KR20230099117A - Broadband wavelength-swept laser using multiple light sources - Google Patents

Abstract

A bidirectional broadband wavelength tunable laser according to an embodiment of the present invention includes a light generator for generating generated light by connecting in parallel a plurality of gain media emitting light having different central wavelengths; a light reflecting unit connected to one end of the light generating unit and reflecting the generated light; a light combining unit connected to the other end of the light generating unit and outputting combined light obtained by combining the generated light; a variable filter unit filtering and reflecting the combined light; an output unit outputting output light that is the filtered combined light; and a control unit controlling the output size and wavelength region of the output light by controlling the light generating unit and the variable filter unit.

Description

Broadband wavelength tunable laser using multiple light sources {BROADBAND WAVELENGTH-SWEPT LASER USING MULTIPLE LIGHT SOURCES}

The present invention relates to a broadband wavelength tunable laser using multiple light sources.

The tunable light source according to the prior art provides a constant DC current to the light source for driving, or provides a step function to the SOA light source to remove optical beat noise generated in the spectrum where two or more semiconductor optical amplifier (SOA) light sources overlap. It was confined to removing noise generated from overlapping spectra by providing on-off modulation.

However, in implementing a broadband wavelength tunable laser using two or more SOA light sources, there is a problem in that losses such as insertion loss occur significantly when a 50:50 coupler is used as in the prior art.

Therefore, there is a need for a broadband tunable laser using a plurality of light sources to solve these problems.

In order to solve the above problems, the present invention is to provide a broadband tunable laser that minimizes loss occurring when combining multiple light sources by combining light sources having different wavelength regions (spectrums) with a WDM combiner and then connecting them. .

A bidirectional broadband wavelength tunable laser according to an embodiment of the present invention for achieving the above object includes a light generation unit for generating generated light by connecting a plurality of gain media in parallel to emit light having different central wavelengths; a light reflecting unit connected to one end of the light generating unit and reflecting the generated light; a light combining unit connected to the other end of the light generating unit and outputting combined light obtained by combining the generated light; a variable filter unit filtering and reflecting the combined light; an output unit outputting output light that is the filtered combined light; and a control unit controlling the output size and wavelength region of the output light by controlling the light generating unit and the variable filter unit.

Preferably, when a plurality of groups are formed by grouping gain media whose wavelength regions do not overlap according to a predetermined criterion among the plurality of gain media, the optical coupling unit is connected to the gain media belonging to each of the plurality of groups. A plurality of WDM combiners (Wavelength Division Multiplexing Combiner); and a coupler combining outputs of the plurality of WDM combiners.

Preferably, the variable filter unit includes a grating for reflecting the filtered combined light, and the output unit receives a zero-order beam reflected from the grating and outputs output light. A collimator may be included.

Preferably, it may further include an amplification unit for amplifying the output light by connecting a plurality of second gain media having the same characteristics as the plurality of gain media in parallel.

Preferably, the light reflection unit may include a plurality of retro-reflectors connected to each of a plurality of generated lights generated by the plurality of gain media.

Preferably, the light reflector includes a plurality of collimators connected to each of a plurality of generated lights generated by the plurality of gain media; and a plurality of mirrors connected to each of the plurality of collimators.

A unidirectional broadband wavelength tunable laser according to an embodiment of the present invention for achieving the above object includes a light generator for generating generated light by connecting a plurality of gain media in parallel to emit light having different central wavelengths; a light combining unit connected to one end of the light generating unit and outputting combined light obtained by combining the generated light; a coupler outputting first split light and second split light from the combined light; a light splitting unit dividing the first split light and inputting the split light to the plurality of gain media; a variable filter unit filtering and reflecting the second split light; an output unit outputting output light that is the filtered second split light; and a control unit controlling the output size and wavelength region of the output light by controlling the light generating unit and the variable filter unit.

Preferably, when a plurality of groups are formed by grouping gain media whose wavelength regions do not overlap according to a predetermined criterion among the plurality of gain media, the optical coupling unit is connected to the gain media belonging to each of the plurality of groups. a plurality of first WDM combiners; and a coupler combining outputs of the plurality of first WDM combiners, wherein the light splitter includes a plurality of second WDM combiners connected to gain media belonging to each of the plurality of groups; and a coupler splitting an output to the plurality of second WDM combiners.

Preferably, the variable filter unit may include a diffraction grating for reflecting the filtered second split light, and the output unit may include a collimator for receiving the zero-order beam reflected from the diffraction grating and outputting output light. .

