Optical waveguide, preparation method and optical amplifier

Abstract

The present invention discloses an optical waveguide, a preparation method and an optical amplifier. The optical waveguide comprises a rare earth ion doped tellurite glass matrix or a rare earth ion doped fluoride glass matrix and all-inorganic cesium lead halide perovskite quantum dots CsPbX3 precipitated in the glass matrix; wherein the volume fraction of CsPbX3 is 0.1-20%, X=Cl, Br, I, Cl 1‑x Br x Or Br 1‑x I x , x=0-1; the rare earth ion is Er 3+ or Nd 3+ The molar percentage of rare earth ions is 0.1-5 mol%. Under light-emitting diode pumping, the optical waveguide of the present invention utilizes perovskite sensitization to achieve rare earth ion near-infrared light signal amplification, and obtains a net gain of optical signal amplification in the entire S+C+L band.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical glass and optical communication, and relates to an optical waveguide, a preparation method and an optical amplifier, in particular to an LED-pumped perovskite quantum dot-sensitized rare earth-doped glass optical waveguide, a preparation method thereof and an optical amplifier using the optical waveguide. Background Art

[0002] The rapid development of mobile internet, the Internet of Things, cloud computing, and 5G networks is driving increasing demand for next-generation optical communication capacity. Optical amplifiers, driven by pump light and based on the principle of stimulated emission, can directly amplify signal light, compensating for the attenuation of optical signals during transmission. They are key components in optical communication systems, and their continuous performance improvements and cost reductions are driving all-optical networks into a new era. Rare-earth-doped optical waveguide amplifiers, which can be integrated with other photonic devices such as optical switches, optical modulators, and arrayed waveguide gratings, are garnering widespread attention and are expected to play an essential role in on-chip integrated optics.

[0003] Chinese invention patent ZL 202221779019.7 discloses an "optical amplifier system" capable of ensuring the overall communication quality of the optical amplifier system. Chinese invention patent CN 202110694346.6 discloses an "optical amplifier and optical communication system." By adaptively adjusting the energy of complementary light corresponding to the signal light, the system dynamically and in real time releases or consumes the pump energy required by each stage of the optical amplifier structure, thereby eliminating transient overshoot. The pump source of this optical amplifier always uses a laser diode (LD) of a specific wavelength to directly pump the intrinsic absorption band of rare earth ions. This is then coupled to the signal laser using a wavelength division multiplexer (WDM) and input from one end of the waveguide. Almost all optical gain experimental results and theoretically established ion rate equations are based on LD laser pumping. However, the large size of LD lasers restricts the ultra-compact integration of devices, and their high cost increases the cost of the equipment.

[0004] The use of light-emitting diodes (LEDs) that are highly commercially mature and low-cost to pump optical waveguides provides great possibilities for device integration and cost reduction. In 2021, Zhang Dan's research group at Xiamen University used a 405nm blue LED to directly pump an erbium ion-doped organic optical waveguide from the top, achieving an internal net gain of 4.5dB / cm. The gain range only covers the C band and part of the L band. In 2015, the gain of the optical amplifier designed by Vu et al. can cover the C+L band and part of the S-band, making it the optical amplifier with the widest gain reported so far. However, its S and L bands only achieve switching gain, and no net gain is obtained. The core issue that causes the above problems is that rare earth ions have extremely low absorption efficiency of pump light in the visible light band, and even no absorption at all in some bands.

[0005] In contrast, all-inorganic cesium lead halide perovskite quantum dots are direct-bandgap semiconductor materials with a large absorption cross-section in the visible light band, 10,000 times stronger than the absorption strength of rare earth ions. Under LED pumping, they can achieve efficient fluorescence emission in the visible light band. Furthermore, their emission wavelength can be easily tuned by adjusting the size and composition of the quantum dots. Chinese invention patent ZL 201910134932.8 discloses "a high-efficiency luminescent perovskite quantum dot material and preparation method," which holds significant significance for research on the performance and luminescence of novel semiconductor quantum dot materials. Chinese invention patent ZL 202011315986.3 discloses "a novel rare earth ion-doped perovskite solar cell." By doping the Cs2AgBiBr6 perovskite light-absorbing layer with rare earths, the bandgap is reduced, the spectral absorption range is broadened, and the photoelectric conversion efficiency of the perovskite solar cell is improved. These inventions focus solely on the perovskite material's luminescence in the visible light band and do not address the impact of the perovskite on the infrared luminescence properties of rare earth ions. Since the luminescence position of quantum dots partially overlaps with the absorption of rare earth ions in the visible light band, the Förster resonance energy transfer conditions are met. Through the energy transfer between quantum dots and rare earth ions, it is expected that quantum dots can sensitize rare earth ions to near-infrared luminescence and obtain near-infrared gain. However, there are currently no reports on using perovskite quantum dots to sensitize rare earth ions to obtain near-infrared gain and light amplification. Summary of the Invention

