Femtosecond optical parametric oscillator based on periodically poled KTiOPO4

We report a femtosecond optical parametric oscillator based on a periodically poled KTiOPO4 crystal for which quasi-phase matching is achieved with a 24-μm poling period. The singly resonant parametric oscillator, synchronously pumped by a Ti:sapphire laser at a wavelength of 758 nm, generates a signal at 1200 nm and an idler at 2060 nm. The maximum signal power conversion efficiency of the device is 22% with a pump depletion of 69%. We tune the signal wavelength over a 200-nm band by changing the cavity length. In addition, pump wavelength tuning provides output tunability in the 1000-1235-nm range. © 1998 Optical Society of America

Investigating Guided Extensive Reading And Vocabulary Knowledge Performance Among Remedial Esl Learners In A Public University In Malaysia

Penyelidikan menyokong pembacaan ekstensif, yang tertumpu pada pembelajaran kebetulan (incidental learning), sebagai wadah utama bagi perkembangan pengetahuan kosa kata bahasa kedua/asing. Research supports extensive reading, which draws on incidental learning, as a primary tool for second/foreign language vocabulary knowledge development

Acoustic modulators for optical fibres

We have examined techniques for acoustic modulation of an optical fibre. A simple coupled mode theory has been developed which shows that by use of an acoustic wave propagating in the direction of the fibre, it is possible to make a single-sideband modulator. Experimental results confirming these ideas are given, along with some ideas for future direction of this work.Nous avons examiné des techniques destinées à la modulation acoustique dans une fibre optique. Une théorie simple de modes couplés a été développée; elle montre qu'en utilisant une onde acoustique se propageant dans la direction de la fibre, il est possible de réaliser un modulateur à bande latérale unique. Des résultats expérimentaux confirmant ces idées sont présentés ainsi que quelques idées sur les directions futures de ce travail

Acoustic modulators for optical fibres

We have examined techniques for acoustic modulation of an optical fibre. A simple coupled mode theory has been developed which shows that by use of an acoustic wave propagating in the direction of the fibre, it is possible to make a single-sideband modulator. Experimental results confirming these ideas are given, along with some ideas for future direction of this work