Preferably, it may further include an amplification unit for amplifying the output light by connecting a plurality of second gain media having the same characteristics as the plurality of gain media in parallel.

The present invention has an effect of minimizing loss that occurs when manufacturing a broadband tunable laser by combining a plurality of light sources by combining light sources having different wavelength regions with a WDM combiner and then connecting them.

1 is a block diagram showing a bidirectional broadband wavelength tunable laser according to an embodiment of the present invention.
2 is a diagram showing a bidirectional broadband wavelength tunable laser according to another embodiment of the present invention.
3A and 3B are views for explaining a light reflector according to an embodiment of the present invention.
4 is a diagram for explaining an optical coupling unit according to an embodiment of the present invention.
5 is a diagram for explaining a wavelength region of a gain medium according to an embodiment of the present invention.
6 is a block diagram showing a unidirectional broadband wavelength tunable laser according to an embodiment of the present invention.
7 is a diagram showing a unidirectional broadband wavelength tunable laser according to another embodiment of the present invention.
8 is a diagram for explaining an optical coupler and a light splitter according to another embodiment of the present invention.

An amplification unit (not shown) may be further included.

The light generator 110 generates generated light by connecting in parallel a plurality of gain media emitting light having different central wavelengths.

That is, the light generator 100 may be configured to connect in parallel a plurality of gain media emitting light having different central wavelengths and wavelength bands in order to implement a broadband wavelength.

For example, referring to FIG. 2, the light generating unit 100 includes SOA1, SOA2, . . . , generated light can be generated by connecting N SOAs of SOAN in parallel.

In another embodiment, the light generator 110 may use a semiconductor optical amplifier (SOA) as a gain medium.

At this time, the SOA is a semiconductor-based optical amplifier that receives current and outputs light according to its characteristics.

The light reflecting unit 120 is connected to one end of the light generating unit 110 and reflects the generated light.

That is, the light reflector 120 may reflect input generated light while being connected to one end of the light generator 110 through which light moves in both directions.

For example, referring to FIG. 2 , the light reflection unit 120 is located on the right side of the light generation unit 110 including the plurality of gain media SOA1, SOA2, ..., SOAN, and can reflect the generated light. .

More specifically, light generated by the light generator 110 may be combined using a 1xN WDM combiner (Wavelength Division Multiplexing Combiner), transferred to a mirror through a collimator, and reflected.

In another embodiment, the light reflection unit 120 may include a plurality of retro-reflectors connected to each of a plurality of generated lights generated by a plurality of gain media.

For example, referring to FIG. 3A , the light reflector 120 may reflect the generated light by individually connecting a retroreflector to each output of a plurality of generated lights.

In another embodiment, the light reflection unit 120 may include a plurality of collimators connected to each of a plurality of generated lights generated by a plurality of gain media and a plurality of mirrors connected to each of the plurality of collimators.

For example, referring to FIG. 3B , the light reflector 120 may reflect the generated light by individually connecting a collimator and a mirror to each output of a plurality of generated lights.

The light combining unit 130 is connected to the other end of the light generating unit 110 and outputs combined light combining the generated light.

That is, the light coupling unit 130 may output combined light by combining input generated light while being connected to the other end of the light generating unit 110 through which light moves in both directions.

For example, referring to FIG. 2, the optical coupling unit 130 is located on the left side of the light generation unit 110 including a plurality of gain media SOA1, SOA2, ..., SOAN, combines the generated light and combines the combined light. can output More specifically, the generated light of the light generator 110 may be combined using a 1xN WDM combiner and then output.

In another embodiment, when a plurality of groups are formed by grouping gain mediums whose wavelength regions do not overlap according to a predetermined criterion among a plurality of gain mediums, the optical coupling unit 130 selects the gain mediums belonging to each of the plurality of groups. It may include a plurality of WDM combiners connected to and a coupler for combining outputs of the plurality of WDM combiners.

For example, it can be assumed that there are a total of four SOA light sources including SOA1, SOA2, SOA3, and SOA4. At this time, referring to FIG. 5, the central wavelength of each SOA light source may be 940 nm for SOA1, 1060 nm for SOA2, 1130 nm for SOA3, and 1190 nm for SOA4.

Here, referring to FIG. 5 , a first group may be configured by grouping SOA1 and SOA3 whose wavelength regions do not overlap, and a second group may be configured by grouping SOA2 and SOA4.

