A WDM device

Abstract

This invention discloses a WDM device, which sequentially includes a three-fiber collimator, a collimating lens, a prism, a WDM film, a quarter-wave plate, and a reflector. The three-fiber collimator includes three fiber heads, a birefringent crystal, and a half-wave plate assembly connected together in sequence. The three fibers of the three fiber heads are designated as port a, port b, and port c. Optical signals are input from port a, optical signals within the reflection band of the WDM film are output from port b, and optical signals within the transmission band of the WDM film are output from port c. This invention has a simple structure and small size.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication, in particular to a WDM device. BACKGROUND

[0002] The existing 3-port WDM device is basically two ends of the fiber, the length is longer; in addition, the existing WDM device is rarely made into a small device with multiple ports, such as 4-port. SUMMARY

[0003] The present application aims to provide a WDM device with simple structure and small size.

[0004] To achieve the above object, the present application adopts the following technical scheme:

[0005] A WDM device sequentially comprises a three-fiber collimator, a collimating lens, a prism, a WDM film, a 1 / 4 wave plate and a mirror;

[0006] The three-fiber collimator comprises a three-fiber head, a birefringent crystal and a 1 / 2 wave plate group connected in sequence; the three fibers of the three-fiber head are port a, port b and port c respectively;

[0007] The optical signal is input from port a, the in-band optical signal reflected by the WDM film is output from port b, and the in-band optical signal transmitted by the WDM film is output from port c.

[0008] The optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the left three 1 / 2 wave plates of the 1 / 2 wave plate group are in the horizontal direction or the vertical direction, and the optical axis of the middle 1 / 2 wave plate is 45° to the horizontal direction; the optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the right three wave plates of the 1 / 2 wave plate group are 45° to the horizontal direction, and the optical axis of the middle 1 / 2 wave plate is in the horizontal direction or the vertical direction.

[0009] The birefringent crystal is a walk-off crystal.

[0010] The prism is a Wollaston prism or a Rochon prism.

[0011] A WDM device sequentially comprises a three-fiber collimator, a first collimating lens, a prism, a first WDM film, a first 1 / 4 wave plate, a second WDM film, a second 1 / 4 wave plate, a second collimating lens and a single-fiber collimator;

[0012] The three-fiber collimator comprises a three-fiber head, a first birefringent crystal and a first 1 / 2 wave plate group connected in sequence; the three fibers of the three-fiber head are port a, port b and port c respectively;

[0013] The three-fiber collimator comprises a second 1 / 2 wave plate, a second birefringent crystal and a single-fiber head connected in sequence; the optical fibers of the single-fiber head are port d respectively;

[0014] The optical signal is input from port a, and the WDM film reflects the in-band optical signal and outputs from port b;

[0015] The wavelength transmitted by the first WDM film and reflected by the second WDM film is output from port c;

[0016] The wavelength transmitted by the first WDM film and also transmitted by the second WDM film is output from port d.

[0017] The first birefringent crystal and the second birefringent crystal are walk-off crystals respectively.

[0018] The prism is a Wollaston prism or a Rochon prism.

[0019] The present application has the following beneficial effects by adopting the above technology:

[0020] 1. The single-end output WDM device has a short product length and a small volume.

[0021] 2. The present application also realizes a 4-port WDM device, which has a small volume, a simple structure and a low cost. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0023] Figure 1 It is a schematic diagram of embodiment 1 of the present application.

[0024] Figure 2 It is a schematic diagram of the optical axis of the 1 / 2 wave plate set in embodiment 1.

[0025] Figure 3 It is a schematic diagram of embodiment 2 of the present application. DETAILED DESCRIPTION

[0026] Embodiment 1

[0027] As shown in Figure 1 or Figure 2 The present application sequentially comprises a three-fiber collimator, a collimating lens 4, a prism 5, a WDM film 6, a 1 / 4 wave plate 7 and a mirror 8.

