RESUMO
Highly efficient coherent beam combining (CBC) of two very-high-power optical amplifiers (VHPOA) with applications to long-range FSO communications such as ground-to-space feeder links is presented. The CBC setup is designed to minimize the telecom signal degradation, with a polarization beam splitter used to minimize the power fluctuations and to control the output polarization state of the beam. The system delivers 80 W output power and is proven to be compatible with 25 Gb/s telecom signals with a less than 1â dB power penalty.
RESUMO
Atmospheric turbulence can generate scintillation or beam wandering phenomena that impairs free space optical (FSO) communication. In this paper, we propose and demonstrate a proof-of-concept FSO communication receiver based on a spatial demultiplexer and a photonic integrated circuit coherent combiner. The receiver collects the light from several Hermite Gauss spatial modes and coherently combine on chip the energy from the different modes into a single output. The FSO receiver is characterized with a wavefront emulator bench that generates arbitrary phase and intensity patterns. The multimode receiver presents a strong resilience to wavefront distortions, compared to a monomode FSO receiver. The system is then used to detect an analog modulation of an optical beam through a random wavefront profile to mimic the transmission of a signal on a degraded optical link.
RESUMO
We report on the use of a 61 beamlets coherent beam combination femtosecond fiber amplifiers as a digital laser source to generate high-power orbital angular momentum beams. Such an approach opens the path for higher-order non-symmetrical user-defined far field distributions.
RESUMO
We report on the coherent beam combining of 61 femtosecond fiber chirped-pulse amplifiers in a tiled-aperture configuration along with an interferometric phase measurement technique. Relying on coherent beam recombination in the far field, this technique appears suitable for the combination of a large number of fiber amplifiers. The 61 output beams are stacked in a hexagonal arrangement and collimated through a high fill factor hexagonal micro-lens array. The residual phase error between two fibers is as low as λ/90 RMS, while a combining efficiency of â¼50% is achieved.
RESUMO
Coherent beam combining in tiled-aperture configuration is demonstrated on seven femtosecond fiber amplifiers using an interferometric phase measurement technique. The residual phase error between two fibers is as low as λ/55 RMS and a combination efficiency of 48% has been achieved. The combined pulses are compressed to 216 fs, delivering 71 W average power at a repetition rate of 55 MHz. Operating the laser system in a nonlinear regime with an estimated B-integral of 5 rad yields a combining efficiency of 45% with the same phase stability. These results pave the way to very large high-power and high energy coherent beam combining systems.
RESUMO
We present a technique for passive coherent fiber beam combining based on digital holography. In this method, the phase errors between the fibers are compensated by the diffracted phase-conjugated -1 order of a digital hologram. Unlike previous digital holography technique, the probe beams measuring the phase errors between the fibers are co-propagating with the phase-locked signal beams. This architecture is compatible with the use of multi-stage isolated amplifying fibers. It does not require any phase calculation algorithm and its correction is collective. This concept is experimentally demonstrated with three fibers at 1.55 µm. A residual phase error of λ/20 is measured.
Assuntos
Algoritmos , Holografia/instrumentação , Aumento da Imagem , Interpretação de Imagem Assistida por Computador/métodos , Processamento de Sinais Assistido por Computador , Desenho de EquipamentoRESUMO
A new architecture for active coherent beam combining of a large number of fibers is demonstrated. The approach is based on a self-referenced quadriwave shearing interferometer and active control with arrays of electro-optic ceramic modulators. Coherent phase combining of 64 independent amplified fibers is obtained. This is to our knowledge the highest reported number of combined fibers. A Strehl ratio degradation less than 2dB is achieved with a residual phase error <λ/10 rms.