Proton-exchanged optical waveguides in Y-cut lithium niobate

The fabrication of proton exchanged monomode optical waveguides on Y-cut lithium niobate is reported. Molten benzoic acid is used, but damage of the crystal surface is avoided.     

Simplified method of eliminating the effect of nonlinearities on process crosscorrelations

A modified msequence is proposed to simplify the instrumentation in using the Gardiner method of identifying the linear channel of a nonlinear process. The class of sequence has properties suited to multivariate crosscorrelation.     

Distribution of monomer configurations in polypropylene as determined with 13C NMR

An amorphous polypropylene sample was examined by using ¹³C NMR at 25.2 MHz and all ten possible methyl resonances from monomer pentads were observed. Assignments were made through a consideration of an additivity relationship among the methyl resonances. Confirmation for the assignments was obtained through observed conformity of the methyl resonance intensity distribution with second-order Markov statistics. The relative intensity distribution of the methyl resonances can be used to characterize the structure of polypropylenes with confidence, since experimentally it is shown that an equal nuclear Overhauser effect exists for each of the methyl resonances.     

Very broad reflection bandwidth (44 nm) chirped fibre gratings andnarrow bandpass filters produced by the use of an amplitude mask

Chirped gratings with very broad reflection bandwidths up to 44 nm and high reflectivity have been produced holographically in boron-codoped and standard telecommunications fibres which have been hydrogen-soaked. A 2 nm wide transmission band has been produced within the broad reflection band by use of an amplitude mask during grating exposure