CN110690639B - High Efficiency Injection Locked Fiber Taper Laser - Google Patents

Abstract

The invention relates to a high-efficiency injection-locked fiber tapered laser, which is composed of a pump source 1, an optical isolator 2, a single-mode active rare-earth-doped fiber 3, and a double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered fiber consists of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core and the inner and outer cladding are n1, n2, and n3, respectively, and n1>n2 >n3, this refractive index distribution enables the high-order mode laser to be coupled to the inner cladding more efficiently, suppressing the mode hopping effect. The high reflection grating 31 and the partial reflection grating 32 are written on both ends of the single-mode active rare-earth-doped fiber 3, and the low-reflection grating 5 is written on the thick end of the double-clad active rare-earth-doped tapered fiber 4. The tilt angle gratings 52 and 53 are written in the upper and lower parts of the region to ensure that the laser is output from the center of the fiber core and reduce the problem of light leakage in the tapered region. The laser has high pumping efficiency, good heat dissipation, can suppress the mode hopping effect, and has high-quality and high-power output light.

Description

High Efficiency Injection Locked Fiber Taper Laser

technical field

The invention relates to a high-efficiency injection-locked fiber cone laser, which belongs to the field of high-power and high-efficiency fiber lasers.

Background technique

Fiber lasers were invented in 1963, and by the end of the 1980s, the first commercial fiber lasers had gone on the market for more than 20 years. Fiber lasers are regarded as a kind of amplifier for ultra-high-speed optical communication. Fiber laser technology presents broad application prospects and huge technological advantages in high-speed and large-capacity wavelength-division multiplexing fiber-optic communication systems, high-precision fiber-optic sensing technology, and high-power lasers. Fiber lasers have many unique advantages, such as: low laser threshold, high gain, good heat dissipation, many tunable parameters, wide absorption and radiation, compatibility with other fiber devices, and small size. Based on these advantages, fiber lasers are gradually replacing the status of traditional solid-state lasers in various fields, playing an increasingly important role. In recent years, the output power of fiber lasers has been rapidly increased, reaching 10-100kW. As an industrial laser, it has become the laser with the highest output power. The technical research of fiber lasers has received widespread attention from countries all over the world, and has become a hot frontier research topic in the international academic community. Its application field has also rapidly expanded from the most mature optical fiber communication network to other broader laser application fields.

With the development of double-clad doped fiber manufacturing technology and high-brightness pump source technology, the output power of fiber lasers has increased rapidly at an alarming rate. At present, the output power of single-mode fiber lasers has exceeded 10,000 watts. In high-power fiber lasers, due to the extremely high laser power density, various nonlinear effects in the fiber have become a key factor limiting the increase of laser power. Therefore, the combined effect of dispersion and nonlinearity needs to be considered. The peak power of ultrashort pulse output is very high, and the resulting nonlinear effect will also lead to the deterioration of the pulse shape. Due to the influence of nonlinear effects, thermal damage, and the brightness of the pump source, the output power of the ultrashort pulse laser of ordinary double-clad fibers is limited, and the continuous wave damage threshold of the single-mode active fiber laser core is 1W/μm^2 [J.Nilsson, J.K.Sahu, Y.Jeong, W.A.Clarkson, R.Selvas, A.B.Grudinin, and S.U.Alam, "High Power Fiber Lasers: New Developments", Proceedings of SPIE Vol.4974, 50-59 (2003)], which The danger of optical damage has become a major challenge in realizing high-power single-mode fiber lasers. In addition to optical damage, the heat generated by the high-power light can damage the fiber and even eventually melt the core. It has been reported in the literature that erbium-ytterbium co-doped fiber lasers can generate 100W heat per meter [J.Nilsson,S.U.Alam,J.A.Alavarez-Chavez,P.W.Turner,W.A.Clakson,and A>B.Grudinin,"High-power and tunable operation of erbium-ytterbium co-doped cladding-pumped fiber laser", IEEE J. Quantum Electron. 39, 987-994 (2003)].

