Broadband Terahertz Refraction Index Dispersion and Loss of Polymeric Dielectric Substrate and Packaging Materials

Motaharifar, Elaheh; Pierce, Richard G.; Islam, Rownak; Henderson, Rashaunda; Hsu, Julia W. P.; Lee, Mark

doi:10.1007/s10762-017-0444-4

Cited by 15 publications

(10 citation statements)

References 17 publications

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“…BCB is a thermosetting resin that is widely employed for encapsulation of electronic components and in planarization experiments due to its mechanical and temperature stability. The relative permittivity and loss tangent of the commonly used photosensitive BCB 4026‐26 and non‐photosensitive CYCLOTENE 3022‐46 are reported to lie in the range 2.41–2.65 and 0.002–0.009 at 1 THz, respectively. These low‐loss dielectric material offers great opportunity to realize low insertion loss waveguides and other high‐efficiency metasurface devices in the terahertz region .…”

Section: Fabrication Of Single and Multilayer Terahertz Metasurface Dmentioning

confidence: 99%

“…These low‐loss dielectric material offers great opportunity to realize low insertion loss waveguides and other high‐efficiency metasurface devices in the terahertz region . The loss tangent of both BCB 4026‐26 and CYCLOTENE 3022‐46 cured films is experimentally shown to fluctuate with frequency in the range of 0.5–5.5 and 10–50 THz, respectively, with existing windows for low loss. However, the property of the film is dependent on the curing conditions such as the exposure fluence and duration, temperature, and degree of oxidation of the films.…”

Section: Fabrication Of Single and Multilayer Terahertz Metasurface Dmentioning

confidence: 99%

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Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Ako

Upadhyay

Withayachumnankul

et al. 2019

Advanced Optical Materials

106

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on distinctive spectral signatures resulting from vibrational modes of covalent and hydrogen bonds. [8,[13][14][15][16] The focus on this spectrally rich region is attributed to the highly coherent and nonionizing nature of terahertz radiation, wide unallocated frequency bands, distinctive wavelengths, and their penetration through a significant depth of dielectric materials. Terahertz technology is geared toward realizing devices that can efficiently manipulate the phase, amplitude, and polarization of terahertz radiations for the above-mentioned myriad of applications.However, progress in this domain is held back by low terahertz power available from compact sources, high free-space path loss, and limited choice of materials that exhibit less absorption of terahertz waves. [17] Owing to the fact that natural materials demonstrate weak wave-matter interaction at terahertz frequencies, terahertz devices with engineered subwavelength resonant metallic inclusions on dielectric spacers have been realized, to interact strongly with an incident electromagnetic wave.In the past, metamaterials have been a promising route to building terahertz devices. These devices have in essence been engineered as 3D resonating elements that effectively manipulate both permittivity and permeability of an effective medium to couple to free space. The underlining disadvantage of these structures is the difficulty involved in the fabrication of 3D geometrical structures using standard semiconductor fabrication techniques. Standard fabrication techniques are generally amenable to 2D design with extrusion of these structures into thickness (the third, vertical dimension). Moreover, the choice and availability of dielectric materials and metals that provide sufficient interaction while retaining device efficiency has proved challenging. [13,[18][19][20] Recently, effective manipulation of electromagnetic wave has been widely demonstrated with 2D metasurfaces, which were originally employed as building blocks for 3D metamaterials. In these lower-dimension designs, effective manipulation of terahertz waves for various applications is achieved by carefully designing sub-wavelength resonant structures as is evident in published review articles. [21,22] Metasurfaces present high degree of compactness that enhances radiation efficiency. Additionally, the planar form factor of metasurfaces enables Manipulation of terahertz radiation opens new opportunities that underpin application areas in communication, security, material sensing, and characterization. Metasurfaces employed for terahertz manipulation of phase, amplitude, or polarization of terahertz waves have limitations in radiation efficiency which is attributed to losses in the materials constituting the devices. Metallic resonators-based terahertz devices suffer from high ohmic losses, while dielectric substrates and spacers with high relative permittivity and loss tangent also reduce bandwidth and efficiency. To overcome these issues, a proper choice of low loss and low relative permittivi...

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Section: Fabrication Of Single and Multilayer Terahertz Metasurface Dmentioning

confidence: 99%

Section: Fabrication Of Single and Multilayer Terahertz Metasurface Dmentioning

confidence: 99%

Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Ako

Upadhyay

Withayachumnankul

et al. 2019

Advanced Optical Materials

106

View full text Add to dashboard Cite

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“…When exposed to ultraviolet (UV) light, SU-8 undergoes cross-linking leading to polymerization, making it insoluble in solvents such as Acetone, Methyl Ethyl Ketone (MEK) or N-Methyl Pyrrolidinone [2]. While optical properties of SU-8 in visible and UV range have been characterized [8], infrared refractive indices of SU-8 were not estimated until recently [9]. Fourier Transform Infrared Spectroscopy (FTIR) measurements using attenuated total reflectance (ATR) method have also been documented before and various IR absorption bands have been assigned to several different functional groups [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Fourier Transform Infrared Spectroscopy (FTIR) measurements using attenuated total reflectance (ATR) method have also been documented before and various IR absorption bands have been assigned to several different functional groups [10][11][12]. Mid-IR dielectric function of SU-8 was first reported by Motaharifar et al [9] using reflection and transmission spectra of a free-standing SU-8 sample. Here, we calculate dielectric function of SU-8 using reflectance data for various thickness of SU-8 films.…”

Section: Introductionmentioning

confidence: 99%

Dynamic optical response of SU-8 upon UV treatment

Ghanekar

Ricci

Tian

et al. 2018

Opt. Mater. Express

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We report the optical properties of SU-8 in the mid-infrared (mid-IR) region before and after UV treatment. Samples consisted of SU-8 films of thickness ranging from 10 um to 157 um deposited on gold coated silicon substrates and were prepared using spin coating. Mid-IR diffuse reflectance measurements were conducted using Fourier transform infrared spectroscopy. Spectra measurements imply a change in optical properties of SU-8 upon exposure to UV and heat treatment. A gradual change in optical properties is seen after each step of UV treatment and the baking process. Reflectance spectra of thin-films were also observed to be thickness dependent. We calculate the dielectric function of SU-8 in the range 2 um to 15 um using the reflectance spectra of the samples.

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“…The refractive index of SU-8 was taken to be 1.85 from Ref. 31. The surface gratings (Au) are defined on top of the waveguide as shown in Fig.…”

mentioning

confidence: 99%

Double-metal waveguide terahertz difference-frequency generation quantum cascade lasers with surface grating outcouplers

Kim

Jung

Jiang

et al. 2018

Applied Physics Letters

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We report terahertz quantum cascade laser (QCL) sources based on intra-cavity difference-frequency generation processed into double-metal waveguides with surface-grating outcouplers. This configuration enables high confinement of the terahertz mode in the device active region and efficient surface extraction of terahertz radiation along the entire length of the waveguide. The devices operate at room temperature at 1.9 THz and produce over 110 lW of peak power output with the mid-infrared-to-terahertz conversion of 150 lW/W 2. The results represent at least a factor of 2 improvement in the performance compared to the best Cherenkov difference-frequency generation QCL devices operating below 2 THz.

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Broadband Terahertz Refraction Index Dispersion and Loss of Polymeric Dielectric Substrate and Packaging Materials

Cited by 15 publications

References 17 publications

Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Dynamic optical response of SU-8 upon UV treatment

Double-metal waveguide terahertz difference-frequency generation quantum cascade lasers with surface grating outcouplers

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