Experimental study of a solar and laser-diode hybrid-pumped fiber laser based on a lens array

This work experimentally investigates a solar and laser-diode hybrid-pumped Nd-doped fiber laser enabled by a port-matched aspheric lens array. A seven-element aspheric lens array is designed and constructed for solar end coupling, in which each lens concentrates sunlight into an individual pump fiber, and a standard 7 × 1 multimode pump combiner aggregates the seven channels into a single pump delivery path. An 808 nm LD is used as a reference pump to quantify the net gain of the solar end-pumping stage by comparing the 1064 nm output with and without the solar channel under otherwise identical cavity conditions. A single-pass bandpass-filter method isolates the 1064 nm laser component, indicating a net slope efficiency increase of 48.77% under hybrid pumping and an average output power enhancement of approximately 1.67 mW. Although solar-only pumping does not yet reach the oscillation threshold, the array-based solar channel provides a measurable positive gain at 1064 nm. The prototype relies exclusively on standard commercial fiber components. It requires neither sensitizers nor complex water-cooling infrastructure, which is attractive for mass- and complexity-constrained deployments such as spaceborne platforms. The array architecture further supports cascaded pump-power scaling by expanding the collection area and increasing the number of pump channels, providing a practical engineering pathway toward solar-only fiber-laser operation.