Joohyun Koh

Effects of bending on the performance of hole-assisted single polarization fibers.

We study the effects of bending on single polarization fiber performance through the use of finite element method in conjunction with the perfectly matched layer (PML) in cylindrical geometry. The cylindrical PML used in this paper allows us to calculate the loss associated with each polarization mode at a given wavelength, specified bending diameter, and specific orientation. We identified a series of bending characteristics of the single polarization fiber by choosing different bending diameters and different orientations. We also conducted experiments to study some aspects of the bending. Good qualitative agreement between numerical and experimental results is found, which helps to understand fiber deployment conditions and can potentially facilitate new design efforts.

Wide band single polarization and polarization maintaining fibers using stress rods and air holes.

We propose a new fiber design using both stress rods and air holes for making wide band single polarization fibers as well as polarization maintaining fibers. The key factor that makes the fiber design possible is that the stress-induced birefringence from the stress rods and the form birefringence from air holes are added constructively, which increases the total birefringence and allows more flexible choice of fiber parameters. We established a finite element model that is capable to study both the stress-optic effect and the wave-guide effect. Through the detailed modeling, we systematically explore the role of each major parameter. Different aspects of the fiber properties related to the fundamental mode cutoff, fiber birefringence and effective area are revealed. As a result, fibers with very large single polarization bandwidth as well as larger effective area are identified.

Wavelength tunable stretched-pulse mode-locked all-fiber erbium ring laser with single polarization fiber.

A wavelength tunable stretched-pulse mode-locked all-fiber ring laser using single polarization fiber (SPF) was demonstrated. In this laser, a segment of SPF was used simultaneously as a polarizer and a tunable filter in the laser cavity. Self-starting mode-locking with femtosecond output pulses was demonstrated. A wavelength tuning of ~20nm was achieved by bending the SPF with different radii.

High-performance single-polarization optical fibers

This paper reviews recent progress and presents new designs and experimental results on single polarization (SP) fibers. The design concept for achieving SP propagation and approaches using either stress induced birefringence or hole-assisted geometrical birefringence for realizing single polarization fibers are described. Designs of hole-assisted SP fibers with either dual holes or a central hole are discussed in details. Effects of fiber parameters on SP fiber performance such as bandwidth, cutoff wavelength, mode field area are analyzed. Results on fabrication and characterization of dual-hole-assisted SP fibers are presented. SP operating windows centered at wavelength from 900 to 1600 mm with bandwidths from 18 to 55 nm are realized. Applications of SP fibers for single mode fiber lasers to produce linear polarized laser output are demonstrated with extinction ratio of 17-20 dB.

Progress in high-power fiber lasers

We review current work on fiber laser systems at Corning. In particular, we describe design and performance of all-glass double-clad laser fibers, broad-area laser pumps, and pump coupling optics. We discuss our approaches using single-polarization fiber and low-nonlinearity photonic band gap fiber as technologies for developing the next generation of high-power fiber lasers.

Cylindrical vector beam generation from spun fiber

Recently there has been considerable interest in the generation of cylindrical vector beams for numerous possible applications in nano-biophotonics, optical imaging, the laser processing of materials and the generation of single photon sources among others. Cylindrical vector optical vortex beams are shown by propagating a fundamental laser mode through a spun ber. The polarization state of the output from the ber is characterized and the the process of this mode conversion will be discussed.

Single polarization fibers and applications

Single polarization fibers are designed so that one polarization propagates, while the other is cut off. Several classes of index profiles can be used. Applications include new transmission systems, sensors, and components

Wide band single polarization and polarization maintaining fibers with stress rods and air holes

We present a novel fiber design using both stress rods and air holes for making wide band single polarization fibers as well as polarization maintaining fibers. The key factor that makes the fiber design possible is that the stress-induced birefringence from the stress rods and the form birefringence from air holes are added constructively, which increases the total birefringence and allows more flexible choice of fiber parameters. We established a finite element model that is capable to study both the stress-optic effect and the wave-guide effect. Through the detailed modeling, we systematically explore the role of each major parameter. Different aspects of the fiber properties related to the fundamental mode cutoff, fiber birefringence and effective area are revealed. As a result, fibers with very large single polarization bandwidth as well as larger effective area are identified.

Challenges in single-polarization fibers (Invited Paper)

We have demonstrated high power, linearly polarized output from an all-fiber laser using an integrated polarizing fiber. In this paper, we will detail the design, fabrication and operation of the single polarization fiber as well as the fiber laser experiments.

Bending Properties of Hole-assisted Single Polarization Fibers

We study effects of bending on single polarization fiber performance. Good qualitative agreement between numerical and experimental results is found, which helps to understand fiber deployment conditions and facilitate new design.