Lasers, optical amplifiers, and amplification methods

An optical amplification method that uses an optical amplifier having:

• an optical amplification medium doped with Er3+ ions and selected from a group of a flouride glass a chalcogenide glass, a telluride glass, a halide crystal, and a lead oxide based glass;
• a rump light source for exciting said Er3+ ions with an oscillation wavelength in a range of 0.96 μm to 0.98 μm;
• and a light source for an excitation to 4I13/2 level, comprising the steps of:
• launching pump light, which is emitted in a same direction as that of light to be amplified and launched into said optical amplification medium from said pump light source for exciting said Er3+ ions with an oscillation wavelength in a range of 0.96 μm to 0.98 μm, into said optical amplification medium;
• and
• launching additional light, which is emitted in an opposite direction of said pump light, from said light source for an excitation to 4I13/2 level into said optical amplification medium.

An optical amplifier for exciting Er3+ ions to a 4I13/2 level including:

• an optical amplification medium doped with Er3+ ions;
• means for inducing and isolating signal light at a wavelength of 1.5 μm in said optical amplification medium;
• and
• a pump light source for the excitation of said optical amplification medium, wherein
• said pump light source includes at least a first light source and a second light source, which emit light at different wavelengths, and
• said first light source is provided as a light source for emitting light at a wavelength corresponding to an energy difference between the 4I13/2 level of said Er3+ ions and an energy level higher than said 4I13/2 level.