[0006] In response to the above-mentioned prior art, the technical problem to be solved by the present invention is to provide an LED-pumped perovskite quantum dot-sensitized rare earth-doped glass optical waveguide, a preparation method thereof, and an optical amplifier using the optical waveguide. Glass is used as a coating matrix. By adjusting the glass composition, heat treatment time and temperature, the type and volume ratio of perovskite precipitation are controlled, and perovskite crystals are precipitated in the glass matrix to sensitize rare earth ions. LED pumping is used to achieve infrared luminescence of the rare earth ions and obtain optical gain.

[0007] In order to solve the above technical problems, an optical waveguide of the present invention comprises a rare earth ion doped tellurite glass matrix or a rare earth ion doped fluoride glass matrix and all-inorganic cesium lead halide perovskite quantum dots CsPbX3 precipitated in the glass matrix; wherein the volume fraction of CsPbX3 is 0.1-20%, X = Cl, Br, I, Cl 1-x Br x Or Br 1-x I x , x=0-1; the rare earth ion is Er 3+ or Nd 3+ , the molar percentage of rare earth ions is 0.1-5 mol.%.

[0008] Furthermore, the length of the optical waveguide in the light propagation direction is 1 mm-100 mm.

[0009] Furthermore, a light emitting diode is used to pump the optical waveguide to realize near-infrared luminescence of rare earth ions and obtain optical gain.

[0010] Furthermore, the light emitting diode is an ultraviolet light emitting diode, a blue light emitting diode or a white light emitting diode.

[0011] Any of the above methods for preparing an optical waveguide, comprising:

[0012] S1: Weigh the raw materials, grind and mix them evenly to obtain a glass batch;

[0013] S2: In a covered heat-resistant container, melting the glass batch obtained in step S1 into a uniform melt;

[0014] S3: Quenching the glass melt obtained in step S2 into bulk glass, annealing at a constant temperature to eliminate internal stress in the glass, and cooling to room temperature in the furnace to obtain precursor glass;

[0015] S4: heat-treating the precursor glass obtained in step S3 in a muffle furnace to obtain perovskite glass-ceramics, wherein the heat treatment temperature is 300° C. to 500° C. and the heat treatment time is 0.3 to 30 hours;

[0016] S5: The glass product heat-treated in step S4 is cut, surface ground and polished to obtain the optical waveguide.

[0017] Furthermore, the melting temperature of the glass batch material is 500-1400°C.

[0018] Furthermore, the melting atmosphere is air.

[0019] An optical amplifier comprises an input optical fiber, a first optical fiber collimator, an LED light source, the optical waveguide according to any one of claims 1 to 4, a second optical fiber collimator, and an output optical fiber; when a signal light source in an amplified wavelength band emits a light beam that converges onto the optical waveguide through the output optical fiber and the first optical fiber collimator, and simultaneously the LED light source emits pump light to illuminate the optical waveguide, the optical signal is amplified by the optical waveguide and then output through the second optical fiber collimator and the output optical fiber.

[0020] Beneficial effects of the present invention:

[0021] Compared to existing technologies, the present invention precipitates all-inorganic cesium-lead halide perovskite quantum dots in rare-earth-doped tellurite or fluoride glass. Rare-earth ions have low absorption in the visible light band, or even no absorption at all in certain bands, making it impossible to effectively utilize the energy of pump light sources with corresponding wavelengths. However, by leveraging the high absorption efficiency of quantum dots in the ultraviolet and the entire visible light band, quantum dots sensitize the rare-earth ions, compensating for this deficiency. This sensitization of the rare-earth ions by quantum dots allows the use of low-cost LEDs as pump light sources, achieving efficient near-infrared emission from the rare-earth ions and ultimately achieving near-infrared light amplification.

