Search

This paper reports a novel launch scheme for coupling light into the skew rays of a graded index fiber. This is accomplished by utilizing a diffractive optical element in conjunction with a single mode fiber to mode match a graded index fiber. Results are used to confirm the fact that the element does improve the coupling into the skew rays of graded index fiber. This approach offers an alternative to existing methods based on tilting and angular offsets for the conditioned launch problem.

We demonstrate an innovative method for fabrication of high-spatial-frequency grating structures. This technique makes use of the near-field diffraction patterns from computer-generated phase holograms for lithographic fabrication of grating structures with periods that are one half that of the phase hologram mask. Linear, rectilinear, and circular gratings were fabricated with this technique. Experimental results from gratings with periods to 0.5 mum and feature sizes to ~0.2 mum are presented.

Graded index fiber has a limited bandwidth due to defects introduced in the fiber manufacturing process. In this paper, an alternative launch technique is presented using a diffractive element to excite specific modes in a fiber to maximize the bandwidth of graded index fiber.

Most laser projectors for LADAR systems are limited to small scan angles as they utilize acousto-optic devices, spatial light modulators, or fine-steering mirrors for beam steering. Additionally, the projected beam is usually circular and Gaussian. In order to improve the functionality of such systems, MEMS-based mirrors and diffractive optics may be used. This paper describes Digital Optics Corporation's work in developing and demonstrating a novel LADAR scanning system that incorporates a MEMS scanning mirror coupled with diffractive optical elements in a compact breadboard system. The MedCam MEMS mirror has been demonstrated with a 2D scan mode across large scan angles. The MEMS mirror system is experimentally compared to a Liquid Crystal Spatial Light Modulator based system. The diffractive elements generate spot arrays or other patterns that are more conductive to target detection schemes that an ordinary gaussian beam shape.

Standard laser welding practices are limited by the intensity profile of the beam and spot size. The introduction of Diffractive Optical Elements (DOE) to the welding process allows for new beam shapes that are better suited to the welding process. A particular problem in laser welding is the joining of dissimilar materials. Because these materials have different material properties including different melting temperatures, it is difficult to synchronize the welding process using a single spot. Additionally, significant thermal stresses are introduced by the welding process because of the keyhole weld shape formed by a gaussian beam. By using a power splitting DOE, two spots of unequal intensity distributions may be projected onto each side of the weld joint. This paper discusses the use of DOEs in laser welding and joining of dissimilar materials. Results are presented from the testing of several candidate aerospace materials.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Silicon v-groove structures have been utilized for passive positioning of optical fiber for fiber optic and opto- electronic applications. In this paper, we will present our results of using micro-machined silicon v-groove arrays to passively align optical fiber arrays to micro rod optics. We will also demonstrate the integration of N fiber arrays bonded into the silicon v-groove with a 1xN micro lens array, which is composed of a 2 inch-phase level diffractive optics. For the assembly of 1x6 fiber array and lens array with 16 phase level diffractive optics, the experimental results indicated that total insertion loss per link is typically 1.5-2.0 dB/channel.