RU186808U1 - Fiber optic phase modulator - Google Patents

Abstract

The invention relates to fiber optic optical radiation control devices. The fiber optic phase radiation modulator is bidirectional. The phase radiation modulator includes a collimator with two fiber optical fibers. The phase radiation modulator includes a reflective mirror mounted on a piezoelectric element to which a control voltage is applied. The technical result consists in reducing the optical losses introduced by the modulator due to the absence of polarization-sensitive optical elements and one fiber collimator, in simplifying the design of the modulator and its adjustment, in increasing the reliability of the phase modulator. 2 ill.

Description

The technical solution relates to fiber-optic devices for controlling optical radiation and can be used for phase modulation of light in fiber-optic devices of quantum electronics (lasers, optical amplifiers, interferometers, etc.), as well as in communication and information processing systems.

The phase modulator device of FIG. 1 [B.N. Nyushkov, V.S. Pivtsov, N.A. Kolyada, A.B. Kaplun, A.B. Meshalkin. Stabilization of a fiber femtosecond laser according to the optical frequency standard using an electro-optical KTP crystal. // Quantum. electron. - 2014 .-- T.45, N5. - S. 486-491].

The device includes (Fig. 1): fiber optic collimators (3) with fiber optic fibers (1 and 2), which can be used as input or output of a modulator; a mirror (4) for reflecting optical radiation; a piezoelectric element (5) to which a mirror is attached; a support (6) to which the piezoelectric element (5) is attached; polarization radiation divider (9) and phase plate λ / 4 (10). All elements of the modulator are fixed on a common basis (8). After the collimator (3) with a fiber waveguide (1), the input optical radiation polarized in the plane of the pattern passes through the polarization divider (9), the λ / 4 phase plate (10) is reflected from the mirror (4) and passes through the phase plate a second time λ / 4 (10). After passing through the λ / 4 phase plate twice, the polarization of the optical radiation changes by 90 ° (the polarization becomes perpendicular to the plane of the figure) and the radiation is reflected from the polarization divider (9) into the output collimator (3) with a fiber waveguide (2). The reflector mirror of the modulator is adjusted so that the optical radiation transmitted through the collimator (3) from the input fiber (1) is reflected in the second (output) fiber with minimal losses. In this case, the modulator is "bidirectional", that is, both fiber optic fibers can be used as input or output of the modulator. Using wires (7), a control voltage is applied to the piezoelectric element, depending on which the thickness of the piezoelectric element changes.

When the thickness of the piezoelectric element changes, the length of the optical path of radiation in the modulator changes, which leads to a change in the phase of the radiation.

This phase modulator device has the following disadvantages:

1. The modulator is polarization-dependent, that is, it transmits optical radiation only with a certain linear polarization. In this case, the input radiation with perpendicular polarization is rejected by the polarization divider (9). Thus, for polarized input radiation, an exact adjustment of its polarization along the modulator axis is required. If partially polarized or non-polarized radiation passes through the modulator, additional polarization losses appear.

2. The modulator design uses expensive polarization-sensitive optical elements (polarization radiation divider (9) and phase plate λ / 4 (10)). These elements complicate the design and alignment of the modulator, as well as increase its cost.

3. The polarization radiation divider (9) and the λ / 4 phase plate (10) introduce additional optical losses, including spectrally-dependent and polarization-dependent.

The technical result obtained from the implementation of the utility model is to eliminate the reduction of optical losses introduced by the modulator due to the absence of polarization-sensitive optical elements and one fiber collimator, which also simplifies its design and alignment, leads to increased reliability and lower cost of the modulator.

This technical result is achieved due to the fact that instead of two fiber collimators, a polarizing radiation divider and a phase plate, the claimed device uses a special fiber collimator with two fiber inputs (one of the fibers is used as the input of the modulator, and the second as the output).

A utility model diagram is shown in FIG. 2.

The device includes (Fig. 2): a fiber optic collimator (3) with two fiber optical fibers (1 and 2), which can be used as an input or output of a modulator; a mirror (4) for reflecting optical radiation; a piezoelectric element (5) to which the mirror is attached, as well as a support (6) to which the piezoelectric element (5) is attached. All elements of the modulator are fixed on a common basis (8).

The device according to FIG. 2 operates as follows: the optical radiation transmitted through the collimator (3) from the “input” optical fiber (1) or (2) is reflected in the second (output) optical fiber. The reflecting mirror of the modulator (4) is adjusted so that the optical loss during the passage of radiation through the modulator is minimal. Like the prototype, the modulator is “bidirectional”, that is, both fiber optic fibers can be used as input or output of the modulator. Using wires (7), a control voltage is applied to the piezoelectric element, depending on which the thickness of the piezoelectric element changes. When the thickness of the piezoelectric element changes, the length of the optical path of radiation in the modulator changes, which leads to a change in the phase of the radiation.

The advantages of the proposed utility model compared to the prototype:

1. More simple and reliable design with fewer elements.

2. In the proposed PM, precise alignment of only one optical element (collimator or mirror) is required, and the prototype design requires precise alignment of two collimators (or collimator and mirror), as well as additional adjustment of the polarization radiation divider and λ / 4 phase plate.

3. Due to the smaller number of optical elements, the proposed PM has lower insertion loss and greater reflection loss.

4. The polarization radiation divider and the phase plate λ / 4 in the design of the prototype introduce additional spectral loss.

5. The proposed PM is polarization-independent, and the prototype modulator passes only one polarization.

6. The proposed PM is significantly cheaper than the prototype.

Claims (1)

Bidirectional fiber-optic phase radiation modulator, including a collimator with two fiber optic fibers and a reflective mirror mounted on a piezoelectric element, to which a control voltage is applied.

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