High packing density 2.5 THz true-time-delay lines using spatially multiplexed substrate guided waves in conjunction with volume holograms on a single substrate

Abstract

A 3-bit true-time-delay lines device having a packing density of 5 lines/cm 2 with a minimum delay step of 100 ps is designed, fabricated and demonstrated. This device is based on substrate guided wave propagation combined with slanted photopolymer volume phase gratings. In this paper, we report the delay and bandwidth measurements for the 3-bit delay lines fabricated on BK-7 glass substrates with a substrate bouncing angle of 45 . The power fluctuation among the outputs due to the cascading fanout effect (a serious drawback for real system applications) is experimentally investigated as well. A power fluctuation controlled to within 610% is achieved. A femtosecond laser pulse is sent through the device and a bandwidth measurement of up to 2.5 THz is obtained. The delay step is measured by employing an ultrafast photodetector together with a sampling scope. The true-time-delay device presented herein has the potential to be integrated with photodetector arrays due to its planar structure on a single substrate together with the surface normal fan-in and fan-out features.

Optical true time delay for phased-array antennas: demonstration of a quadratic White cell

“…In optical TTD, the signal from ͑or to͒ each antenna element is intensity modulated onto a separate light beam, and each light beam is directed through paths of varying lengths to introduce relative time delays. These paths can be in fibers or waveguides [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] or in free space. 18 -21 Most approaches use fibers or waveguides.…”

Silicon nanomembrane-based compact true-time-delay module on unconventional substrates

“…Photonic true-time-delay (TTD) offers better performance with reduced cost, size, weight, and power (C-SWaP) over traditional electronic solutions, especially for simultaneous multi-user, multi-target tracking capability in phased array sensor applications. Several photonic TTD schemes have been proposed to take advantages of an optical feed for TTD, including WDM technique [2][3][4][5], slow-light waveguide technique [6], monolithic waveguide technique [7], acousto-optic (AO) integrated circuit technique [8][9][10], Fourier optical technique [11][12][13], bulky optics techniques [14][15][16][17][18][19], Bragg-fiber technique, dispersive fiber technique [20][21][22][23][24], fiber grating technique [25][26], and substrate guided wave techniques [27][28][29]. Use of photonic systems on air-borne and space-borne platforms or integration of several communication and sensing units on a single chip for improved reliability will require individual components to have smaller size, lower power consumption, and lighter weight.…”

Wavelength-controlled hologram-waveguide modules for continuous beam scanning in a phased-array antenna system

“…The digitalized true-time-delay modules using hologram-waveguidebased technique were demonstrated [4,5], in which time delay modules were designed for working in both the 850 nm and the 1550 nm wavelength regions. A quasi-analog true-time-delay scheme was proposed and demonstrated [6], an improvement compared with digitalized schemes, but continuous time delays are available only in a narrow range.…”