In order to overcome the existing traditional double-clad single-mode fiber lasers with limited output single-mode laser power and with the increase of optical power, the output beam quality deteriorates, and the defects in heat resistance, etc., authorized announcement number: CN201282264Y, announcement date : 2009.7.29, provided "multiple multi-mode fiber bundles of ultra-high power single-mode lasers"; Authorization announcement number: CN100589295C, announcement date: 2010.2.10, provided "seed laser injection type active fiber rod single-mode laser" , which are used to achieve high-power single-mode laser output. However, the coupling between the multiple active rare earth doped cores in these fiber lasers is related to the distance between the multiple active rare earth doped cores, and the distance between the multiple active rare earth doped cores is required to be within a certain range. Therefore, the manufacturing difficulty of the active fiber is increased, and the yield is low. At the same time, in order to maintain the coupling conditions between the cores, these lasers have high requirements on the stability of the external environment and are not applicable. The seed laser injection type active fiber rod single-mode laser has low pump light-output light conversion efficiency due to its small active fiber rod mode field area and its pumping method, and its output optical power also decreases accordingly. lower quality.

SUMMARY OF THE INVENTION

In order to overcome the complex manufacturing process of the existing traditional double-clad single-mode fiber laser, the requirement for the stability of the external environment is high, the conversion efficiency of pump light to output light is low, the output single-mode laser power is limited, and with the increase of optical power With the increase of the output beam quality, the quality of the output beam is deteriorated, and the defects such as heat resistance, etc., are presented. A high-efficiency injection-locked fiber taper laser is proposed.

The purpose of this invention is to realize through the following technical solutions:

A high-efficiency injection-locked fiber taper laser includes a pump source, an isolator, a common single-mode active rare-earth-doped fiber, and a double-clad active rare-earth-doped tapered fiber; the double-clad active rare-earth-doped tapered fiber is composed of Active rare-earth-doped core, inner cladding and outer cladding are composed of refractive indices n1, n2, and n3, respectively, and n1>n2>n3. The refractive index distribution of this fiber is different from that of traditional double-clad active fiber n1> The refractive index distribution of n2=n3, this refractive index distribution can ensure that the higher-order modes excited by the optical transmission process are more effectively coupled to the inner cladding, and obtain a higher signal absorption rate, and can also suppress the mode instability to a certain extent. effect.

Using an ultraviolet laser or a femtosecond laser to write a high-reflectivity tilt-angle grating corresponding to the laser wavelength in the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber, which reduces the light leakage in the tapered region of the fiber, The laser oscillating back and forth in the laser cavity is reflected and scattered by the inclined fiber grating and then recoupled to the center of the fiber core, which limits the laser output area, greatly improves the pumping efficiency, and also greatly improves the output laser power and quality.

The pump light passes through the common single-mode active rare-earth-doped fiber resonator to generate the seed source laser. After the seed source laser enters the double-clad active rare-earth-doped tapered fiber, active phase locking and laser amplification can be achieved, thereby obtaining high power and high quality. laser output.

The characteristics of the invented laser are: writing a high reflection grating corresponding to the laser wavelength and a partial reflection grating corresponding to the laser wavelength on both ends of an ordinary single-mode active rare-earth-doped fiber; using an ultraviolet laser or a femtosecond laser to perform active doping on the double-cladding layer. Write a partial reflection grating corresponding to the laser wavelength on the thick end of the rare earth tapered fiber, or coat the thick end face of the double-clad active rare earth doped tapered fiber with a partial reflection film corresponding to the laser wavelength; use an ultraviolet laser or a femtosecond laser to High reflection tilt angle grating corresponding to the laser wavelength is written into the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber; The thin ends of the rare-earth-doped tapered fibers are connected to form the resonant cavity.

The pumping methods used by the pump source are divided into forward end-face pumping, backward end-face pumping, side pumping, simultaneous forward end-face pumping and backward end-face pumping, and simultaneous forward end-face pumping and side pumping. pumping, simultaneous backward end pumping and side pumping, simultaneous forward end pumping, backward end pumping and side pumping.

