Optically pumped thin slab waveguide single mode laser

Abstract

The application discloses an optical-pumped thin-plate waveguide single-mode laser, which comprises an integrated encapsulation substrate, a heat dissipation component arranged on one side of the substrate, a cladding arranged on the other side of the substrate and a single-mode transmission component arranged in the cladding, and the refractive index of the single-mode transmission component is higher than that of the cladding. The optical-pumped thin-plate waveguide single-mode laser with the above structure has the advantages of good heat dissipation performance, low laser threshold, high stability, simple and compact structure, stable operation, flexible preparation method and the like, and can realize high-quality and high-power continuous single-mode laser output.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser technology, in particular to a thin waveguide single-mode laser pumped by light. BACKGROUND

[0002] Solid-state lasers have wide application prospects in the international frontier fields of production and scientific research. An important development trend of future optically pumped solid-state lasers requires high-power, high-efficiency and high-beam-quality laser output. The thermal effect in the solid-state laser gain medium is one of the important factors restricting the development of solid-state lasers. With the increase of output power, the medium thermal effect seriously reduces the conversion efficiency and destroys the beam quality, which not only affects the stability of the cavity, but also changes the spot size of the TEM00 mode, obviously limiting the power expansion of the TEM00 laser.

[0003] At present, the waveguide laser is generally a high aspect ratio structure, which is composed of a high refractive index waveguide layer and a low refractive index cladding layer. The numerical aperture of this structure is large, which has a good binding effect on non-diffraction limited beams, can effectively prevent free space divergence, has higher pump light absorption efficiency, and has good heat dissipation capacity, which can conduct the waste heat generated during laser emission in time, and effectively overcome the performance degradation caused by thermal effect.

[0004] At present, the mainstream method of on-chip waveguide laser is to use femtosecond laser direct writing, ion implantation and ion exchange technologies to prepare optical waveguides and resonant cavities in laser crystals to limit the transmission of light field. This kind of technology induced by laser or ion beam energy changes the refractive index of the crystal inside, the refractive index difference between the waveguide and the surrounding medium is small, the spot mode size is large, the numerical aperture is small, and the absorption efficiency is low.

[0005] In order to realize the single-mode output of the waveguide laser, the mainstream methods and corresponding disadvantages are as follows: 1. Reduce the refractive index difference between the waveguide and the cladding layer. This method will result in a decrease in numerical aperture, a decrease in light field binding ability, and a decrease in absorption efficiency; 2. Use a smaller single-mode strip waveguide. This method reduces the mode field area, limiting the output power of the laser; 3. Use a ridge waveguide. In this kind of waveguide structure, the optical energy will be dispersed into the etching residue, increasing the loss of light propagation, and the ridge waveguide with thick etching residue has poor heat dissipation capacity. SUMMARY

[0006] To solve the above problems, the present application provides a thin waveguide single-mode laser pumped by light, which has the advantages of good heat dissipation performance, low laser threshold, high stability, simple and compact structure, stable operation, flexible preparation method, etc., and can realize high-quality and high-power continuous single-mode laser output.

[0007] In order to achieve the above object, the application provides a kind of optical pumping thin slice waveguide single mode laser, including integrated package substrate, heat dissipation component arranged on one side of substrate, cladding arranged on the other side of substrate and single mode transmission component arranged in cladding, the refractive index of single mode transmission component is higher than cladding.

[0008] Preferably, the single mode transmission component is gain medium waveguide, and the gain medium waveguide includes input straight waveguide, gain waveguide and output tapered ridge waveguide connected in sequence, and the material of the input straight waveguide and the gain waveguide is yttrium aluminum garnet;

[0009] The gain waveguide includes input gain waveguide and output gain waveguide arranged in opposite directions and equidistant spirals, and the input gain waveguide and the output gain waveguide are connected through an S-shaped waveguide;

[0010] One end of the input straight waveguide is connected with an optical fiber, and the other end is connected with the first output tapered ridge waveguide through the input gain waveguide, the S-shaped waveguide and the output gain waveguide in sequence.

[0011] Preferably, the first output tapered ridge waveguide includes a connecting taper and a ridge waveguide, one end of the connecting taper is connected with the output gain waveguide, and the other end is connected with the ridge waveguide, and the thickness of the connecting taper is the same as the etching residual thickness on the ridge waveguide.

