Optical waveform measurement by optical sampling with a mode-locked laser diode

Mode locking of semiconductor laser with curved waveguide and passive mode expander

“…The principle of optical sampling is to combine a high bit rate signal at frequency f 0 , with a stream of short optical pulses at a lower frequency f 0 -∆ f. The optical nonlinear effect of sum-frequency mixing can then be used 6,7 to extract information about the signal at the frequency ∆ f. The generated signal is now at a much lower repetition frequency and can be analysed with conventional detection te chniques, with a resolution of the order of the pulsewidth of the sampling pulses being used.…”

Optical signal generation at millimeter-wave repetition rates using semiconductor lasers with pulsed subharmonic optical injection

“…T HE generation of optical pulses from semiconductor lasers at millimeter-wave repetition rates and higher has attracted considerable interest due to its importance in high-speed optical communications [1], [2], microwave photonic systems [3], [4], and optical signal processing [5], [6]. Significant progress has been made in improving the performance of such optical pulse trains with regard to increasing their repetition rate, stability [7], tunability [8], compactness, and driving electronics requirements.…”

All-optical sampling and magnification based on XPM-induced focusing

“…This process allows us to experimentally demonstrate a 40-GHz sampling operation as well as an 8-dB magnification of an arbitrary shaped nanosecond signal around 1550 nm in a 5-km long normally dispersive fiber. The experimental observations are in quantitative agreement with numerical and theoretical analysis.In modern photonic systems, the sampling process has widespread applications in the fields of optical communications, metrology, clocking, sensing, spectral comb or arbitrary waveform generation.In this context, nonlinear effects have been demonstrated as potential key technologies to develop alloptical sampling devices [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . In most of these techniques, an ultrashort pulse train acts as an optical gate and the basic physical phenomena under use include four-wave mixing (FWM) 10 , cross-phase modulation (XPM) 11 , nonlinear polarization rotation 13 and Raman soliton self-frequency shifting 14 .…”

“…As long as the fiber length does not exceed few nonlinear lengths (defined as 1/γP0), the level of the new spectral components generated by FWM in the pump spectrum remain 10 dB below the original components centered at ± ωp 16 . We can thus neglect as a first rough approximation the impact of these additional spectral components and therefore consider that the sinusoidal pump intensity profile is preserved upon propagation except for propagation losses, that is |v(z,t)| 2 =P0 cos(ωpt) 2 …”