摘要 |
A multi-chip pump unit comprising a light source and a filter for directing light from the light source towards an optical fiber, wherein the filter exhibits one of either (i) relatively low transmissivity and high reflectivity at a wavelength of the light source, and relatively high transmissivity and low reflectivity at a wavelength greater than the wavelength of the light source; or (ii) relatively high transmissivity and low reflectivity at a wavelength of the light source, and relatively low transmissivity and high reflectivity at a wavelength greater than the wavelength of the light source. |