Abstract: A fibre laser assembly includes a pump laser assembly for optical pumping of an active fibre with first pump radiation of a first pump wavelength and means for the generation of second pump radiation at a second pump wavelength, which lies between the first pump wavelength and the wavelength of the seed laser. Doping concentration, length of the active fibre, and power of the first pump radiation are coordinated such that the active fibre absorbs the first pump radiation in the first fibre portion to >90%, the radiation of the second pump wavelength in the first fibre portion is amplified by the first pump radiation to generate the second pump radiation, and the laser radiation of the seed laser is amplified in the remaining second fibre portion by the second pump radiation.

Abstract: A hybrid optical amplifier is proposed that includes a preamplifier element formed of single-clad Ho-doped optical fiber and a power amplifier element formed of single-clad Tm-doped (or Tm—Ho co-doped) optical fiber. The preamplifier is used to impart gain to an input signal propagating at a wavelength ?S in the presence of a first pump beam operating at ?P1, creating an amplified output over a defined transmission bandwidth. The power amplifier element is disposed at the output of the preamplifier element and provides an additional level of gain to the output of the preamplifier element in the presence of a second pump beam operating at ?P2. A passband filter may be used between the preamplifier and the power amplifier to ensure that only wavelength components within the defined transmission bandwidth are applied as an output to the power amplifier.

Abstract: A doped fiber amplifier is proposed that includes both a Ho-doped amplifier (used as a preamplifier) and a Tm-doped amplifier (used as a power amplifier). The Ho-doped preamplifier typically uses a single clad (SC) optical fiber as the gain element, with both the propagating signal and pump beam introduced into the Ho-doped core of the SC fiber. The Tm-doped power amplifier typically utilizes a double clad (DC) optical fiber as the gain element, which allows for a multimode pump to propagate within the Tm-doped core region and inner cladding, providing efficient high power amplification of the signal received at its input.

Abstract: A hybrid optical amplifier is proposed that includes a preamplifier element formed of single-clad Ho-doped optical fiber and a power amplifier element formed of single-clad Tm-doped (or Tm—Ho co-doped) optical fiber. The preamplifier is used to impart gain to an input signal propagating at a wavelength ?S in the presence of a first pump beam operating at ?P1, creating an amplified output over a defined transmission bandwidth. The power amplifier element is disposed at the output of the preamplifier element and provides an additional level of gain to the output of the preamplifier element in the presence of a second pump beam operating at ?P2. A passband filter may be used between the preamplifier and the power amplifier to ensure that only wavelength components within the defined transmission bandwidth are applied as an output to the power amplifier.

Abstract: A doped fiber amplifier is proposed that includes both a Ho-doped amplifier (used as a preamplifier) and a Tm-doped amplifier (used as a power amplifier). The Ho-doped preamplifier typically uses a single clad (SC) optical fiber as the gain element, with both the propagating signal and pump beam introduced into the Ho-doped core of the SC fiber. The Tm-doped power amplifier typically utilizes a double clad (DC) optical fiber as the gain element, which allows for a multimode pump to propagate within the Tm-doped core region and inner cladding, providing efficient high power amplification of the signal received at its input.