M. Z. M. Khan

100 Gb/s Single Channel Transmission Using Injection-Locked 1621 nm Quantum-Dash Laser

A single channel 100 Gb/s dual–polarization quadrature phase shift keying transmission based on injection-locked broadband quantum-dash Fabry–Pérot laser, and employing external modulation, has been demonstrated. By employing a far L–band ~1621-nm sub-carrier, −17.4-dBm sensitivity at the bit error rate <inline-formula> <tex-math notation=LaTeX>

Far L-band Single Channel High Speed Downstream Transmission using Injection-locked Quantum-dash Laser for WDM-PON

3.8times 10^{-3}

Hydraulic Autofrettage Technology: A Review

</tex-math></inline-formula> has been obtained after 10 km standard single mode fiber transmission. Besides, an injection locked mode wavelength tunability of ~23 nm, which translates to ~50 sub-carriers, is accomplished. These results favor the viability of deploying broadband quantum-dash lasers as unified upstream and downstream transmitters in next generation wavelength division multiplexed-based passive optical networks.

64 Gb/s quantum-dash laser based indoor free space optical communication

We demonstrate an externally modulated single channel 64 Gbit/s DP-QPSK transmission based on injectionlocked Fabry-Pérot broadband quantum-dash laser at far L-band ~1621 nm wavelength. A receiver sensitivity of -16.7 dBm has been observed after 10 km SMF transmission, with power penalty of ~2 dB, under the FEC threshold. We also propose that these novel quantum-dash laser diode could be a route towards next generation 100Gbit-PONs as a unified upstream and downstream transmitters.

Broadband Lasing Characteristics of a Chirped InAs/InP Quantum-Dash Laser

Thick-walled cylinders play a unique role in military, automobiles, aircraft and oil fields. The autofrettage method is used to increase the fatigue life of thick-walled components like gun barrel, titanium alloy tubes, nuclear reactor vessels, high pressure oil field pipes and LDPE. There are three types of autofrettage processes and hydraulic is the one applied mostly. The autofrettage process uses a pressure that is high enough to plastically deform the bore of the part but not so high that it bursts the component, is applied to the inside of tube. The result is that after the pressure is removed, the elastic recovery of the outer wall put the inner wall into compression, providing a residual compressive stress. In this research paper a study has been carried out to investigate the progress made in different fields by the hydraulic technique and proposals are sought for future work.Copyright

Self-injection locked InAs/InP quantum-dash laser for high capacity optical communication system

We demonstrate a single channel free space optical dual polarization - quadrature phase shift keying (DP-QPSK) transmission using an injection-locked InAs/InP quantum dash (Qdash) laser by employing external modulation. A receiver sensitivity of −19 dBm at ∼1621 nm is observed over a 4 m indoor channel at 64 Gb/s transmission rate. This stems the potential of Qdash lasers as a source in optical wireless communication, which is being considered as an alternative optical access technology for future high speed communication networks.

Optical wireless communication at 100 Gb/s using L-band Quantum-dash laser

We investigate the temperature dependent spectral characteristics of an InAs multi-stacked quantum-dash-inwell laser. The multi-stack active medium optical transitions are dispersed by varying the thickness of AlGaInAs barrier layers. The analysis is carried out via a Fabry-Perot 700 μm long-cavity laser with a ridge width of 2 μm at different temperatures. A lasing bandwidth of >40 nm is observed at room temperature with total optical power of >150 mW. Moreover, broadening of lasing spectrum is observed with increasing the temperature, due possibly to a thermionic assisted emission and to optical pumping, enabling a full exploitation of the inhomogeneous optical transitions within the active region which indicates an increase in the available states in the active region. Therefore, proper optimization of the multi-stack active medium is required to fully utilize these optical transitions while maintaining high quantum efficiency, and proper bandgap engineering the device structure.

Modeling and Simulation of Multi-Stage Autofrettage in Pressure Vessels

We report, for the first time to our knowledge, on the self-injection locking of chirped InAs/InP quantum-dash (QDash) lasers with ∼6.5 nm locked Fabry-Perot mode tunability, in the L-band wavelength emission. The modes exhibited ∼30 dB side mode suppression ratio (SMSR) with ∼8–9 dBm mode power. Generally, the locked mode SMSR and tunability is found to be limited by the L-band amplifier amplified spontaneous emission noise. This demonstration paves the potential deployment of widely tunable self-locked broadband QDash laser modes as sub-carriers generator in the next generation high capacity fiber based and wireless optical networks.

A Comparative Parametric Study of Single Step and Double Step Swage Autofrettage in Swaged Metal Tubes

An indoor 100 Gb/s wireless communication is demonstrated using external coherent injection-locking of InAs/InP Quantum-dash (QDash) laser. Receiver power sensitivities of −18.4 dBm and −17.4 dBm at ∼1621.3 nm are observed after propagating along a 2 m and 4 m indoor free-space channels, respectively, while adopting dual polarization quadrature phase shift keying (DP-QPSK) modulation scheme. Moreover, characterization of this far L-band QDash laser showed an injection locked Fabry-Perot mode tunability of ∼19 nm with > 35 dB side-mode-suppression-ratio. To the authors knowledge, this is the first demonstration of showcasing QDash lasers as a viable candidate in optical wireless communication, an attractive alternate optical access technology for next generation high capacity networks.

Broadly Tunable Self-injection Locked InAs/InP Quantum-dash Laser Based Fiber/FSO/Hybrid Fiber-FSO Communication at 1610 nm

Thick-walled cylinders play a unique role in cutting edge technologies. These are used in armament industry, aircraft field, automobiles and nuclear reactors. Autofrettage is an effective technique of increasing the fatigue life and bearing capacity of thick-walled cylinders. The most commonly used methods of autofrettage are mechanical, hydraulic and powder gas. In this research paper a study has been carried out of the multi-staging autofrettage process of pressure vessels. The analysis of the autofrettage process is carried out using finite element based software ANSYS, COSMOS. The stress visualization is obtained in the most powerful graphical tool MATLAB. The results obtained are compared with available experimental data.© 2009 ASME