Narrow linewidth generation at 1 THz using cascaded Brillouin fiber lasers and quasi-optic UTC-PD

International audienceNarrow linewidth THz generation using a cascaded Brillouin fibre laser structure and a unitraveling carrier photodiode is proposed. Using two distributed feedback lasers separated by > 1 THz with 1 MHz initial linewidth, the linewidth of the realized THz source is found to be < 100 Hz at 1014.7 GHz without use of any active stabilization of the laser cavity or any microwave reference

Multicore fiber for cold-atomic cloud monitoring

International audienceThanks to an all solid core photonic crystal fiber (PCF) used as a multicore fiber, we propose and experimentally demonstrate what is to our knowledge a new optical detection scheme for the spontaneous emission collection of cold atoms. A Magneto-Optical Trap (MOT) is placed in front of a polished PCF end-face. As they display a higher optical index than the surrounding cladding silica, the 108 rods (equivalent to a 108 pixels camera) of this PCF are light guiding and behave like an array of detectors. Both global and local properties of the trapped atoms are probed. A MOT lifetime is reported. We also take advantage of the multi-core geometry for a real time detection of the center-of-mass motion of the atomic cloud

Ultrawide-bandwidth single-channel 0.4-THz wireless link combining broadband quasi-optic photomixer and coherent detection

Free space communications with huge data capacity have become a key point for the development of mobile access, services, and network technologies convergence. Wireless links using emerging terahertz technologies, also referred to as T-ray communications, have become an intensive research field within last years since T-rays at the millimeter/submillimeter frontier remain more robust in terms of scintillation, dielectric obstacles, and fog compared with near-infrared signals. Using a passive THz hot-spot which can be fed by fiber optic networks, we investigate up bit rates up to 46 Gbps for a THz wireless transmission system at 400-GHz carrier frequency. Using a THz photomixer integrated with a specific broadband antenna and heterodyne electronic detection, we investigate the eye diagrams using 1- W received power, highlighting the high sensitivity and ultra-wideband behavior of the whole THz system

Mode-hopping suppression in long Brillouin fiber laser with non-resonant pumping

International audienceWe propose a reliable method for stabilizing narrow linewidth Brillouin fiber lasers with non-resonant pumping. Mode-hopping is suppressed by means of a phase-locked loop that locks the pump-Stokes detuning to a local radio-frequency (RF) oscillator. Stable single-mode operation of a 110-m-long Brillouin fiber laser oscillating at 1.55 mu m is demonstrated for several hours. The beat note between two independent Stokes waves presents a phase noise level of -60 dBc/Hz at 100 Hz with a -20 dB/decade slope, and a FWHM linewidth lower than 50 Hz. (C) 2016 Optical Society of Americ

THz communications using photonics and electronic devices: the race to data-rate

International audienceWith the mass development of mobile data transfers, wireless communications have recently entered a new area: the carrier frequency is now entering the THz region. After a brief overview of context and key features of THz communication, focus is given on photonic-based THz emitters based on quasi-optic UTC-PDs. A special design of wideband photomixer is presented and its applications for narrow bandwidth THz generation. Using this photomixer, communication links at 200, 400 and 600 GHz are presented

Single-mode operation with no mode-hops of a 110m long Brillouin fiber laser with non-resonant pumping

International audienceStimulated Brillouin scattering (SBS) has received much attention for decades for its numerous applications in sensors, optical amplification or design of narrow-linewidth lasers. In particular, optical fibers present Brillouin gain with a narrow bandwidth of a few tens of MHz. This permits to realize Brillouin fiber lasers (BFL) emitting Stokes lines with potential ultra-narrow linewidths. Standard architectures are based on the use of a long fiber loop in order to provide sufficient gain. The loop is then resonant for the pump requiring servo-control to lock the pump frequency to the loop resonance. Furthermore, the whole pump power may not be injected in the cavity, as the pump spectrum may be broader than the cavity resonance. Conversely, non-resonant pumping enables to fully exploit the pump power. However, as the pump-resonator detuning may drift, it suffers from mode-hopping of the Stokes wave

Stabilisation d’un laser Brillouin fibré non résonant pour la pompe : application à la génération de porteuse opto-RF ultra-pure

International audienceNous présentons une nouvelle méthode de stabilisation d’un laser Brillouin fibré de faible largeur de raie dont la pompe est non résonante pour la cavité fibrée. Les sauts de mode sont supprimés au moyen d'une boucle à verrouillage de phase qui verrouille l’écart en fréquence entre l’onde de pompe et l’onde Stokes sur un oscillateur local RF. L‘oscillation monomode, à 1,55 µm, d’un laser Brillouin fibré de 110 m de long, est démontrée pendant plusieurs heures, avec une largeur de raie optique inférieure 50 Hz. Le bruit de phase associé est égal à -60 dBc/Hz à 100 Hz avec une pente de -20 dB/décade

22 Gbps wireless communication system at 0.4 THz

International audienceBy combining a lJTC-PD as a THz emitter and a 400 G Hz Schottky-based heterodyne detection, we realized an indoor THz link working up to 22 Gbps at 400 GHz carrier frequency with ultra-low THz power. The eye diagram at receiver is clearly opened are the system is working with only 1 mu W received THz power

Narrow linewidth tunable terahertz radiation by photomixing without servo-locking

International audienceA beatnote, tunable from dc to 1 THz, provided by a dual-frequency laser is used to feed an unitravelling carrier photodiode in order to produce a highly coherent THz signal radiated by a transverse-electromagnetic-horn antenna. The THz signal is detected and analyzed by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature without phase locking the beatnote. So far, the dynamic range evolves from 58 dB at 282 GHz to 15 dB at 1.026 THz, and the measured linewidth is better than 30$~$ kHz. Linewidth narrowing using a Brillouin fiber laser pumped by the dual-frequency laser leads to a beatnote of 500-Hz linewidth at 1$~$THz