[0012] Preferably, the thickness of the connecting taper is 4 μm, the ridge height of the ridge waveguide is 6 μm, the ridge width is 10 μm, the etching residual height is 4 μm, and the etching residual width is 26 μm.

[0013] Preferably, the total length of the gain medium waveguide is 70 cm, the aperture is 10 μm, and is greater than the core diameter of the single mode optical fiber;

[0014] The cross section of the input straight waveguide and the gain waveguide is a square with a side length of 10 μm;

[0015] The maximum curvature radius of the equidistant spiral of the gain waveguide is 2 cm, the minimum curvature radius is 0.7 cm, and the pitch is 1.67 mm.

[0016] Preferably, the gain medium waveguide is a solid laser doped with luminescent ions;

[0017] The material of the gain medium waveguide is one of rare earth garnet, vanadate crystal, lithium niobate, ruby, emerald, sapphire and any combination thereof, and the doped luminescent ions are one of Nd, Yb, Tm, Ho and any combination thereof.

[0018] Preferably, the single-mode transmission component is a resonant cavity with an F-P type standing wave cavity, and the single-mode transmission component comprises, in sequence, an incident grating, the F-P type resonant cavity, an outgoing grating and a second output tapered ridge waveguide, the incident grating and the outgoing grating constituting two mirrors of the F-P resonant cavity, and the reflectivity of the outgoing grating is lower than that of the incident grating.

[0019] Preferably, the substrate is a rectangle with a side length of 4-5 cm or a circle with a diameter of 4-5 cm made of a semiconductor material, and the substrate is made of one of silicon, silicon carbide, silicon nitride, gallium arsenide, diamond and any combination thereof.

[0020] Preferably, the cladding is made of one of silicon, silicon dioxide and silicon nitride and any combination thereof.

[0021] Preferably, the heat dissipation component is one of a heat sink, a water cooling channel and an air cooling channel and any combination thereof arranged on the substrate.

[0022] The present application has the following advantages:

[0023] 1. The gain medium waveguide simultaneously functions as light field restriction and laser gain, and has the advantages of simple structure and easy production;

[0024] 2. The laser gain medium is sparsely distributed on the chip, and the planar waveguide structure can timely conduct the waste heat generated in the emission of the laser, effectively overcoming the performance degradation caused by the thermal effect, and realizing high-quality and high-power continuous output;

[0025] 3. The design of the output tapered ridge waveguide ensures single-mode output without size limitation, and the mode in the waveguide matches the mode form in the optical fiber, so that the output light can directly enter the coupling optical fiber;

[0026] 4. The integrated arrangement makes the structure more compact, the operation more stable, and easy to industrialize.

[0027] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the present application;

[0029] Figure 2 FIG. 3 is an arrangement diagram of the gain medium waveguide of the embodiment of the present application;

[0030] Figure 3 FIG. 5 is a structural schematic diagram of the output tapered ridge waveguide of the embodiment of the present application;

[0031] Figure 4 FIG. 7 is a graph of the effective refractive index variation of the output tapered ridge waveguide of the embodiment of the present application;

[0032] Figure 5 This is a mode distribution diagram of the output tapered ridge waveguide of Embodiment 1 of the present invention;

[0033] Figure 6 This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0034] Wherein: 1. Single-mode transmission component; 1a1. Input straight waveguide; 1a2. Gain waveguide; 1a3. First output tapered ridge waveguide; 1a31. Connecting taper; 1a32. Ridge waveguide; 1b1. Incident grating; 1b2. FP type resonant cavity; 1b3. Outgoing grating; 1b4. Second output tapered ridge waveguide; 2. Cladding; 3. Substrate. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0036] A thin-film waveguide single-mode laser with optical pumping includes a monolithically packaged substrate 3, a heat dissipation component disposed on one side of the substrate 3, a cladding layer 2 disposed on the other side of the substrate 3, and a single-mode transmission component 1 disposed within the cladding layer 2. The refractive index of the single-mode transmission component 1 is higher than that of the cladding layer 2. The substrate 3 is a rectangle with a side length of 4cm-5cm or a circle with a diameter of 4cm-5cm made of semiconductor material, and the material of the substrate 3 is one or any combination of silicon, silicon carbide, silicon nitride, gallium arsenide, and diamond. The cladding layer 2 is one or any combination of silicon, silicon dioxide, and silicon nitride. The heat dissipation component is one or any combination of a heat sink, a water-cooling channel, and an air-cooling channel disposed on the substrate 3.

