This work discusses the development of a frequency chirped, low repetition rate, semiconductor based mode-locked
laser having reduced noise over previous demonstrations. Specifically, we present a major upgrade on the 100 MHz
harmonically mode-locked Theta (Θ) laser cavity design in the form of the introduction of an intra-cavity fiberized
Fabry-Perot etalon. The initial demonstration of the Theta cavity design offered improved energy per pulse and a linearly
chirped pulse output compared to conventional cavity designs. Nonetheless, it suffered from pulse-to-pulse timing and
energy noise. The noisy operation arises from the harmonic nature of the laser. To mitigate this effect we have inserted a
fiberized etalon within the laser cavity.
The intra-cavity etalon stores and inter-mixes the pulses of the harmonically mode-locked laser, as well as enforces
lasing on a single optical mode-set from the multiple interleaved sets supported by the mode-locked laser due to its
harmonic nature. This leads to the generation of a stable optical frequency comb with 100 MHz spacing and the
suppression of the RF super-mode noise spurs, which results in a reduction of the laser noise. Due to fiber length drift in
both the fiberized laser cavity and the fiberized etalon, a long-term stabilization scheme is necessary. An intra-cavity
Hansch - Couillaud scheme is employed. The laser outputs chirped pulses with 10 nm of bandwidth.
This work provides an in depth analysis of both the development of the Theta cavity with the intra-cavity etalon and
the performance of the developed laser system.