Terahertz beam propagation measured through three-dimensional amplitude profile determination

Reiten, Matthew T.; Harmon, S. A.; Cheville, R. A.

doi:10.1364/josab.20.002215

Cited by 45 publications

(30 citation statements)

References 31 publications

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“…Different lens shapes (collimating, hemispherical and hyperhemispherical shapes) have been thoroughly characterized by Rudd and Mittleman [138]. Reiten et al performed careful measurements and simulations of the propagation of THz beams through hyperhemispherical lenses and the subsequent optical system of a THz-TDS setup [139,140]. They showed that the THz beam profile emerging from a lens-coupled photoconductive emitter is accurately described by a superposition of Laguerre-Gauss modes, and also discussed the influence of spherical aberration and surface waves on the propagation.…”

Section: Static Terahertz Time-domain Spectroscopymentioning

confidence: 99%

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Terahertz spectroscopy and imaging – Modern techniques and applications

Jepsen

Cooke

Koch

2010

Laser & Photonics Reviews

1,746

977

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Over the past three decades a new spectroscopic technique with unique possibilities has emerged. Based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts in the far-infrared, this technique has become known as terahertz time-domain spectroscopy (THz-TDS). In this review article the authors describe the technique in its various implementations for static and time-resolved spectroscopy, and illustrate the performance of the technique with recent examples from solid-state physics and physical chemistry as well as aqueous chemistry. Examples from other fields of research, where THz spectroscopic techniques have proven to be useful research tools, and the potential for industrial applications of THz spectroscopic and imaging techniques are discussed.

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Section: Static Terahertz Time-domain Spectroscopymentioning

confidence: 99%

“…12 where the ATR prism has been loaded with distilled water. Figure 12a shows 139 index of refraction p is r = n 1 q 1 (n 1 =n 2 ) 2 sin 2 θ n 2 cos θ n 1 q 1 (n 1 =n 2 ) 2 sin 2 θ +n 2 cos θ : (38) This equation has the solutionŝ…”

Section: Attenuated Total Reflection (Atr) Thz-tdsmentioning

confidence: 99%

Terahertz spectroscopy and imaging – Modern techniques and applications

Jepsen

Cooke

Koch

2010

Laser & Photonics Reviews

1,746

977

View full text Add to dashboard Cite

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“…Because of the inversion symmetry of the resulting 2040 m 2040 m, 4-array centered on ÿ22:5; ÿ15 , the original overlap calculation also applies to the 4-array. The effective array size is considered to be determined by the spatial extent (at the array) of the planar phase coherence of the THz beam, due to the residual phase variation and curvature [36]. The 2 mm 2 mm, 4-array is comparable in size to the spatial phase variations of an incoming 6 mm, 1=e diameter.…”

Section: Volume 93 Number 19 P H Y S I C a L R E V I E W L E T T E Rmentioning

confidence: 99%

Observation of a New Type of THz Resonance of Surface Plasmons Propagating on Metal-Film Hole Arrays

Grischkowsky

2004

Phys. Rev. Lett.

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Highly conducting metal-film subwavelength hole arrays, lithographically fabricated on highresistivity silicon wafers in optical contact with thick silicon plates, have been characterized by terahertz time-domain spectroscopy with subpicosecond resolution and over a frequency range from 0.5 to 3 THz with 5 GHz resolution. Awell-defined ringing structure extending to more than 250 psec is observed on the trailing edge of the transmitted THz pulse. In the frequency domain this ringing structure corresponds to a new type of extremely sharp resonant line structure between the fundamental surface plasmon modes of the hole array. A simple theoretical model is presented and shows good agreement with the experimental data. DOI: 10.1103/PhysRevLett.93.196804 PACS numbers: 73.20.Mf, 41.20.Jb, 42.25.Fx, 78.47.+p Although the microwave and terahertz transmission through thin-metal films or metal foils perforated periodically with apertures has been studied since 1967 [1][2][3][4][5][6], unusual high-transmission resonances through subwavelength hole arrays were only recently discovered [7,8] at optical frequencies. These resonances occurred at wavelengths different from those predicted by the classic diffraction theory [2]. Since this discovery much work has been done to experimentally characterize the transmission of thin subwavelength hole arrays in the optical [9-21], infrared [22], and THz [23][24][25][26][27][28] regions. The enhanced transmission is now understood to be due to the excitation of surface plasmon (SP) resonances [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]24,25,[27][28][29][30][31][32][33]. The SP enhancement can be affected by the refractive index of the adjacent medium [9,12], the shape and orientation of the holes [10,20,27], and the thickness of the metal film [16]. In all these measurements, SP enhanced transmission has been observed only at the frequencies determined by the integral order SP modes coupled to the array [7,8]. Here, we present observations of a new type of high-transmission, extremely narrow resonances at frequencies between those of the integral order SP modes. These resonances correspond to SP propagation in directions different than those allowed by the integral order modes. We call these resonances fractional order surface plasmons (FSP), which are made possible by the high conductivity of metal films at THz frequencies.In this Letter, we present a time-domain and frequency-domain study of the amplitude and phase transmission properties of a thin-metal-film subwavelength hole array, lithographically fabricated on a silicon wafer. The utilized THz time-domain spectroscopy (THz-TDS) technique measures the complete THz electric field pulse with subpicosecond time resolution [34]. For this characterization a subpicosecond THz pulse is incident on the hole array. The transmitted THz pulse consisted of an attenuated subpicosecond pulse due to the classical electromagnetic transmission of the array, followed by a dramatic ringing structure, extending to approximatel...

