Browsing by Subject "Wavelength division multiplexing"
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Item Dense wavelength division multiplexing (DWDM) for optical networks(2001-08) Qiao, Jie; Chen, Ray T.Item Developing an all optical switch using digital micromirror device (DMD) array for wavelength division multiplexing (WDM) applications(Texas Tech University, 2002-05) Sundaram, SriramA relational non-interferometric polarization-insensitive space division 1 x 4 all optical switch based on the digital mirror array device is described and analyzed. An insertion loss of -5.5dBm, crosstalk less than -37.1 dBm and bit-error-rates of less than 10"^ have been measured at 2.5Gb/s. The performance of the switch in multiwavelength applications to variable optical attenuator, multicasting and dynamic gain equalization is described. The fast switching speed of -15 |is of the digital micromirrors provides dynamic switching in all the before mentioned applications, ensuring optimum network performance at all times.Item High performance dense wavelength division multiplexing/demultiplexing based on blazed grating and ion-exchanged glass waveguide technique(2004) Zou, Jizuo; Chen, Ray T.Dense Wavelength Division Multiplexing (DWDM) is one of the key technologies in today’s high bit rate optical communications. In this dissertation, we conducted research on blazed grating based DWDM devices, which are advantageous over other WDM technologies in many aspects. Theoretical analysis showed that three major challenges exist for the grating based DWDMs, i.e., pulse broadening, 1dB passband and device dimensions. Specifically, the pulse broadening induced by the optical path delay of grating is a bottleneck for data bit rate. To overcome these challenges, we proposed integrating an ion-exchanged glass waveguide fan-out chip into the DWDM. In order to fabricate this single-mode fiber-compatible waveguide fan-out, both purely thermal ion exchange and field-assisted ion exchange have been investigated. Waveguide properties under different fabrication conditions were compared for optimization. With the optimized field-assisted process, we obtained waveguides with propagation loss and mode mismatch to SMF of 0.16dB/cm and 0.1dB, respectively. Based on this ion exchange process, we designed and fabricated the waveguide fan-out chip that contains 48 S-bend channel waveguides. This waveguide fan-out was then successfully bonded with a standard 48-channel SMF fiber array, with an average total insertion loss of 0.7dB for each channel and very good uniformity. Finally, a 48-channel 100GHz-spacing DWDM centered at wavelength of 1550nm was designed and demonstrated. The performance of this DWDM device has verified the effectiveness of the proposed solution and the successfulness of the ion-exchanged glass waveguide technique.Item High performance wavelength-division multiplexing schemes for optical networks(2001-12) Deng, Xuegong; Chen, Ray T.Item Mathematical models of wavelength division multiplexing devices(Texas Tech University, 2000-12) Huang, ShunWith the Intemet booming in recent years, the demand for high-speed transmission over communications networks is increasing at a tremendous rate. There has been a lot of effort trying to explore technologies to enhance the capacity and the utility of transmission media. Since it is well-known that the transmission capacity of optical fiber is enormous and that optical fibers are getting cheaper and cheaper, people have been trying to find more effective ways to utilize the available bandwidth. Wavelength division multiplexing (WDM) is one such technology. It is used to transmit multiple wavelengths of light in a single optical fiber (Figure 1.1 [1]). WDM takes advantage of the 25,000 GHz capacity in the passband of light of optical fibers, reaching a capacity 1,000 times greater than the traditional multiplexing technology, time division multiplexing (TDM), which can only carry around 2.5 gigabit per second in a single fiber. It can be expected that as optical technologies become more and more mature, the price of optical devices will drop and communications networks in the fiiture will be dominated by optical networks.Item Wavelength-selective micro- and nano-photonic devices for wavelength division multiplexing networks(2005) Jiang, Wei; Chen, Ray T.On the road toward the information age, the enormous bandwidth demanded by the explosive growth of Internet traffic has been supplied by fiber-optic communications technology; in particular, the widespread use of Wavelength-Division Multiplexing (WDM) techniques. My research focused on Optical Add-Drop Multiplexers (OADMs) and wavelength demultiplexers, two key devices for WDM technology. Various approaches, including nanophotonic approaches based on photonic crystals, were employed in the research. First, a variety of ball lens-based OADMs were designed and implemented. The overall performance of the ball lens-based OADMs was competitive compared to that of commercial GRIN lens-based OADMs, while the former devices were more cost-effective and simpler in packaging. Optical Add-Drop Multiplexers are one of the promising applications of photonic crystals. Prior theories have been limited to devices with frequencyindependent coupling and simple mirror symmetry. Through my research, a general model was developed to understand the optical add-drop process in realistic photonic crystal-based OADMs, where the interactions between the waveguides and cavities are frequency dependent and cavity modes depart from the accidental degeneracy of frequency. Furthermore, a class of devices with more freedom in choice of symmetry were proposed. An original idea was proposed to utilize the inevitable optical loss in a way that improves device performance. The last part of my research was aimed at developing a wavelength demultiplexer based on the superprism effect in photonic crystals. In the course of this research, a general and rigorous refraction theory was developed for a photonic crystal of any lattice type, any surface orientation, and any surface termination. The theory solved some long-standing problems in grating diffraction as well. Refraction at naturally emerging quasi-periodic surfaces was treated in a unified way with the refraction on periodic surfaces. A new concept, surface-dependent mode degeneracy, was introduced and was shown to be crucial to understanding photonic crystal refraction. Arbitrary incident beam profiles were investigated. The first-ever practical demultiplexer design that has less than 3dB loss over a 25-nm spectrum is given based on this theory. The theory is anticipated to be instrumental in understanding some interesting research topics such as photonic crystal slab-based superlenses.