[0028] The three-fiber collimator comprises a three-fiber head 1, a birefringent crystal 2 and a 1 / 2 wave plate set 3 connected in sequence; the three optical fibers of the three-fiber head 1 are port a, port b and port c respectively.

[0029] The optical signal is input from port a, the WDM film 6 reflects the in-band optical signal from port b, and the WDM film 6 transmits the in-band optical signal from port c.

[0030] The optical axes of the upper and lower 1 / 2 wave plates in the left three 1 / 2 wave plates of the 1 / 2 wave plate set 3 are in the horizontal direction or the vertical direction, and the optical axis of the middle 1 / 2 wave plate is at 45° to the horizontal direction; the optical axes of the upper and lower 1 / 2 wave plates in the right three 1 / 2 wave plates of the 1 / 2 wave plate set 3 are at 45° to the horizontal direction, and the optical axis of the middle 1 / 2 wave plate is in the horizontal direction or the vertical direction.

[0031] Transmission from port a to port b: the optical signal from the optical fiber at the upper end (port a) is transmitted into the WDM device described in the application through the three-fiber head 1, and then into the birefringent (walk-off) crystal, the optical signal is divided into o light and e light with mutually perpendicular polarizations in the birefringent crystal 2, and is separated in space (separated in the direction perpendicular to the paper), then the o light and e light continue to propagate to the 1 / 2 wave plate set 3, and after passing through the 1 / 2 wave plates, the polarization states of the two beams of light become the same direction, then the two beams of light enter the collimating lens 4 together to collimate the two beams of light respectively, next the two collimated beams of light pass through the prism 5 (Wollaston prism or Rochon prism), then are reflected by the WDM film 6, the reflected light passes through the prism 5 (Wollaston prism 5 or Rochon prism 5) again to reach the collimating lens 4, and after being converged by the collimating lens 4, enters the 1 / 2 wave plate and the birefringent (walk-off) crystal in the middle (port b) of the three-fiber head 1, and after the two beams of light (o light and e light) are combined in the birefringent crystal 2, are output from the optical fiber at port b.

[0032] It should be noted that the optical signal from port a to port b is the wavelength reflected by the WDM film 6 in the band.

[0033] Port a to port c transmission: the optical signal from the fiber of port a enters the WDM device through the three-fiber head 1, then enters the birefringent crystal 2, the optical signal is divided into o light and e light with perpendicular polarization in the birefringent crystal 2, and the o light and e light are separated in space (separated in the direction perpendicular to the paper), then the o light and e light continue to propagate to the 1 / 2 wave plate group 3, after passing through the 1 / 2 wave plate, the polarization states of the two beams of light become the same direction, then the two beams of light enter the collimating lens 4 to collimate the two beams of light respectively, then the two collimated beams of light pass through the prism 5 (Wollaston prism 5 or Rochon prism 5), then pass through the WDM film 6, and the transmitted light passes through the 1 / 4 wave plate 7 to reach the mirror 8, after being reflected on the mirror 8, the optical signal passes through the 1 / 4 wave plate 7 again, so that the polarization direction of the optical signal is rotated by 90°, then the optical signal is transmitted through the WDM film 6 again, so that when the optical signal passes through the prism 5 (Wollaston prism 5 or Rochon prism 5) again to reach the optical path of port c, after converging through the collimating lens 4, the optical signal enters the 1 / 2 wave plate and the birefringent crystal in the middle (port c) of the three-fiber head 1, and the two beams of light (o light and e light) are combined in the birefringent crystal 2 and then output from the fiber of port c.

[0034] It should be noted that the optical signal from port a to port c is the wavelength transmitted by the WDM film 6 within the band.

