged in the resonant cavity assembly; after the gain fiber is excited by the blue light, red light and green light lasers are generated simultaneously, and the residual blue light is combined with the red light and the green light into white light laser in a multimode output fiber. The white light fiber laser has the advantages of high conversion efficiency, simple structure, easy miniaturization and the like.

Description

Technical Field

[0001] This application relates to the fields of laser display, laser lighting, and visible light wireless communication, and specifically to an all-fiber white laser for laser display. Background Technology

[0002] In recent years, Li-Fi technology has emerged to alleviate RF spectrum constraints. It utilizes light-emitting diodes (LEDs) as white light sources, enabling high-speed communication while providing LED lighting. While LEDs offer advantages such as high efficiency and long lifespan, their luminous efficiency is limited by the "efficiency degradation" effect, and their high-speed performance is constrained by narrow direct modulation bandwidth. In contrast, laser-based white light sources offer high brightness, high energy efficiency, good beam directionality, wider direct modulation bandwidth, and faster response speed, making them more suitable for high-brightness solid-state lighting and high-speed, long-distance communication. Furthermore, white laser sources can also be used as backlights in laser displays. Therefore, white lasers are playing an increasingly important role in numerous fields such as lighting, indoor lighting and communication (Li-Fi), underwater communication, and laser displays, attracting widespread attention from researchers.

[0003] Currently, there are three main ways to generate white laser light: 1. White laser light is synthesized by generating RGB three primary colors or multicolor lasers from several independent lasers. In this approach, the multiple laser sources are usually fabricated individually and assembled separately, making miniaturization and integration difficult and resulting in high manufacturing costs.

[0004] 2. Using yellow fluorescent functional materials to convert blue laser light into white laser light. In this approach, the fluorescent functional material needs to withstand very high laser bombardment to produce high-brightness white light, which places high demands on material technology. Furthermore, the optical collimation is weakened, and more fluorescent stray light is generated during the conversion.

[0005] 3. White laser light is generated by producing a supercontinuum through optical nonlinear effects. This approach typically requires an ultrafast laser as the fundamental frequency input light, which is expensive and has low conversion efficiency, making it unsuitable for miniaturized and integrated applications. Furthermore, the spectral intensity generated by this approach is relatively fixed, making it difficult to control the intensity of each component spectrum and thus hindering the adjustment of the emitted laser color.

[0006] Therefore, a highly efficient white laser capable of simultaneously outputting RGB primary colors—a "holistic" laser that is easily miniaturized and integrated—has become a research focus. The key challenge lies in creating materials that simultaneously and efficiently emit RGB primary colors or multiple colors. Semiconductor materials, with their advantages of high efficiency, ease of electrical injection, and ease of integration, have always been the preferred choice for light-emitting materials. However, traditional technical difficulties with this approach include lattice mismatch in semiconductors emitting different colors, leading to a decrease in crystal photoelectric quality; secondly, semiconductor lasers suffer from a "green gap," with low green light efficiency, and long-wavelength (red) semiconductor materials absorb the light emitted by short-wavelength (blue, green) semiconductor materials, making it difficult to achieve simultaneous multi-color lasing. Recently developed nanoscale semiconductor materials still face problems such as difficulty in obtaining them and high cost.

[0007] Rare-earth ion-doped materials can generate abundant visible light wavelength transitions under blue laser pumping, making a "monolithic" white laser possible. Compared with rare-earth-doped crystal lasers with spatial structures and poor stability, downconversion rare-earth ion-doped fiber lasers can achieve an all-fiber structure through fiber coating technology and fiber grating fabrication technology, and have significant advantages such as high efficiency, good stability, simple structure, and easy miniaturization.

[0008] Current research has also made some progress. For example, by using blue light to pump holmium-praseodymium co-doped fluoride fiber to generate multi-wavelength fluorescence emission, white light fluorescence can be obtained. This fully demonstrates the potential of rare-earth-doped white fiber lasers.

[0009] Similarly, praseodymium-doped fluoride optical fibers can generate red and green light emission when pumped by blue light, making them an ideal choice for directly generating three primary color lasers to achieve white light lasers.

[0010] In laser display, compared to semiconductor laser sources, fiber laser sources exhibit a greater spectral width expansion with increasing power, lower speckle contrast, and are less affected by speckle noise in image display.

[0011] In addition, Chinese patent application CN116031735A discloses a white hybrid laser source based on a visible light fiber laser, which has the following shortcomings: it generates lasers of different wavelengths through multiple gain fibers and then combines them into white light, making the structure too complex and difficult to miniaturize. Summary of the Invention

[0012] To address the aforementioned technical issues, an all-fiber white laser for laser display is proposed, comprising: a blue light pump source; the blue light pump source being connected to a resonant cavity assembly via a multimode pigtail; a gain fiber being disposed within the resonant cavity assembly; after the pump blue light excites the gain fiber, red and green laser light are simultaneously generated, and combined with the residual pump blue light in the multimode output fiber to form a white laser light.

