Liquid filled prismatic louver façade for enhanced daylighting in high-rise commercial buildings.

A liquid filled prismatic louver (LFPL) façade that can perform daylight and thermal energy harvesting with the potential to offer enhanced natural illumination levels to office spaces and thermally assist secondary thermal driven applications is proposed and analyzed. We focus the present simulation study on the evaluation of daylight enhancement in indoor space by redirecting light from a window opening to the ceiling of the room, and then-after a diffusive reflection from the ceiling-onward to the work plane of the room. Illumination simulations using LightTools, a forward ray tracing illumination simulation software, are performed for an office building space located in New York City. We show that the LFPL system achieves deeper natural light penetration, better uniformity and higher illuminance levels compared to an office space without the LFPL system. We further extend our study to a number of other representative cities in the continental US, covering different climatic zones. The LFPL system achieves good daylight harvesting performance. Finally, we discuss the potential of the LFPL system to capture solar infrared radiation heat within the liquid (e.g., water) volume and use it to assist in secondary thermal energy applications.

Switchable dual-wavelength SOA-based fiber laser with continuous tunability over the C-band at room-temperature.

We propose and demonstrate a simple compact, inexpensive, SOA-based, dual-wavelength tunable fiber laser, that can potentially be used for photoconductive mixing and generation of waves in the microwave and THz regions. A C-band semiconductor optical amplifier (SOA) is placed inside a linear cavity with two Sagnac loop mirrors at its either ends, which act as both reflectors and output ports. The selectivity of dual wavelengths and the tunability of the wavelength difference (Δλ) between them is accomplished by placing a narrow bandwidth (e.g., 0.3 nm) tunable thin film-based filter and a fiber Bragg grating (with bandwidth 0.28 nm) inside the loop mirror that operates as the output port. A total output power of + 6.9 dBm for the two wavelengths is measured and the potential for higher output powers is discussed. Optical power and wavelength stability are measured at 0.33 dB and 0.014 nm, respectively.

Tunable multi-wavelength SOA based linear cavity dual-output port fiber laser using Lyot-Sagnac loop mirror.

We propose and demonstrate a simple dual port tunable from the C- to the L-band multi-wavelength fiber laser based on a SOA designed for C-band operation and fiber loop mirrors. The laser incorporates a polarization maintaining fiber in one of the fiber loop mirrors and delivers multi-wavelength operation at 9 laser lines with a wavelength separation of ~2.8 nm at room temperature. We show that the number of lasing wavelengths increases with the increase of the bias current of the SOA. Wavelength tunability from the C to L-band is achieved by exploiting the gain compression of a SOA. Stable multi-wavelength operation is achieved at room temperature without temperature compensation techniques, with measured power and the wavelength stability within < ±0.5 dB and ±0.1 nm, respectively.

Dual Sagnac loop mirror SOA-based widely tunable dual-output port fiber laser.

A widely tunable (30 nm) fiber laser based on a double Sagnac loop mirror configuration is proposed and demonstrated. A semiconductor optical amplifier (SOA) placed between the two loop mirrors acts as the gain medium. The fiber laser has two output ports with adjustable optical power outputs. Wavelength tunability is obtained through the use of a thin film tunable filter, while optical power adjustability is accomplished by proper adjustment of each of the loop mirror reflectivity via a polarization controller. A total output power of + 9 dBm is measured and the potential for higher output powers is discussed. Optical power stability of better than +/- 0.15 dB is measured for 6 hours.

Demonstration of an all-digital 7-bit 33-channel photonic delay line for phased-array radars.

A 7-bit multichannel photonic delay line for phased-array antenna control is demonstrated. Multichannel (33-pixel) ferroelectric liquid-crystal (FLC) devices are used as polarization rotation elements, and polarization beam-splitter cubes are used as polarization elements that route the optical signals to different paths. The controller is remotely fed by a unique fiber-optic-array design that uses gradient-index lens collimators for the input single-mode polarization-maintaining fibers. The optical signal is collected by a similar fiber array that uses multimode fibers for improved coupling efficiency. Photonic delay-line (PDL) design issues such as multiport assemblies, multipixel FLC designs, and delay-line architectures are discussed. Furthermore, various PDL parameters are examined. High electrical isolation numbers are obtained for both the within-channel leakage noise (e.g., less than -70 dB) and the interchannel cross talk (e.g., less than -90 dB). Optical and electrical insertion loss is examined for the PDL as well as for the overall system. A high-compression dynamic range of 149 dB x Hz and a spurious free dynamic range of 105 dB x Hz(2/3) are presented.

Synchronous amplitude and time control for an optimum dynamic range variable photonic delay line.

A synchronous-amplitude-controlled and time-delay-controlled photonic controller for phased-array antenna applications is proposed and demonstrated. Amplitude control is based on a variable optical attenuator system that operates in synchronism with the photonic delay line (PDL). This amplitude control system can provide both the signal calibration for the different PDL channels and settings required for driving the antenna elements of a phased-array radar and the optimum optical power levels that impinge on the photodetector for optimum fiber-optic-link performance. Various variable amplitude control modules based on ferroelectric liquid crystals, polymer-dispersed liquid crystals, and photoconductive devices are proposed. We show that the dynamic range loss due to a switched-PDL inherent structure loss can be compensated when we control the optical power from the laser, using the synchronous optical attenuation system. For the first time to our knowledge, full dynamic range loss compensation is demonstrated for an external-modulation-fed 3-bit switched PDL with a structure optical insertion loss of 5.5 dB. A compression dynamic range of 158 dBxHz was measured at 6 GHz, and a spurious free dynamic range of 111 dBxHz(2/3) was estimated. Feasibility of the dynamic range compensation technique for multichannel, higher-insertion-loss PDL systems is discussed.

Directly modulated semiconductor-laser-fed photonic delay line with ferroelectric liquid crystals.

A 3-bit binary photonic delay line is demonstrated at 1 GHz by use of a directly modulated semiconductor laser and remote interconnection fiber optics. Three types of free-space delay-bit geometries are tested for 5.69-ns, 1.67-ns, and 8.8-ps designed delay bits. This is the first time, to our knowledge, that a photonic delay line is demonstrated with ferroelectric liquid-crystal optical on-off devices for optical path switching and active polarization noise filtering. Three-dimensional imaging optics and antireflection-coated optics (for all but five components) are used successfully to minimize photonic delay-line insertion losses and interchannel cross talk. The 3-bit system is fully characterized for measured and designed performance.

Phased-array antenna, maximum-compression, reversible photonic beam former with ternary designs and multiple wavelengths.

A novel, switched, photonic delay-line ternary design combined with a wavelength-multiplexed transmit-receive beam-former architecture is proposed. One-dimensional antenna beam steering by use of a single-channel, wavelength-dependent switched photonic delay line in cascade with a multichannel wavelength-independent switched photonic delay line is proposed for hardware-compressed, phased-array antenna control with subarray antenna partitioning. Beam-former architecture extensions to two-dimensional antenna beam steering are described.