[0022] This invention utilizes perovskite quantum dots to sensitize rare-earth ion-doped glass optical waveguides. Through Förster resonance energy transfer, it boosts the pumping efficiency of rare-earth ions in the ultraviolet and visible light bands to over 1,000 times that of existing optical amplifiers. This enables the efficient pumping of rare-earth ions by low-cost LEDs for the first time, achieving near-infrared broadband luminescence and gain. Furthermore, the optical amplifier boasts the largest known net gain bandwidth, covering the S+C+L bands and more than three times the gain bandwidth of commercial optical amplifiers.

[0023] The present invention proposes the precipitation of perovskite quantum dots in rare-earth-doped tellurite or fluoride glass, which has the following characteristics: 1) Unlike commercial optical waveguide amplifiers, which are mostly based on quartz glass, the low concentration of rare-earth ions in quartz glass results in low gain per unit length and a narrow near-infrared emission peak. This results in a narrow gain bandwidth (covering only the C band) for existing optical amplifiers, severely impacting the expansion capabilities of communication systems. Rare-earth-doped tellurite or fluoride glass has the advantages of high rare-earth solubility, low phonon energy, and high luminescence efficiency. In particular, its rich microstructure enables rare-earth ions to achieve a wider near-infrared emission bandwidth through inhomogeneous broadening, helping to expand the gain bandwidth of optical amplifiers to cover the S+C+L bands. 2) Perovskite quantum dot sensitization improves the absorption efficiency of rare-earth ions for visible light energy, achieving for the first time near-infrared broadband optical amplification in glass optical amplifiers pumped by ultraviolet or visible light LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the transmission spectrum of the glasses prepared in Examples 1, 2 and 4;

[0025] Figure 2 is a transmission electron microscope HAADF dark field image of the perovskite glass prepared in Example 4;

[0026] Figure 3 is the excitation spectrum of the glasses prepared in Examples 1, 2 and 4 monitored at 1540 nm;

[0027] Figure 4 is the near-infrared emission spectrum of the glass prepared in Examples 1-5 under 465 nm excitation;

[0028] Figure 5 is the near-infrared emission spectrum of the glasses prepared in Examples 2, 6-9 under 380 nm excitation;

[0029] Figure 6 is the near-infrared emission spectrum of the glass prepared in Example 10 under 465 nm excitation;

[0030] Figure 7 is the visible light emission spectrum of the glasses prepared in Examples 1, 2 and 4 under excitation at a wavelength of 465 nm;

[0031] Figure 8 The fluorescence decay curves of the glasses prepared in Example 2 and Example 4 under 465 nm excitation and 510 nm monitoring;

[0032] Figure 9 is a schematic diagram of an optical amplifier;

[0033] Figure 10 This is the near-infrared gain spectrum of the perovskite glass waveguide prepared in Example 4 under blue LED pumping. The inset shows the spectral coverage of the blue LED.

[0034] Figure 11 This is the near-infrared gain spectrum of the perovskite glass waveguide prepared in Example 4 under white light LED pumping, and the inset is the spectral coverage of the white light LED. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] The present invention uses a light emitting diode (LED) to pump a glass optical waveguide and utilizes perovskite sensitization to achieve rare earth ion near-infrared light signal amplification, thereby obtaining a net gain of optical signal amplification in the entire S+C+L band.

[0037] The optical waveguide of the present invention comprises a rare earth ion doped tellurite glass matrix or a rare earth ion doped fluoride glass matrix and all-inorganic cesium lead halide perovskite quantum dots CsPbX3 precipitated in the glass matrix; wherein the volume fraction of CsPbX3 is 0.1-20%, the glass matrix occupies 80-99.9% of the volume fraction of the optical waveguide, and X = Cl, Br, I, Cl 1-x Br x Or Br 1-x I x , x=0-1; the rare earth ion is Er 3+ or Nd 3+ The rare earth ions are externally doped, and the molar percentage of the rare earth ions is 0.1-5 mol.%.

[0038] The optical waveguide works in a gas environment or a vacuum environment with a refractive index lower than that of the glass matrix, and the gas serves as the cladding of the optical waveguide.

[0039] The length of the optical waveguide in the light propagation direction is 1 mm to 100 mm.

[0040] Light emitting diodes are used to pump the optical waveguide to realize near-infrared luminescence of rare earth ions and obtain optical gain.

