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Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique.

Phing SH, Mazhorova A, Shalaby M, Peccianti M, Clerici M, Pasquazi A, Ozturk Y, Ali J, Morandotti R - Sci Rep (2015)

Bottom Line: Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved.Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane.A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique.

View Article: PubMed Central - PubMed

Affiliation: 1] INRS-EMT, University of Quebec, 1650, Blvd. Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada [2] Laser Centre, Ibnu Sina ISIR, UTM, 81310 UTM Skudai, Malaysia.

ABSTRACT
Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane.

No MeSH data available.


OKE results on super-λ THz source.(a) THz peak field vs. UV pump delay at different excitation fluencies. (b) The THz power vs. the blade position. (c) The OKE measurements resolved at 1 THz are plotted as the THz field versus the blade position. (d) The OKE measurement for a UV pump delay of 6 ps compared with the beam waist of the optical pump. The inset shows the reconstructed spatio-temporal map.
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f3: OKE results on super-λ THz source.(a) THz peak field vs. UV pump delay at different excitation fluencies. (b) The THz power vs. the blade position. (c) The OKE measurements resolved at 1 THz are plotted as the THz field versus the blade position. (d) The OKE measurement for a UV pump delay of 6 ps compared with the beam waist of the optical pump. The inset shows the reconstructed spatio-temporal map.

Mentions: To highlight the effect of the carrier temporal dynamics, OKE measurements have been taken at several UV pump delays (tpump,UV = 1 ps, 3 ps, 5 ps, 6 ps, 7 ps, 8 ps, 10 ps and 15 ps), indicated by arrows in Fig. 2. Our experimental results at each pump delay are presented in Fig. 3. The set of data plotted in Fig. 3a illustrates the dependence of the THz decay from the UV pump energy. The OKE measurement performed for a UV pump energy of 95 μJ is shown in Fig. 3b where the THz power obtained by the integral of the squared field over time is plotted versus the blade position. Noteworthy, as the THz beam waist is significantly super-λ, the OKE does not introduce any significant changes in the field phase18 (i.e. the waveform just scales as the beam is clipped by the edge). This is also highlighted in Fig. 3c, which shows the OKE measurements resolved around the frequency 1 THz (λ = 300 μm), extracted as the square-root of the THz power spectral density at 1 THz: the curve matches closely the one obtained from the full spectrum, at any tested delay.


Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique.

Phing SH, Mazhorova A, Shalaby M, Peccianti M, Clerici M, Pasquazi A, Ozturk Y, Ali J, Morandotti R - Sci Rep (2015)

OKE results on super-λ THz source.(a) THz peak field vs. UV pump delay at different excitation fluencies. (b) The THz power vs. the blade position. (c) The OKE measurements resolved at 1 THz are plotted as the THz field versus the blade position. (d) The OKE measurement for a UV pump delay of 6 ps compared with the beam waist of the optical pump. The inset shows the reconstructed spatio-temporal map.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4339802&req=5

f3: OKE results on super-λ THz source.(a) THz peak field vs. UV pump delay at different excitation fluencies. (b) The THz power vs. the blade position. (c) The OKE measurements resolved at 1 THz are plotted as the THz field versus the blade position. (d) The OKE measurement for a UV pump delay of 6 ps compared with the beam waist of the optical pump. The inset shows the reconstructed spatio-temporal map.
Mentions: To highlight the effect of the carrier temporal dynamics, OKE measurements have been taken at several UV pump delays (tpump,UV = 1 ps, 3 ps, 5 ps, 6 ps, 7 ps, 8 ps, 10 ps and 15 ps), indicated by arrows in Fig. 2. Our experimental results at each pump delay are presented in Fig. 3. The set of data plotted in Fig. 3a illustrates the dependence of the THz decay from the UV pump energy. The OKE measurement performed for a UV pump energy of 95 μJ is shown in Fig. 3b where the THz power obtained by the integral of the squared field over time is plotted versus the blade position. Noteworthy, as the THz beam waist is significantly super-λ, the OKE does not introduce any significant changes in the field phase18 (i.e. the waveform just scales as the beam is clipped by the edge). This is also highlighted in Fig. 3c, which shows the OKE measurements resolved around the frequency 1 THz (λ = 300 μm), extracted as the square-root of the THz power spectral density at 1 THz: the curve matches closely the one obtained from the full spectrum, at any tested delay.

Bottom Line: Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved.Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane.A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique.

View Article: PubMed Central - PubMed

Affiliation: 1] INRS-EMT, University of Quebec, 1650, Blvd. Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada [2] Laser Centre, Ibnu Sina ISIR, UTM, 81310 UTM Skudai, Malaysia.

ABSTRACT
Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane.

No MeSH data available.