| 摘要 |
<p>A photonic bandgap fiber functions as a polarization maintaining fiber, and comprises a core which consists of a solid-state material, a clad which is provided around the core, a periodic structure region which is provided in a portion of the clad near the core and in which a plurality of high-refractive-index portions each having a higher refractive index than the clad are arranged to form a periodic structure, a low-refractive-index region which is provided in another portion of the clad near the core and has a lower average refractive index than the core, and a stress applying portion which is provided in a region of the low-refractive-index region near the periodic structure region and has a thermal expansion coefficient different from that of the other portions of the low-refractive-index region.</p> |