The beneficial effects of the invention are as follows: the optical fiber laser adopts a double-clad active rare-earth-doped tapered optical fiber whose refractive index distribution is different from that of a traditional double-clad active rare-earth-doped fiber. The refractive indices of the core, inner cladding and outer cladding are n1, n2, and n3, respectively, and n1>n2>n3, while the refractive index distribution of the traditional double-clad active rare-earth-doped fiber is n1>n2=n3, and the double cladding has The advantage of this refractive index distribution of the source rare-earth-doped tapered fiber is that it can ensure that the higher-order modes excited by the optical transmission process are more efficiently coupled to the inner cladding to obtain a higher signal absorption rate, so that the wavelength of the incident pump light can be appropriate. By moving to the short wavelength direction, the mode instability effect can be suppressed to a certain extent, and the output light of high quality and high power can be obtained.

At the same time, using the reflection and scattering effects of the tilt-angle fiber grating on the incident light, use an ultraviolet laser or a femtosecond laser to write high reflection corresponding to the laser wavelength in the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber. The tilt angle grating reduces the light leakage in the tapered area of the fiber, so that the laser oscillating back and forth in the laser cavity is reflected and scattered by the tilt angle fiber grating and then recoupled to the center of the fiber core, ensuring that the laser is output in a smaller area, thereby improving the The pump efficiency is greatly improved, and the output optical power and laser quality are greatly improved. Moreover, the large mode field area of the double-clad active rare-earth-doped tapered fiber can make the laser have better heat dissipation. The fiber laser has a simple structure, low requirements for external environmental conditions, and good practical application.

Description of drawings

Figure 1 is a schematic longitudinal cross-sectional view of a high-efficiency injection-locked fiber tapered laser with forward end-pumping and double-clad active rare-earth-doped tapered fiber butt end with a reflection grating written at the end.

Figure 2 is a longitudinal section of a side-pumped, high-efficiency injection-locked fiber taper laser with a high-efficiency injection-locked fiber taper laser coated on one end of an ordinary single-mode active rare-earth-doped fiber with a high-reflection coating, and a double-clad active rare-earth-doped tapered fiber with a thick end coated with a reflective coating on the end. Schematic.

Figure 3 is a schematic longitudinal cross-section of a back-end-pumped, double-clad active rare-earth-doped tapered fiber with a high-efficiency injection-locked fiber tapered laser with a reflection grating written at the end of the thick end.

Figure 4 is a schematic longitudinal cross-sectional view of a high-efficiency injection-locked fiber taper laser with multiple pump sources forwarding end-face pumping and a double-clad active rare-earth-doped tapered fiber with a reflection grating written at the end of the thick end.

Figure 5 is a schematic longitudinal cross-sectional view of a high-efficiency injection-locked fiber taper laser with multiple pump sources forward end-pumping and side-pumping, and a double-clad active rare-earth-doped tapered fiber with a reflection grating written at the end of the thick end.

Figure 6 is a longitudinal cross-sectional schematic diagram of a high-efficiency injection-locked fiber taper laser with multiple pump sources forward end-face pumping and backward end-face pumping, double-clad active rare-earth-doped tapered fiber butt end face coated with reflective film.

Figure 7 is a schematic longitudinal cross-section of a back-end-pumped and side-pumped, double-clad active rare-earth-doped tapered fiber butt end face coated with a reflective film on the end face of a high-efficiency injection-locked fiber taper laser.

