US-12625324-B2 - Optical fiber filter with ultra-wide tuning range

US12625324B2US 12625324 B2US12625324 B2US 12625324B2US-12625324-B2

Abstract

An optical fiber filter has an ultra-wide tuning range and includes a two-dimensional mechanical rotating mirror, a collimating and beam expanding system, and two gratings. An input fiber emits a multi-wavelength optical signal into the rotating mirror, which reflects the signal to the system to form collimated beams. In turn, the collimated beams are incident on the gratings that disperse the light of different wavelengths to different angles. Lights of different diffraction angles are input into an output fiber by adjusting the rotating mirror. The rotating mirror can be used to switch between gratings of different wavebands to tune optical wavelengths in an ultra-wide range.

Inventors

Yongkang Hu
Ketang Tan

Assignees

II-VI DELAWARE, INC.

Dates

Publication Date: 20260512
Application Date: 20230727
Priority Date: 20201218

Claims (15)

1 . An optical fiber filter, the optical fiber filter comprising: a two-dimensional mechanical rotating mirror disposed in optical communication with at least one multi-wavelength optical signal input to the optical fiber filter, the two-dimensional mechanical rotating mirror being configured to rotate in two-dimensions and being configured to reflect the at least one multi-wavelength optical signal; a collimating and beam expanding system disposed in optical communication with the at least one reflected multi-wavelength optical signal; two gratings each disposed in optical communication with the collimating and beam expanding system and being configured to disperse the at least one reflected multi-wavelength optical signal into light of different wavelengths at different diffraction angles; first reflection components correspondingly arranged on input ends of the two gratings; and second reflection components correspondingly arranged on output ends of the two gratings, wherein the two-dimensional mechanical rotating mirror is configured to select the light of at least one of the different diffraction angles as at least one filtered signal for output to at least one output optical fiber, and wherein a first dimension of the two-dimensional mechanical rotating mirror is configured to tune a wavelength for the filtered signal; and wherein a second dimension is configured to switch between the two gratings to achieve an ultra-wide tuning range.
2 . The optical fiber filter of claim 1 , wherein the two gratings comprise a C-band grating and an L-band grating; and wherein the first dimension of the two-dimensional mechanical rotating mirror is configured to tune the wavelength for the filtered signal; and wherein the second dimension is configured to switch between the C-band and L-band gratings to achieve an ultra-wide tuning range in the entire C+L bands.
3 . The optical fiber filter of claim 1 , wherein the two-dimensional mechanical rotating mirror is configured to adjust power of the at least one filtered signal.
4 . The optical fiber filter of claim 1 , wherein at least one of the gratings comprise a multi-level cascade structure of gratings selected from the group consisting of transmissive gratings, reflective gratings, or a combination of transmissive gratings and reflective gratings.
5 . The optical fiber filter of claim 1 , wherein the two-dimensional mechanical rotating mirror includes an actuator to position the two-dimensional mechanical mirror in two dimensions.
6 . The optical fiber filter of claim 5 , further comprising a control circuitry that operates the actuator to position the two-dimensional mechanical mirror.
7 . The optical fiber filter of claim 1 , further comprising a single input optical fiber and a single output optical fiber.
8 . The optical fiber filter of claim 1 , further comprising: an input optical fiber; two output optical fibers, wherein the input optical fiber and the two output optical fibers are independent components; first total reflection components correspondingly arranged on front ends of the two gratings; and groups of lenses correspondingly arranged on rear ends of the two gratings, each of the groups disposed in communication with one of the two output optical fibers and being configured to couple the respective filtered signal from the respective grating into a respective one of the two output optical fibers.
9 . The optical fiber filter of claim 1 , the optical fiber filter further comprising: first and second input optical fibers for output to first and second output optical fibers; a first optical fiber circulator in communication with the first input optical fiber and the first output optical fiber; a second optical fiber circulator in communication with the second input optical fiber and the second output optical fiber; first total reflection components correspondingly arranged on front ends of the two gratings and being configured to reflect the at least one multi-wavelength optical signal to the respective gratings; and second total reflection components correspondingly arranged on rear ends of the two gratings, each of the second total reflection components being configured to return a respective filtered signal meeting a Littrow condition along a retracing path to the first and second optical fiber circulator for output from the first and second output optical fiber, respectively.
10 . An optical fiber filter, the optical fiber filter comprising: at least one input optical fiber; at least one output optical fiber; at least one optical fiber circulator in communication with the at least one input optical fiber and the at least one output optical fiber; a two-dimensional mechanical rotating mirror disposed in optical communication with at least one multi-wavelength optical signal from the at least one input optical fiber, the two-dimensional mechanical rotating mirror being configured to rotate in two-dimensions and being configured to reflect the multi-wavelength optical signal; a collimating and beam expanding system disposed in optical communication with the at least one multi-wavelength optical signal; two gratings each disposed in optical communication with the collimating and beam expanding system and configured to disperse the at least one multi-wavelength optical signal into light of different wavelengths at different diffraction angles; first total reflection components correspondingly arranged on front ends of the two gratings and being configured to reflect the at least one multi-wavelength optical signal to the respective gratings; and second total reflection components correspondingly arranged on rear ends of the two gratings, each of the second total reflection components being configured to return a respective filtered signal to the at least one optical fiber circulator, wherein the two-dimensional mechanical rotating mirror is configured to select the light of at least one of the different diffraction angles as the respective filtered signal for output to the output optical fiber, and wherein a first dimension of the two-dimensional mechanical rotating mirror is configured to tune a wavelength for the filtered signal; and wherein a second dimension is configured to switch between the gratings to achieve an ultra-wide tuning range.
