KR101838245B1

KR101838245B1 - Pulse generating apparatus having interferometer for selectively generating mode-locked pulse and noise like pulse

Info

Publication number: KR101838245B1
Application number: KR1020150154656A
Authority: KR
Inventors: 김승만; 신윤상; 송준엽; 하태호; 이재학; 김용진; 이창우
Original assignee: 한국기계연구원
Priority date: 2015-11-04
Filing date: 2015-11-04
Publication date: 2018-03-13
Also published as: KR20170052332A

Abstract

An apparatus for generating a selective mode pulse of a mode lock pulse and a noise pulse includes a laser diode for outputting light and a polarization controller for generating a mode lock pulse or a noise pulse by adjusting the polarization of the pulse, And a control unit that is optically connected to the output terminal and is electrically connected to the polarization control unit to sense and disperse the light output from the resonator and to divide and interfere with the light output from the resonator to detect whether an interference signal is generated, And a signal detection controller for transmitting a control signal to stop the operation of the polarization controller when it is confirmed that the pulse or the noise pulse is generated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and method for generating selective pulses of a mode lock pulse and a noise pulse with an interferometer,

The present invention relates to a pulse generating apparatus, and more particularly, to a selective pulse generating apparatus capable of generating a dual mode pulse in a single resonator.

Most of the fiber-based laser resonators are composed of optical fibers, so that they are simple in configuration, easy to operate with a turn-key system and insensitive to changes in the environment, and can be operated for a long time. In addition, using fiber optic components in the communication band, it has various advantages that are industrially applicable such as low price and utilization in communication band.

A mode-locked pulse generates a spectrum having a wavelength width of several to several tens of nanometers (see FIG. 13A), which is formed at a repetition rate frequency interval corresponding to the resonator length, and has a frequency range of several tens to several millions of frequency modes (See FIG. 13B). The phases of the respective frequency modes generate pulses of picosecond (ps) to femtosecond (fs) width on the time axis and form a repeated pulse train at a cycle corresponding to the repetition rate (see FIGS. 13C and 13D). The generated mode lock pulse has a high peak output and high time and space coherence, making it suitable for non-thermal processing and precise distance measurement.

Noise like pulses form a spectrum having a wavelength width of several tens to several hundreds of nanometers or more (see FIG. 14A), and the phases of the respective frequency modes do not coincide with each other so that a narrow width pulse is not generated ), And a noise pulse repeated in a period corresponding to the repetition rate on the time axis is formed (see FIGS. 14C and 14D). The generated noise pulse is a light source suitable for accurate shape measurement because it has low time coherence and high spatial coherence.

In some cases, mode locking pulses or noise pulses have been observed in the form of a specific resonator. However, when generating a mode locking pulse and a noise pulse in one resonator, it is necessary to select one of the generated pulses.

SUMMARY OF THE INVENTION The present invention has been accomplished on the basis of the technical background described above, and it is an object of the present invention to provide a mode lock having an interferometer capable of selectively generating a desired pulse by sensing a mode lock pulse and a noise pulse generated in a single resonator, And an apparatus for generating a selective pulse of a pulse and a noise pulse.

An apparatus for generating a selective pulse of a mode lock pulse and a noise pulse according to an exemplary embodiment of the present invention includes a laser diode for outputting light and a polarization controller for generating a mode lock pulse or a noise pulse by controlling polarization of the pulse, And a mode locking unit that is optically connected to an output terminal of the resonator and is electrically connected to the polarization control unit to detect generation of the mode lock pulse or the noise pulse output from the resonator, And a signal detection controller for confirming the generation of the pulse or the noise pulse and transmitting the control signal to stop the operation of the polarization controller.

