A sideband-injection locked extended cavity diode laser for interrogating cold trapped Strontium ions

A simple optical sideband injection locking technique is demonstrated to frequency offset-lock a 674 nm slave extended cavity diode laser to a single frequency source. By injecting light from a master laser into either sideband of the frequency modulated extended cavity slave laser, it is shown that the carrier of the slave is frequency locked to the master laser with a relative linewidth much less than 10 Hz. The locking bandwidth is investigated to determine the largest capture range. An observation of the 674 nm 2 S 1/2– 2 D 5/2 transition in a single ion of 88 Sr + was performed using this laser system, yielding ≈1 kHz linewidth Zeeman structure, limited by the master laser linewidth. National Physical Laboratory