Photonic crystal fiber

A photonic crystal fiber (PCF),

• wherein the PCF is for laser processing,
• wherein the PCF has a 1-cell structure in which an effective area Aeff is 1600 μm2 or more, a bending loss in a fundamental mode with a bending radius of 140 mm is 1.0 dB/m or less in light having a wavelength of 1070 nm, and air holes having diameters d are arranged at intervals Λ, wherein the air holes extend in a propagation direction of light,
• wherein a number of propagation modes is set to 2 or more and 4 or less to raise an index of beam quality M2 of output light up to 3.3, by including the air holes having diameters d and intervals Λ in a design region surrounded by a polygon having vertices
• A3 (0.56, 40.00),
• C3 (0.90, 54.38), and
• I (0.90, 91.88), and
• wherein coordinates are represented by (d/Λ, Λ), and a propagation of 30 kW·m or more and 300 kW·m or less is enabled for light having a wavelength of 1050 nm or more.

A photonic crystal fiber (PCF),

• wherein the PCF is for laser processing,
• wherein the PCF has a 7-cell structure in which an effective area Aeff is 800 μm2 or more, a bending loss in a fundamental mode with a bending radius of 140 mm is 1.0 dB/m or less in light having a wavelength of 1070 nm, and air holes having diameters d are arranged at intervals Λ, wherein the air holes extend in a propagation direction of light,
• wherein a number of propagation modes is set to 2 or more and 4 or less to raise an index of beam quality M2 of output light up to 3.3, by including the air holes having diameters d and intervals Λ in a design region surrounded by a polygon having vertices
• A2 (0.21, 11.77),
• C2 (0.50, 13.68),
• C3 (0.60, 20.18),
• F (0.50, 14.47),
• G (0.69, 22.08),
• H (0.68, 23.67),
• I (0.70, 24.30),
• J (0.70, 32.87), and
• K (0.80, 50.00), and
• wherein coordinates are represented by (d/Λ, Λ), and a propagation of 30 kW·m or more and 150 kW·m or less is enabled for light having a wavelength of 1050 nm or more.

A photonic crystal fiber (PCF),

• wherein the PCF is for laser processing,
• wherein the PCF has a 7-cell structure in which an effective area Aeff is 1600 μm2 or more, a bending loss in a fundamental mode with a bending radius of 140 mm is 1.0 dB/m or less in light having a wavelength of 1070 nm, and air holes having diameters d are arranged at intervals Λ, wherein the air holes extend in a propagation direction of light,
• wherein a number of propagation modes is set to 2 or more and 4 or less to raise an index of beam quality M2 of output light up to 3.3, by including the air holes having diameters d and intervals Λ in a design region surrounded by a polygon having vertices
• A3 (0.27, 16.06),
• C3 (0.60, 20.18),
• G (0.69, 22.08),
• H (0.68, 23.67),
• I (0.70, 24.30),
• J (0.70, 32.87), and
• K (0.80, 50.00), and
• wherein coordinates are represented by (d/Λ, Λ), and a propagation of 30 kW·m or more and 300 kW·m or less is enabled for light having a wavelength of 1050 nm or more.

A photonic crystal fiber (PCF),

• wherein the PCF is for laser processing,
• wherein the PCF has a 7-cell structure in which an effective area Aeff is 3200 μm2 or more, a bending loss in a fundamental mode with a bending radius of 140 mm is 1.0 dB/m or less in light having a wavelength of 1070 nm, and air holes having diameters d are arranged at intervals Λ, wherein the air holes extend in a propagation direction of light,
• wherein a number of propagation modes is set to 2 or more and 4 or less to raise an index of beam quality M2 of output light up to 3.3, by including the air holes having diameters d and intervals Λ in a design region surrounded by a polygon having vertices
• A4 (0.40, 24.78),
• C4 (0.70, 30.01),
• J (0.70, 32.87), and
• K (0.80, 50.00), and
• wherein coordinates are represented by (d/Λ, Λ), and a propagation of 30 kW·m or more and 600 kW·m or less is enabled for light having a wavelength of 1050 nm or more.

A photonic crystal fiber (PCF),

• wherein the PCF is for laser processing,
• wherein the PCF has a 7-cell structure in which an effective area Aeff is 4800 μm2 or more, a bending loss in a fundamental mode with a bending radius of 140 mm is 1.0 dB/m or less in light having a wavelength of 1070 nm, and air holes having diameters d are arranged at intervals Λ, wherein the air holes extend in a propagation direction of light,
• wherein a number of propagation modes is set to 2 or more and 4 or less to raise an index of beam quality M2 of output light up to 3.3, by including the air holes having diameters d and intervals Λ in a design region surrounded by a polygon having vertices
• A5 (0.53, 32.87),
• C5 (0.73, 37.00), and
• K (0.80, 50.00), and
• wherein coordinates are represented by (d/Λ, Λ), and a propagation of 30 kW·m or more and 900 kW·m or less is enabled for light having a wavelength of 1050 nm or more.