KR20090116493A - Multi-light source switching laser - Google Patents

Abstract

PURPOSE: A multi-light source switching laser is provided to perform a broadband light source and a wavelength variable light source by selectively changing an optical path through an optical switch. CONSTITUTION: In a multi-light source switching laser, an optical amplifier(11) generates an optical signal of a broadband wavelength area. A first and a second polarization controller(12,13) are connected to an output end and a feedback input end of the optical amplifier. A first and a second polarization controllers arrange a polarization state of an optical signal, and an optocoupler(14) divides a part of the output optical signal of the optical amplifier, and an optocoupler outputs the other to an output terminal of a multi light source switching laser. An optical switch(15) connects a first select terminal(Port1) or a second select terminal(Port2) to a fixed end. A reflecting mirror(16) reflects an incident through a first select terminals to the first select terminal.

Description

Multi-light source switching laser

The present invention relates to a laser used as a light source in various fields made of optical signals, including optical communication, optical fiber sensor calling system, and more particularly, can be used as a broadband light source or a wavelength variable light source according to the needs of each application. Multi light source switching laser.

A light source refers to an optical device that continuously generates a uniform amount of light in a set wavelength range. There are various types of light sources. When a light source is classified according to the wavelength of light, a light source having a fixed wavelength is generated. The short wavelength light source to generate | occur | produce, the wavelength variable light source which can vary the wavelength of light within a predetermined wavelength range, and the broadband light source which generate | occur | produces the light containing all the wavelengths which belong to a broadband wavelength range.

In the above, the variable-wavelength light source is used in fields required for the application target, such as optical communication, optical device characteristic measurement, optical fiber sensor system, and medical imaging system.

More specifically, for example, tunable light sources are used in various fields such as optical communication, call of fiber optic safety sensors, and optical component testing and measurement, and more recently, spectroscopy and optical coherence tomography. Its use extends to the field of biological imaging, including optical coherence tomography (OCT).

In addition, broadband light sources are also widely used in the field of optical communication.

However, in the related art, since the broadband light source and the wavelength variable light source are implemented in independent forms, there is a problem in that all the light sources must be purchased when both the broadband light source and the wavelength variable light source are used.

The present invention is to solve the problem of having to purchase each of the products separately, if you want to use both a broadband light source and a variable wavelength light source, the operation as a broadband light source and a variable wavelength light source in one structure by changing the optical path It is an object of the present invention to provide a multi-light source switching laser.

As a means for solving the above problems, the multi-light source switching laser according to an embodiment of the present invention, an optical amplifier for generating an optical signal in the broadband wavelength region by natural amplification emission, amplifying the feedback input optical signal; An optical coupler for dividing the output optical signal of the optical amplifier into two, one outputting to an output terminal; An optical switch including a fixed end connected to a feedback input end of the optical amplifier and a first end and a second select end to connect the first or second selector to a fixed end; A reflection member connected to a first selection end of the optical switch to reflect the optical signal incident from the optical switch back to the optical switch; And a variable band pass filter provided between the second selection end of the optical switch and the optical coupler to select a specific wavelength from the remaining optical signals distributed by the optical coupler and output the specific wavelength to the optical switch.

The multi-light source switching laser further includes first and second polarization controllers connected to the output terminal and the feedback input terminal of the optical amplifier to align the polarization states of the optical signals to have maximum transmission and gain.

The optical amplifier is implemented as a semiconductor optical amplifier (SOA) in which amplified spontaneous emission (ASE) occurs when a bias current is applied.

The variable band pass filter may include a collimator for transforming an optical signal input from the optical coupler into parallel rays; A diffraction grating for spatially separating the wavelength of the optical signal by adjusting the direction of parallel light output from the collimator differently for each wavelength; A lens for collimating an optical signal having wavelengths spatially separated by the diffraction grating in a horizontal direction and concentrating in a vertical direction to form a horizontal spectral bar; A slit plate having one or more slits for passing an optical signal having a specific wavelength when passing through a horizontal spectral bar formed at the lens by rotating at a constant speed in the focal plane of the lens; And a reflecting member disposed on the focal plane of the lens so as to be close to the slit plate and reflecting an optical signal having a specific wavelength passing through the slit.

