Fiber optical gain equalizer
First Claim
1. An optical device comprising:
- an input fiber for inputting an input optical signal;
an output fiber for outputting an output optical signal;
an optical path between said input fiber and said output fiber;
a substrate comprising at least one step with predefined parameters, said at least one step being disposed in part of said optical path and adding a phase shift to light passing therethrough; and
a variable phase shifting element controlled by an applied signal, disposed serially with said at least one step in said part of said optical path, and pixilated such that it shifts the phase of light passing through at least a portion of said part of said optical path;
such that the optical interference between light traversing that part of said optical path containing said at least one step and light traversing those parts of said optical path not containing said at least one step results in a wavelength dependent transmission through said device.
12 Assignments
0 Petitions
Accused Products
Abstract
A fiber optical device, whose wavelength profile can be dynamically controlled in real time by the application of control voltages. The device can be used as a fiber optical gain equalizer or a wavelength selective filtering device which is compact, polarization insensitive, and of low manufacturing costs. The device comprises a stepped transparent substrate, through which the input beam is passed. Within the optical paths of the stepped regions of the substrate, electronically variable phase shifting elements are located, each operative to change the phase of the light passing through its associated step, and thus effectively adding tunability to the height of each step. Planar liquid crystal elements may be used as these elements. The elements may be pixelated, each pixel preferably affecting the phase of the light passing through a fraction of the area of the associated step, such that the interference so can be used to vary the transmission through that step. The pixels thus effectively add tunability to the area of each step. Electronic control of the height and area of each step enables the generation and dynamic control of complex transmission profiles.
-
Citations
25 Claims
-
1. An optical device comprising:
-
an input fiber for inputting an input optical signal; an output fiber for outputting an output optical signal; an optical path between said input fiber and said output fiber; a substrate comprising at least one step with predefined parameters, said at least one step being disposed in part of said optical path and adding a phase shift to light passing therethrough; and a variable phase shifting element controlled by an applied signal, disposed serially with said at least one step in said part of said optical path, and pixilated such that it shifts the phase of light passing through at least a portion of said part of said optical path; such that the optical interference between light traversing that part of said optical path containing said at least one step and light traversing those parts of said optical path not containing said at least one step results in a wavelength dependent transmission through said device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of adjusting the spectral transmission profile of an optical path, comprising the steps of:
-
providing an input fiber for inputting an input signal to said path; providing an output fiber for outputting an output signal from said path; disposing a substrate having at least one stepped area with predefined parameters in said optical path; disposing a variable phase shifting element controlled by an applied signal, serially with said at least one stepped area in said optical path, said element being pixilated such that it shifts the phase of light passing through at least a portion of said part of said optical path; and adjusting said applied signal such that the optical interference between light traversing said at least one stepped area and light traversing those parts of said optical path not containing said at least one stepped area produces the desired spectral transmission profile of said optical path. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
-
-
23. A method of changing the spectral profile of an input optical signal to a predetermined profile, comprising the steps of:
-
determining the effective wavelengths and amplitudes of a predetermined number of Fourier components of the spectral profile of said input optical signal; determining the effective wavelengths and amplitudes of said predetermined number of equivalent Fourier components of said predetermined spectral profile; calculating a transfer function according to the ratio of each of said predetermined number of Fourier components of the spectral profile of said input optical signal to each of said predetermined number of Fourier components of said predetermined profile; providing a substrate having a plurality of stepped areas, one stepped area for each determined Fourier component; and passing said input optical signal through said substrate; wherein the height of each of said stepped areas is predetermined according to the wavelength of said transfer function associated with its stepped area, and the area of each of said stepped areas is predetermined according to the amplitude of said transfer function associated with its stepped area. - View Dependent Claims (24, 25)
-
Specification