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Packet-modulated communication may play a pivotal role in the future of short-range communications at terahertz (THz) frequencies. As with ultra-wideband communication, the advantageous of this type of communication are its extremely short duration, immunity to multipath fading, wide bandwidth and low power spectral density. However, due to the lack of a fast modulation method, packet-modulated pulse communication at THz frequencies has not yet been demonstrated. Here we present a method for the generation and modulation of a coded THz pulse train. Our scheme is based on the combination of a spintronic THz emitter (STE) with an echelon mirror and a digital micromirror device. This highly scalable configuration is capable of modulating hundred or more THz pulses in parallel with sub-picosecond accuracy and is versatile for various modulation protocols. Strikingly, the temporal resolution of our modulation scheme depends on geometric optics and not on a high-speed electronic device. Furthermore, the ability of STEs to generate quasi-continuous THz pulses offers an alternative solution to the photomixer, a key THz communication technology, and thus could lead to a promising new THz communication modality.

We demonstrate a new technique for the generation and the active modulation of a THz pulse train using the combination of a terahertz (THz) spintronic emitter with an echelon mirror and a digital micromirror device (DMD).

We have developed a unique THz source combining an average power of 53 mW and maximal field strength of 310 kV/cm. This source is based on lithium niobate crystal pumped by an industrial sub-mJ Ytterbium laser, coupled with an innovative pulse compression technique. Well balanced and highly scalable, this system contributes to democratizing the accessibility of intense and powerful THz pulses.

We experimentally report on the spectral broadening of lasers pulses from an Ytterbium (Yb) laser with 0.8μJ energy level via self-phase modulation in cadmium sulfide (CdS) semiconductor crystal. Then, by frequency doubling the pulse into a beta barium borate crystal (BBO), the spatial beam profile is cleaned out while maintaining the bandwidth enhancement. At the end, the laser pulse, around 512 nm, is compressed up to 45 fs using two standard transmissive grating resulting in a pulse compression factor of 6.13.

We have developed a 53 mW terahertz pulse source with peak electric field around 310 kV/cm. Our demonstration is based on the tilted-pulse front excitation method in a lithium niobate crystal coupled to an affordable commercial ytterbium laser.

We report on the electro-optical (EO) detection of subpicosecond terahertz (THz) pulses using a cut non-centrosymmetryc crystal of zinc sulphide (ZnS). Its EO efficiency, using the second harmonic generation (SHG) of an Ytterbium (Yb) laser (514 nm,) is compared to the EO efficiency using a cut crystal of cadmium telluride (CdTe) at the fundamental wavelength of the laser (1028 nm).

Using an affordable ytterbium laser with sub-mJ of energy combined with a novel pulse compression technique, we demonstrate an extremely competitive state-of-the-art terahertz (THz) source with 53 mW of average power and 310 kV/cm at focus from the tilted-pulse front pumping scheme in lithium niobate at room temperature. Key points of this demonstration include the use of a pump pulse duration of 280 fs in combination with an echelon mirror. Our results present unmatched combined characteristics and are highly competitive with the existing THz sources pumped at the mJ range. This demonstration is a step towards the democratization of access to intense and powerful THz pulses., 6 pages, 5 figures, 1 table

In this work, we experimentally demonstrate the generation of 30 nm of spectral broadening in a bulk cadmium sulfide (CdS) semiconductor generated by a 280 fs long pulse at 1.024 µm wavelength and with a microjoule energy level. Using second-harmonic generation in barium borate, the complex ring pattern induced by self-focusing due to the strong nonlinear interaction of the laser pulse in the pair of CdS crystals is filtered out using second-harmonic nonlinear crystal to recover a Gaussian shape spatial profile. We also present the temporal compression of the resulting 512 nm laser pulse up to 45 fs by using a pair of standard transmissive gratings, leading to a pulse compression factor of 6.13. This technique is compact, inexpensive, and robust and produces ultrafast optical pulses from an input laser pulse whose duration and energy range are generally incompatible with a straightforward compression method in nonlinear optical fibers.

In this work, we study terahertz (THz) generation and detection from CdTe crystal pumped by an Ytterbium (Yb) laser at $1.045 {\mu } \mathrm {m}$ wavelength. We compare the performances of THz emission and detection of CdTe crystals to those of GaP crystals and show 50% higher efficiency for detection and 5 times higher efficiency for generation of THz waves from the CdTe crystal.

Cost effective imaging is required for a wide range of scientific and engineering applications. For electromagnetic waves in the terahertz (THz) frequency range, a key missing element that has prevented widespread applications in this spectral range is an inexpensive and efficient imaging device. In recent years, vanadium oxide based thermal sensors have rapidly entered the market for night vision capability. At the same time, sensors based on this technology have been applied to the THz domain, but with two orders of magnitude larger pricing range. Here we show that, with a simple modification, a commercially available thermal imaging camera can function as a THz imaging device. By comparing a commercially available THz camera and this low-cost device, we identify the main sensitivity difference is not attributed to anything intrinsic to the devices, but rather to the analog-to-digital converter and dynamic background subtraction capability. This demonstration of a low-cost THz camera may aid in the rapid development of affordable THz imaging solutions for industrial and scientific applications.

We studied the effect of surface plasmon resonance of laser ablation synthesized gold NPs on the optical properties of the bent fibers (NSs),. the performance of the decorated fiber is investigatedas humidity sensor.

In this work, we study THz generation and detection using cadmium telluride (CdTe) crystals pumped by amplified (1.025 μm wavelength) and oscillator (1.045 μm wavelength) ytterbium (Yb) lasers. For each laser, we compare the performances of the CdTe THz emitter and detector to those of GaP crystals. Under optimum conditions, we demonstrate that the former shows 3 and 5 times better performances compared with the latter for detection and generation, respectively. When pumped by an amplified Yb laser, we find that the CdTe crystal is more efficient than the GaP crystal for emission at optical fluences lower than 250 μJ/cm2. Although CdTe has some limitations in comparison with GaP, such as high THz absorption above 1 THz and the appearance of two-photon absorption at relatively low optical intensity, our findings demonstrate the potential of this crystal to be used as the emitter and detector in combination with the Yb laser.