Arbitrary free spectral range control of optical frequency combs based on an optical tapped delay line structure cascaded with a phase modulator

We propose and demonstrate a simple method to accomplish arbitrary free spectral range (FSR) control of optical frequency combs (OFC). The approach is based on the combination of an optical tapped delay line (OTDL) structure and a phase modulator (PM). The OTDL structure is utilized to multiply the FSR of input OFC, and the PM is used to divide the FSR of the consequent OFC. We illustrate that the proposed method allows one to divide or multiply the FSR of original OFC by any anticipated integer or fractional factor. Numerical simulation results match well with our theoretical analysis.     

A cost-effective ultra-dense WDM PON system with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz

In this paper, an experimental scheme for cordwood color division multiplexing（CDM） visible light communication（VLC） system is proposed. The principle and structure of the experimental scheme are described. Right angle prisms and band-pass filter are used to make the unit of the optical collector and splitter. We can add or subtract the unit as we need. The cordwood CDM-VLC system can also be effectively used as a model to accomplish color shift keying and color division duplexing. The experimental system provides a new way for researching VLC.     

Switchable down-, up- and dual-chirped microwave waveform generation with improved time-bandwidth product based on polarization modulation and phase encoding

A switchable down-, up- and dual-chirped microwave waveform generation technique with improved time-bandwidth product (TBWP) is proposed and demonstrated based on a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) cascaded with a polarization modulator (PolM). By properly controlling the phase shifts of the radio frequency signals applied to the DP-DPMZM, switchable down-, up- and dual-chirped waveforms with simultaneous frequency and bandwidth doubling can be generated. To enlarge the TBWP further, splitting parabolic signal and phase-encoding splitting parabolic signal are used to drive the PolM for the enhancement of bandwidth and time duration. Numerical results demonstrate the generation of down-, up- and dual-chirped microwave waveform with TBWP of 8, 160 and 10240. The proposed method may find applications in future multifunction radar systems due to the high performance and flexibility.