[0013] The above technical solution provides an overall structure for an all-fiber white laser for laser display. By connecting the blue pump source, resonant cavity components, and gain fiber, it realizes the function of lasing red and green light and combining them with the pump blue light to form white light, thus realizing an all-fiber white laser that can be used for laser display and provides white light output.

[0014] Specifically, the blue light pump source is a semiconductor laser with a built-in multimode pigtail: the blue light pump source is connected to the resonant cavity assembly via the multimode pigtail.

[0015] The above technical solution uses a semiconductor laser with a built-in multimode pigtail as the blue light pump source, and connects the resonant cavity assembly through the multimode pigtail to ensure the effective transmission of pump light, solve the connection problem between the blue light pump source and the resonant cavity assembly, and facilitate the realization of an all-fiber structure.

[0016] Specifically, the resonant cavity assembly includes a first fiber end face coating mirror coated on a multimode pigtail and a second fiber end face coating mirror coated on a multimode output fiber.

[0017] The above technical solution forms a resonant cavity assembly by depositing fiber end face coating mirrors on multimode pigtails and multimode output fibers, providing the necessary optical feedback for laser generation.

[0018] Specifically, the first fiber end face coating mirror is designed to have high transmittance in the blue light band, high reflectivity in the green light band, and high transmittance in the red light band.

[0019] The above technical solution, with its first fiber end-face coating mirror design, achieves high transmittance in the blue light band, high reflectance in the green light band, and high transmittance in the red light band. This helps to realize laser oscillation and synthesis in specific bands, control the transmission and reflection of light in the resonant cavity, and promote the generation of red and green lasers.

[0020] Specifically, the second fiber end face coating mirror is designed to be highly reflective in the blue light band, partially reflective in the green light band, and highly transparent in the red light band.

[0021] The above technical solution, with the design of the second fiber end face coating mirror, achieves high reflectivity in the blue light band, partial reflection in the green light band, and high transmittance in the red light band. This adjusts the reflection and output of light within the resonant cavity, which is beneficial for the synthesis and output of white light.

[0022] Specifically, the resonant cavity assembly also includes: a copper sleeve; a multimode pigtail connected to the input end of the gain fiber via the copper sleeve; and a multimode output fiber connected to the output end of the gain fiber via the copper sleeve.

[0023] The above technical solution uses copper sleeves to ensure low-loss connection between the fiber end face coating mirror and the gain fiber, which is beneficial to forming a compact all-fiber linear cavity structure for laser oscillation.

[0024] Specifically, the blue light pump source operates at a wavelength of 443nm and has a maximum power of 60W.

[0025] The above technical solution specifies the operating wavelength of the blue light pump source, and its high power output provides an important foundation for realizing high-power white light lasers.

[0026] Specifically, the gain fiber is a double-clad praseodymium-doped fiber.

[0027] The above technical solution uses double-clad praseodymium-doped fiber for gain, which helps to improve the conversion efficiency of the laser.

[0028] Specifically, this also includes: multimode output fiber tail end; multimode output fiber tail end outputting white laser light.

[0029] The above technical solution features a multimode output fiber tail end that undergoes precision polishing, facilitating the connection and use of the laser with other devices and providing an output interface for easy integration with external equipment.

[0030] Compared with the prior art, the beneficial results of this application are as follows: 1. This invention uses praseodymium-doped fluoride optical fiber as the gain medium, which is reasonably priced and has good heat dissipation performance, eliminating the need for an additional heat dissipation system; 2. This invention uses a single optical fiber and two fiber end-face coated mirrors to form the laser resonance, realizing an all-fiber structure without any free space components. The structure is simple and easy to miniaturize. 3. The red light, green light and residual pump blue light generated by this invention are uniformly entered into the core of the multimode fiber and mixed to form white light, which is finally output from the tail end of the multimode output fiber. The operation is simple. 4. This invention can achieve combinations of red, green, and blue primary color lasers with different power ratios by designing the film system of the fiber end face coating mirror and changing the fiber length, thereby obtaining white lasers with different color temperatures. Attached Figure Description

[0031] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of this application. Other embodiments and many anticipated advantages of these embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0032] Figure 1 This is a schematic diagram of the structure of an all-fiber white laser for laser display according to an embodiment of this application; Figure 2This is a film system curve of the first fiber end face coating of an all-fiber white light laser for laser display according to an embodiment of this application; Figure 3 This is a film system curve of the second fiber end face coating of an all-fiber white light laser for laser display according to an embodiment of this application; Figure 4 This is a spectrum of mixed white light from an all-fiber white laser for laser display according to an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a coated mirror for an all-fiber white laser used in laser display, according to an embodiment of this application.

