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A low-frequency electrical spectrum analysis method is researched for evaluating broadband characteristics of high-speed dual-parallel Mach-Zehnder modulators (DPMZMs) based on dual-frequency modulation and fixed-frequency bias. The method enables the broadband and high-resolution evaluation for the modulation depth and half-wave voltage of a high-speed DPMZM by using a low-frequency photodetector...
An on-wafer and self-calibrated scheme is proposed and demonstrated for self-referenced microwave characterization of a silicon integrated optical transceiver. The proposed self-calibration method enables on-wafer selective extraction of microwave characteristic parameters of high-speed modulators and photodiodes in the integrated optical transceiver, without the need for extra electrical-to-optical...
Massive MIMO (multiple - input - multiple - output) and full-dimensional MIMO systems in next-generation cellular communications systems as well as high-data-rate military systems have garnered considerable attention recently. For the assessment of their performance, knowledge of the 3D propagation channel characteristics, i.e., azimuth and elevation of the multipath components (MPCs) is essential...
This paper presents the design of a small patch antenna, which consists of one unit cell of composite right/left handed transmission line (CRLH TL). Due to the resonant frequency of the CRLH TL unit cell is determined not by the physical length but by the inductance and capacitance values loaded in the cell, the size of the patch antenna consisting CRLH TL unit cell can be reduced by tuning the LC...
In this paper, a coplanar-waveguide (CPW)-coupled-fed elliptical monopole antenna (CCFEMA) is presented for UWB applications. The antenna has a large bandwidth covering the frequency band from 2.8 GHz to 16.5 GHz with return loss larger than 10 dB and radiation pattern similar to that of a dipole antenna. With an appropriate modification of the radiation patches, a band-notched antenna based on the...
This paper presents the design of compact and ultra-wideband (UWB) time-delay lines inspired by the use of composite right/left-handed transmission line (CRLH TL) unit cell. A conventional CRLH TL unit cell is used as the basic elements for the design of time-delay lines and a rotated version of the unit cell is used to achieve ultrawide bandwidth operation. Time-delay lines for large time delays...
This paper presents the design of a rectangular-shaped ultra-wideband (UWB) time-delay line inspired by the use of composite right/left-handed transmission line (CRLH TL) unit cells. A rotated version of a conventional CRLH TL unit cell is used as the basic elements to achieve UWB operation. For comparison, time-delay lines using the right-handed transmission line (RH TL) and CRLH TL unit cells are...
This paper presents the design of ultra-wideband time-delay lines in microwave frequency inspired by the composite right/left-handed transmission line (CRLH TL) unit cell. A rotated version of the conventional CRLH TL unit cell is used to achieve an ultrawide bandwidth. For comparison, the time-delay lines using the conventional CRLH TL unit cells, right-handed transmission line (RH TL) and periodic...
This paper presents a design of ultra-wideband time-delay line inspired by the composite right/left-handed transmission line (CRLH TL) unit cell. A rotated version of the conventional CRLH TL unit cell is used to increase the operating bandwidth. The time-delay line is optimized using computer simulation and then fabricated on a PCB for measurement. For comparison, the time-delay lines using the right-handed...
The frequency comb technique is a very useful method to measure the frequency of lasers accurately. The authors proposed a new method that is simpler and can be used for both high and low repetition rate frequency combs without the help of a wavemeter. The method is a two-step process. The authors first obtain a rough estimate of N by changing the repetition rate fr. a small amount such that no mode...
We report recent improvement in absolute frequency measurement of the 115In+5s21S0-5s5p 3P0 clock transition at 236.5 nm. Using a narrowline laser as a local oscillator, a linewidth of 43 Hz for the transition is resolved. The uncertainty of the transition frequency's centroid is 18 Hz, leading to a fractional uncertainty of 1.4 x 10-14. In the experiment, a single 115In+is trapped in a three-ring...
We report an improved absolute frequency measurement of the 5s21S0 -5s5p 3P0 narrowline clock transition at 236.5 nm, for a single trapped and laser cooled 115In+. Using a narrowline laser as the local oscillator, a linewidth of 43 Hz for the transition is resolved. For absolute frequency measurement we use an optical frequency comb referenced to a cesium clock The transition frequency is found to...
We demonstrate a method to determine the absolute mode number of a frequency comb when it is used for high precision laser frequency measurement, without the help of wavemeters. Our technique involves changing the repetition rate of the frequency comb in a two-steps process. Guidelines for choosing the correct repetition rates for different laser linewidths are given. As a demonstration, the absolute...
We report a new method for high-precision refractive index measurement using a Michelson interferometer setup with frequency combs as the light source. The method has a sensitivity of 6.2times10-9 and a standard error of 7.4times10-8.
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