The variable band pass filter may further include an optical circulator for transmitting an optical signal input from the optical coupler to the collimator, and an optical signal input from the collimator to the optical switch.

Since the multi-light source switching laser according to the present invention can be used as a broadband light source and a wavelength variable light source by selectively changing the optical path using an optical switch, for the convenience of the user, in addition, two types of light sources are combined into one structure. By providing it, a cost reduction effect can be obtained.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

In addition, throughout the specification, when a part is 'connected' to another part, it is not only 'directly connected' but also 'indirectly connected' with another element in between. Include. In addition, the term 'comprising' a certain component means that the component may be further included, without excluding the other component unless specifically stated otherwise.

1 is a block diagram showing the basic structure of a multi-light source switching laser according to the present invention.

Referring to FIG. 1, the multi-light source switching laser according to the present invention is connected to an optical amplifier 11 for generating an optical signal in a broadband wavelength region, and to an output side and a feedback input side of the optical amplifier 11, respectively, for maximum transmission and First and second polarization controllers 12 and 13 for aligning the polarization states of the optical signal to have a gain, and an output optical signal of the optical amplifier 11 transmitted through the first polarization controller 12. The optical coupler 14 which divides a part and feeds it back to the optical amplifier 11 and outputs the rest to the output terminal of the multi-light source switching laser, first and second selection ports Port1 and Port2 and the second polarization controller 13. An optical switch 15 having a fixed end connected to the feedback input of the optical amplifier 11 to connect the first selection port Port1 or the second selection port Port2 with the fixed end; and the optical switch 15 Is connected to the first selection port (Port1) of the first selection port (Port1) A reflection member 16 which reflects the incident light back to the first selection port Port1, and between the second selection port Port2 of the optical switch 15 and the optical coupler 14, In the optical signal fed back from the coupler 14 to the optical amplifier 11, a wavelength of a specific band is filtered and transmitted to the second selection port Port2, and the variable wavelength of the filtering includes a variable bandpass filter 17. It is done by

In the above-described configuration, the optical amplifier 11 is for amplifying and outputting an optical signal input to a feedback input terminal while generating an optical signal in a broadband wavelength region. For example, when a bias current is applied, a natural amplification emission ( Amplified spontaneous emission (ASE) is generated to output a wideband optical signal, and is implemented as a SOA (Semiconductor Optical Amplifier) that amplifies and outputs an optical signal input to a feedback input terminal. The optical amplifier 11 may be implemented as any other wideband light source such as another gain chip capable of generating an optical signal, a broadband light source using an EDF, or a Fabry-perot laser.

The first and second polarization controllers 12 and 13 are polarization states of an optical signal output from the optical amplifier 11 or fed back into the optical amplifier 11 for the optical amplifier 11 depending on the polarization state. Is arranged to have a maximum transfer gain.

The optical coupler 14 distributes the input optical signal, for example, by dividing the input light into 10:90 or 20:80 and the like, and outputs 80% or 90% of the power of the input optical signal to the output terminal. And feed back the remaining 10% or 20% of power.

The variable band pass filter 17 is for filtering an optical signal having a specific wavelength. The variable band pass filter 17 may use any type of band pass filter having a narrow output bandwidth compared to an input bandwidth as well as a Fabry-perot type variable band pass filter. In one embodiment of the present invention, a slit-type wavelength selective filter is proposed as the variable band pass filter 17.

The reflecting member 16 is embodied as a mirror, for example.

In the above-described configuration, the optical amplifier 11, the first and second polarization controllers 12 and 13, the optical coupler 14, the optical switch 15 and the reflective member 16 have a ring structure deformed by an optical fiber ( connected by ring-cavity geometry, the output of the multi-light source switching laser according to the invention is obtained from the optical coupler 14.