11 . The optical fiber filter of claim 10 , further comprising: a second optical fiber circulator in communication with a second input optical fiber and a second output optical fiber; and second total reflection components correspondingly arranged on rear ends of the two gratings, each of the second total reflection components being configured to return a respective filtered signal meeting a Littrow condition along a retracing path to the first and second optical fiber circulator for output from the first and second output optical fiber, respectively.
12 . The optical fiber filter of claim 10 , wherein the gratings comprise a multi-level cascade structure of gratings selected from the group consisting of transmissive gratings, reflective gratings, or a combination of transmissive gratings and reflective gratings.
13 . The optical fiber filter of claim 10 , wherein the two gratings comprise a C-band grating and an L-band grating; and wherein a first dimension of the two-dimensional mechanical rotating mirror is configured to tune a wavelength for the filtered signal; and wherein a second dimension is configured to switch between the C-band and L-band gratings to achieve the ultra-wide tuning range in the entire C+L bands.
14 . The optical fiber filter of claim 10 , wherein the two-dimensional mechanical rotating mirror is configured to adjust power of the respective filtered signal.
15 . The optical fiber filter of claim 10 , wherein the two gratings comprise a C-band grating and an L-band grating.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent Ser. No. 11,822,127, filed Nov. 22, 2021, which claims priority to Chinese Application No. 202011513667.3, filed Dec. 18, 2020, the entire contents of which are hereby incorporated by reference herein. FIELD The present disclosure is directed to the field of optical fiber communications and optical fiber sensing, and more particularly, to an optical fiber filter with an ultra-wide tuning range. BACKGROUND Dense Wavelength Division Multiplexing (DWDM) optical fiber communication plays a dominate role in long-distance and large-capacity communications. With the explosive growth of network services, DWDM transmission channels are extending from the traditional 80 or 96 channels to 120 channels and are even being expanded to L band. An optical channel performance monitor is an indispensable device for monitoring system health in a DWDM optical communication system. A tunable optical fiber filter is the core optical engine of the optical channel performance monitor. The working wavelength range to be monitored requires a corresponding extension for tuning. At present, the tuning range for the wavelength of mainstream tunable optical fiber filters on the market is 40 to 50 nm. A single independent device cannot meet the ultra-wide C+L tuning range, and two independent devices have to be used to complete the tuning or scanning of the C or L band, respectively. The disadvantage of this method is high cost and large volume. SUMMARY OF THE DISCLOSURE To solve deficiencies in the prior art, the present disclosure provides an optical fiber filter with an ultra-wide tuning range. The optical fiber filter has low cost, a simple structure, stable performance, and high reliability. The optical fiber filter can be used with an optical channel monitor in a DWDM optical communication system and can realize a C+L ultra-wide tuning range. In order to realize the above objective, the following technical solutions are used in the present disclosure. The optical fiber filter with the ultra-wide tuning range includes a two-dimensional mechanical rotating mirror, a collimating and beam expanding system, and two gratings. At an input of the filter, an input optical fiber emits a multi-wavelength optical signal to the two-dimensional mechanical rotating mirror. The optical signal is reflected to the collimating and beam expanding system to form collimated beams. The collimated beams are incident on the gratings that generate dispersion to scatter different wavelengths at different angles. Light at the different diffraction angles is ultimately input into an output optical fiber for output of the filter by the adjustment of the two-dimensional mechanical rotating mirror. In one arrangement, the optical fiber filter uses a dual optical fiber structure having an optical fiber circulator with the input optical fiber and the output optical fiber. In this arrangement, the optical fiber filter includes first total reflection components correspondingly arranged on front ends of the two gratings, and includes second total reflection components correspondingly arranged on rear ends of the two gratings. Collimated beams from the collimating and beam expanding system are reflected by the first total reflection components and enter into the respective gratings, which disperse the beams to the second total reflection components. Reflected wavelengths pass through the respective gratings and return to the optical fiber circulator along a retracing path for output from the output optical fiber. In another configuration, the input optical fiber and the output optical fiber can be two independent components, and there can be two output optical fibers. In this other arrangement, the optical fiber filter includes first total reflection components correspondingly arranged on front ends of the two gratings, and groups of lenses are correspondingly arranged on rear ends of the two gratings. The two output optical fibers are arranged correspondingly to the two groups of lenses, and optical signals from the gratings are coupled into corresponding output optical fibers via the groups of lenses. In the configurations, the gratings can be a multilevel cascade structure of a transmissive grating, a reflective grating, or a group of the two. In the configurations, movement of the two-dimensional mechanical rotating mirror in a first dimension can be used for wavelength tuning, and movement in a second dimension can be used to expand the wavelength tuning range to make it switchable between C-band and L-band gratings to achieve an ultra-wide tuning range in the entire C+L bands. The two-dimensional mechanical rotating mirror can also adjust the power of the output optical signal. The above technical solutions are used in the present disclosure, and have the following beneficial effects: a two-dimensional mechanical rotating mirror is used to switch between gratings of differen