Laser-based polymer stereolithography of vertically integrated narrow bandpass filters operating in K band

Laser-based polymer stereolithography (SL) processing is used to create vertically integrated resonators and filters in K band. This technique allows for vertical integration of filters owing to its three-dimensional fabrication capabilities and therefore allows for compact high-Q filter realizations in a small cross-sectional area. Quality factors of resonators up to 1735 are measured. An insertion loss as low as 0.27 dB is measured in a vertically integrated two-pole filter with a bandwidth of 2.12%. Without tuning, all relevant filter aspects are within 3% of simulation, with the center frequency varying only 0.15%.