Polarized light interference type comb filter

Abstract

The invention relates to a polarized light interference type comb filter which comprises a first port, a second port and a third port. The first port is used for transmitting a first optical signal through a first optical path; the second port is used for transmitting a second optical signal; the third port is used for transmitting a third optical signal; the first optical signal is divided into the second optical signal and the third optical signal through the first optical path by a first dividing / synthesizing optical crystal, a second dividing / synthesizing optical crystal and an interfering crystal group; the interfering crystal group is arranged between the first opening / closing optical crystal and the second dividing / synthesizing optical crystal; and a reflecting mirror is used for receiving, returning and outputting the second optical signal and the third optical signal. The polarized light interference type comb filter is characterized in that: the second optical signal reflected by the reflecting mirror is transmitted along the first optical path of the first optical signal to pass through the interfering crystal group and then second optical signal is deviated from the first optical signal through a beam deviation device and outputted through the second port, the third optical signal reflected by the reflecting mirror is transmitted along the second optical path of the second optical signal to pass through the interfering crystal group and then the third optical signal is outputted through the second port, and the third optical signal reflected by the reflecting mirror is transmitted along the second optical path to pass through the interfering crystal group and then the third optical signal is outputted through the third port. The interfering crystal group is only provided with four beams, therefore, the volume of the interfering crystal group is reduced greatly, and the cost is lowered.

Description

technical field [0001] The invention relates to the technical field of optical communication devices, in particular to a low-cost polarized light interference comb filter. Background technique [0002] With the rapid development of information communication, the information exchange of voice, image and data is increasing day by day. Especially with the wide application of the Internet, people have put forward higher requirements for broadband communication. In order to meet people's demand for broadband communication with low-cost and high-quality systems in the shortest possible time, wavelength division multiplexing (WDM) technology is widely used. Using the principle of transmission in light to increase the number of channels can double the signal transmission, and wavelength division multiplexing can expand the capacity of optical fiber communication without the need to set up new optical fiber channels. Reduced network construction costs. [0003] Another way to incr...

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Problems solved by technology

[0004] The birefringent crystal-type optical comb filter of the prior art is an optical comb filter with a compact structure using mirrors, and U.S. Patent No. 6,697,198 discloses a crystal-type optical comb filter of this reflective structure ,like figure 1 As shown: the first signal beam incident from the first port 400 passes through the first optical path D1 and is separated into upper and lower beams by the first deviation crystal 415, then passes through an interference crystal group 418, and passes through the second deviation crystal 430 to separate the first light beam. A signal beam is split into the second and third signal beams, which are reflected back by the mirror 450. The second deviation crystal 430 respectively passes through the second path D2 and the third path D3 through the above-mentioned interference crystal group 418, and then passes through the second port quasi The output of the collimator 495 and the collimator 490 input by the third port, because the first signal beam is separated into the second signal beam and the third signal beam respectively through the second optical path and the second deviation crystal 430 through the first optical path Three optical paths, the two paths of the second optical path, the third optical path and the first optical path pass through the interference crystal group 418 again and then are coupled out through the collimator 495 and the collimator 490, so that the interference crystal group 418 Including the six beams of the above-mentioned first, second, and third optical paths, the interference crystal group 418 needs to have a larger volume to accommodate the six beams, thereby increasing the cost of the device

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