We present a continuously tunable nonrecursive radio-frequency (RF) photonic filter. The filter provides fine tuning through the use of a novel RF phase shifter and coarse tuning using an all optical variable time delay. This architecture permits wide-band continuous tuning of the filter null frequency and is useful in applications such as moving target indication (MTI) in an airborne radar.

Tunable filters for wavelength-division multiplexing transmission system are essential. Fiber Bragg grating (FBG) is one of the best candidates for this application. The wavelength shift of FBGs can be tuned by applying different temperature, hydrostatically pressure and strains (in traction or/and compression). A comprehensive study of using these three parameters as being tunable filters was ...

We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longi...

This study presents a new process using inductively a coupled plasma dry etching method to manufacture a long-period fiber grating filter with exact period, vertical sidewalls, and smooth etched surfaces, and the filter is thus named a perfectly notched long-period fiber grating (NLPFG). This process can dramatically reduce production time, and thereby provide higher volume production. The fabr...

We propose and demonstrate a tunable photonic radio frequency notch filter. The filter has a single delay line architecture and incorporates a new wavelength-selective true-time-delay. The time delay in the feed-forward ioop can be varied by simply changing the optical wavelength resulting in a shift of the null of the filter response. Application in radar systems is discussed.

In the last two decades, current-mode (CM) circuits have received more attention. These types of circuits offer many advantages such as wider bandwidth, bigger dynamic range, better linearity and more IC suitability when compared with voltage mode (VM) topologies [1, 2]. In addition to this, electronic tunability is also one of the other important issues in electronic design since it allows us ...

We report a new electrically tunable color filter to actively adjust the correlated color temperature of white light-emitting diodes. With four passive cholesteric films and an active polarization rotator, both circular polarizations of the incident light are utilized to generate complementary blue and yellow colors. The blue/yellow ratio can be tuned by the applied voltage of the polarization ...

Today’s direct-conversion SDR platforms are capable of tuning over extremely wide frequency ranges compared to traditional superheterodyne transceiver architectures. However, these radios can suffer from a number of problems due to a lack of front-end RF filtering, including poor dynamic range and desensitization. In this paper, we examine preliminary work on a tunable bandpass filter we are de...

Integrated label-free photonic biosensors provide an excellent limit of detection in combination with a low-cost disposable. Their application has thus far been limited by the necessity of an expensive tunable laser. In this article, we present a novel sensor, eliminating the tunable laser by combining a sensitive Mach-Zehnder interferometer with a broadband light source and an on-chip spectral...

We demonstrate an automatic tunable transversal notch filter based on uniform fiber Bragg gratings and a broadband optical source. High tunability can be performed by stretching the fiber with the gratings written in series. Also, high sidelobe supression can be achieved by introducing tunable attenuators in a parallel configuration of the gratings.