Abstract

We present a mode-locked fiber laser with an intracavity diode laser as pump source and modulator. The integrated arrangement with a fiber loop reflector as the output mirror is shown in Fig. 1. The strained GaInAs:AlGaAs QW diode laser had a stripe width of 3 μm, a length of 600 μm and the rear facet had a high reflection coating over a wide spectral range. The facet emitting into the cavity was anti-reflection-coated at 1.5 μm with a residual reflectivity of ~4%. The internal mirror of the pump laser diode was especially chosen so as to have moderate reflectivity at 0.98 μm to maximize the output pump power while having a low reflectivity at 1.5 μm to integrate the laser diode as intracavity etalon and as modulator in a fiber laser. The laser diode emits up to 70 mW of total power in the fundamental spatial mode. The pump light at 980 nm was directly coupled to the Er³⁺-doped fiber through drawn tapered fiber microlens. The coupling efficiency of the pump beam into the erbium-doped fiber was ~50%. The Er³⁺-doped fiber was long enough (~8 m) to absorb a significant fraction of the pump power.

© 1993 Optical Society of America