Fiber Bragg gratings (FBG) offer an attractive method of strain sensing owing to their fiber-based, wavelength encoded operation. In this paper we present a novel passive narrowband interrogation method for FBG strain measurements
A ring-type fiber laser with an external birefringent Bragg grating reflector is presented. The birefringent grating has a polarization-dependent transmission/reflection spectrum and by adjusting an intracavity polarization controller, a tunability range of 0.6 nm is achieved.
The Floquet-Bloch approach is utilized to analyze light propagation through fiber Bragg gratings. For sinusoidal gratings, the Mathieu equation is directly derived from the wave equation. The resulting stability diagram is then used to study the reflection and transmission properties of semi- infinite, as well as finite gratings. Bandwidth broadening and wavelength shifts with increasing UV exposure are demonstrated.
A novel industrial CO<SUB>2</SUB> laser is presented, based on a proprietary combination of rf excitation, conductive cooling and a specially fitted resonator, conforming with size and shape of the discharge. This design results in the most compact laser-head of the kilowatt-class that is available on the market. The current model, ICCL 1000, generates about 1200 watts, in a high quality beam suitable for metal-cutting applications.
An optical resonator with holes on-axis for applications in a FEL oscillator was recently proposed by Pantell et al. These authors presented an analytical approach based on approximating the field inside the resonator by a truncated expansion in Gauss-Laguerre modes. The authors performed further investigation of this configuration by using a Fox and Li type code which was recently applied to the analysis of a laser resonator with internal circular aperture. This numerical approach allows one to check the range of validity of Pantell's solutions, the parameters for which they constitute the lowest-loss mode and to map the transverse profile of the mode at different planes inside the resonator.
The effects of hard apertures on the transversal mode distribu-
tion and on the output near and far field distributions are investig-
ated both theoretically and experimentally. Wavefronts propagating in
different directions inside a C02 laser cavity were measured at the
same plane and found to have different transversal amplitude prof 1-
les. The influence of intracavity aperture's location and diameter on
the near field distribution and on far field beam quality were
measured and calculated. Quantitative figures of merit are introduced
to evaluate the departure of the transversal mode patterns from ideal