Polarization-maintaining optical fiber amplifier employing externally applied stress-induced birefringence

An optical amplifier with a rare-earth-doped polarization-maintaining optical fiber, the amplifier comprising:

• a mandrel having a selected diameter;
• a rare-earth-doped polarization-maintaining optical fiber having one or more cladding layers and having linear birefringence greater than a random birefringence;
• and
• a pump source which is coupled to said optical fiber;
• wherein said rare-earth-doped polarization-maintaining optical fiber is coiled around said mandrel under tension;
• wherein said rare-earth-doped polarization-maintaining optical fiber is secured around said mandrel to thereby maintain said tension;
• wherein said mandrel diameter is chosen to avoid significant bend loss;
• wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Ho3+, Er3+, Sm3+ and Tm3+;
• wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm;
• and
• wherein said tension is chosen to avoid undesirable weakening of said polarization-maintaining fiber.

A method of forming a linear polarization-maintaining optical fiber amplifier, the method comprising the steps of:

• providing a rare-earth-doped non-polarization-maintaining optical fiber having one or more cladding layers and having a random birefringence;
• providing a mandrel having a selected diameter;
• coiling said non-polarization-maintaining optical fiber under a selected tension around said mandrel to induce a linear birefringence greater than said random birefringence in said non-polarization-maintaining optical fiber thereby forming a polarization-maintaining optical fiber;
• securing said polarization-maintaining optical fiber to said mandrel to thereby maintain said tension;
• and
• coupling a pump source to polarization-maintaining optical fiber;
• wherein said mandrel diameter is chosen to avoid significant bend loss;
• wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Er3+, Sm3+, Ho3+ and Tm3+;
• wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm;
• and
• wherein said tension is chosen to avoid undesirable weakening of said non-polarization maintaining fiber.

A method of forming a linear polarization-maintaining optical fiber for use in an amplifier, the method comprising the steps of:

• providing a rare-earth-doped non-polarization-maintaining optical fiber having one or more cladding layers, a diameter, a high NA and a random birefringence;
• providing a mandrel having a selected diameter;
• coiling said non-polarization-maintaining optical fiber around said mandrel to induce a linear birefringence greater than said random birefringence in said non-polarization-maintaining optical fiber thereby forming a polarization-maintaining optical fiber;
• and
• securing said polarization-maintaining optical fiber to said mandrel to thereby maintain said tension;
• and
• wherein said mandrel diameter is chosen to avoid significant bend loss;
• wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Ho3+, Er3+, Sm3+ and Tm3+;
• wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm;
• and
• wherein said diameter of said non-polarization-maintaining optical fiber is from about 50 μm to about 1000 μm.

An optical amplifier with a rare-earth-doped polarization-maintaining optical fiber, the amplifier comprising:

• a mandrel having a selected diameter;
• a rare-earth-doped polarization-maintaining optical fiber having one or more cladding layers, a high NA, and having linear birefringence greater than a random birefringence;
• and
• a pump signal source which is coupled to said optical fiber;
• wherein said rare-earth-doped polarization-maintaining optical fiber is coiled around said mandrel;
• wherein said rare-earth-doped polarization-maintaining optical fiber is secured around said mandrel to thereby maintain said tension;
• wherein said mandrel diameter is chosen to avoid significant bend loss;
• wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Ho3+, Er3+, Sm3+ and Tm3+;
• wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm;
• and
• wherein said diameter of said polarization-maintaining optical fiber is from about 50 μm to about 1000 μm.

A method of forming a linear polarization-maintaining optical amplifier for use in an amplifier, the method comprising the steps of:

• providing a rare-earth-doped non-polarization-maintaining optical fiber having one or more cladding layers, a diameter, a high NA and a random birefringence;
• providing a mandrel having a selected diameter;
• coiling said non-polarization-maintaining optical fiber around said mandrel to induce a linear birefringence greater than said random birefringence in said non-polarization-maintaining optical fiber thereby forming a polarization-maintaining optical fiber;
• and
• securing said polarization-maintaining optical fiber to said mandrel to thereby maintain said tension;
• and
• coupling a pump source to polarization-maintaining optical fiber;
• wherein said mandrel diameter is chosen to avoid significant bend loss;
• wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Er3+, Sm3+, Ho3+ and Tm3+;
• wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm;
• and
• wherein said non-polarization-maintaining optical fiber diameter is from about 50 μm to about 1000 μm.