Reflection-type polarization-independent optical isolator, optical isolator/amplifier/monitor, and optical system

#1. Field of the Invention

#The present invention relates to a polarization independent optical isolator and, more particularly, to a reflection type of a polarization independent isolator.

#2. Description of the Related Art

#These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:

#FIG. 1 is a schematic view of a prior-art polarization dependent optical isolator.

#FIGS. 2A and 2B are side views of the operation of a prior-art polarization independent optical isolator in both the forward (FIG. 2A) and reverse (FIG. 2B) light propagation directions.

#Reference will now made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

#Beginning with FIGS. 8A and 8B, and in all other subsequent figures included herein, solid and/or dashed lines with directional arrows affixed represent signal (light ray) trajectories and circles containing one or two double-headed arrows represent light beam polarization directions of the signals to which they are adjacent. Neither these trajectory indicators nor polarization direction indicators represent actual physical components of the embodiments to which they apply, and are provided as visual aids for the reader. Furthermore, the polarization direction indicators are all drawn and are always drawn as if the respective device were viewed end-on from a fixed reference point at the left side of the respective figure.

#The first embodiment of the polarization independent optical isolator of the present invention is illustrated in a side view in FIG. 8A and FIG. 8B. FIG. 8A and FIG. 8B illustrate operation of this first embodiment of the polarization independent optical isolator 800 of the present invention during, respectively, forward and reverse propagation of light therethrough.