Figure 8 shows the high-efficiency injection-locked fiber taper laser with multiple pump sources forward end-pumped, backward end-pumped and side-pumped, double-clad active rare-earth-doped tapered fiber butt end with reflective coating on the end face Schematic diagram of longitudinal section.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Example 1

In this example, a high-efficiency injection-locked fiber taper laser, as shown in Figure 1, includes: a pump source 1, an optical isolator 2, a common single-mode active rare-earth doped fiber 3, a double-clad active doped fiber Rare Earth Tapered Fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The doping ions of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 are all erbium ions, and the core diameter of the common single-mode active rare-earth-doped fiber 3 is 9 μm, and the cladding diameter is 125 μm; Double-clad active rare earth-doped tapered fiber 4. The diameter of the thin end fiber is d1=9μm, the diameter of the inner cladding is d2=90μm, and the diameter of the outer cladding is d3=125μm; The layer diameter d3=4500μm, the fiber length is 10 meters, and the inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or quincunx-shaped. A grating 31 with a reflection coefficient over 99% and a grating 32 with a reflection coefficient of 80% are respectively written on both ends of the common single-mode active rare-earth-doped fiber 3 . A femtosecond laser is used to write a grating 5 with a reflectivity of 5%-8% at the thick end of the double-clad active rare-earth-doped tapered fiber 4, and the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 The regions are written into gratings 52 and 53 with a grating tilt angle of 45° and a reflectivity of 99% using an ultraviolet laser or a femtosecond laser, respectively. The pump source 1 performs forward end-face pumping.

Embodiment 2

In this example, a high-efficiency injection-locked fiber tapered laser, as shown in FIG. 2 , includes: a pump source 13 , a common single-mode active rare-earth-doped fiber 3 , and a double-clad active rare-earth-doped tapered fiber 4 . The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The doping ion type of the ordinary single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 is ytterbium ion, the core diameter of the ordinary single-mode active rare-earth-doped fiber 3 is 6 μm, and the cladding diameter 125μm; double-clad active rare-earth-doped tapered fiber 4 thin end fiber diameter d1 = 6μm, inner cladding diameter d2 = 80μm, outer cladding diameter d3 = 125μm; thick end core diameter d1 = 300μm, inner cladding diameter d2 = 400μm , the outer cladding diameter d3=500μm, the fiber length is 2 meters, and the inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or plum-shaped. A grating 31 with a reflection coefficient of more than 99% and a grating 32 with a reflection coefficient of 80% are written on both ends of the common single-mode active rare-earth-doped fiber 3, respectively, and a layer of reflectivity of 100% is coated on the front end face of the optical fiber on the side of the grating 31. reflective film 8. A reflective film 51 with a reflectivity of 5%-8% is coated on the end face of the thick end of the double-clad active rare-earth-doped tapered fiber 4, and the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 Except for the center of the fiber core, all gratings 54 and 55 with a grating inclination angle of 80° and a reflectivity of 99% are written by an ultraviolet laser. The outer cladding 43 and inner cladding 42 of the thick end of the double-clad active rare-earth-doped tapered optical fiber 4 are engraved with V-shaped, concave-shaped or arbitrary-shaped grooves, and the pump source 13 uses this groove to perform side pumping.

Embodiment 3

In this example, a high-efficiency injection-locked fiber taper laser, as shown in FIG. 3, includes: a pump source 12, a bipartite mirror 62, a reflector 61, a common single-mode active rare-earth-doped fiber 3, a double-cladding Active Rare Earth Doped Tapered Fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The doping ion type of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 is holmium ions, the core diameter of the common single-mode active rare-earth-doped fiber 3 is 2 μm, and the cladding diameter is 400 μm; Double-clad active rare-earth-doped tapered fiber 4. The diameter of the thin end fiber is d1=2μm, the diameter of the inner cladding is d2=350μm, and the diameter of the outer cladding is d3=400μm; The layer diameter d3=1600 μm, the fiber length is 5 meters, and the inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or quincunx-shaped. A grating 31 with a reflection coefficient of more than 99% and a grating 32 with a reflection coefficient of 80% are written on both ends of the common single-mode active rare-earth-doped fiber 3, respectively, and a layer of reflectivity of 100% is coated on the front end face of the optical fiber on the side of the grating 31. reflective film 8. Write a grating 5 with a reflectivity of 5%-8% at the thick end of the double-clad active rare-earth-doped tapered fiber 4, and use an ultraviolet laser in the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 Alternatively, the femtosecond laser writes gratings 52 and 53 with a grating tilt angle of 10° and a reflectivity of 99%, respectively. The pump source 12 performs backward end-face pumping of the laser cavity through the bipartite mirror 62 and the mirror 61 .

