The fundamental vibrational-rotational absorption signature of almost all the chemical compounds lies in the Mid- IR spectrum (λ=3-15μm) thus offering superior light-analyte interaction in this regime. In particular, the successful inscription of infrared-spectroscopy in a multi-pass cell has significantly boosted its use mainly in the gas-sensing application at the sub-ppm/ppb level. However, the requirement of bulky, alignment sensitive, and need of expertise-hands makes it inappropriate for many fields especially in portable applications like stand-alone environment monitoring, detection of chemical-warfare-agent in the battlefield, Astro-biological applications, etc. An external disruption-free handheld device (i.e., unaffected from any external vibration, physical stress, and thermal variations) with high specificity and selectivity are still prerequisites for such in-situ applications. The advancements in photonics have shown enormous possibilities to miniaturize all spectroscopic components to a single chip. In this context, the slow light-assisted engineered photonic structure on a QCL/QCD (quantum confined laser and detector) is most promising to replace bulky multi-pass cell optics. In principle, it slows down the light with several folds to enhance the light-analyte interaction and thus open an avenue for an on-chip sensing platform. Most efficient QCLs demonstration explored in the InP platform, also a selection of InP-InGaAs eliminates the requirement of the costly wafer-bonding process. In this paper, we consider slow-light assisted and wavelength-tunable periodic photonic structures. The device is designed such that it supports transverse magnetically polarized mode directly emitted from QCLs. It eliminates the use of any additional polarization-rotator (conversion from TM to TE mode) which reduces fabrication complexity and additional space on the chip.
Over the past decade, in the near-infrared spectral region, optical phased array (OPA) technology has advanced from basic concepts to demonstrations in efficient, high-resolution, wide-angle systems. Extension to the mid-infrared spectral region has only recently begun. In this work, at λ = 4.6 μm, on an InGaAs/InP platform, we demonstrate the operation of a 32-channel OPA beam steering device. Through thermo-optic tuning we steer the beam laterally within a ±11.5° field-of-view.
Plastic optical fiber level measurement sensor based on in-line side holes is investigated theoretically and experimentally. The sensor consists of a plastic optical fiber with in-line side holes spaced about 5 cm apart. The 0.9 diameter in-line side holes were fabricated by micro-drilling. An analytical expression of the sensor transmittance was obtained using a simple ray optics approach. The measurements of the sensor transmittance were performed with a 55 cm height Mass cylinder. Both results show that the sensor transmittance increases as the number of side holes filled with water increases. The research results indicate that the plastic optical fiber based on in-line side holes can be used for water level measurement.
An algorithm to reduce data burst processing delay in group scheduling in core nodes of optical burst switching networks has been proposed. Since, in this algorithm, look-up tables containing all the void time information in scheduling windows are generated as soon as the primary group scheduling session terminates, it becomes faster to reassign dropped data bursts to proper voids, if any, by referring to the tables. The group scheduling with this algorithm showed almost the same performance as the previous group scheduling in regard to channel utilization and wavelength conversion rate. On the other hand, per-burst processing time has been reduced dramatically in the load region of higher than 0.8 and burst loss probability has been improved more under lighter traffic condition.
We discuss a number of operation and maintenance (OAM) issues in optical burst-switched (OBS) networks and propose an OAM framework in this respect. Four OBS functions are identified as bases for the proposed framework. These are the burst termination function, the burst transmission function, the switching function, and the routing and switching control function. The study focuses on the unique aspects of OBS networks and how they can be addressed from an OAM point of view. We propose an OAM architecture and investigate the functional, network, and node aspects of it. Novel OAM-capable structures for core and edge OBS nodes are introduced for the first time.
Reflectively tapped fiber-optic delay-line matched filters with metal film reflectors evaporated on cleaved fiber ends have been fabricated. This novel device can provide ultra-high speed signal processing capability, small size, and low loss, and be used as an optical packet address detector for all-optical wavelength division multiplexing switching networks. Using the filters, detection of 2.5 Gb/s, 6-bit packet addresses for optical ring networks has been successfully demonstrated. Experimental and calculation results on correlation outputs of the filters are reported.
Two types of fiber optic reflectively tapped delay line matched filters are produced for use as photonic packet address detectors in an optical ring network. Dielectric films evaporated on cleaved fiber ends function as light taps for the filters. Experimental results and theoretical calculation on photonic packet address detectors with 1 Gbps address code of (101) are reported.
A photonic packet switching device is designed for WDM based optical slotted ring networks which are suitable for B-ISDN access network and LAN/MAN. For the design, we devised a fiber optic delay line matched filter as a means of address filtering at the destination node and developed an efficient address decoding algorithm to accommodate the maximum available number of nodes in the ring network. Based on the algorithm, the maximum available number of node addresses in the ring is 3,432 for the case of 16-bit address. The design objectives of the photonic packet switching device are to eliminate the optical-to-electrical conversion at the address processing, to remove optical data from the ring at the destination nodes so that the slots can be reused a number of times in a rotation, and to be compatible with B-ISDN based on ATM concerning services, bit rate, interface, and switching node. The network architecture using the photonic packet switching device is also described. The simulation results show that the major part of the cell transfer delay in the network is coming from the propagation delay from a source to a destination. It was also observed that the average transfer delay characteristic of the network depends upon the aggregated transmission capacity of the network.
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