Polymer waveguide end facet roughness and optical input/output coupling loss for OPCB applications
Electro-optical printed circuit board technology (EOCB) based on integrated planar polymer optical waveguides has been the subject of research and development for many years to provide a cost viable, fully integrated system embedded optical interconnect solution, however a number of constraints of this technology have yet to be overcome. Optical coupling loss at the input and output of the waveguides is one of the major issues and waveguide end facet roughness is one of the main sources of the coupling loss which is investigated in this paper. The results of a comprehensive investigation of the end facet roughness of multimode polymer waveguides, fabricated on FR4 printed circuit boards, PCBs, and its effect of optical loss are presented theoretically and experimentally. The waveguide end facet roughness was measured using an atomic force microscope, AFM, when the waveguides were cut using a milling router with various numbers of cutting edges called flutes. The optimized cutting parameters are derived and the optical coupling loss, between the laser source and the waveguide, due to the different roughness magnitudes is measured by experiment for the first time. To improve the surface quality and decrease the waveguide optical loss, a new fabrication technique for reducing the end facet roughness after cutting is proposed and demonstrated. The insertion loss was reduced by 2.60 dB ± 1.3 dB which is more than that achieved by other conventional methods such as index matching fluid.
Optical Waveguide End Facet Roughness and Optical Coupling Loss
This paper investigates the end facet roughness of multimode polymer channel waveguides fabricated on FR4 printed circuit boards, PCBs, when cut at right angles to their optical axis by milling routers for optical butt-coupling connectors and compares it with that resulting from dicing saws and polishing and proposes a novel end facet treatment. RMS surface roughness of waveguide end facets, measured by AFMs, are compared for a range of rotation speeds and translation speeds of a milling router. It was found that one-flute routers gave significantly less rough surfaces than two or three-flute routers. The best results were achieved for a one-flute router when the milling bit was inserted from the PCB side of the board with a rotation speed of 15,000 rpm and a translation speed of 0.25 m/min which minimized the waveguide core end facet RMS roughness to 183 ± 13 nm and gave input optical coupling loss of 1.7 dB ± 0.5 B and output optical coupling loss of 2.0 dB ± 0.7 dB. The lowest RMS roughness was obtained at chip loads of 16 μm/revolution. High rotation speeds should be avoided as smearing of the end facet occurs possibly due to polymer heating and softening. For the first time to our knowledge, channel waveguide optical insertion loss is shown to be linearly proportional to the ratio of the waveguide core end facet RMS roughness to its autocorrelation length. A new fabrication technique for cut waveguide end facet treatment is proposed and demonstrated which reduces the insertion loss by 2.60 dB ± 1.3 dB which is more than that achieved by the closest available index matching fluid which gave 2.23 dB ± 1.2 dB. The new fabrication method gives a more robust end facet for use in commercial products.
Judicial Review, Socio-Economic Rights and the Human Rights Act
INTRODUCTION 1 THE ROLE OF COURTS IN THE PROTECTION OF SOCIO-ECONOMIC RIGHTS: INTERNATIONAL AND DOMESTIC PERSPECTIVES I. The Indivisibility of Human Rights II. The Protection of Socio-economic Rights in Domestic Courts III. Conclusion 2 THE REGIONAL PROTECTION OF SOCIO-ECONOMIC RIGHTS: EUROPE I. Introduction II. The European Convention on Human Rights (ECHR) 1950 III. The Protection of Socio-economic Rights in the ECHR IV. The Protection of Socio-economic Rights in EC/EU Law V. Conclusion 3 COURTS, THE UK CONSTITUTION AND THE HUMAN RIGHTS ACT 1998 I. Introduction II. Reading and Giving Effect to ECHR Rights in UK Courts III. Conclusion 4 JUDICIAL REVIEW: DEFERENCE, RESOURCES AND THE HUMAN RIGHTS ACT I. Introduction II. The Constitutional Foundations of Judicial Review III. Public Law, Deference and the Human Rights Act IV. Conclusion 5 FROM NEED TO 'CHOICE' IN PUBLIC SERVICES: THE BOUNDARIES OF JUDICIAL INTERVENTION IN PRIORITISATION DISPUTES I. Introduction II. NHS Rationing: The Role of Courts in Disputes over Access to Medical Services III. Local Authority Resource Allocation Disputes IV. Interpreting Local Authority Statutory Duties Post-HRA V. Conclusion 6 ARTICLES 3 AND 8 ECHR: FAILURE TO PROVIDE AND POSITIVE OBLIGATIONS IN THE SOCIO-ECONOMIC SPHERE I. Introduction II. Anufrijeva, Article 8 ECHR and Maladministration in the Provision of Welfare III. Article 3 ECHR: Respect for Dignity IV. Conclusion 7 ARTICLE 14 ECHR AND THE UNEQUAL DISTRIBUTION OF PUBLIC GOODS AND SERVICES IN THE UNITED KINGDOM I. Introduction II. Socio-economic Entitlements and the Limits of Substantive Fairness in Article 14 ECHR III. Carson's Case: Refusal of Up-rated Payments to Pensioners Abroad 283 IV. Reynolds' Case: The Intensity of Scrutiny in Other 'Status Disputes' V. Equality and Human Rights VI. Conclusion 8 ARTICLE 6 ECHR: JUDICIAL REVIEW, DUE PROCESS AND THE PROTECTION OF SOCIO-ECONOMIC RIGHTS I. Introduction II. What is a Civil Right for the Purposes of Article 6 ECHR? III. The Quality of Administrative Justice: The Scope of Article IV. Conclusion