Fig. 1. (a) Schematic overview of the proposed spectral interferometry for precision micro-dispersion measurement. (b) Diagram for propagation of light pulses in the measured medium. (c) Measurable media: lens, SMF (single-mode fiber), air. (d) Nine groups of simulated interference spectra. Comb, optical frequency comb; EOM, electro-optic modulator; OC, optical coupler; Col, collimator; CW, continuous wave laser; BS, beam splitter; REF, reference mirror; OSA, optical spectrum analyzer.

Fig. 2. Phase demodulation process of interference spectrum. (a) The interference spectrum after the envelope is removed. (b) The phase curve of (a) after Hilbert transformation. (c) The phase curve of (b) after phase unwinding. (d) The process of solving the PCVTP. Similarly, (e)–(h) for Lk=1.6  mm and (i)–(l) for Lk=2.4  mm.

Fig. 3. (a) Triangular and periodic characteristics of interference phase. (b) Schematic diagram of spectral-interferometry-based diff-iteration (SiDi) method. (c) Micro-dispersion curve calculation flow chart.

Fig. 4. (a) Calculation results of PCVTPs using different step d. (b) Simulation results of dispersion curve for SMF core using different step d. (c) Error band of simulation results.

Fig. 5. Experimental structure and light source characterization. (a) Image of the butterfly-packaged MRR. (b) Image of the micro-ring resonator with a free spectral range of 48.97 GHz. (c) Experimental diagram for dispersion measurement of glass. (d) Experimental system structure. (e) Typical optical spectrum of the single SMC. Left inset, enlarged comb lines. (f) Typical interference spectrum of the OFC-based micro-dispersion measurement system. ECDL, external cavity diode laser; EDFA, erbium-doped optical fiber amplifier; FPC, fiber polarization controller; OC, optical coupler; SMF, single-mode fiber; Col, collimator; Cir, circulator; REF, reference mirror; OSA, optical spectrum analyzer.

Fig. 6. Experimental data processing and results. (a) Nine groups of interference spectra. (b) PCVTPs obtained by two experiments. (c) Dispersion calculation results for 14 m SMF. (d) Phase generated by SMF + glass. (e) Phase generated by SMF. (f) Phase generated by glass. (g) Dispersion calculation results and relative error for 0.05 m glass.