Integrated ring resonators have attracted a considerable interest in optical communications because of their small size and wide range of applicability. Here we consider several aspects of these devices, beginning with a tunable hybrid ring resonators consisting of a silicon over insulator (SOI) ring covered with a polymer layer in a variable electric field. Varying the field changes the polymer refractive index and consequently the resonance condition of the cavity. This device offers a large degree of optical confinement together with a high modulation speed. Subsequently, we design and present fabrication results for a Wavelength Division Multiplexing (WDM) multiplexer/demultiplexer formed from a series of ring resonators with two channels separated by 50 GHz each that is predicted to exhibit a free spectral range (FSR) of 100 GHz , signal dispersion less than 30 ps/nm and a signal cross-talk less than -23 dB. Finally, we analyze the application of the coupled ring waveguide circuit to rotation sensors based on the Sagnac phase shift. Here, however our analysis indicates that a single ring, of the same area exhibits a higher degree of sensitivity to rotational motion than a multiple ring circuit.

The coherent system has been extensively studied in recent years. The reasons are that receiver sensitivity is better than Intensity Modulation with Direct Detection (IM/DD) and the spectral efficiency of wavelength division multiplexing (WDM) is increased. The modulation formats of the coherent system are Amplitude shift keying (ASK), Phase shift keying (PSK), and Frequency shift keying (FSK). The detection techniques are Homodyne detection and Heterodyne detection, both of them need a laser light source in the receiver called as the Local oscillator (LO). In the previous study, the Quadrature phase shift keying (QPSK) modulation format with Pseudo Random Binary Sequence (PRBS) 27-1 to transmit 51km was investigated, and the pilot carrier method realized the Homodyne Detection. The merit of the pilot carrier is that the LO is not necessary in the receiver. In this master thesis, the optical signal of the QPSK modulation format with PRBS 215-1 is transmitted over 500km using the pilot carrier method. A WDM system demonstration is also conducted to increase the system capacity. The Bit error rate (BER) is calculated by the MATLAB program. The BER performance of 20G bit/s, 500 km transmission system using the QPSK with single channel and multiplexed channels were measured.

The purpose of this study is to use multi-functional optical fiber processing platform produce 2X2 single-mode fiber coupler, and use theory and simulation to analyze, as the basis of the starting, development of novel fused coupler device. The characteristics of this coupler is a 2x2 single-mode fiber coupler in which a single-mode fiber replaced by our laboratory to manufacture the capillary fiber. The use of this coupler is similar to the use of single-mode fiber refractive index of the solution pumped capillary fiber to a liquid switch fiber coupler. We know that the refractive index decreases as the wavelength increases, the slope of the different materials for this change is different, and due to the different materials, the thermal coefficient of refractive index is different, so we can be found in the case of different temperatures, the refractive index of the two materials are equal, and other wavelength is different, therefore, only when the same refractive index of the wavelength in order to fully coupled. The advantages of this coupling is temperature control of its maximum coupling wavelength range, and the capillary fiber core is liquid, we can use this measurement technique for the development of liquid, if the later then the single-mode fiber to replace the other refractive index different fiber, you can use this method to measure the other liquid. Next, use simulation software to simulate this coupler, the coupling wavelength and coupling efficiency values of the change in refractive index different cases, in order to facilitate the produce this novel fused coupler device.

Use the adjustable diameter fiber splicing platform to manufactured coupler, N fibers were put into the appropriate aperture silica capillaries, and then changed the taper model to manufactured fiber coupler [1], and adjusted the taper model and fusion parameters to reduce the fiber transmission loss and reduce the diameter of the fibers to achieve the optical coupling effect. We preferred to the Eisenmann & Weidel in 1988 [2]. It is a low loss of the fusion type equilateral triangle of 3¡Ñ3 fiber coupler. And we will study the asymmetric shape of an 3¡Ñ3 fiber coupler, the research method is the use of arc heating. The fiber has smaller heating area and the heating position which can be controlled. With the parameters which BeamPorp, we cut the fiber coupler and to discuss its cross-section. By the different geometric distribution of fibers, and the core spacing, we discuss the spectra of the OSA to change the coupling site. We changed the interior structure to make the power coupling to a marked effect; if we could control the asymmetric coupler explicitly then we could achieve the transmission power [3], power coupling, and the multiple spectra of light.