[0033] The meanings of the numbers in the diagram are as follows: 1. Blue light pump source; 2. Multimode pigtail; 3. Gain fiber; 4. Multimode output fiber; 5. Output multimode fiber tail end; 6. Copper sleeve; 7. First fiber end face coating mirror; 8. Second fiber end face coating mirror. Detailed Implementation

[0034] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description and illustrate illustrative specific embodiments in which the present application may be practiced. In this regard, directional terms such as “top,” “bottom,” “left,” “right,” “up,” “down,” etc., are used with reference to the orientation of the described figures. Because components of the embodiments can be positioned in several different orientations, directional terms are used for illustrative purposes and are by no means limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the present application. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the present application is defined by the appended claims.

[0035] like Figure 1 As shown, an all-fiber white laser for laser display includes: a blue light pump source 1; the blue light pump source 1 is connected to a resonant cavity assembly via a multimode pigtail 2; a gain fiber 3 is disposed inside the resonant cavity assembly; after the pump blue light excites the gain fiber 3, red light and green light lasers are generated simultaneously, and combined with the residual pump blue light in the multimode output fiber 4 to form a white light laser.

[0036] It is known that this application only needs a single gain fiber 3 to achieve the synthesis of three different wavelengths of RGB lasers, thereby obtaining white light.

[0037] Blue light pump source 1 is a semiconductor laser with a built-in multimode pigtail 2: Blue light pump source 1 is connected to the resonant cavity assembly through multimode pigtail 2.

[0038] The resonant cavity assembly includes a first fiber end face coating mirror 7 coated on the multimode pigtail 2 and a second fiber end face coating mirror 8 coated on the multimode output fiber.

[0039] The first fiber end-face coated mirror 7 is designed to have high transmittance in the blue light band, high reflectivity in the green light band, and high transmittance in the red light band.

[0040] The second fiber end face coating mirror 8 is designed to be highly reflective in the blue light band, partially reflective in the green light band, and highly transparent in the red light band.

[0041] The resonant cavity assembly also includes: a copper sleeve 6; a multimode pigtail 2 connected to the input end of the gain fiber 3 through the copper sleeve 6; and a multimode output fiber 4 connected to the output end of the gain fiber 3 through the copper sleeve 6.

[0042] The blue light pump source 1 operates at a wavelength of 443nm and has a maximum power of 60W.

[0043] Gain fiber 3 double-clad praseodymium fluoride-doped fiber.

[0044] It also includes: a multimode output fiber with four tails; and a multimode output fiber tail that outputs white laser light.

[0045] Multimode pigtail 2 and multimode output fiber 3 are the same type of fiber, both being quartz fiber with a core size of 105μm.

[0046] In this embodiment, the gain fiber 3 is a double-clad praseodymium-doped fluoride (Pr) fiber. 3+ ZBLAN optical fiber has a core diameter of 7.5 μm and an inner cladding with a double D-shaped profile of 115 × 125 μm. From an energy level perspective, Pr... 3+ ground state energy levels of ions 3 H4 absorbs 441nm pump lasing to 3 P2 energy level, 3 P2 nonradiative transition to 3 P1 / 3 P0, 3 P1→ 3 H5 produces 520.9nm green light. 3 P0→ 3 F2 produces 635.5nm red light.

[0047] In this embodiment, both the first fiber end-face coated mirror 7 and the second fiber end-face coated mirror 8 are dielectric films deposited on the end faces of the multimode pigtail 2 and the multimode output fiber 3 using ion beam assisted evaporation coating technology. The reflectivity of the coated mirrors in different visible light bands can be controlled through film design. The first fiber end-face coated mirror 7 and the second fiber end-face coated mirror 8 form a resonance of green and red light.

[0048] Furthermore, the pump blue light enters the resonant cavity through the first fiber end-face coated mirror 7, which has high blue light transmittance, to excite the gain fiber 3. The design of the first fiber end-face coated mirror 7 and the second fiber end-face coated mirror 8 allows the green light to obtain more gain feedback, thus enabling it to compete with the red light, which has a stronger gain, and achieve the simultaneous generation of red and green laser light.

[0049] Specifically, the first fiber end face coating mirror 7 is connected to the input end of the gain fiber 3 through the copper sleeve 6, and the second fiber end face coating mirror 8 is connected to the output end of the gain fiber 3 through the copper sleeve 6.

[0050] Specifically, the first fiber end face coating mirror 7 coated on the multimode pigtail 2 is designed to have a transmittance greater than 95% in the blue light band, a reflectance greater than 98% in the green light band, and a transmittance greater than 95% in the red light band.