In this case, referring to FIG. 4, the optical combiner 130 includes a WDM combiner connected to SOA1 and SOA3 and a WDM combiner connected to SOA2 and SOA4, and combines the outputs of the two WDM combiners. may include a 50:50 coupler that

In this way, the optical coupler 130 combines gain media whose wavelength domains do not overlap and connects them to the WDM combiner, thereby reducing loss occurring in an area adjacent to the spectrum of the SOA light source and preventing distortion of the spectrum. It can be prevented.

The variable filter unit 140 filters and reflects the combined light.

For example, the variable filter unit 140 may be based on a Fabry-Perot filter or a polygon scanning filter. However, the tunable filter unit 140 is not limited thereto, and may be based on various types of filters that generate a tunable laser by sweeping combined light.

More specifically, referring to FIG. 2 , an output unit 150 connected to the optical coupling unit 130 and implemented using a collimator, a diffraction grating, a polygon scanning filter, a mirror, and the like is shown. At this time, the mirror may reflect the combined light and give it back.

The output unit 150 outputs output light that is the filtered combined light.

That is, the output unit 150 outputs output light using the combined light filtered by the variable filter unit 140 .

In another embodiment, the variable filter unit 140 includes a grating for reflecting the filtered combined light, and the output unit 150 generates a zero-order beam reflected from the grating. It may include a collimator that receives an input and outputs an output light.

That is, the variable filter unit 140 may reflect the filtered combined light using the diffraction grating, and the output unit 150 may receive the zero-order beam reflected from the diffraction grating and output it as output light. In this case, the zero-order beam may refer to light in which the filtered combined light is reflected from the diffraction grating according to Snell's law.

The control unit 160 controls the light generation unit 110 and the variable filter unit 140 to control the output size and wavelength range of the output light.

For example, the control unit 160 may control the output size of the output light by controlling the current applied to the plurality of gain media included in the light generating unit 110 . In addition, the controller 160 may control the wavelength region of the output light by controlling the operation of the polygon scanning filter included in the variable filter unit 140 .

Finally, an amplification unit (not shown) connects in parallel a plurality of second gain media having the same characteristics as the plurality of gain media to amplify the output light.

For example, the amplification unit (not shown) is connected to the output unit 150 and receives the output light, inputs it to a 1xN WDM combiner, and connects a plurality of (N) gain media included in the light generation unit 110 and Input to a plurality of second gain media having characteristics of the same central wavelength and wavelength region, and the output may be combined using another 1xN WDM combiner.

Through this, the amplification unit (not shown) may amplify the output light as a whole to reduce the difference in characteristics of each spectrum.

6 is a block diagram showing a unidirectional broadband wavelength tunable laser according to an embodiment of the present invention.

Referring to FIG. 6, a unidirectional broadband tunable laser 600 according to an embodiment of the present invention includes a light generator 610, an optical coupler 620, a coupler 630, a light splitter 640, and a variable filter. It includes a unit 650, an output unit 660 and a control unit 670. In addition, it may optionally further include an amplification unit (not shown).

The light generator 610 generates generated light by connecting in parallel a plurality of gain media emitting light having different central wavelengths.

The light combining unit 620 is connected to one end of the light generating unit 610 and outputs combined light combining the generated light.

That is, the light coupling unit 620 may output combined light by combining input generated light while being connected to one end of the light generating unit 610 through which light travels in a unidirectional direction.

For example, referring to FIG. 7 , the light coupling unit 620 is located on the right side of the light generation unit 610 including a plurality of gain media SOA1, SOA2, ..., SOAN, combines the generated light, and combines the generated light. light can be emitted. More specifically, light generated by the light generator 610 may be combined and output using a 1xN WDM combiner (Wavelength Division Multiplexing Combiner).

The coupler 630 outputs first split light and second split light from the combined light.

For example, the coupler 630 may receive the combined light and divide it 50:50 to output first split light and second split light.

The light splitting unit 640 splits the first split light and inputs it to a plurality of gain media.

That is, the light splitter 640 may split the input first split light and input the split light to a plurality of gain media while being connected to the other end of the light generator 610 through which light moves in a single direction.

For example, referring to FIG. 7 , the light splitting unit 640 is located on the left side of the light generating unit 610 including a plurality of gain media SOA1, SOA2, ..., SOAN, and splits the first split light to each It can be input to the gain medium. More specifically, the first split light may be split using a 1xN WDM combiner and then output to N gain media.

The variable filter unit 650 filters and reflects the second split light.

The output unit 660 outputs the filtered output light that is the second split light.

The control unit 670 controls the light generation unit 610 and the variable filter unit 650 to control the output size and wavelength range of the output light.

