Terahertz Slot Dielectric Waveguide Implemented on the Silicon-BCB-Quartz Platform

Broadband Terahertz Photonic Integrated Circuit with Integrated Active Photonic Devices

“…The measured absorption coefficient is larger than the simulated value of a HRFZ-Si waveguide placed on crystalline quartz, i.e., ≈0.13 dB/cm, due to the presence of a 5-9 µm layer of ethyl cyanoacrylate-based superglue ( r = 2.72, tan δ = 0.067 at 1 THz [41]) underneath the waveguides. Excess loss due to superglue, though not detrimental to the waveguide operation, can be easily avoided using other low-loss adhesives, such as BCB [12]. Dielectric waveguides are prone to dispersion as the effective mode permittivity of the guided mode increases with increasing frequency as a larger fraction of the wave is concentrated within the high index HRFZ-Si guide.…”

“…Similar to integrated circuits in the RF and microwave domain [7,8] or photonic integrated circuits at the telecom bands in the near infrared there exist integrated terahertz systems. These include electronic systems based on fundamental oscillators at the lower end of the terahertz range [9] or frequency multiplier-based systems [6], both frequently using hollow metallic waveguides with microstrip transitions to active elements, as well as dielectric waveguide-based systems [10][11][12]. While the waveguide concepts generally allow for large bandwidths, the lack of broadband characterization tools as well as comparatively narrowband transitions to active elements typically restrict the operational bandwidth to typically not more than 10-50% of the centre frequency.…”

“…Headland et al showed silicon waveguide-based THz systems working between 260-390 GHz [18]. Multiple topologies of silicon on insulator (SoI)-based waveguides [19,20] and integrated Terahertz resonators [21,22], waveguides based on silicon-BCB-quartz platform [12] and suspended silicon THz waveguides [23,24] report relatively low losses between 0.4-1 dB/cm, and feature a bandwidth ranging between 100-250 GHz. Free-standing multimode dielectric waveguides with excellent transitions were demonstrated using dielectric rod waveguides [25,26].…”

Interaction between a Waveguide Mode and an Absorptive Medium

“…On the right hand side of (11), the first term is the loss of the guiding region of the waveguide, and the second term is the loss of the material sample. Using ( 6), (7), and (11), the mode attenuation constant will be:…”

“…In 2 a formulation for the interaction factor is presented when electromagnetic wave passes through a periodic structure. Although same formulation has been used for waveguide-based setup [4][5][6][7] , it is shown in this article that this form is not sufficiently accurate for the waveguide-based cases.…”