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“…However, recent measurements show that our THz beams are not Gaussian. 11 If a Gaussian beam were assumed, the absorption would be reduced by only 0.03 cm Ϫ1 at 2 THz. Second, we expect some loss as the structure likely has gaps of several microns between the plates and the mirror edges allowing leakage of the guided mode, although significant efforts were made to reduce this effect.…”

Section: ͑2͒mentioning

confidence: 99%

A THz transverse electromagnetic mode two-dimensional interconnect layer incorporating quasi-optics

Coleman

Grischkowsky

2003

Applied Physics Letters

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We report the demonstration of a planar THz interconnect layer capable of transmitting subpicosecond pulses in the transverse electromagnetic ͑TEM͒ mode over arbitrarily long paths with low absorption and no observable group velocity dispersion. Quasioptical elements are incorporated within the interconnect layer forming a configurable THz bandwidth TEM-mode planar interconnect with negligible group velocity dispersion and low loss. For a 146 mm guided path length, including four reflections, the pulses are broadened by the frequency dependent absorption of the interconnect layer from 0.28 to 0.32 ps, and attenuated by the factor 0. Terahertz ͑THz͒ waveguides have recently been demonstrated to be an alternative to high-speed coplanar transmission lines. [1][2][3][4] For frequencies up to 3.5 THz, the attenuation coefficient of metal waveguides has been shown to be less than 1/10 that of lithographically defined transmission lines on dielectric substrates. Within the passband of the waveguide, the measured power coupling into the waveguide was typically 40% of the incoming THz power. For the single conductor circular and rectangular metal waveguides the observed excessive THz pulse broadening was caused by the extreme group velocity dispersion ͑GVD͒ near the cutoff frequency. Such pulse broadening does not occur for the transverse electromagnetic ͑TEM͒ mode of a parallel-plate metal waveguide, since it has no cutoff frequency. The group and phase velocities of the TEM mode are determined solely by the dielectric. Recent experiments have shown efficient quasioptic coupling of freely propagating subpicosecond ͑subps͒ pulses of THz radiation into parallel-plate metal waveguides and the subsequent low-loss, single TEM mode propagation exhibiting negligible GVD. 3,4 Consequently, a THz interconnect, 5 capable of propagating subps pulses with minimal loss and no distortion, has been realized.However, all of these demonstrations involved quasioptical input and output coupling of freely propagating THz beams into and out of the THz waveguides. The remaining challenge is to efficiently connect the THz TEM waveguide with integrated circuitry. To address this problem we have begun to study a macroscopic planar interconnect approach using two-dimensional ͑2D͒ quasioptics. The interconnect consists of two relatively large ͑many centimeters͒ metal plates separated from each other by approximately 100 m. Within this 100 m thick, free-space interconnect layer, planar quasioptical components are placed to guide, collimate, or focus the propagating THz TEM waves. This 2D planar quasioptics approach has the potential to realize a spatially localized point-to-point interconnect with the low-loss, broad bandwidth, and negligible GVD of the single-mode THz TEM planar metal waveguides. This 2D interconnect is related to previous works by Mink, in which he proposed and demonstrated the hybrid dielectric slab-beam waveguide ͑HDSBW͒. 6,7 The HDSBW uses two distinct waveguiding principles to guide electromagnetic waves in a dielectric slab...

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Terahertz beam propagation measured through three-dimensional amplitude profile determination

Cited by 45 publications

References 31 publications

Terahertz spectroscopy and imaging – Modern techniques and applications

Terahertz spectroscopy and imaging – Modern techniques and applications

Observation of a New Type of THz Resonance of Surface Plasmons Propagating on Metal-Film Hole Arrays

A THz transverse electromagnetic mode two-dimensional interconnect layer incorporating quasi-optics

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