915 nm Single-Frequency Nd:YAG Crystal-Derived Fiber Laser

Abstract

This page is based on the paper "915 nm Single-Frequency Nd:YAG Crystal-Derived Fiber Laser" published in Acta Optica Sinica, Vol. 41, No. 22 (2021), DOI: 10.3788/AOS202141.2206001. The authors reported a 915 nm single-frequency fiber laser using an Nd:YAG crystal-derived fiber prepared by the molten-core method.

In this work, a 2.5 at.% Nd:YAG crystal was used as the core precursor and a high-purity silica tube was used as the cladding material. The resulting Nd:YAG-derived fiber showed a transmission loss of 8 dB/m and a gain coefficient of 1.16 dB/cm at 915 nm. Based on an ultra-short distributed Bragg reflector (DBR) cavity, the team achieved stable single-frequency operation with an optical signal-to-noise ratio higher than 50 dB.^[1]

Experimental configuration redrawn from the paper

The paper uses an ultra-short-cavity DBR structure to force single-longitudinal-mode oscillation. This approach is especially suitable for crystal-derived silica fibers because the gain per unit length is higher than in ordinary low-doped silica rare-earth fibers, allowing the cavity to remain short while still providing sufficient gain.

For AOG CRYSTAL's application perspective, this work is important because it connects the high spectroscopic quality of Nd:YAG with the flexible integration advantages of fiber devices. It shows that Nd:YAG is not limited to conventional bulk rods and microchip cavities, but can also be engineered into short-cavity narrow-linewidth fiber lasers.

Key performance and paper analysis

According to the paper and the later review that cites it, the 915 nm laser output was centered at 915.37 nm, with a maximum output power of 13.5 mW and a slope efficiency of about 3.9%. The output optical signal-to-noise ratio was greater than 50 dB, confirming stable single-frequency behavior.^[1][2]

Another important conclusion is that the emission intensity of this Nd:YAG crystal-derived fiber remains broadly comparable over the 890-920 nm band. The paper therefore suggests that by changing the grating center wavelength, this material platform has strong potential for single-frequency lasers across the 890-920 nm range, which is valuable for compact blue-generation, spectroscopy, precision sensing, and narrow-line pump-source development.^[1]

Why this Nd:YAG application matters

Most commercial discussions of Nd:YAG crystals focus on 1064 nm bulk lasers, Q-switched lasers, or harmonic generation. This paper shows a different direction: using the Nd:YAG composition as a high-gain crystalline precursor for silica-compatible short-cavity fiber devices.

The application value lies in combining short active length, good spectral purity, and easier fiber integration. Compared with traditional bulk resonators, this route is promising for compact single-frequency sources, integrated laser modules, and future wavelength-converted visible or blue systems based on frequency doubling of the 900 nm band.