Embodiment 4

In this example, a high-efficiency injection-locked fiber cone laser, as shown in FIG. 4 , the laser includes: a pump source 1, a pump source 14, ..., a pump source 1N, an optical combiner 7, and an optical isolator 2 , Ordinary single-mode active rare-earth-doped fiber 3, double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The optical combiner 7 couples the plurality of pump lights into the transmission fiber. The doping ions of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 are all thulium ions, and the core diameter of the common single-mode active rare-earth-doped fiber 3 is 1 μm, and the cladding diameter is 80 μm; Double-clad active rare earth-doped tapered fiber 4. The diameter of the thin end fiber is d1=1μm, the diameter of the inner cladding is d2=60μm, and the diameter of the outer cladding is d3=80μm; The layer diameter d3 = 1000 μm, the fiber length is 2 meters, and the inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or quincunx-shaped. A grating 31 with a reflection coefficient over 99% and a grating 32 with a reflection coefficient of 80% are respectively written on both ends of the common single-mode active rare-earth-doped fiber 3 . A grating 5 with a reflectivity of 5%-8% is written at the thick end of the double-clad active rare-earth-doped tapered fiber 4 using an ultraviolet laser or a femtosecond laser, and the double-clad active rare-earth-doped tapered fiber 4 tapers The upper and lower half regions of the region are respectively written into gratings 52 and 53 with a grating inclination angle of 20° and a reflectivity of 99% by using an ultraviolet laser or a femtosecond laser. Pump source 1, pump source 14, . . . , pump source 1N perform forward end-face pumping.

Embodiment 5

In this example, a high-efficiency injection-locked fiber cone laser, as shown in FIG. 5 , the laser includes: a pump source 1, a pump source 13, a pump source 14, ..., a pump source 1N, and an optical combiner 7 , Optical isolator 2, common single-mode active rare-earth-doped fiber 3, double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The optical combiner 7 couples the plurality of pump lights into the transmission fiber. The doping ions of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 are all neodymium ions, and the core diameter of the common single-mode active rare-earth-doped fiber 3 is 3 μm, and the cladding diameter is 125 μm; Double-clad active rare-earth-doped tapered fiber 4. The diameter of the thin end fiber is d1=3μm, the diameter of the inner cladding is d2=100μm, and the diameter of the outer cladding is d3=125μm; The layer diameter d3=255μm, the fiber length is 1 meter, and the inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or quincunx-shaped. A grating 31 with a reflection coefficient over 99% and a grating 32 with a reflection coefficient of 80% are respectively written on both ends of the common single-mode active rare-earth-doped fiber 3 . A grating 5 with a reflectivity of 5%-8% is written at the thick end of the double-clad active rare-earth-doped tapered fiber 4 using an ultraviolet laser or a femtosecond laser, and the double-clad active rare-earth-doped tapered fiber 4 tapers The upper and lower half regions of the region are respectively written into gratings 52 and 53 with a grating tilt angle of 30° and a reflectivity of 99% by using an ultraviolet laser or a femtosecond laser. The pump source 1, the pump source 14, . . . , the pump source 1N performs forward end-face pumping, and the pump source 13 performs side-side pumping. The outer cladding 43 and inner cladding 42 of the thick end of the double-clad active rare-earth-doped tapered optical fiber 4 are engraved with V-shaped, concave-shaped or arbitrary-shaped grooves, and the pump source 13 uses this groove to perform side pumping.