[0037] like Figures 1-3 As shown in Embodiment 1, the single-mode transmission component 1 is a gain dielectric waveguide. The gain dielectric waveguide includes an input straight waveguide 1a1, a gain waveguide 1a2, and an output graded ridge waveguide 1a32 connected in sequence. The input straight waveguide 1a1 and the gain waveguide 1a2 are both made of yttrium aluminum garnet. The gain waveguide 1a2 includes an input gain waveguide and an output gain waveguide arranged in opposite directions and at equal intervals. The input gain waveguide and the output gain waveguide are connected by an S-shaped waveguide. One end of the input straight waveguide 1a1 is connected to an optical fiber. In this embodiment, the input straight waveguide 1a1 can be connected to the coupling optical fiber / grating optical fiber by means of adhesive bonding, coupler coupling, optical fiber fusion splicing, etc. The other end is connected to the first output graded ridge waveguide 1a3 in sequence via the input gain waveguide, the S-shaped waveguide, and the output gain waveguide.

[0038] Preferably, the first output tapered ridge waveguide 1a3 includes a connecting taper 1a31 and a ridge waveguide 1a32. One end of the connecting taper 1a31 is connected to the output gain waveguide, and the other end is connected to the ridge waveguide 1a32. The thickness of the connecting taper 1a31 is the same as the thickness of the etch residue on the ridge waveguide 1a32. In this structure, the higher-order modes in the ridge waveguide 1a32 will diverge into the etch residue after propagating through several wavelengths, thereby achieving single-mode output.

[0039] Preferably, the thickness of the connecting taper 1a31 is 4μm, the ridge height of the ridge waveguide 1a32 is 6μm, the ridge width is 10μm, and the height of the etch residue is 4μm and the width is 26μm.

[0040] Preferably, the total length of the gain dielectric waveguide is 70cm, the aperture is 10μm, and it is larger than the core diameter of the single-mode fiber, thereby playing the role of optical field confinement and laser gain; the cross-sections of the input straight waveguide 1a1 and the gain waveguide 1a2 are both squares with a side length of 10μm; the maximum radius of curvature of the equidistant helix of the gain waveguide 1a2 is 2cm, the minimum radius of curvature is 0.7cm, and the pitch is 1.67mm.

[0041] Preferably, the gain dielectric waveguide is a solid-state laser doped with luminescent ions; the material of the gain dielectric waveguide is one or any combination of rare earth garnet, vanadate crystal, lithium niobate, ruby, emerald, and sapphire, and the doped luminescent ions are one or any combination of Nd, Yb, Tm, and Ho.

[0042] In this embodiment, for the output light with a wavelength of 1.03 μm, when passing through the region of the graded ridge waveguide 1a32, the higher-order modes will diverge into the etch residue after propagating for two or three wavelengths, thereby obtaining a single-mode output. Moreover, its propagation mode matches the mode morphology in the optical fiber. The output light can be directly inserted into the coupling fiber and used directly on the chip, or it can be output to the off-chip using methods such as tapered fiber / lens end face coupling, tapered fiber evanescent coupling, and grating coupling. It can also be connected to an optical fiber amplifier or directly integrated into an on-chip optical waveguide amplifier for further optical amplification.

[0043] like Figure 4 and Figure 5 As shown, the effective refractive index of the TE0 mode in the etch residue is greater than that of the TE1 mode and higher-order modes in the ridge region. Therefore, the higher-order modes in the ridge region will diverge into the etch residue. The higher-order modes will diverge into the etch residue after propagating for several wavelengths, and only the fundamental mode can propagate in the ridge region, thus achieving single-mode transmission.

[0044] In summary, this embodiment achieves optical amplification without a resonant cavity. Furthermore, light only needs to travel a single distance in the waveguide, effectively suppressing thermal effects. The structure, which eliminates the need for coatings or etched Bragg gratings, is also easier to manufacture.

