Design and measurement of a bandpass filter at 300 GHz based on a highly efficient binary grating

A bandpass filter for 300 GHz with a stopband at 450 GHz based on a highly efficient binary grating as a frequency-selective element was developed and optimized. The geometry of the grating was carefully designed for a maximum difference angle between reflected beams at 300 and 450 GHz and for maximum efficiency at 300 GHz. The grating efficiency was optimized using a rigorous theory of diffraction, yielding a maximum efficiency of over 99.5% neglecting conductor losses. Antennas and elliptical mirrors are used for optimum quasi-optical illumination of the grating and Gaussian beam shaping. After an optimization and a comprehensive examination of the grating in an experimental heterodyne measurement setup at 300 GHz, the filter was implemented fixed tuned into a small housing with waveguide flanges. The fixed tuned setup with corrugated feed horns results in an overall flange-to-flange insertion loss of only 2.8 dB.

[1]  P. Goldsmith,et al.  Quasi-optical techniques , 1992, Proc. IEEE.

[2]  I. Mehdi,et al.  Fabrication of 200 to 2700 GHz multiplier devices using GaAs and metal membranes , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[3]  C. Winnewisser,et al.  Efficient analysis of quasi-optical filters by a hybrid MoM/BI-RME method , 2001 .

[4]  Erich N. Grossman,et al.  Spectral transmittance of lossy printed resonant-grid terahertz bandpass filters , 2000 .

[5]  R. Judaschke,et al.  A multi-element 150/300 GHz spatial power dividing/combining frequency doubler , 2002, 2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278).

[6]  Haiyong Xu,et al.  Fabrication of integrated THz sources , 2002, Twenty Seventh International Conference on Infrared and Millimeter Waves.

[7]  Martin Collischon,et al.  Line-selective resonators with variable reflectivity gratings (VRG) for slab-laser geometry , 2000, LASE.

[8]  L. Schmidt,et al.  Flexible Low-Loss Dielectric Waveguides for THz Frequencies with Transitions to Metal Waveguides , 2003, 2003 33rd European Microwave Conference, 2003.

[9]  J L Hesler,et al.  Resonant metal-mesh bandpass filters for the far infrared. , 1994, Applied optics.

[10]  K. Oughstun,et al.  Electromagnetic theory of gratings , 1982, IEEE Journal of Quantum Electronics.

[11]  M. Bozzi,et al.  A 300 GHz quasioptical schottky frequency doubler , 1997 .