Embodiment 6

In this example, a high-efficiency injection-locked fiber taper laser, as shown in FIG. 6 , the laser includes: a pump source 1, a pump source 12, a pump source 14, ..., a pump source 1N, and an optical combiner 7 , Optical isolator 2, bipartite mirror 62, mirror 61, common single-mode active rare-earth-doped fiber 3, double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The optical combiner 7 couples the plurality of pump lights into the transmission fiber. The doping ions of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 are all erbium-ytterbium co-doped ions. The core diameter of the common single-mode active rare-earth-doped fiber 3 is 20 μm, and the cladding Diameter 400μm; double-clad active rare-earth-doped tapered fiber 4 thin end fiber diameter d1=20μm, inner cladding diameter d2=350μm, outer cladding diameter d3=400μm; thick end core diameter d1=2000μm, inner cladding diameter d2= 3000μm, outer cladding diameter d3=3800μm, fiber length is 8 meters, inner cladding structure can be circular, D-shaped, rectangular, hexagonal, octagonal, eccentric circular, star-shaped or plum-shaped. A grating 31 with a reflection coefficient over 99% and a grating 32 with a reflection coefficient of 80% are respectively written on both ends of the common single-mode active rare-earth-doped fiber 3 . A reflective film 51 with a reflectivity of 5%-8% is coated on the end face of the thick end of the double-clad active rare-earth-doped tapered fiber 4, and the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 The gratings 52 and 53 with a grating tilt angle of 55° and a reflectivity of 99% are written by an ultraviolet laser or a femtosecond laser, respectively. The pump source 1 , the pump source 14 , . . . , the pump source 1N perform forward end-face pumping, and the pump source 12 performs backward end-face pumping of the laser cavity through the bipartite mirror 62 and the mirror 61 .

Embodiment 7

In this example, a high-efficiency injection-locked fiber taper laser, as shown in Figure 7, includes: a pump source 12, a pump source 13, a bipartite mirror 62, a reflector 61, and a common single-mode active rare-earth-doped fiber 3. Double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. Common single-mode active rare-earth-doped fiber 3 and double-clad active rare-earth-doped tapered fiber 4 are doped ions of erbium-doped or ytterbium-doped or holmium-doped or thulium-doped or neodymium-doped or erbium-ytterbium co-doped ions. Mode active rare-earth-doped fiber 3 has a core diameter of 10 μm and a cladding diameter of 125 μm; double-clad active rare-earth-doped tapered fiber 4 has a fine end fiber diameter d1=10 μm, inner cladding diameter d2=100 μm, and outer cladding diameter d3=125 μm ; The diameter of the butt end core is d1=500μm, the diameter of the inner cladding is d2=800μm, the diameter of the outer cladding is d3=1000μm, the length of the fiber is 4 meters, and the inner cladding structure can be circular, or D-shaped, rectangular, hexagonal, Octagon, eccentric round, star or quincunx. A grating 31 with a reflection coefficient exceeding 99% and a grating 32 with a reflection coefficient of 80% are written on both ends of the ordinary single-mode active rare-earth-doped fiber 3, respectively, and a layer of reflectivity 100% is coated on the front end face of the optical fiber on the side of the grating 31. reflective film 8. A reflective film 51 with a reflectivity of 5%-8% is coated on the end face of the thick end of the double-clad active rare-earth-doped tapered fiber 4, and the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 The gratings 52 and 53 with a grating tilt angle of 60° and a reflectivity of 99% are written by an ultraviolet laser or a femtosecond laser, respectively. The pump source 12 carries out backward end-face pumping of the laser cavity through the bisecting mirror 62 and the mirror 61; the outer cladding 43 and the inner cladding 42 of the thick end of the double-clad active rare-earth-doped tapered fiber 4 are engraved with a V-shaped, concave A zigzag or arbitrarily shaped groove is used by the pump source 13 for side pumping.

