Broadband lasers for photo-ionization and repumping of trapped ions

A frequency-stable, broadband laser is presented for experiments on trapped ions. Because the design is based on widely available semiconductor optical amplifier technology, similar lasers can be realized for virtually any wavelength in the near-infrared, and the coherence properties and output power allow for efficient second harmonic generation. No closed-loop frequency stabilization for addressing Doppler- or naturally broadened, dipole-allowed transitions is needed, and the light source can be turned on and off during a measurement cycle with submicrosecond response time. As a case study, a 921.7-nm laser with an output power of 20 mW and a linewidth of 10 GHz is realized, which is then frequency doubled to 460.9 nm for excitation of strontium as the first step in photo-ionization. The excitation efficiency is compared to that achievable with a narrow-linewidth distributed Bragg reflector laser as well as to theory.