The signal sensing controller includes a light sensing unit for sensing a pulse output from the resonator, a control signal generating unit coupled to the light sensing unit and generating a signal for controlling the polarization controlling unit according to the pulse sensed by the light sensing unit, An application program unit connected to the control signal generator and connected to the polarization controller to transmit the control signal generated by the control signal generator to the polarization controller, And an interferometer unit electrically connected to the program unit and detecting whether an interference signal is generated depending on the type of light output from the resonator.

The optical sensing unit may include a dispersion optical system for spatially dispersing the light output from the resonator by frequency, and a first region in which the center of the dispersed light is incident from the dispersion optical system, A second region, and a third region that is set at an outer periphery of the second region, wherein a light sensor is positioned for each of the regions, and light scattered from the dispersion optical system is detected for each of the regions .

The optical sensor outputs an electrical signal corresponding to a mode lock pulse when the light is sensed over the first area and the second area and outputs a noise pulse when the light is sensed over the first area to the third area. Can be output.

The dispersion optical system may include a grating or a prism.

The optical sensor may include a plurality of optical sensors, and the plurality of optical sensors may be linear or planar.

The optical sensor may include a first photodiode located in the second region outside the first region and a second photodiode located in the third region outside the second region.

The optical sensing unit includes a light splitter for dividing the light output from the resonator into at least two divided light beams, a first optical system for inputting the first divided light beams output from the optical splitter and blocking the continuous wave and the Q- A second optical filter for receiving a second split light output from the optical splitter and blocking a mode lock pulse spectrum region, a first photodiode for detecting light transmitted through or reflected from the first optical filter, And a second photodiode that transmits the second optical filter or senses the reflected light.

The optical sensing unit may include a first optical filter that receives light output from the resonator and blocks a continuous wave and a Q-switching spectral region, a second optical filter that transmits light transmitted through or reflected from the first optical filter, A first photodiode for sensing a second split beam output from the beam splitter, a second optical beam splitter for receiving a second split beam output from the beam splitter, A filter, and a second photodiode that transmits the second optical filter or detects the reflected light.

The optical sensing unit may include an optical coupler that splits the light output from the resonator into at least two divided lights, a first optical system that receives the first split light output from the optical coupler, A second optical filter that receives a second split light output from the optical coupler and blocks a mode locking pulse spectrum region, a first photodiode that detects light transmitted through or reflected from the first optical filter, And a second photodiode that transmits the second optical filter or senses the reflected light.

The optical sensing unit may include a first optical filter that receives light output from the resonator and blocks a continuous wave and a Q-switching spectral region, a second optical filter that transmits light transmitted through or reflected from the first optical filter, A first photodiode for detecting a second split beam outputted from the optical coupler, a second optical beam splitter for receiving a second split beam outputted from the optical coupler, A filter, and a second photodiode that transmits the second optical filter or detects the reflected light.

Wherein the interferometer section comprises: a light splitter that divides the light output from the resonator into a first split light and a second split light; a second splitting optical system that is spaced apart from the optical splitter by a length of a first optical path corresponding to a pulse repetition rate length, A second mirror that is spaced apart from the optical splitter by a length of a second optical path corresponding to a multiple of two or more times the pulse repetition rate length and reflects the second divided light, And a photodiode for detecting whether or not an interference signal is generated by receiving the first divided light and the second divided light reflected from the second mirror.

Wherein the interferometer section comprises: an optical coupler for dividing the light output from the resonator to form a first optical path and a second optical path; an optical path difference retarder formed on the second optical path for generating a path delay; A second optical coupler coupled to the second optical coupler for coupling the first split light passing through the first optical path and the second split light passing through the second optical path, And a photodiode for detecting whether an interference signal is generated.

Wherein the interferometer section comprises: an optical coupler for dividing the light output from the resonator to form a first optical path and a second optical path; an optical path difference delayer connected to the first optical path for generating a path delay; A mirror connected to the optical path and reflecting the incident light, and a second splitting light which is connected to the optical coupler and passes through the first optical path and a second split light passing through the second optical path, And a photodiode that senses light.