Embodiment 8

In this example, a high-efficiency injection-locked fiber taper laser, as shown in Figure 8, includes: a pump source 1, a pump source 12, a pump source 13, a pump source 14, ..., a pump source 1N , Optical beam combiner 7, optical isolator 2, bisecting mirror 62, mirror 61, common single-mode active rare-earth-doped fiber 3, double-clad active rare-earth-doped tapered fiber 4. The double-clad active rare-earth-doped tapered optical fiber 4 is composed of an active rare-earth-doped core 41, a core, an inner cladding 42, and an outer cladding 43. The refractive indices of the core, the inner cladding and the outer cladding are n1, n2, n3 and n1>n2>n3. The optical combiner 7 couples the plurality of pump lights into the transmission fiber. The doping ions of the common single-mode active rare-earth-doped fiber 3 and the double-clad active rare-earth-doped tapered fiber 4 are all erbium-doped or ytterbium-doped or holmium-doped or thulium-doped or neodymium-doped or erbium-ytterbium co-doped ions. Mode active rare earth doped fiber 3 has a core diameter of 30 μm and a cladding diameter of 1000 μm; double-clad active rare earth doped tapered fiber 4 has a fine end fiber diameter d1=30 μm, inner cladding diameter d2=800 μm, and outer cladding diameter d3=1000 μm ; The diameter of the butt end fiber core is d1=2500μm, the diameter of the inner cladding is d2=3000μm, the diameter of the outer cladding is d3=4500μm, the fiber length is 7 meters, and the inner cladding structure can be circular, or D-shaped, rectangular, hexagonal, Octagon, eccentric round, star or quincunx. A grating 31 with a reflection coefficient over 99% and a grating 32 with a reflection coefficient of 80% are respectively written on both ends of the common single-mode active rare-earth-doped fiber 3 . A reflective film 51 with a reflectivity of 5%-8% is coated on the end face of the thick end of the double-clad active rare-earth-doped tapered fiber 4, and the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber 4 The gratings 52 and 53 with a grating tilt angle of 70° and a reflectivity of 99% are written by an ultraviolet laser or a femtosecond laser, respectively. Pump source 1, pump source 14, ..., pump source 1N carry out forward end-face pumping; pump source 12 carries out backward end-face pumping to the laser cavity through bipartite mirror 62 and mirror 61; The outer cladding 43 and inner cladding 42 of the thick end of the source rare-earth-doped tapered optical fiber 4 are engraved with V-shaped, concave-shaped or arbitrary-shaped grooves, and the pump source 13 uses such grooves for side pumping.

Claims (1)

1. A high-efficiency injection-locked fiber tapered laser, comprising a pump source (1), an optical isolator (2), a common single-mode active rare-earth-doped fiber (3), and a double-clad active rare-earth-doped tapered fiber (4); the double-clad active rare-earth-doped tapered optical fiber (4) is composed of a rare-earth-doped core (41), an inner cladding (42) and an outer cladding (43), and the rare-earth-doped core (41), the inner cladding (43) 42) and the refractive index of the outer cladding (43) are n1, n2 and n3 respectively, and there are n1>n2>n3, the refractive index distribution of this fiber is different from the refractive index of the traditional double-clad active fiber n1>n2=n3 This kind of refractive index distribution can ensure that the high-order modes excited by the optical transmission process are more effectively coupled to the inner cladding to obtain a higher signal absorption rate, and at the same time, it can also suppress the mode instability to a certain extent; The invented laser is characterized in that a high reflection grating (31) corresponding to the laser wavelength and a partial reflection grating (32) corresponding to the laser wavelength are written on both ends of an ordinary single-mode active rare-earth-doped fiber (3), A low-reflection grating (5) corresponding to the laser wavelength is written on the thick end of the source rare earth-doped tapered optical fiber (4), or a part corresponding to the laser wavelength is plated on the thick end face of the double-clad active rare-earth-doped tapered optical fiber (4) Reflective film (51), in which high-reflectivity tilt-angle gratings (52) corresponding to laser wavelengths are respectively written on the outer edges of the cladding (42) in the upper and lower half regions of the tapered region of the double-clad active rare-earth-doped tapered optical fiber (4). and 53), or write tilted volume gratings (54 and 55) in the cladding (42) in the upper and lower half of the tapered region of the double-clad active rare-earth-doped tapered fiber (4), respectively.

Images