The invention relates to phosphate-based glasses suitable for use as a solid laser medium, doped with Er3+ and sensitized with Yb, in eye-safe applications. In particular, the invention relates to improving the physical properties of such phosphate-based laser glass composition, particularly with regards to strength of the glass structure and improved thermal shock resistance.

A phosphor element includes an incident face for an excitation light, an emitting face opposing the incident face and a side face, and the element converts at least a part of the incident excitation light incident onto the incident face to fluorescence and emits the fluorescence from the emitting face. The emitting face has an area larger than an area of the incident face. The phosphor element comprises an inclination region in which an inclination angle of the side face with respect to a vertical axis perpendicular to the emitting face is monotonously increased from the incident face toward the emitting face, viewed in a cross-section perpendicular to the emitting face and along the longest dividing line halving the emitting face.

According to an aspect of an embodiment, an optical amplification system may include a broadband pump source and an optical fiber doped with phosphorus. The broadband pump source may be configured to generate a pumping beam. The pumping beam may include a pumping wavelength range between 1330 nm and 1400 nm. The optical fiber may be configured to receive the pumping beam and an input optical signal. The input optical signal may include a first component that may correspond to a first wavelength range and a second component that may correspond to a second wavelength range. The pumping beam may cause Raman amplification to the first component and the pumping beam may cause Raman amplification to the second component. The amplification of the first component and the second component by the pumping beam may produce an amplified optical signal.

Example optical amplification apparatuses and example signal amplification methods are provided. One example optical amplification apparatus is connected to an optical fiber. The optical amplification apparatus includes a first pump laser and a first gain medium. The first pump laser is configured to emit first pump light. The first gain medium is configured to receive the first pump light and first multi-channel optical signals from the optical fiber; and perform gain amplification on the first multi-channel optical signals based on the first pump light, where the first pump light overlaps each of the first multi-channel optical signals in the first gain medium.