[0041] In some embodiments of the present invention, the light emitting diode is an ultraviolet light emitting diode, a blue light emitting diode or a white light emitting diode, and the diode includes but is not limited to the above diodes.

[0042] The method for preparing the optical waveguide of the present invention comprises the following steps:

[0043] S1. According to the glass optical waveguide components, accurately weigh the raw materials, fully grind and mix them to obtain a glass batch material;

[0044] S2. Melting: In a covered heat-resistant container, melt the glass batch obtained in step S1 into a uniform melt;

[0045] S3, forming and annealing: the glass liquid obtained in step S2 is taken out of the furnace, poured into a mold to be quenched into a block of glass, annealed at a constant temperature to eliminate the internal stress of the glass, and cooled to room temperature with the furnace to obtain the precursor glass.

[0046] S4, heat treatment: heat-treating the precursor glass obtained in step S3 in a muffle furnace to obtain perovskite glass-ceramics, with the heat treatment temperature being 300° C. to 500° C. and the heat treatment time being 0.3 to 30 hours.

[0047] S5. Cutting, surface grinding, and polishing the glass product after the heat treatment in step S4 to obtain the perovskite glass-ceramic optical waveguide.

[0048] The glass matrix, perovskite material and rare earth are all introduced as raw materials using corresponding compounds.

[0049] In step S2, the covered heat-resistant container includes an alumina crucible, a quartz crucible, or a platinum crucible.

[0050] The mold in step S3 includes a copper mold and is used after preheating.

[0051] The constant temperature annealing is performed in a precision annealing furnace.

[0052] In some embodiments of the present invention, the melting temperature of the glass batch material is 500-1400°C.

[0053] In certain embodiments of the present invention, the melting atmosphere is air.

[0054] An optical amplifier using the optical waveguide of the present invention includes a single-mode input optical fiber 1, a first optical fiber collimator 2, an LED light source 3, the optical waveguide 4, a second optical fiber collimator 5, and a multimode output optical fiber 6. When a signal light source in the amplified band emits a light beam that passes through the single-mode input optical fiber 1 and the first optical fiber collimator 2 and converges onto the optical waveguide 4, while the LED light source 3 emits pump light to illuminate the optical waveguide 4, the optical signal is amplified by the optical waveguide 4 and then output through the second optical fiber collimator 5 and the multimode output optical fiber 6.

[0055] The following is an example with reference to specific parameters:

[0056] According to the above preparation method, an optical waveguide is prepared according to the components of the embodiments in Tables 1 to 3. The specific steps include:

[0057] (1) Accurately weighing raw materials according to their composition, grinding and mixing them thoroughly to obtain a glass batch;

[0058] (2) The glass batch materials of Examples 1-9 were transferred to an alumina crucible and covered, and then melted, formed, annealed, and cooled in an air atmosphere to obtain a precursor glass, which was then heat-treated to obtain a perovskite quantum dot glass, wherein the melting temperature was 850°C, the temperature was increased to the melting temperature at a rate of 10°C / min, the temperature was cooled to 750°C, and then cast and formed, the annealing temperature was 270°C, the holding time was 3 hours, the heat treatment temperature was 340°C, and the heat treatment time was 15 hours;

[0059] The glass batch material of Example 10 was transferred to a platinum crucible and covered, and then melted, formed, annealed, and cooled in an air atmosphere to obtain a precursor glass, which was then heat treated to obtain perovskite quantum dot glass, wherein the melting temperature was 1100°C, the temperature was increased to the melting temperature at a rate of 5°C / min, and the glass was cast and formed. The annealing temperature was 400°C, the holding time was 3 hours, the heat treatment temperature was 440°C, and the heat treatment time was 15 hours.

[0060] (3) Cut the glass, grind and polish the surface to obtain the perovskite glass optical waveguide.

