Fig. 1. Schematic diagram of principle for direct optical vector analysis technique based on broadband electrical modulation

Fig. 2. Schematic diagram of principle for indirect optical vector analysis technique

Fig. 3. Schematic diagram of optical vector network analyzer based on optical interference^[12]

Fig. 4. Schematic diagram of optical vector analysis technique based on optical interference

Fig. 5. Schematic diagram of the OVA based on SSB modulation^[27]

Fig. 6. Measurement results of spectral response for an ultra-narrow band phase-shifted FBG^[27]. (a) Measurement results of magnitude response; (b) measurement results of phase response

Fig. 7. Architecture of OVA based on optical frequency comb and asymmetric DSB modulation^[73]

Fig. 8. Structure and principle of optical vector analysis technique based on dual-radio-frequency modulation^[80]. (a) Structure schematic diagram of the dual-radio-frequency modulation scheme; (b) principle of time to frequency conversion based on dual-radio-frequency modulation

Fig. 9. Schematic diagram of frequency calibration based on fiber resonator^[10]

Fig. 10. Spectra of branches and structure of optical vector analysis based on resonator calibration^[10]. (a) Spectra of branches; (b) schematic diagram of the structure

Fig. 11. Schematic diagram of phase measurement scheme based on Kramers-Kronig relationship^[37]

Fig. 12. Schematic diagram of optical vector analysis based on fractional delay scheme^[38]

Fig. 13. Schematic diagram of optical vector analysis for a four-tap FIR filter^[38]. (a) Chip architecture; (b) chip layout; (c) insertion loss spectrum after normalization; (d) photomicrograph; (e) recovered impulse response and measured impulse response amplitude using commercial equipment; (f) powers and phases of the four taps as a function of the electrical power applied onto phase shifter 1; (g) spectral characteristics of SPC; (h) phases of the four taps as a function of electrical power

Fig. 14. Schematic diagrams of optical vector analysis based on long delay reference path. (a) Schematic diagram of optical vector analysis scheme; (b) schematic diagram of time-domain signal

Fig. 15. Experimental results for on-chip Kramers-Kronig phase recovery^[37]. (a) Layout of the 16-tap FIR chip; (b) photo of the fabricated chip; (c) packaged chip; (d) measured powers of the 16 taps; (e) power splitting ratio of MZIs 4‒8; (f) measured phases of the 16 taps; (g) phase of phase shifter 16; (h) measured insertion loss spectrum of a certain configuration of the tap coefficient; (i) phase response recovered via Hilbert transform; (j) power and (k) phase of the impulse response or tap coefficient recovered from inverse Fourier transform of the frequency response, or measured using an OVA; (l) poles and zeros recovered via a Z-transform of the frequency response