Search results for "Amplifier"
showing 10 items of 239 documents
Parametric frequency conversion of optical simulton pulses
2007
We present an analytical description of the parametric frequency conversion of short solitary wave optical pulses in quadratic nonlinear crystals controlled by means of a continuous wave background.
Emergence of extreme events in fiber-based parametric processes driven by a partially incoherent pump wave
2009
Modulation instability (MI) generated by a picosecond coherent pulse has been recently identified as the key element of the generation of optical rogue-waves in supercontinuum-based systems [1]. Similar rare but highly energetic pulse structures can also appear in non-solitonic configurations such as Raman amplifiers driven by a partially incoherent pump wave propagating in fibres with low group velocity dispersion [2]. Therefore, one may wonder whether optical rogue-like event can also occur in MI-based amplifier because both Raman and parametric amplifiers benefit from a quasi-instantaneous gain. We provide here experimental evidence of rare optical events in a parametric amplifier in pre…
Collisions between similaritons in optical fiber amplifiers
2009
We consider the self-similar amplification of two optical pulses of different wavelengths in order to investigate the effects of a collision between two similaritons. We theoretically demonstrate that similaritons are stable against collisions in a Raman amplifier: similaritons evolve separately in the amplifier without modification of the scaling of their temporal width and chirp and by conserving their velocities, only interact during their overlap and regain their parabolic form after collision. We show both theoretically and experimentally that the collision of two similaritons induces a sinusoidal modulation inside the overlap region, whose frequency decreases during the interaction. T…
<title>Optical sensing for early cardiovascular diagnostics</title>
2000
A sensor device for noninvasive detection and analysis of the pulsating blood flow waveforms by means of the reflective single-period photoplethysmorgraphy (SPPPG) technique has been designed and clinically tested. The sensor is operated jointly with any standard PC, by connecting the sensor head to the AD-card and using a separate hard disc with the signal processing software; all circuits are fed by the PC power supply. After processing, normalized shape of the mean SPPPG signal and its parameters are calculated and displayed; the measurement/processing time does not exceed 2 minutes. The clinically detected SPPPG signal shapes and corresponding parameters are presented and discussed. The…
Coupling evanescently low loss Silicon-on-insulator (SOI) ridge waveguides(WGs) including high Q nanocavities: For light control
2011
We have fabricated a multislotted optical nanoresonator with several spatial field distributions which are all addressable by the wavelength. The reported structure consists in an array of evanescently coupled single mode photonic crystal nanocavities. By using a scanning near-field optical microscope, we quantify the morphology of the different optical mode volumes and show that they consist in grids of light confined at the subwavelength scaleOver the last recent years, optical microcavities have proven their ability to slow down, control and even trap light inside an ultra small volume. Several approaches have led to quality factor (Q) records allowing to reach high photon life-time for …
Halide perovskite amplifiers integrated in polymer waveguides
2016
Semiconductor organometallic halide perovskites (CH 3 NH 3 PbX 3 , X=Cl, Br, I) (HPVK) have emerged as a new promising material able to improve the optoelectronic technology performance. Although this material has mostly been applied to improve the efficiency of photovoltaic devices, it also shows amazing properties for photonic applications. In particular, HPVK exhibits high photoluminescence (PL) quantum yield (up to 70%) at room temperature together with a tunable band-gap controlled by its chemical composition. In addition, since HPVKs is deposited in solution at room conditions, it can be easily incorporated in different photonic structures to efficiently exploit its emission propertie…
Record Phase Sensitive Extinction Ratio in a Silicon Germanium Waveguide
2015
A binary step-like phase response and phase-sensitive extinction ratio in excess of 28dB under CW pump operation was demonstrated in a 20mm-long low birefringence SiGe waveguide, using a polarization-assisted phase sensitive amplifier scheme.
Highly-chirped similaritons generation from a mode-locked fiber laser
2007
In this communication, we report experimental and numerical results on dynamics and propagation of self-similar pulses in a passively mode-locked ytterbium doped DC fiber laser.
Observation of a nonlinear microfiber resonator
2008
Measurements of the intensity transfer function of a silica microfiber resonator are shown to follow a wide variety of hysteresis cycles, depending on the cavity detuning and the scanning frequency of the range of input powers. We attribute these observations to a nonlinear phase shift of thermal origin and provide a simple model that reproduces well our measurements. The response time is found to be around 0.6 ms.
Ultrafast Gain Recovery in Quantum Dot based Semiconductor Optical Amplifiers
2007
Summary form only given. The limiting factor in ultrahigh bit rate amplification is the ultrafast population recovery in the resonant level, which is mainly limited by carrier capture and relaxation processes in the QD. We use pump-probe measurements resonant to the QDs confined states energies (ground and excited state) to investigate the response to a four fs-pulse train of 1 THz repetition rate. A deep insight about the capture process implied is then obtained, and direct capture from the wetting layer is identified as the dominant mechanism in the high current regime.