Axion Haloscopes: Moving from Microwaves to Mm-Waves

The axion is a well-motivated dark matter candidate particle. Axions are expected to convert to photons in the presence of a strong magnetic field. This photon signal can be enhanced using resonant electromagnetic cavities. Current experiments are searching for axions in the microwave regime, but the possible axion mass range extends to much higher frequencies. This work will discuss the use of microwave cavities in current experiments as well as the challenges and possible approaches to moving to the mm-wave and THz regimes in the future.