In this thesis, we propose a potentially inexpensive light source for the mulit-channel wavelength division multiplexing (WDM) system applications. The spectrum-sliced incoherent light source (SILS) is alternative conventional laser source for the WDM system owing to its simplicity and flexibility. However, the spectrum-sliced source suffers from the intensity noise and spontaneous-spontaneous beat noise. Thus, it is necessary to increase the optical bandwidth or decrease the electrical bandwidth (by varying the bit rate ) to improve the signal to noise ratio (SNR). We used the intra-channel four wave mixing (IC-FWM device) before the receiver to suppresses the intensity noise of the light source, thus greatly expands the optical bandwidth of the received signal. We not only demonstrated the capability of an 8 ¡Ñ 2.5 Gb/s, DWDM with 200 GHz channel spacing transmission system by utilizing only one spectrum-sliced source, but also investigate the cross-talk issue of SILS in the fiber Bragg grating-based optical add/drop multiplexer (FBG-based OADM) and the Mach-Zehnder fiber Bragg grating-based optical add/drop multiplexer (MZ FBG-based OADM) systems.

ABSTRACT In this thesis, we investigate the amplification characteristics of gain-flattened L-band (1570-1600 nm) erbium-doped fiber amplifier (EDFA) by employing the 1480 nm bi-directional pumping configuration. L-Band EDFAs are attractive because the use of L-band and C-band (1530-1560 nm) EDFAs in parallel greatly expands the amplification wavelength region. We adjusted the length of erbium-doped fiber (EDF) to achieve the flat amplification characteristics in the 1573-1600 nm wavelength region without using gain equalizers. The L-band EDFA exhibited a signal gain of 23 dB with good uniformity (less than 1 dB) and a noise figure of 6.9 dB for a 1580 nm signal of 16-channel WDM system. We also used the simulation tools to investigate the characteristics of L-band EDFA with the same configuration. The simulation results quite agree with the experimental data.

This thesis examines the equation of state of copper at Warm Dense Matter states, between 1-100 eV and .1-10 times solid density. Protons accelerated off a thin metal foil irradiated with a high intensity laser beam flash heat solid density copper to between 5-10 eV before significant expansion occurs. The measured temperature and expansion are compared against simulations using various equations of states. The production and characterization of the laser system and proton beam used to heat the matter is also presented. / text

Integrated ring resonators have attracted a considerable interest in optical communications because of their small size and wide range of applicability. Here we consider several aspects of these devices, beginning with a tunable hybrid ring resonators consisting of a silicon over insulator (SOI) ring covered with a polymer layer in a variable electric field. Varying the field changes the polymer refractive index and consequently the resonance condition of the cavity. This device offers a large degree of optical confinement together with a high modulation speed. Subsequently, we design and present fabrication results for a Wavelength Division Multiplexing (WDM) multiplexer/demultiplexer formed from a series of ring resonators with two channels separated by 50 GHz each that is predicted to exhibit a free spectral range (FSR) of 100 GHz , signal dispersion less than 30 ps/nm and a signal cross-talk less than -23 dB. Finally, we analyze the application of the coupled ring waveguide circuit to rotation sensors based on the Sagnac phase shift. Here, however our analysis indicates that a single ring, of the same area exhibits a higher degree of sensitivity to rotational motion than a multiple ring circuit.

The predicted growth in mobile phone traffic and the move towards enhanced mobility will lead to a need for a wireless infrastructure that provides increasing bandwidth per user. It is envisaged that our world will become increasingly interconnected, with mobile communications enabling us to perform an increasing range of tasks. / Future wireless networks will require an optical network to provide antenna Base Stations with sufficient bandwidth to provide individual users with a larger bandwidth. The combined optical and wireless network is referred to as a “fibre-radio” or “radio-over-fibre” or “fibre-wireless”; network. It is expected that such high-capacity networks will use Wavelength Division Multiplexing (WDM) to increase the total bandwidth transmitted over the optical access network. Such a high-capacity network would not be achievable using a single wavelength or using a copper or coax network. Optical crosstalk is present in WDM optical networks and degrades the received signal quality, increasing the bit-error-rate. Two types of crosstalk occur, depending on whether the crosstalk channel is a different wavelength to the signal or at the same wavelength (out-of-band and in-band crosstalk, respectively). An important consideration for fibre-radio networks is whether or not the optical network transports data at baseband, using standard intensity modulation, or at an RF frequency, using subcarrier modulation. The nature of the optical modulation scheme has implications for the design of the Central Office and the Base Stations, and potentially for optical crosstalk. (For complete abstract open document)

Techn. Universiẗat, Diss., 2003--Berlin.