The resonator may include any one of a ring cavity optical fiber resonator, a figure 8 cavity optical fiber resonator, and a figure 9 cavity optical fiber resonator.

The resonator may be a ring-shaped optical fiber resonator, and the ring-shaped optical fiber resonator may form a loop by connecting the gain medium connected to the laser diode and the pulse shaping section to each other.

The 8-shaped optical fiber resonator includes a gain medium connected to the laser diode, a first gain control unit connected to the first gain control unit and the second gain control unit, The polarization control section forms a first loop, the second polarization controller and the pulse shaping section form a second loop, and the first loop and the second loop may be connected through an optical coupler.

Wherein the resonator is a nine-figure-shaped optical fiber resonator, the polarization controller includes a first polarization controller and a second polarization controller, and the nine-figure optical fiber resonator comprises a gain medium connected to the laser diode, The polarization control section forms a loop, and the second polarization control section, the pulse shaping section, and the mirror are sequentially connected to the loop through an optical coupler.

According to the apparatus for generating selective pulses of the mode lock pulse and the noise pulse according to the embodiment of the present invention, a desired pulse is selectively generated by sensing a mode lock pulse and a noise pulse generated by a single resonator and controlling the resonator .

FIG. 1 is a schematic diagram showing an apparatus for generating a selective pulse of a mode lock pulse and a noise pulse according to an embodiment of the present invention. Referring to FIG.
FIGS. 2A and 2B are schematic diagrams illustrating a polarization controller included in a resonator in an apparatus for generating selective pulses of a mode lock pulse and a noise pulse according to an embodiment of the present invention. FIG. 2A shows a polarization control unit based on a bulk optical system, and FIG. 2B shows a polarization control unit based on a fiber optic optical system.
3A to 3C are graphs showing spectral energy densities according to wavelengths of light. FIG. 3A shows the spectral energy density of each wavelength of the continuous wave, FIG. 3B shows the spectral energy density of Q-switching by wavelength, FIG. 3C shows the spectral energy density of the mode lock pulse and the noise pulse, .
4A and 4B are schematic diagrams for explaining a configuration and a sensing method of the optical sensing unit in the apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to an embodiment of the present invention. FIG. 4B is a schematic diagram showing the division of pulses according to the area of the optical sensor to which the dispersion optical system emission light is incident. FIG.
5A and 5B are schematic diagrams for explaining the configuration and sensing method of the optical sensing unit in the apparatus for generating a selective pulse for a mode locking pulse and a noise pulse according to another embodiment of the present invention. FIG. 5B is a table showing distinctions of pulses according to detection conditions of a photodiode to which the dispersion optical system emission light is incident. FIG.
6A and 6B are schematic diagrams illustrating an optical sensing unit in an apparatus for generating a selective pulse for a mode lock pulse and a noise pulse according to another embodiment of the present invention. FIG. 6A shows a light sensing unit based on a bulk optical system, and FIG. 6B shows a light sensing unit based on an optical fiber.
FIGS. 7A to 7C are schematic diagrams showing a configuration of an interferometer unit in a mode pulse generating apparatus and a noise pulse generating apparatus according to an embodiment of the present invention. FIG. 7A shows a bulk optical system based interferometer unit, 7c shows an optical fiber based interferometer unit, and FIG. 7d is a table showing distinction of pulses according to detection conditions of a photodiode and an interferometer unit of the light sensing unit.
8A and 8B are schematic diagrams for explaining the configuration and sensing method of the optical sensing unit in the apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention. 8B is a table showing distinctions of pulses according to detection conditions of the photodiodes to which the dispersion optical system emission light is incident.
9A to 9E are schematic diagrams illustrating an optical sensing unit in an apparatus for generating a selective pulse for a mode lock pulse and a noise pulse according to another embodiment of the present invention. FIGS. 9A and 9B show a light sensing unit based on a bulk optical system, FIGS. 9C and 9D show an optical fiber based optical sensing unit, and FIG. 9E is a table showing whether or not a photodiode signal is detected according to a pulse state.
Figs. 10A and 10B are graphs showing a blocking region of an optical filter applied to the optical sensing unit shown in Figs. 9A to 9E, wherein Fig. 10A shows a blocking region of the first optical filter, Fig. And shows a blocking region of the filter.
11 is a schematic diagram showing a state in which an 8-shaped resonator is applied to an apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention.
12 is a schematic diagram showing a state in which a nine-character resonator is applied to an apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention.
13A to 13D are graphs showing the characteristics of the mode lock pulse.
14A to 14D are graphs showing the characteristics of the noise pulse.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification. In addition, since the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