The operation mode of the multi-light source switching laser configured as described above can be divided into two modes, a multi light source mode and a wavelength variable light source mode.

First, in the multi light source mode, the fixed end of the optical switch 15 selects the first selection port Port 1. In this case, the feedback input of the optical amplifier 11 is connected to the reflective member 16, and the ring circulation structure from the optical coupler 14 and the variable band pass filter 17 to the optical amplifier 11 is disconnected. Lose.

Therefore, the wideband optical signal generated by the natural amplification emission ASE of the optical amplifier 11 is output to both sides of the first and second polarization controllers 12 and 13. The wideband optical signal output to the second polarization controller 13 is reflected by the reflecting member 16 through the optical switch 15, and the optical signal reflected by the reflecting member 16 is again the optical switch 15 and The light is incident on the optical amplifier 11 through the second polarization controller 13. The optical amplifier 11 amplifies the incident optical signal. As the above process is repeated, the power of the broadband optical signal emitted from the optical amplifier 11 may be increased.

The wideband optical signal of the appropriate power generated from the optical amplifier 11 is output to the output terminal through the first polarization controller 12 and the optical coupler 14.

Next, in the variable wavelength light source mode, the fixed end of the optical switch 15 is connected to the second selection port Port2. In this case, the optical amplifier 11 and the variable band pass filter 17 are connected in a ring circulation structure.

Therefore, the optical signal generated by the natural amplification emission in the optical amplifier 11 is transmitted to the variable band pass filter 17 through the first polarization controller 12 and the optical coupler 14, the variable band pass filter 17 Extracts and outputs only an optical signal having a selected wavelength among the output optical signals of the optical amplifier 11. The extracted optical signal of the specific wavelength is fed back into the optical amplifier 11 through the optical switch 15 and the second polarization controller 13, and the optical amplifier 11 has a specific wavelength of the feedback input as described above The optical signal is amplified and output together with the optical signal by the natural amplification emission.

As the above-described process is repeated, the power of the specific wavelength optical signal is gradually increased, and as a result, the natural amplification emission is suppressed, so that an optical signal having a specific wavelength having an appropriate power can be obtained from an output terminal.

As described above, the multi-light source laser according to the present invention can selectively provide a wideband optical signal and an optical signal having a desired wavelength by adjusting the optical path using the optical switch 15.

2 shows a detailed structure of a variable band pass filter using a slit as an example of the variable band pass filter 17, and FIG. 3 is an exemplary view of the slit plate.

2 and 3, the slit-type wavelength selective filter transmits the optical signal input from the optical coupler 14 to the collimator 15 and transmits the optical signal input from the collimator 15 to the optical switch. An optical circulator 21 to be transmitted to (15), a collimator 22 for adjusting the output optical signal of the optical amplifier 11 input from the optical circulator 21 to parallel rays, and A diffraction grating 23 for spatially separating the wavelength of the output optical signal of the optical amplifier 11 transmitted through the collimator 22, and the wavelength is spatially separated by the diffraction grating 23 A lens 24 for collimating an optical signal in a horizontal direction and concentrating in a vertical direction, and an optical signal having a specific wavelength in the optical signal transmitted from the lens 24 by rotating at a constant speed in the focal plane of the lens 24. Four or more slits to filter And a slit plate 25 movable in a horizontal direction, and a reflecting member 26 disposed on the focal plane of the lens 24 so as to be close to the slit plate 25 to totally reflect an optical signal having a specific wavelength passing through the slit. ).

The optical circulator 21 may include a first port P1 connected to the optical coupler 14, a second port P2 connected to the collimator 22, and a third port connected to the optical switch 15 ( P3), the optical signal inputted to the first port P1 is transmitted to the second port P2, and the optical signal inputted to the second port P2 is transmitted to the third port P3. The optical signal filtered by the wavelength selective filter 16 is prevented from being returned to the output side of the optical amplifier 11.

