Optical vector analysis based on double-sideband modulation and stimulated Brillouin scattering

Abstract

A high-resolution and high-accuracy optical vector analysis based on optical double-sideband modulation and stimulated Brillouin scattering is proposed and experimentally demonstrated. Different from the conventional OVA based on optical single-sideband modulation, in which the measurement range is limited by the bandwidth of the microwave and optoelectronic components, and the measurement accuracy is restricted by the high-order sidebands, the proposed technique measures the magnitude and phase responses by making use of both ±1st-order sidebands without spectrum response aliasing. As a result, the measurement range is doubled, and the high-order, sideband-induced errors only appear at specific frequencies that are predictable and removable. A proof-of-concept experiment is carried out. The transmission response of a fiber Bragg grating, in a range of 80 GHz, is measured with a resolution of less than 667 kHz by using 40 GHz microwave components.

Ultrahigh-Resolution Optical Vector Analyzers

“…To simultaneously solve the problems described above, OVAs based on optical dual-sideband (ODSB) modulation were created [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. They have the following advantages: A doubled measurement frequency range up to 80 GHz with an element base based on lithium niobate (LiNbO 3 ), and an ultrahigh resolution of about 667 kHz, which depends on the quantity of control points of measurements of the electrical vector network analyzer, and which can be increased.…”

“…The disadvantage of this method is that there are measurement errors caused by the incompletely suppressed first-order sideband in the OSSB-signal (Figure 9). A similar approach was implemented in [30]; at the output of the DD-DPMZM, a four-frequency signal was obtained, which interacted with the absorption and gain contours caused by the stimulated Brillouin scattering (SBS) effect. One of the sidebands was suppressed, while the other was amplified and became a shifted carrier.…”

“…However, the high sensitivity of the SBS effect to external conditions is a drawback that complicates any practical implementation ( Figure 10). The schematic diagram of the OVA based on asymmetric ODSB and SBS: TLS-tunable laser source; MZM-Mach-Zehnder modulator; DPMZM-dual-parallel MZM; RF-radio frequency; LO-local oscillator; EDFA-erbium doped fiber amplifier; SMF-single-mode fiber; DUT-device under test; PD-photodetector; BPF-bandpass filter; PMD-phase-magnitude detector; PU-processing unit; red lines-optical signal; blue lines-electrical signal; dotted line-data path; ω 0 -the frequency of optical carrier; ω m -the modulation frequency; ∆ω-a fixed frequency shift (adapted from [30]).…”

Optical vector analysis based on asymmetrical optical double-sideband modulation using a dual-drive dual-parallel Mach-Zehnder modulator

“…Recently, an OVA based on optical double-sideband (ODSB) modulation is proposed [17,18], which characterizes the optical devices using both of the two first-order sidebands without frequency aliasing by shifting the frequency of the optical carrier. Compared with the OSSB-based OVA, the ODSB-based OVA has a doubled measurement range, and better nonlinearity immunity which leads to a higher accuracy and a larger dynamic range.…”

“…In this case, however, the phase response cannot be accurately measured due to the large phase noise between the two separated optical paths. In [18], the carrier-shifted ODSB signal was generated with the assistance of stimulated Brillouin scattering (SBS) effects in an optical fiber. Since only one transmission path is required, both the magnitude and phase responses can be measured.…”