Enhanced Sample Rate, combined with the low-noise system architecture and the tailored brick-wall frequency response in the HDO4000A, HDO6000A, HDO8000A and MDA800A series oscilloscopes dramatically improves the measurement precision when the input frequency signals are very high frequency, such as a high-frequency sine wave or fast edge.

We present a novel low-loss 3-spot mode coupler to selectively address 6 spatial and polarization modes of a few-mode fiber. The coupler is used in a 66 MIMO-transmission experiment over a 154-km hybrid span consisting of 129-km depressed-cladding and 25-km graded-index few-mode fiber.

We experimentally demonstrate 8 dB of mode-equalized distributed Raman gain using a backward pumping scheme. The equivalent noise figure of the amplifier is -1.5 dB, and the amplifier was successfully employed to demonstrate 6-channel mode-multiplexed MIMO transmission over 137-km few-mode fiber.

Low differential group delay (DGD) between the modes of a graded-index few-mode fiber is obtained by combining segments with DGD of opposite sign. Transmission of mode-multiplexed 620-GBd QPSK over a record distance of 1200 km is demonstrated.

Oscilloscopes utilize both hardware and software tools to enhance the resolutionof time measurements. Happily, most of the processing is transparent. The primary display from an oscilloscope is amplitude versus time. Most of the focuswhen using oscilloscopes is on the vertical axis, including amplitude resolution, analogbandwidth, and vertical accuracy. The time axis does not seem to get equal billing.That’s because oscilloscope time bases are very good.