High-quality optical sinc-shaped Nyquist pulses with a virtual zero roll-off factor are obtained from the generation of a phase-locked, rectangular-spectrum frequency comb. Tunability over more than 4 frequency decades is demonstrated with <1% power distortion. OCIS codes: (060.4510) Optical communications; (060.4080) Modulation; (320.5540) Pulse shaping.

LEDs are likely to be used for general lighting applications due to their high efficiency and longer life. To cover wide output range on lighting application some of control methods are adopts. In the proposed method, the interleaved DCM fly back converter is favoured. DCM operation can accomplish high PF for wide output power range. To achieve high efficiency, new pulse duty cycle control meth...

We propose a CMOS vision chip, an image sensor with pixel-level signal processing, to serve as a replacement for degenerated photoreceptor cells in the retina. In our approach, a vision chip is implanted underneath the retina (the subretinal space). For efficient electric stimulation, we utilize a pulse frequency modulation (PFM). Each pixel consists of a photosensor and a signal processor. Eac...

Hyperbolic Frequency Modulation (HFM) signal has certain tolerance to Doppler shift. However, during ranging, the unidirectional modulated HFM cannot eliminate delay at output of matched filtering, and thus there is a ranging error. After combined positive negative echo signals are filtered, Doppler-induced closely related proportional frequency, bandwidth pulse width transmitted signals. By us...

in scpc-dama satellite networks, the baseband rrc pulse shaping is utilized to reduce the bandwidth and inter symbol interference (isi). but the variation in carrier's envelope, which expands the spectrum and ultimately increases the bandwidth, causes isi and quadrature channel crosstalk (qcc). the goal of this paper is to introduce a method to shape baseband rrc pulses, in order to make a near...

Short-Time Fourier Transform-Brillouin Optical Time-Domain Reflectometry (STFT-BOTDR) implements STFT over the full frequency spectrum to measure the distributed temperature and strain along the optic fiber, providing new research advances in dynamic distributed sensing. The spatial and frequency resolution of the dynamic sensing are limited by the Signal to Noise Ratio (SNR) and the Time-Frequ...

A theoretical proposal to double the pulse repetition frequency by alternated current modulation of two orthogonal high order transverse modes of a vertical cavity surface emitting laser (VCSEL) is presented. Static and dynamic characteristics of weakly index guided VCSELs in a multitransverse mode regime are analysed. An eecient model that takes into account all the transverse modes supported ...

Intra-pulse modulation recognition under negative signal-to-noise ratio (SNR) environment is a research challenge. This article presents a robust algorithm for the recognition of 5 types of radar signals with large variation range in the signal parameters in low SNR using the combination of the Short-time Ramanujan Fourier transform (ST-RFT) and pseudo-Zernike moments invariant features. The ST...

In this work we set upon showing theoretically that the use of accelerating spatiotemporal Quasi-Phase-Matching (QPM) in media with parametric optical interactions makes it possible to generate a time-reversed replica of the pump pulse envelope in a frequency converted component. We construct the geometrical form for the modulation that will lead to an up-converted envelope-time-reversed replic...