[0061] Table 1. Composition of optical waveguides in Examples 1-5

[0062] Example No. <![CDATA[TeO2]]> <![CDATA[Ga2O3]]> ZnO CbD <![CDATA[PbBr2]]> AgCl <![CDATA[ErF3]]> Example 1 85 5 10 1.5 Example 2 77.35 4.55 9.1 3 6 0.7 Example 3 77.35 4.55 9.1 3 6 0.7 0.1 Example 4 77.35 4.55 9.1 3 6 0.7 1.5 Example 5 77.35 4.55 9.1 3 6 0.7 5

[0063] Table 2. Composition of optical waveguides in Examples 6-9

[0064] Example No. <![CDATA[TeO2]]> <![CDATA[Ga2O3]]> ZnO CbD <![CDATA[PbBr2]]> AgCl <![CDATA[NdF3]]> Example 6 85 5 10 0.7 Example 7 77.35 4.55 9.1 3 6 0.7 0.1 Example 8 77.35 4.55 9.1 3 6 0.7 0.7 Example 9 77.35 4.55 9.1 3 6 0.7 5

[0065] Table 3. Composition of optical waveguide in Example 10

[0066] Example No. <![CDATA[AlF3]]> YF3 <![CDATA[MgF3]]> BaF2 <![CDATA[SrF2]]> <![CDATA[CaF2]]> CbD <![CDATA[PbBr2]]> AgCl <![CDATA[ErF3]]> Example 10 35 6 10 10 10 20 3 6 0.5 1.5

[0067] 2. Characterization Test

[0068] The optical waveguide's glass transition temperature and crystallization temperature were measured using differential scanning calorimetry (DSC), photoluminescence spectra were obtained using an Omnifluo-113 fluorescence spectrometer, transmission spectra were measured using a UV spectrophotometer, and fluorescence decay curves were measured using a tunable optical polypropylene (OPP) excitation source. A blue (465 nm) LED / white light LED was used as the pump source, and a supercontinuum light source was used as the signal light. Spectral analysis was performed using a highly sensitive near-infrared spectrometer (NIRQuest 1.7).

[0069] 3. Performance Comparison

[0070] The transmission spectra of the glasses prepared in Examples 1, 2 and 4 are as follows: Figure 1 As shown, all glasses have good transmittance, with transmittance higher than 70%, and the absorption cutoff edge of the sample with perovskite precipitation red-shifts to 520nm, broadening the short-wave absorption range; comparing Example 2 with Example 4, the precipitation of perovskite crystals does not affect the transmittance of the glass.

[0071] The glass-ceramics obtained in Example 4 was used as a representative for transmission electron microscopy (TEM) analysis. Figure 2 This proves that there are CsPbBr3 crystals in the glass, and their size reaches nanometer level, which further proves that the prepared microcrystalline glass has good transmittance.

[0072] The excitation spectra of the glasses prepared in Examples 1, 2 and 4 are as follows: Figure 3 As shown, by comparing Example 2 and Example 4, the absorption cross section of the short-wave portion of the rare earth-doped glass is broadened after crystallization, which makes it possible to pump the near-infrared luminescence of the rare earth ions by short-wavelength.

[0073] The near-infrared luminescence spectra of the glasses prepared in the above examples 1-5 under 465 nm excitation are as follows: Figure 4 It is shown that the precipitation of CsPbBr3 crystals can make the near-infrared luminescence of Er ions be pumped by short-wavelength.

[0074] The near-infrared luminescence spectra of the glasses prepared in the above examples 2, 6-9 under 380nm excitation are as follows: Figure 5 It is shown that the precipitation of CsPbBr3 crystals can make the near-infrared luminescence of Nd ions be pumped by short-wavelength.

[0075] The near-infrared luminescence spectrum of the glass prepared in Example 10 under 465 nm excitation is as follows: Figure 6 It is shown that the precipitation of CsPbBr3 crystals in fluoride glass can enable the near-infrared luminescence of Er ions to be short-wave pumped.

[0076] The visible emission spectra of the glasses prepared in Examples 1, 2 and 4 under 465 nm wavelength excitation are as follows: Figure 7 As shown, the emission band with a peak value near 520nm comes from the luminescence of CsPbBr3 crystal. Comparing Example 2 and Example 3, the luminescence intensity is correspondingly weakened after Er ion doping, indicating that there is energy transfer between CsPbBr3 crystal and Er ions.

[0077] The fluorescence decay curves of the glasses prepared in Example 2 and Example 4 under 465 nm excitation and 510 nm monitoring are as follows: Figure 8 As shown, the lifetimes of the glasses prepared in Example 2 and Example 4 were 10.50 ns and 9.12 ns, respectively. The lifetimes of the glasses prepared in the above examples all reached the extremely short nanosecond level, and the changes in lifetimes also confirmed the energy transfer between the CsPbBr3 crystals and the Er ions.

