RESUMEN
We report on the generation of four spatially multiplexed picosecond 40 GHz pulse trains in a km long 6 LP multimode optical fiber. The principle of operation is based on the parallel nonlinear compression of initial beat signals into well separated pulse trains owing to intramodal multiple four-wave mixings. A series of four 40 GHz dual-frequency beatings at different wavelengths are simultaneously injected into the ${{\rm LP}_{01}}$LP01, ${{\rm LP}_{11}}$LP11, ${{\rm LP}_{02}}$LP02, and ${{\rm LP}_{12}}$LP12 modes of a 1.8 km long graded-index few-mode fiber. The combined effects of Kerr nonlinearity and anomalous chromatic dispersion lead to the simultaneous generation of four spatially multiplexed frequency combs, which correspond in the temporal domain to the compression of these beat signals into picosecond pulses. The temporal profiles of the output pulse trains demultiplexed from each spatial mode show that well-separated picosecond pulses with negligible pedestals are then generated.
RESUMEN
We demonstrate experimentally a simultaneous threefold modal and wavelength conversion process of a 10-Gbit/s On/Off keying signal in a 1.8-km long graded-index 6-LP-mode fiber. The principle of operation is based on a phase-matched inter-modal four-wave mixing phenomenon occurring between the fundamental mode and 3 higher-order modes of the fiber. The converted signals show well-opened eye-diagrams and error-free processing.
RESUMEN
We demonstrate successful transmission of four 45 Gbps PAM4 single-channels through OM4 multimode fibers (MMFs) and wideband MMF using a PAM4 PHY chip and four vertical cavity surface emitting lasers (VCSELs) with wavelengths ranging over short wavelength division multiplexing (SWDM) grid. Real-time bit error ratios (BERs) < 2 × 10-4 were achieved for all four 45 Gbps PAM4 SWDM grid channels over 100 m, 200 m, and 300 m of wideband OM4 MMFs. All four channel received PAM4 optical eyes are shown after propagating through 100 m, 200 m, and 300 m of wideband OM4 as well as 100 m and 200 m conventional OM4 MMFs. The measured BERs as a function of the inner eye optical modulation amplitudes (OMAs) are shown for all four SWDM grid channels. Inner eye OMAs ranged from -16.2 dBm to -13.5 dBm for different channels over different OM4 MMF types at the KP4 BER threshold of 2 × 10-4.
RESUMEN
We demonstrate a few-mode erbium-doped fiber amplifier employing a mode-selective photonic lantern for controlling the modal content of the pump light. Amplification of six spatial modes in a 5 m long erbium-doped fiber to â¼6.2 dBm average power is obtained while maintaining high modal fidelity. Through mode-selective forward pumping of the two degenerate LP21 modes operating at 976 nm, differential modal gains of <1 dB between all modes and signal gains of â¼16 dB at 1550 nm are achieved. In addition, low differential modal gain for near-full C-band operation is demonstrated.
RESUMEN
Low-loss all-fiber photonic lantern (PL) mode multiplexers (MUXs) capable of selectively exciting the first six fiber modes of a multimode fiber (LP01, LP11a, LP11b, LP21a, LP21b, and LP02) are demonstrated. Fabrication of the spatial mode multiplexers was successfully achieved employing a combination of either six step or six graded index fibers of four different core sizes. Insertion losses of 0.2-0.3 dB and mode purities above 9 dB are achieved. Moreover, it is demonstrated that the use of graded index fibers in a PL eases the length requirements of the adiabatic tapered transition and could enable scaling to large numbers.
RESUMEN
Optimal dense wavelength-division multiplexed transmission is obtained based on high-order periodic dispersion-managed solitons in a dispersion-slope-compensated fiber link.
RESUMEN
We report the operation of an in-line Nd:YAG resonator using self-pumped phase conjugation in Cr(4+): YAG at lambda=1.064microm in the nanosecond regime. The output beam has a high-quality diffraction-limited TEM(00) mode and a pulse shape of ~15ns , showing the self- Q -switching ability of the resonator. A maximum extraction of 18mJ and a maximum reflectivity of 2.0 are measured. A transient model provides insight into the energy characteristics and the dynamics of such an in-line resonator.
RESUMEN
We demonstrate a self-pumped phase-conjugate diode-pumped Nd:YAG loop resonator. In the injected configuration a maximum phase-conjugate reflectivity of 32 is obtained. The output beam has a pulse shape of ~30 ns , which shows the self- Q -switching ability of the resonator. By use of a low-refractive-output coupler, a self-starting version was produced. The resonator operated in a stable diffraction-limited TEM(00) mode, even with severe intracavity phase aberrations. A maximum energy of 5.5 mJ (2.4% of the energy of the high-brightness stacks that was incident upon the Nd:YAG crystals) in a 20-ns single-longitudinal-mode pulse was measured.
RESUMEN
Whereas surgery is no longer used for treatment of pyelocaliceal and lower ureter lithiasis, it remains a valid method in lithiasis of lumbar ureter poorly accessible to endoscopy. A direct approach to lumbar (or pelvic) ureter by posterior vertical lombotomy considerably reduces operation time, pain and duration of hospital stay and disability. Results in a series of 42 cases indicate that surgery remains an excellent and perhaps most effective therapy for lumbar ureter calculi, with the condition that the conventional posterolateral lombotomy be abandoned.