As shown in FIG. 3, the slit plate 25 has a slit 32 having a predetermined length and a predetermined width on a circular rotating plate 31 rotating counterclockwise (or clockwise) with respect to a center point. At least one formed, wherein the slits 32 are formed at a predetermined angle. In addition, the rotating plate 31 is implemented to be movable in the horizontal direction. The slit plate implemented as shown in FIG. 3 may sequentially scan wavelengths in the pass band. The slit plate 25 is not limited to the form of FIG. 3 and may be modified in various forms as necessary. For example, in some cases, the slit plate 25 may be implemented not to rotate, in which case the slits are formed parallel to each other on the slit plate 25. In this case, the slit plate 25 selectively outputs only a specific wavelength within the pass band.

In the variable band pass filter 17 having the above-described structure, the bandwidth of the optical signal to be filtered is proportional to the width of the slit 25, the wavelength variable speed is proportional to the rotational speed of the slit 25, The filtering repetition rate is proportional to the number of slits 25, and the wavelength of the optical signal to be filtered depends on the position of the slits 25 on the optical axis.

The operation of the variable band pass filter described above is as follows.

First, the optical signal output from the optical amplifier 11 is input to the first port P1 of the optical circulator 21 through the first polarization controller 12 and the optical coupler 14.

The optical circulator 21 outputs an output optical signal of the optical amplifier 11 input to the first port P1 to the second port P2.

The collimator 22 is connected to the second port P2 of the optical circulator 21, and a diffraction grating 23 is disposed behind the collimator 22, so that the optical circulator 21 The optical signal output from the second port P2 is output as parallel rays by the collimator 22, and the diffraction grating 23 changes the direction of parallel rays output from the collimator 15 for each wavelength, The wavelength of the output optical signal of the optical amplifier 11 is spatially separated.

The optical signal of which the wavelength is spatially separated is focused through the lens 24 disposed at the rear end of the diffraction grating 23 and is incident on the reflecting member 26. Here, the reflective member 26 is implemented as a mirror, for example. The lens 24 outputs each wavelength in parallel in the horizontal direction and concentrates one point in the vertical direction, and outputs a horizontal spectral bar.

The slit plate 25 and the reflecting member 26 disposed on the focal plane of the lens 24 select and reflect a specific region from the wide-spectrum horizontal spectrum bar. More specifically, the slit plate 25 and the reflecting member 26 are disposed as close as possible geometrically, and when the horizontal spectral bar reaches the slit plate 25, it is formed on the slit plate 25 The spectrum of the position corresponding to the slit passes through the slit and is reflected by the reflecting member 26. Here, the wavelength of the optical signal reflected through the slit, that is, filtered, depends on the horizontal position (position on the optical axis) of the slit plate 25. That is, as shown in Figure 2, the wavelength of the region where the slit is located in the horizontal spectrum bar where the wavelength is horizontally separated. Therefore, the wavelength selected can be adjusted by moving the said slit board 25 to a horizontal direction. At this time, the slit plate 25 and the reflector material 26 should be consistent with the focal plane of the lens 162.

Therefore, the bandwidth of the optical signal filtered by the slit plate 25 is proportional to the width of the slit formed in the slit plate 25, the filtering speed is proportional to the rotational speed of the slit plate 25, and the filtering repetition rate is It is proportional to the number of slits.

As described above, the optical signal having a specific wavelength reflected by the reflective member 26 through the slit plate 25 is transmitted back to the collimator 22 through the lens 24 and the diffraction grating 23.

The filtered optical signal is incident to the second port P2 of the optical circulator 21 by the collimator 22 and then transmitted to the optical switch 15 through the third port P3.

By the above-described process, the multi-light source switching laser according to the present invention can select light having a desired wavelength in the tunable light source mode.

FIG. 4 is a graph illustrating characteristics of the variable bandpass filter having the structure described with reference to FIGS. 2 and 3. The output spectrum of the variable bandpass filter having a slit width of 100 μm is shown. Referring to FIG. 4, the 3-dB bandwidth of the output signal of the variable band pass filter is represented as 0.8 nm and exhibits uniform characteristics in the entire pass band. The 3-dB bandwidth is determined by the width of the slit. When the width of the slit is narrower, narrower output spectral characteristics can be obtained.

