Sub-picosecond phase-sensitive optical pulse characterization on a chip

New CMOS-compatible platforms based on silicon nitride and Hydex for nonlinear optics

“…Linear propagation losses as low as 5 -7 dB/meter have been achieved, allowing for the use of extremely long waveguide spirals [14,63]. Figure 1b shows a schematic of a 45-cm-long spiral waveguide contained within a square area of 2.5 mm x 2.5 mm and pigtailed to a singlemode fiber via low loss on-chip beam expanders, as well as a SEM picture of its cross section (before cladding deposition).…”

“…Ultrafast optical signal measurements have been achieved using time-lens temporal imaging on a silicon chip [105,106] and waveguide-based Frequency-Resolved Optical Gating (FROG) [107], but these are either phase insensitive or require waveguide-based tunable delay lines -a difficult challenge. Recently [14], a device capable of both amplitude and phase characterization of ultrafast optical pulses was reported, operating via a novel variation of Spectral Phase Interferometry for Direct Electric-Field Reconstruction (SPIDER) [108 -115] based on FWM in a Hydex waveguides. Here, pulse reconstruction was obtained with the aid of a synchronized incoherently related clock pulse.…”

“…Also, typical SPIDER methods work best with optical pulses shorter than 100 fs [114] (small time-bandwidth products (TBP)) and peak powers > 10 kW, and hence are not ideally suited to telecommunications. The device reported in [14] measured pulses with peak powers below 100 mW, with a frequency bandwidth greater than a terahertz and on pulses as wide as 100 ps, yielding a record TBP > 100 [114]. The technique employed in this device is commonly referred to as X-SPIDER.…”

“…All-optical signal generation and processing [1,2] have been highly successful at enabling a vast array of capabilities, such as switching and de-multiplexing of signals at unprecedented speeds [3,4], parametric gain [5] on a chip, Raman lasing [6], wavelength conversion [7], optical logic [8], all-optical regeneration [9,10], radio-frequency (RF) spectrometry at THz speeds [11,12], as well as entirely new functions such as ultra-short pulse measurement [13,14] and generation [15] on a chip, optical temporal cloaking [16], and many others. Phase sensitive functions [14,17], in particular, will likely be critical for telecommunications systems that are already using phase encoding schemes [18,19].…”

“…Phase sensitive functions [14,17], in particular, will likely be critical for telecommunications systems that are already using phase encoding schemes [18,19]. The ability to produce these devices in integrated form -photonic integrated circuits (PICs) -will reap the greatest dividends in terms of cost, footprint, energy consumption and performance, where demands for greater bandwidth, network flexibility, low energy consumption and cost must all be met.…”