Photonic chirped radio-frequency generator with ultra-fast sweeping rate and ultra-wide sweeping range.

A high-performance photonic sweeping-frequency (chirped) radio-frequency (RF) generator has been demonstrated. By use of a novel wavelength sweeping distributed-feedback (DFB) laser, which is operated based on the linewidth enhancement effect, a fixed wavelength narrow-linewidth DFB laser, and a wideband (dc to 50 GHz) photodiode module for the hetero-dyne beating RF signal generation, a very clear chirped RF waveform can be captured by a fast real-time scope. A very-high frequency sweeping rate (10.3 GHz/µs) with an ultra-wide RF frequency sweeping range (~40 GHz) have been demonstrated. The high-repeatability (~97%) in sweeping frequency has been verified by analyzing tens of repetitive chirped waveforms.

Four-wave-mixing-based wavelength conversion using a single-walled carbon-nanotube-deposited planar lightwave circuit waveguide.

We demonstrated a single-walled carbon-nanotube-deposited planar lightwave circuit (PLC) waveguide for four-wave-mixing (FWM)-based wavelength conversion. FWM is generated from the interaction between the propagating light through the PLC waveguide and the deposited carbon nanotubes (CNTs) on the overcladding-removed core of the waveguide. The third-order nonlinearity of the CNTs is originated from the interband transitions of the pi electrons causing nonlinear polarization similar to other highly nonlinear organic optical materials. FWM-based tunable wavelength conversion of a 10 Gbit/s non-return-to-zero signal is achieved with a power penalty of 3 dB in the bit-error-rate measurements. To our knowledge, this is the first demonstration of a CNT-technology-based device for integrated photonic applications.

Saturable absorbers incorporating carbon nanotubes directly synthesized onto substrates and fibers and their application to mode-locked fiber lasers.

We present novel carbon-nanotube-based saturable absorbers. Using the low-temperature alcohol catalytic chemical-vapor deposition method, high-quality single-walled carbon nanotubes (SWNTs) were directly synthesized on quartz substrates and fiber ends. We successfully applied the SWNTs to mode lock a fiber laser producing subpicosecond pulses at a 50-MHz repetition rate.