Next, FIG. 5 is a graph showing the relationship between the horizontal position of the slit on the optical axis and the output wavelength in the slit-type variable band pass filter. Referring to the graph, it can be seen that the output wavelength of the variable band pass filter varies linearly according to the horizontal position on the optical axis of the slit.

That is, by using the slit-type variable band pass filter having the structure as shown in FIG. 2 described above, the multi-light source switch laser according to the present invention can provide linear variable characteristics in the wavelength variable light source mode.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

According to the present invention, a cost reduction effect can be obtained by providing a broadband light source and a variable wavelength light source that are applied to various fields such as an optical communication field, a biological image field, and a call system of an optical fiber sensor through a single structure.

1 is a view showing a schematic structure of a multi-light source switching laser according to the present invention.

2 is a block diagram illustrating an example of a variable band pass filter included in the multi-light source switching laser according to the present invention.

3 is an exemplary view of the slit plate shown in FIG. 2 in the multi-light source switching laser according to the present invention.

4 is a graph illustrating transfer characteristics of the variable band pass filter.

5 is a graph showing the relationship between the position of the slit and the wavelength in the tunable laser according to the present invention.

Claims (8)

An optical amplifier for generating an optical signal in a wide-band wavelength region by natural amplification emission and for amplifying a feedback input optical signal; An optical coupler for dividing the output optical signal of the optical amplifier into two, one outputting to an output terminal; An optical switch connecting a first end or a second selection end to a fixed end including a fixed end connected to a feedback input end of the optical amplifier and first and second selection ends; A reflection member connected to a first selection end of the optical switch to reflect the optical signal incident from the optical switch back to the optical switch; And And a variable band pass filter provided between the second selection end of the optical switch and the optical coupler to select a specific wavelength from the remaining optical signals distributed by the optical coupler and output the specific wavelength to the optical switch. The method of claim 1, And first and second polarization controllers connected to the output terminal and the feedback input terminal of the optical amplifier, respectively, to align polarization states of the optical signals to have maximum transmission and gain. The optical amplifier of claim 1, wherein the optical amplifier And a semiconductor optical amplifier (SOA) in which amplified spontaneous emission (ASE) occurs when a bias current is applied. The method of claim 1, wherein the variable band pass filter, A collimator for transforming the optical signal input from the optical coupler into parallel light; A diffraction grating for spatially separating the wavelength of the optical signal by adjusting the direction of parallel light output from the collimator differently for each wavelength; A lens for collimating an optical signal having wavelengths spatially separated by the diffraction grating in a horizontal direction and concentrating in a vertical direction to form a horizontal spectral bar; A slit plate having one or more slits formed thereon and positioned on a focal plane of the lens, for passing an optical signal of a specific region among horizontal spectral bars through the slits; And And a reflecting member disposed on a focal plane of the lens so as to be close to the slit and reflecting an optical signal having a specific wavelength passing through the slit. The method of claim 4, wherein the variable band pass filter, And an optical circulator for transmitting the optical signal input from the optical coupler to the collimator, and the optical signal input from the collimator to the optical switch. The method of claim 4, wherein The bandwidth of the optical signal filtered by the variable bandpass filter is proportional to the width of the slit, the variable wavelength wavelength is proportional to the rotational speed of the slit, the variable filtering repetition rate is proportional to the number of the slit Multi light source switching laser. The method of claim 4, wherein The variable band pass filter, the wavelength of the filtered optical signal is variable according to the horizontal position of the slit plate, the multi-light source switching laser. The method of claim 4, wherein the slit plate is The multi-light source switching laser, characterized in that formed on the focal plane of the lens in front of the reflective member, the one or more slits are formed at a predetermined angle with respect to the center point on the rotating plate movable in the horizontal direction.

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