[0078] The schematic diagram of an optical amplifier using an optical waveguide is shown in Figure 9 As shown in the figure, signal light is emitted by a tunable fiber laser and focused into a glass waveguide via a first fiber collimator. Pump light, emitted by a blue or white LED, illuminates the glass waveguide from the top. A second fiber collimator converges the amplified signal light into a multimode fiber, thereby achieving LED-pumped perovskite-sensitized rare-earth ion-doped glass waveguide and amplifying near-infrared signal light.

[0079] The near-infrared gain spectrum of Er ions in the perovskite glass waveguide prepared in Example 4 under blue LED pumping is as follows: Figure 10 The results show that the switching gain range covers the E+S+C+L+U bands, with the highest switching gain reaching 20.96dB at 1530nm under blue light pumping. The net gain range covers the S+C+L bands, with the highest net gain reaching 6.52dB at 1530nm under blue light pumping.

[0080] The near-infrared gain spectrum of Er ions in the perovskite glass optical waveguide prepared in Example 4 under white light LED pumping is as follows: Figure 11 The results show that the switching gain range covers the E+S+C+L+U bands, with the highest switching gain reaching 27.44dB at 1530nm under white light pumping. The net gain range covers the S+C+L bands, with the highest net gain reaching 15.85dB at 1530nm under white light pumping.

[0081] As can be seen from the above embodiments, rare earth-doped perovskite glass optical waveguides can be pumped by LEDs to achieve infrared luminescence of rare earth ions and obtain optical gain. In addition, the luminescence properties of the glass can be regulated by adjusting the composition. The introduction of the various raw material compounds listed in the present invention and the adjustment of the upper and lower limits of various process parameters can all achieve the present invention. The embodiments are not listed one by one here.

Claims

1. An optical waveguide, characterized in that: It includes a rare earth ion doped tellurite glass matrix or a rare earth ion doped fluoride glass matrix and all-inorganic cesium lead halide perovskite quantum dots CsPbX3 precipitated in the glass matrix; Among them, the volume fraction of CsPbX3 is 0.1–20%, X=Cl, Br, I, Cl 1-x Br x Or Br 1-x I x , x=0-1; the rare earth ion is Er 3+ or Nd 3+ , the molar percentage of rare earth ions is 0.1-5 mol%.

2. The optical waveguide according to claim 1, wherein: The length of the optical waveguide in the light propagation direction is 1 mm to 100 mm.

3. The optical waveguide according to claim 1, wherein: Light emitting diodes are used to pump the optical waveguide to realize near-infrared luminescence of rare earth ions and obtain optical gain.

4. An optical waveguide according to claim 3, characterized in that: The light emitting diode is an ultraviolet light emitting diode, a blue light emitting diode or a white light emitting diode.

5. The method for preparing an optical waveguide according to any one of claims 1 to 4, characterized in that: include: S1: Weigh the raw materials, grind and mix them evenly to obtain a glass batch; S2: In a covered heat-resistant container, melting the glass batch obtained in step S1 into a uniform melt; S3: Quenching the glass melt obtained in step S2 into bulk glass, annealing at a constant temperature to eliminate internal stress in the glass, and cooling to room temperature in the furnace to obtain precursor glass; S4: heat-treating the precursor glass obtained in step S3 in a muffle furnace to obtain perovskite glass-ceramics, wherein the heat treatment temperature is 300° C. to 500° C. and the heat treatment time is 0.3 to 30 hours; S5: The glass product heat-treated in step S4 is cut, surface ground and polished to obtain the optical waveguide.

6. The preparation method according to claim 5, characterized in that: The melting temperature of the glass batch material is 500-1400°C.

7. The preparation method according to claim 5, characterized in that: The melting atmosphere was air.

8. An optical amplifier, characterized in that: The optical waveguide includes an input optical fiber, a first optical fiber collimator, an LED light source, the optical waveguide according to any one of claims 1 to 4, a second optical fiber collimator, and an output optical fiber. When a signal light source in an amplified wavelength band emits a light beam that converges to the optical waveguide through the output optical fiber and the first optical fiber collimator, and the LED light source emits pump light to illuminate the optical waveguide, the optical signal is amplified by the optical waveguide and then output through the second optical fiber collimator and the output optical fiber.

Images