[0035] Embodiment 2

[0036] As shown in Figure 3 , a WDM device sequentially comprises a three-fiber collimator, a first collimating lens 4, a prism 5, a first WDM film 6, a first 1 / 4 wave plate 7, a second WDM film 8, a second 1 / 4 wave plate 9, a second collimating lens 10, and a single-fiber collimator;

[0037] The three-fiber collimator comprises a three-fiber head 1, a first birefringent crystal 2, and a first 1 / 2 wave plate group 3 connected in sequence; the three fibers of the three-fiber head 1 are port a, port b, and port c respectively;

[0038] The three-fiber collimator comprises a second 1 / 2 wave plate 11, a second birefringent crystal 12, and a single-fiber head 13 connected in sequence; the fiber of the single-fiber head 13 is port d;

[0039] The optical signal is input from port a, and the WDM film reflects the optical signal within the band and outputs from port b;

[0040] The first WDM film 6 transmits the wavelength within the band, and the second WDM film 8 reflects the wavelength within the band and outputs from port c;

[0041] The first WDM film 6 transmits the wavelength within the band, and the second WDM film 8 also transmits the wavelength within the band and outputs from port d.

[0042] Port a to port b transmission: the optical signal from the fiber of the left upper end (port a) enters the WDM device described in the present application through the three-fiber head 1, then enters the first birefringent (walk-off) crystal, the optical signal is divided into o light and e light with mutually perpendicular polarization in the first birefringent crystal 2, and is separated in space (separated in the direction perpendicular to the paper), then the o light and e light continue to propagate to the first 1 / 2 wave plate group 3, after passing through the first 1 / 2 wave plate, the polarization states of the two beams of light become the same direction, then the two beams of light enter the first collimating lens 4 together to collimate the two beams of light respectively, next the two collimated beams of light pass through the prism 5 (Wollaston prism 5 or Rochon prism 5), then are reflected by the first WDM film 6, the reflected light passes through the prism 5 (Wollaston prism 5 or Rochon prism 5) again to reach the first collimating lens 4, after converging through the first collimating lens 4, the light enters the first 1 / 2 wave plate and the first birefringent (walk-off) crystal in the middle of the three-fiber head 1 (port b), after the two beams of light (o light and e light) are combined in the first birefringent crystal 2, the light is output from the fiber of port b.

[0043] It should be noted that the optical signal from port a to port b is the wavelength reflected by the first WDM film 6 within the band.

[0044] Port a to port c transmission: the optical signal from the fiber of the left upper end (port a) enters the WDM device described in the present application through the three-fiber head 1, then enters the first birefringent (walk-off) crystal, the optical signal is divided into o light and e light with mutually perpendicular polarization in the first birefringent crystal 2, and is separated in space (separated in the direction perpendicular to the paper), then the o light and e light continue to propagate to the first 1 / 2 wave plate group 3, after passing through the first 1 / 2 wave plate, the polarization states of the two beams of light become the same direction, then the two beams of light enter the first collimating lens 4 together to collimate the two beams of light respectively, next the two collimated beams of light pass through the prism 5 (Wollaston prism 5 or Rochon prism 5), then are transmitted by the first WDM film 6, the transmitted light passes through the first 1 / 4 wave plate 7 to reach the second WDM film 8, after being reflected on the second WDM film 8, the optical signal passes through the first 1 / 4 wave plate 7 again, so that the polarization direction of the optical signal is rotated by 90°, then the optical signal is transmitted again through the first WDM film 6, so that when the optical signal passes through the prism 5 (Wollaston prism 5 or Rochon prism 5) again to reach the optical path of port c, after converging through the collimating lens, the light enters the first 1 / 2 wave plate and the first birefringent (walk-off) crystal in the middle of the three-fiber head 1 (port c), after the two beams of light (o light and e light) are combined in the birefringent crystal, the light is output from the fiber of port c.

[0045] It should be noted that the optical signal from port a to port c is the wavelength in the passband of the first WDM film 6 and is the wavelength in the passband of the second WDM film 8.

