We present a novel mode selective coupling technique for step index fiber. This technique utilizes phase matching for excitation of higher-order modes while suppressing the fundamental mode. Using this technique, a phase element is fabricated and tested to demonstrate the high coupling efficiency to the LP11 mode. In addition, we derive an analytical expression of the coupling efficiency of the LP11 using a single phase element.
Bending loss is the biggest drawback to hollow waveguides used for light delivery applications such as laser ablation. One way to overcome this limitation without changing the fiber design or fabrication is to engineer the input light to excite specific modes with better optical properties. Our first order calculations of the transmission and bending losses inside the cylindrical hollow waveguides showed that the TE<sub>01</sub> mode suffers the least amount of losses. To selectively excite this mode, it is desired to design an optical component that converts incident linearly polarized light into a rotating wave similar to the TE<sub>01</sub> mode. This work focuses on the design and fabrication of a subwavelength structure that converts the input polarization into that of the TE<sub>01</sub> mode.
In this paper, we present a new photo-mask technology capable of forming a continuous relief micro-optic profile on thick photo-resist. This technique eliminates many of the drawbacks of gray-scale and half-tone masking technology. An optical stepper is used to fabricate binary phase gratings of pi phase depth on a transparent quartz reticle. When the phase reticle is used in the stepper an analog intensity profile is created on the wafer. The period is constrained allowing for control of the 0<sup>th</sup> order in the stepper. The duty cycle of the phase gratings can be varied in such a way to provide the proper analog intensity profile for a wide range of micro-optics on the photo-resist. The design, analysis, and fabrication procedures of this technique will be discussed.
In this paper we present the fabrication of refractive micro optical elements by additive sculpting of the photoresist using binary amplitude masking techniques. We also present the fabrication of micro optical elements by pre sculpting the photoresist before reflow. This enables the use of fewer masking patterns while allowing us to obtain smooth profiles on the resist. The resist can be pre sculpted into any shape by using a set of binary patterns thus allowing us to fabricate refractive beam shaping elements.
An innovative fabrication technique is introduced that is based on multiple exposure techniques for micro-optics fabrication. This approach is compatible with conventional lithography systems used in Integrated Circuit manufacturing and can be applied to thick and thin photoresists. The additive concept is centered on the idea of using multiple exposures to remove the desired amount of resist without resorting to multiple etching steps.
This presentation will explain how the additive technique, used with thin and thick resists, will revolutionize our capability to efficiently form refractive lenses and micro-optics for optical beam shaping and transforming. The quality and reproducibility of these elements will also be discussed.
Micro-Optics have begun to play a key role in micro-photonic systems and devices. This is largely due to the fact that semiconductor processing has enabled one to incorporate complex optical functions and integration features into the actual optical substrates. In this paper, key application areas of micro-optics are demonstrated for mode matching, gain equalization, and spectral filtering.