Fig. 2: Experimental setup.
From: All-fiber optical nonreciprocity based on parity-time-symmetric Fabry-Perot resonators
a Schematic of the experimental setup for forward and backward transmission measurements. Optical paths for forward and backward transmission are shown by the blue and red lines, respectively. The shared optical paths for both forward and backward transmission are shown by the yellow lines. The optical path for the pump light is shown by the purple line. b A fabricated all-fiber nonreciprocal device based on parity-time-symmetric FP resonators. c A fabricated single FP resonator on an EYDF to characterize the gain-saturation nonlinearity in the FP resonator. OVA: optical vector analyzer; VOA: variable optical attenuator; PC: polarization controller; EDFA: erbium-doped fiber amplifier; OC: optical coupler; PM: power meter; WDM: wavelength division multiplexer; FBG: fiber Bragg grating; PT: parity-time; FP: Fabry-Perot interferometer; EYDF: erbium-ytterbium co-doped fiber.
