Advances in high power laser diodes in the 1400–1910nm wavelength regime

The emission wavelength of a Fabry-Perot laser diode is determined by the gain spectrum of the semiconductor active layer, but this gain spectrum is “flat” (with characteristic width ∼ 20 nm), and strongly temperature dependent, resulting in a broad, poorly defined and highly temperature dependent spectrum. This is especially true for lasers lasing near 1900nm, where the typical spectral width of a Fabry-Perot diode laser is ∼15nm and the wavelength tunes with temperature by ∼0.5 nm per °C. An important application is pumping of Ho:YAG, but the absorption line at 1908 nm is relatively narrow (<3 nm) which challenges the capabilities of conventional laser diodes for the abovementioned reasons.