[0051] Specifically, the second fiber end-face coating mirror 8, coated on the multimode output fiber 4, is designed to have a reflectivity of approximately 95% in the blue light band, a reflectivity of approximately 60% in the green light band, and a transmittance of more than 95% in the red light band. The second fiber end-face coating mirror 8 is designed to have high blue light reflectivity, which can make full use of blue light pumping and improve efficiency, while allowing a small amount of residual blue light to pass through.

[0052] More specifically, such as Figure 5 As shown, in a specific embodiment, the first fiber end face coating mirror 7 and the first fiber end face coating mirror 8 are made of alternating stacks of Ta2O5 layers and SiO2 layers with different thicknesses.

[0053] In this embodiment, the specific thicknesses of the Ta2O5 layer and SiO2 layer in the first optical fiber end face coated mirror 8 are 177nm-25nm-145nm-33nm-104nm-49nm-58nm-71nm-119nm-25nm-74nm-49nm-84nm-25nm-92nm-48nm-81nm-47nm-66nm-53nm-83nm-26nm-114nm-25nm-92nm-40nm-66nm-25nm.

[0054] Furthermore, the red and green laser light generated by the gain fiber 3, along with the residual pump blue laser light, are transmitted and mixed in the core of the multimode output fiber 4 to become white light, which is finally output from the end 5 of the multimode output fiber outside the cavity.

[0055] This invention uses praseodymium-doped fluoride optical fiber as the gain medium. The fiber has excellent heat dissipation performance, eliminating the need for an additional cooling system. A single optical fiber and two fiber end-face coated mirrors are used to form the laser resonance, achieving an all-fiber structure without any free-space components. This simple structure is easily miniaturized.

[0056] RGB three-primary-color lasers are mixed in the core of a multimode fiber to form white light, which is then output from the tail end of the multimode output fiber, making the operation simple. This invention can achieve combinations of red, green, and blue three-primary-color lasers with different power ratios and obtain white lasers of different color temperatures by designing the coating system of the fiber end-face coating mirror and changing the fiber length.

[0057] It is obvious that those skilled in the art can make various modifications and alterations to the embodiments of this application without departing from the spirit and scope of this application. In this way, this application also aims to cover such modifications and alterations if they fall within the scope of the claims and their equivalents. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used for profit. Any reference numerals in the claims should not be considered limiting in scope.

Claims

1. An all-fiber white laser for laser displays, characterized in that, include: Blue light pump source; The blue light pump source is connected to the resonant cavity assembly via a multimode pigtail; the resonant cavity assembly contains a gain fiber; the blue light pump source generates pump blue light, which, after being excited by the gain fiber, simultaneously generates red and green laser light, which are then combined with the residual pump blue light in the multimode output fiber to form white laser light. The resonant cavity assembly includes a first fiber end-face coated mirror deposited on the multimode pigtail and a second fiber end-face coated mirror deposited on the multimode output fiber. The first fiber end-face coated mirror is designed to have high transmittance in the blue light band, high reflectivity in the green light band, and high transmittance in the red light band. Specifically, it is designed to... The first fiber end-face coating mirror has a transmittance greater than 95% in the blue light band, a reflectance greater than 98% in the green light band, and a transmittance greater than 95% in the red light band. The second fiber end-face coating mirror is designed to be highly reflective in the blue light band, partially reflective in the green light band, and highly transmittant in the red light band. Specifically, it is designed to have a reflectance of approximately 95% in the blue light band, a reflectance of approximately 60% in the green light band, and a transmittance greater than 95% in the red light band. Through the design of the first and second fiber end-face coating mirrors, the green light can obtain more gain feedback, thereby competing with the red light which has a stronger gain, and realizing the simultaneous generation of red and green laser light.

2. The all-fiber white laser for laser display according to claim 1, characterized in that, The blue light pump source is a semiconductor laser with a built-in multimode pigtail: the blue light pump source is connected to the resonant cavity assembly through the multimode pigtail.

3. The all-fiber white laser for laser display according to claim 2, characterized in that, The resonant cavity assembly further includes: a copper sleeve; the multimode pigtail is connected to the input end of the gain fiber through the copper sleeve; and the multimode output fiber is connected to the output end of the gain fiber through the copper sleeve.

4. The all-fiber white laser for laser display according to claim 1, characterized in that, Also includes: Multimode output fiber tail; The tail end of the multimode output fiber is configured for outputting synthesized white laser light.

5. A white fiber laser for laser display according to any one of claims 1 to 4, characterized in that, The blue light pump source operates at a wavelength of 443nm and has a maximum power of 60W.

6. A white fiber laser for laser display according to any one of claims 1 to 4, characterized in that, The gain fiber is a double-clad praseodymium-doped fiber.

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