Pham Q. Thai

Limitations by Group Delay Ripple on Optical Beam-forming With Chirped Fiber Grating

This paper investigates the effect of group delay ripple on optical beam-formers using chirped fiber grating. Such optical beam-formers were promised to have many advantages over their electrical beam-forming counter-parts. However, mathematical analysis and simulation results have shown that the group delay ripple causes many drawbacks such as the limitation in operation frequency, RF signal bandwidth, and the number of elements. The most advantageous feature of optical beam-formers, which is squint-free operation for wideband, high frequency signals, is severely affected when chirped grating is used.

A Novel Simplified Dual Beam-Former Using Multichannel Chirped Fiber Grating and Tunable Optical Delay Lines

A multiple beam former using multichannel chirped fiber grating (MCFG) and tunable optical delay lines is investigated in this paper. The simulation results shown in this paper exhibited that it could form two beams, which could be operated squint-free and independently from each other at 6 GHz. The use of a MCFG along with tunable optical delay lines has greatly reduced the system complexity and components requirements. Moreover, our proposed beam-former is able to operate using fewer tunable laser sources than other similar approaches. Successfully addressing this problem in the components cost would make the implementation of the scheme far more feasible.

Simplified optical dual beamformer employing multichannel chirped fiber grating and tunable optical delay lines

A multi beam-former using multi-channel chirped fiber grating (MCFG) and tunable optical delay lines is proposed in this paper. Simulation results shown that it could form two beams, which could be operated squint-free and independent from each other at 6 GHz. The use of MCFG incorporation with tunable optical delay lines has greatly reduced the system complexity and components requirement. Moreover, our proposed beam-former is more robust against group delay ripple, which is the main reason for directivity error in other beam-former using chirped fiber grating.

Hybrid optical beamformers and their robustness against group delay ripples errors

In this paper, the negative effect of group delay ripples on optical beamformers using chirped grating is investigated. A promising solution in the form of hybrid approach for optical beamformer is also presented. Both transmitting and receiving systems using this approach have been demonstrated and examined against the group delay fluctuations.

Optical Dual-beam Beam-former Employing Multi-channel Chirped Fiber Grating

A dual-beam beam-former using multi-channel chirped fiber grating (MCFG) is proposed in this paper. Simulation results shown that it could form two beams, which could be operated squint-free and independent from each other at 2.1 GHz. The use of MCFG reduced the system complexity and components requirement. Moreover, sidelobe ratios were greatly reduced in comparison with other proposed methods thanks to windowing techniques.

Hybrid optical beam-former in receiver mode

In this paper, an optical beam-former in receiving mode has been proposed and experimentally demonstrated. The requirement in systems hardware has been dramatically reduced using a hybrid approach between dispersive and non-dispersive delay. The proposed system is capable of supporting RF signals from L-band to X-band, with large coverage and strong robustness against the gratings group delay ripples.

Photonic 2-D beam-former using multi-channel chirped fiber grating and optical delay lines with multiple beams capability

A 2-D multiple beams beam-former using multi-channel chirped fiber grating (MCFG) and tunable optical delay lines is investigated in this paper. The simulation results shown in this work exhibited that it was capable of forming beams in 2-D plane, which could be operated independently from each other at 8 GHz. The use of a MCFG along with tunable optical delay lines has greatly reduced the system complexity and components requirements. Simulations also indicated that our proposed scheme is more robust against group delay ripple, an inevitable error in every grating.

Dual-band Optical Phased Array Antenna Using, Multichannel Chirped Fiber Grating

A dual-beam dual-band multibeamformer using multichannel chirped fiber grating (MCFG) is proposed in this paper. Simulation results shown that it could form two beams, which could be operated squint-free, and independent from each other while transmitting different data streams. Moreover, the use of MCFG reduced the system complexity and components requirement greatly in comparison with other proposed methods.