[0045] As shown in Figure 6 Embodiment two, single mode transmission component 1 is a resonant cavity with F-P type standing wave cavity, single mode transmission component 1 includes incident grating 1b1, F-P type resonant cavity 1b2, exit grating 1b3 and second output tapered ridge waveguide 1b4 arranged in turn, incident grating 1b1 and exit grating 1b3 constitute two mirrors of F-P resonant cavity, and the reflectivity of exit grating 1b3 is lower than that of incident grating 1b1.

[0046] In this embodiment, when the gain is greater than the loss, laser emission is formed and output from exit grating 1b3, then through the output tapered ridge waveguide, single mode output light is obtained.

[0047] Therefore, the application adopts the above-mentioned structure of the optically pumped thin slice waveguide single mode laser, has the advantages of good heat dissipation performance, low laser threshold, high stability, simple and compact structure, stable operation, flexible preparation method, etc., and can realize high-quality, high-power continuous single mode laser output.

[0048] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A light-pumped thin-film waveguide single-mode laser, characterized in that: It includes an integrally packaged substrate, a heat dissipation component disposed on one side of the substrate, a cladding layer disposed on the other side of the substrate, and a single-mode transmission component disposed within the cladding layer, wherein the refractive index of the single-mode transmission component is higher than that of the cladding layer. The single-mode transmission component is a gain dielectric waveguide, which includes an input straight waveguide, a gain waveguide, and an output tapered ridge waveguide connected in sequence. The input straight waveguide and the gain waveguide are both made of yttrium aluminum garnet. The gain waveguide includes an input gain waveguide and an output gain waveguide arranged in opposite directions and at equal intervals, and the input gain waveguide and the output gain waveguide are connected by an S-shaped waveguide; One end of the input straight waveguide is connected to an optical fiber, and the other end is connected to the first output tapered ridge waveguide in sequence via the input gain waveguide, the S-shaped waveguide, and the output gain waveguide. The first output tapered ridge waveguide includes a connecting taper and a ridge waveguide. One end of the connecting taper is connected to the output gain waveguide, and the other end is connected to the ridge waveguide. The thickness of the connecting taper is the same as the etch residue thickness on the ridge waveguide.

2. The optically pumped thin-film waveguide single-mode laser according to claim 1, characterized in that: The thickness of the connecting taper is 4μm, the ridge height of the ridge waveguide is 6μm, the ridge width is 10μm, and the height and width of the etch residue are 4μm and 26μm respectively.

3. The optically pumped thin-film waveguide single-mode laser according to claim 1, characterized in that: The total length of the gain dielectric waveguide is 70cm, and the aperture is 10μm, which is larger than the core diameter of a single-mode fiber. Both the input straight waveguide and the gain waveguide have square cross-sections with a side length of 10 μm; The maximum radius of curvature of the gain waveguide equidistant helix is ​​2cm, the minimum radius of curvature is 0.7cm, and the pitch is 1.67mm.

4. The optically pumped thin-film waveguide single-mode laser according to claim 1, characterized in that: The gain dielectric waveguide is a solid-state laser doped with luminescent ions; The gain dielectric waveguide is made of one or any combination of rare earth garnet, vanadate crystal, lithium niobate, ruby, emerald, and sapphire, and the doped luminescent ions are one or any combination of Nd, Yb, Tm, and Ho.

5. A single-mode laser with optical pumping on a thin-film waveguide according to claim 1, characterized in that: The single-mode transmission component is a resonant cavity with an FP-type standing wave cavity. The single-mode transmission component includes an incident grating, an FP-type resonant cavity, an output grating, and a second output tapered ridge waveguide arranged in sequence. The incident grating and the output grating constitute two reflectors of the FP resonant cavity, and the reflectivity of the output grating is lower than that of the incident grating.

6. The optically pumped thin-film waveguide single-mode laser according to claim 1, characterized in that: The substrate is a rectangle with a side length of 4cm-5cm or a circle with a diameter of 4cm-5cm made of semiconductor material, and the substrate material is one of silicon, silicon carbide, silicon nitride, gallium arsenide, diamond and any combination thereof.

7. The optically pumped thin-film waveguide single-mode laser according to claim 1, characterized in that: The cladding material is one of silicon, silicon dioxide, silicon nitride, or any combination thereof.

8. A single-mode laser with optical pumping on a thin-film waveguide according to claim 1, characterized in that: The heat dissipation component is one of the following: heat sink, water cooling channel, air cooling channel, or any combination thereof, which are disposed on the substrate.

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