We comment on a recent Letter [Opt. Lett. 35, 4121 (2010)], in which the authors discuss an optimal pulse-width modulation (OPWM) method for sinusoidal fringe generation. We consider that the comparison of the squared binary method (SBM) and the sinusoidal pulse-width modulation (SPWM) method has considerable deficiencies.

Abstract Nowadays, laser communication has received great achievements owing to its advantages, e.g., large channel capacity, easy miniaturization of system and strong anti-interference ability in different conditions. Pulse position modulation (PPM), as an important technology that transmit signal with lower power, is attracting much attention. However, the performance scheme highly depends on...

We demonstrate pulse shaping via arbitrary phase modulation with a reflective, 1×4096 element, liquid crystal spatial light modulator (SLM). The unique construction of this device provides a very high efficiency when the device is used for phase modulation only in a prism based pulse shaper, namely 85%. We also present a single shot characterization of the SLM in the spatial domain and a single...

Abstract Pulse-Position Modulation (PPM) is a modulation method that only makes every pulse in the carrier sequence change with time but without changing shape and amplitude of signal. In this paper, PPM system designed. Firstly, an appropriate mathematical model established to represent transmission, signal After that, we write code add white Gaussian noise channel. Then transmission process s...

This paper introduces a simple yet effective circuit topology to directly generate and modulate UWB pulses using baseband signals. The same circuit can be used to achieve Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), ON-OFF Keying (OOK) and Phase Shift Keying (PSK) by making changes in the baseband data. The method does not require the use of potentially expensive component...

Gas detection with hollow-core photonic bandgap fibre (HC-PBF) and pulsed photothermal (PT) interferometry spectroscopy are studied theoretically and experimentally. A theoretical model is developed and used to compute the gas-absorption-induced temperature and phase modulation in a HC-PBF filled with low-concentration of C2H2 in nitrogen. The PT phase modulation dynamics for different pulse du...