In another embodiment, when a plurality of groups are formed by grouping gain mediums whose wavelength regions do not overlap according to a predetermined criterion among a plurality of gain mediums, the optical coupler 620 is applied to the gain mediums belonging to each of the plurality of groups. It includes a plurality of connected first WDM combiners and a coupler for combining outputs of the plurality of first WDM combiners, and the optical splitter 640 includes a plurality of second WDMs connected to gain media belonging to each of a plurality of groups. It may include a combiner and a coupler for splitting an output to the plurality of second WDM combiners.

This is similar to the case of configuring a plurality of groups by grouping the gain medium while explaining FIG. 1 above. However, referring to FIG. 8 , the light coupler 620 located on the left side of the plurality of gain media may also be grouped using a WDM combiner and coupler like the light splitter 640 .

In another embodiment, the variable filter unit 650 includes a grating for reflecting the filtered combined light, and the output unit 660 includes a zero-order beam reflected from the grating. ) may be input and a collimator for outputting output light may be included.

Finally, an amplification unit (not shown) connects in parallel a plurality of second gain media having the same characteristics as the plurality of gain media to amplify the output light.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (10)

a light generator for generating generated light by connecting in parallel a plurality of gain media emitting light having different central wavelengths;
a light reflecting unit connected to one end of the light generating unit and reflecting the generated light;
a light combining unit connected to the other end of the light generating unit and outputting combined light obtained by combining the generated light;
a variable filter unit filtering and reflecting the combined light;
an output unit outputting output light that is the filtered combined light; and
A control unit controlling the output size and wavelength region of the output light by controlling the light generating unit and the variable filter unit.
A bidirectional broadband wavelength tunable laser comprising a. According to claim 1,
When a plurality of groups are formed by grouping gain media whose wavelength regions do not overlap according to a predetermined criterion among the plurality of gain media,
The optical coupling part
a plurality of WDM combiners (Wavelength Division Multiplexing Combiners) connected to gain media belonging to each of the plurality of groups; and
A coupler combining the outputs of the plurality of WDM combiners
A bidirectional broadband wavelength tunable laser comprising a. According to claim 1,
The variable filter unit
A diffraction grating for reflecting the filtered coupled light;
the output section
A collimator that receives the zero-order beam reflected from the diffraction grating and outputs output light
A bidirectional broadband wavelength tunable laser comprising a. According to claim 1,
An amplification unit for amplifying the output light by connecting a plurality of second gain media having the same characteristics as the plurality of gain media in parallel.
A bidirectional broadband wavelength tunable laser further comprising a. According to claim 1,
The light reflector
A plurality of retro-reflectors connected to each of the plurality of generated lights generated by the plurality of gain media
A bidirectional broadband wavelength tunable laser comprising a. According to claim 1,
The light reflector
a plurality of collimators connected to each of a plurality of generated lights generated by the plurality of gain media; and
A plurality of mirrors connected to each of the plurality of collimators
A bidirectional broadband wavelength tunable laser comprising a. a light generator for generating generated light by connecting in parallel a plurality of gain media emitting light having different central wavelengths;
a light combining unit connected to one end of the light generating unit and outputting combined light obtained by combining the generated light;
a coupler outputting first split light and second split light from the combined light;
a light splitting unit dividing the first split light and inputting the split light to the plurality of gain media;
a variable filter unit filtering and reflecting the second split light;
an output unit outputting output light that is the filtered second split light; and
A control unit controlling the output size and wavelength region of the output light by controlling the light generating unit and the variable filter unit.
A unidirectional broadband wavelength tunable laser comprising a. According to claim 7,
When a plurality of groups are formed by grouping gain media whose wavelength regions do not overlap according to a predetermined criterion among the plurality of gain media,
The optical coupling part
a plurality of first WDM combiners connected to gain media belonging to each of the plurality of groups; and
A coupler combining outputs of the plurality of first WDM combiners;
The light splitter
a plurality of second WDM combiners connected to gain media belonging to each of the plurality of groups; and
Unidirectional broadband wavelength tunable laser, characterized in that it comprises a coupler for splitting the output to the plurality of second WDM combiners. According to claim 7,
The variable filter unit
A diffraction grating for reflecting the filtered second split light;
the output section
A collimator that receives the zero-order beam reflected from the diffraction grating and outputs output light.
A unidirectional broadband wavelength tunable laser comprising a. According to claim 7,
An amplification unit for amplifying the output light by connecting a plurality of second gain media having the same characteristics as the plurality of gain media in parallel.
A unidirectional broadband wavelength tunable laser further comprising a.

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