[0046] Transmission from port a to port d: the optical signal from the optical fiber of the left upper end (port a) is transmitted into the WDM device described in the present application through the three-fiber head 1, and then enters the first birefringent crystal, the optical signal is divided into o light and e light with mutually perpendicular polarizations in the first birefringent crystal 2, and is spatially separated (separated in the direction perpendicular to the paper), and then the o light and e light continue to propagate to the first 1 / 2 wave plate set 3, the polarization state of the two beams of light changes to the same direction after passing through the first 1 / 2 wave plate, and then the two beams of light enter the first collimating lens 4 to collimate the two beams of light respectively, and then the two collimated beams of light pass through the prism 5 (Wollaston prism or Rochon prism), and then are transmitted through the first WDM film 6, and the transmitted light reaches the second WDM film 8 after passing through the first 1 / 4 wave plate 7 (the polarization state of the optical signal changes from linearly polarized light to circularly polarized light after passing through the first 1 / 4 wave plate 7), and then the optical signal is transmitted again and converges through the second collimating lens 10 to enter the second 1 / 2 wave plate 11 and the second birefringent crystal, and the two beams of light (o light and e light) are combined in the second birefringent crystal 12 and are output from the optical fiber of the port d of the single-fiber head 13.

[0047] It should be noted that the optical signal from port a to port d is the wavelength in the passband of the first WDM film 6 and is also the wavelength in the passband of the second WDM film 8.

[0048] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are illustrative rather than limiting the present application, and it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. A WDM device, characterized by: It sequentially comprises a three-fiber collimator, a collimating lens, a prism, a WDM film, a 1 / 4 wave plate and a mirror; The three-fiber collimator comprises a three-fiber head, a birefringent crystal and a 1 / 2 wave plate set connected together in sequence; the three fibers of the three-fiber head are port a, port b and port c respectively; The light signal is input from port a, the in-band light signal reflected by the WDM film is output from port b, and the in-band light signal transmitted by the WDM film is output from port c; The optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the left row of three 1 / 2 wave plates of the 1 / 2 wave plate set are in the horizontal direction or the vertical direction, and the optical axis of the middle 1 / 2 wave plate is at 45° to the horizontal direction; the optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the right row of three wave plates are at 45° to the horizontal direction, and the optical axis of the middle 1 / 2 wave plate is in the horizontal direction or the vertical direction.

2. A WDM device according to claim 1, characterised in that: The birefringent crystal is a walk-off crystal.

3. A WDM device according to claim 1, characterized in that: The prism is a Wollaston prism or a Rochon prism.

4. A WDM device, characterized by: It sequentially comprises a three-fiber collimator, a first collimating lens, a prism, a first WDM film, a first 1 / 4 wave plate, a second WDM film, a second 1 / 4 wave plate, a second collimating lens and a single-fiber collimator; The three-fiber collimator comprises a three-fiber head, a first birefringent crystal and a first 1 / 2 wave plate set connected together in sequence; the three fibers of the three-fiber head are port a, port b and port c respectively; The three-fiber collimator comprises a second 1 / 2 wave plate, a second birefringent crystal and a single-fiber head connected together in sequence; the fiber of the single-fiber head is port d; The light signal is input from port a, and the in-band light signal reflected by the WDM film is output from port b; The wavelengths in the band transmitted by the first WDM film and reflected by the second WDM film are output from port c; The wavelengths in the band transmitted by the first WDM film and also in the band transmitted by the second WDM film are output from port d; The optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the left row of three 1 / 2 wave plates of the first 1 / 2 wave plate set are in the horizontal direction or the vertical direction, and the optical axis of the middle 1 / 2 wave plate is at 45° to the horizontal direction; the optical axes of the upper 1 / 2 wave plate and the lower 1 / 2 wave plate in the right row of three wave plates are at 45° to the horizontal direction, and the optical axis of the middle 1 / 2 wave plate is in the horizontal direction or the vertical direction.

5. A WDM device according to claim 4, characterised in that: The first birefringent crystal and the second birefringent crystal are walk-off crystals respectively.

6. A WDM device according to claim 4, characterised in that: The prism is a Wollaston prism or a Rochon prism.

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