L-band amplification with detuned 980nm pump

A method of operating an optical amplifier for improved gain and pump-to-signal conversion efficiency in a long wavelength spectral region (L-band) of the emission spectrum of a rare earth doped gain medium having a known pump absorption band, comprising the steps of:

• a) providing an optical signal to the amplifier having a large-signal input power;
• and
• b) providing pumping light to the amplifier having a wavelength that is detuned from a center wavelength of the known pump absorption band for amplifying the optical signal such that a value of the amplified signal power at any detuned pump wavelength is greater than the amplified signal power at the pump band center wavelength.

A method of operating an optical amplifier for improved gain and pump-to-signal conversion efficiency in a long wavelength spectral region (L-band) of the emission spectrum of a rare earth doped gain medium having a known pump absorption band, comprising the steps of:

• a) providing an optical signal to the amplifier having a large-signal input power;
• and
• b) providing pumping light to the amplifier having a wavelength that is detuined from a center wavelength of the known pump absorption band for amplifying the optical signal such that a measured value of ASE traveling counterdirectionally to the pump light is less at any detuned pump wavelength than the measured ASE at the pump band center wavelength.

An optical amplifier, comprising:

• a rare earth doped gain stage having an emission spectrum and a known pump wavelength absorption band for amplifying an input signal having a wavelength in a long wavelength region of the emission spectrumn and a large input signal power;
• a pump light source emitting an operating wavelength at a value different from a center wavelength of the pump absorption band, coupled to the gain stage;
• wherein an amplified output signal has a signal power at said operating wavelength greater than an output signal when the operating wavelength is substantially the same as the center wavelength.