Introduction
Operation principle
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig1.jpg)
Fig.1 Schematic of X-FROG measurement for optical arbitrary waveforms using the PPLN waveguide. OAW: optical arbitrary waveform; LD: laser diode; MZM: Mach-Zehnder modulator; BPG: bit pattern generator; OC: optical coupler; PPLN: periodically poled lithium niobate; TF: tunable filter; CCD: charge-coupled device; OSA: optical spectrum analyzer |
Theory model
Simulation results and discussion
Effects of the complexity of OAW
Effects of different shapes of gate pulses
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig5.jpg)
Fig.5 Measured X-FROG traces of arbitrary waveform (when the gate pulse is chirped). (a) Original FROG trace of the signal pulse; (b) retrieved FROG trace of the signal pulse; (c) intensity (blue) and phase (red) of the original FROG trace; (d) intensity and phase of the retrieved FROG trace |
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig6.jpg)
Fig.6 Measured X-FROG traces of the arbitrary waveform (when the gate pulse is Gaussian). (a) Original FROG trace of the signal pulse; (b) retrieved FROG trace of the signal pulse;(c) intensity (blue) and phase (red) of the original FROG trace; (d) intensity and phase of the retrieved FROG trace |
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig7.jpg)
Fig.7 Measured X-FROG traces of the arbitrary waveform (when the gate pulse is rectangular). (a) Original FROG trace of the signal pulse; (b) retrieved FROG trace of the signal pulse; (c) intensity (blue) and phase (red) of the original FROG trace; (d) intensity and phase of the retrieved FROG trace |
Effects of the nonlinear length of PPLN waveguide
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig8.jpg)
Fig.8 Measured X-FROG traces of the arbitrary waveform. (a) Original FROG trace of the signal pulse; retrieved FROG trace of the signal pulse when the waveguide length L is (b) 20 mm, (c) 25 mm, and (d) 30 mm; (e) intensity (blue) and phase (red) of the original FROG trace; intensity and phase of the retrieved FROG trace when the waveguide length L is (f) 20 mm, (g) 25 mm, and (h) 30 mm |
Tab.1 Values of A and P in the case of different L |
L/mm | A | P |
---|---|---|
20 | 7.4975 × 10–10 | 0.18436 |
25 | 6.7923 × 10–10 | 018365 |
30 | 7.9048 × 10–10 | 0.18633 |
Effects of phase mismatching
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-1-70/thumbnail/foe-16070-wc-fig9.jpg)
Fig.9 Measured X-FROG traces of the arbitrary waveform. (a) Original FROG trace of the signal pulse; retrieved FROG trace of the signal pulse when the polarization period mismatched is (b) 0 nm, (c) 3 nm, and (d) 6 nm; (e) intensity (blue) and phase (red) of the original FROG trace; intensity and phase of the retrieved FROG trace when the polarization period mismatching is (f) 0 nm, (g) 3 nm, and (h) 6 nm |
Tab.2 Values of A and P in the case of different polarization period mismatches |
/nm | A | P |
---|---|---|
0 | 0.18365 | |
3 | 5.9712 × 10-9 | 0.25371 |
6 | 9.4727 × 10-8 | 0.51026 |