Microwave Arbitrary Waveform Generation Research Articles

Photonic generation of microwave arbitrary waveforms using stimulated Brillouin scattering and Sagnac loop

Photonic generation of microwave arbitrary waveforms using stimulated Brillouin scattering and Sagnac loop

Dispersive Fourier Transformation for Versatile Microwave Photonics Applications

Dispersive Fourier transformation (DFT) maps the broadband spectrum of an ultrashort optical pulse into a time stretched waveform with its intensity profile mirroring the spectrum using chromatic dispersion. Owing to its capability of continuous pulse-by-pulse spectroscopic measurement and manipulation, DFT has become an emerging technique for ultrafast signal generation and processing, and high-throughput real-time measurements, where the speed of traditional optical instruments falls short. In this paper, the principle and implementation methods of DFT are first introduced and the recent development in employing DFT technique for widespread microwave photonics applications are presented, with emphasis on real-time spectroscopy, microwave arbitrary waveform generation, and microwave spectrum sensing. Finally, possible future research directions for DFT-based microwave photonics techniques are discussed as well.

Fiber Bragg gratings for microwave photonics subsystems

Microwave photonics (MWP) is an emerging filed in which photonic technologies are employed to enable and enhance functionalities in microwave systems which are usually very challenging to fulfill directly in the microwave domain. Various photonic devices have been used to achieve the functions. A fiber Bragg grating (FBG) is one of the key components in microwave photonics systems due to its unique features such as flexible spectral characteristics, low loss, light weight, compact footprint, and inherent compatibility with other fiber-optic devices. In this paper, we discuss the recent development in employing FBGs for various microwave photonics subsystems, with an emphasis on subsystems for microwave photonic signal processing and microwave arbitrary waveform generation. The limitations and potential solutions are also discussed.

Photonic generation of microwave arbitrary waveforms

In this paper, techniques to generate microwave arbitrary waveforms based on all-fiber solutions are reviewed, with an emphasis on the system architectures based on direct space-to-time pulse shaping, spectral-shaping and wavelength-to-time mapping, temporal pulse shaping, and photonic microwave delay-line filtering. The generation of phase-coded and frequency-chirped microwave waveforms is discussed. The challenges in the implementation of the systems for practical applications are also discussed.

Large Time-Bandwidth Product Microwave Arbitrary Waveform Generation Using a Spatially Discrete Chirped Fiber Bragg Grating

We propose and experimentally demonstrate an approach to generating large time-bandwidth product (TBWP) microwave arbitrary waveforms based on optical pulse shaping using a single spatially discrete chirped fiber Bragg grating (SD-CFBG). The SD-CFBG functions to perform simultaneously spectral slicing, frequency-to-time mapping, and temporal shifting of the input optical pulse, which leads to the generation of an optical pulse burst with the individual pulses in the burst temporally spaced by the time delays determined by the SD-CFBG. With the help of a bandwidth-limited photodetector (PD), a smooth microwave waveform is obtained. The SD-CFBG is fabricated using a linearly chirped phase mask by axially shifting the photosensitive fiber to introduce a spatial spacing between two adjacent sub-gratings during the fabrication process. By properly designing the fiber shifting function, a large TBWP microwave arbitrary waveform with the desired frequency chirping or phase coding can be generated. An equation that relates the fiber shifting function and the microwave waveform frequency chirping is derived. The photonic generation of large TBWP microwave waveforms with a linear, nonlinear and stepped frequency chirping is experimentally demonstrated.

Simultaneous Optical Spectral Shaping and Wavelength-to-Time Mapping for Photonic Microwave Arbitrary Waveform Generation

Photonic microwave arbitrary waveform generation (AWG) based on simultaneous optical spectral shaping and wavelength-to-time mapping in a single specially designed linearly chirped fiber Bragg grating (LCFBG) is proposed. In the proposed approach, the spectrum of a transform-limited ultrashort optical pulse is spectrally shaped, and at the same time is wavelength-to-time mapped by the LCFBG to generate a microwave pulse with a shape identical to that of the shaped optical spectrum. By designing the LCFBG to have an arbitrary reflection profile, a microwave arbitrary waveform is generated. A simple and effective technique to synthesize the LCFBG with an arbitrary reflection response is proposed. Since amplitude-only index modulation is required, the designed LCFBG can be easily fabricated. Two examples showing the generations of a chirped microwave pulse and an ultra-wideband monocycle pulse are experimentally demonstrated.

Spectral line‐by‐line shaping for optical and microwave arbitrary waveform generations

AbstractSpectral line‐by‐line shaping is a key enabler towards optical arbitrary waveform generation, which promises broad impact both in optical science and technology. In this paper, generation of optical and microwave arbitrary waveforms using the spectral line‐by‐line shaping technique is reviewed. Compared to conventional pulse shaping, significant new physics arises in the line‐by‐line regime, where the shaped pulse fields generated from one laser pulse now overlap with those generated from adjacent pulses. This leads to coherent interference effects related to the properties of optical frequency combs which serve as the source in these experiments. We explore such effects in a series of experiments using several different high‐repetition‐rate optical combs, including harmonically mode‐locked lasers and continuous‐wave lasers that are externally phase modulated either with or without the help of an optical cavity. As an application of line‐by‐line pulse shaping, we describe generation of microwave electrical arbitrary waveforms that can be reprogrammed at rates approaching 10 GHz.

Photonic Microwave Arbitrary Waveform Generation Using a Virtually Imaged Phased-Array (VIPA) Direct Space-to-Time Pulse Shaper

We present the first direct space-to-time pulse shaper using a virtually imaged phased array as the spectral disperser. We use this pulse shaper to demonstrate generation of 10-50-GHz arbitrary microwave waveforms with time apertures as large as 1.0 ns and peak-to-peak amplitudes as high as 400 mV.