In the present invention, the term " on " means to be located above or below the object member, and does not necessarily mean that the object is located on the upper side with respect to the gravitational direction. Also, throughout the specification, when an element is referred to as "including" an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

Hereinafter, an apparatus for generating selective pulses of a mode lock pulse and a noise pulse according to embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram illustrating an apparatus for generating a selective pulse of a mode lock pulse and a noise pulse according to an exemplary embodiment of the present invention. FIG. 7 is a schematic diagram showing a polarization controller included in a resonator in a generating apparatus. FIG.

1, the pulse generating apparatus 10 according to the present embodiment includes a resonator 100 for generating pulses and a signal sensing controller 200 for sensing the type of the generated pulse and controlling the resonator 100 . The resonator 100 includes a polarization controller 140 connected to a laser diode 120 that outputs light, a pulse shaping unit 150, and a gain medium 130.

In this embodiment, the resonator 100 is a ring cavity optical fiber resonator. The gain medium 130, the polarization controller 140 and the pulse forming unit 150 are connected to each other to form a loop. An isolator is provided between the gain medium 130 and the polarization controller 140, (135) are connected. An optical coupler 145 is connected between the polarization controller 140 and the pulse forming unit 150 to output light and may be connected to an input terminal of the signal detecting controller 200.

The signal detection controller 200 includes a light sensing part 210 connected to an output terminal of the resonator 100 to sense the type of generated pulse, a control signal generator 240 for generating a control signal according to the type of the generated pulse And an application program unit 250 connected to the polarization controller 140 to apply the generated control signal. The signal detection controller 200 includes an interferometer unit 270 that is optically connected to the output terminal of the resonator 100 and is electrically connected to the application program unit 250 and detects whether an interference signal is generated depending on the type of pulse do. The interferometer unit 270 can distinguish between a mode lock pulse and a noise pulse generated in the resonator 100.

The polarization controller 140 may form a resonator condition that generates a mode lock pulse or a noise pulse by adjusting the polarization of the pulse within the resonator 100. [ 2A and 2B, in the resonator 100 according to the present embodiment, the polarization controller 140 includes a single polarizer 144, 144 'and a plurality of wave plates 142 , 146, 142 ', 146'. As another example, a polarization beam splitter (PBS) may be applied instead of the polarizers 144 and 144 '.

The wave plates 142, 146, 142 ', 146' are of bulk type and optical fiber type and comprise a combination of a half wavelength (? / 2) plate and a quarter wavelength (? Or rotating or twisting or pushing the optical fiber to adjust the polarization of the resonating pulses.

The polarizer 144 or 144 'or the polarizing beam splitter has a bulk type and an optical fiber type, and serves as artificial saturable absorption in a ring-shaped resonator. A beam collimator 141 or 149 may be introduced to apply the laser beam to the space to apply the bulk type wave plates 142 and 146 and the polarizer 144. [

2A shows a bulk optical system based polarization control unit 140 in which a single polarizing plate 144 is interposed between a pair of wave plates 142 and 146 on an optical path, A beam collimator 149 is provided in front of the first wave plate 142 and behind the second wave plate 146. FIG. 2B shows a polarization controller 140 'based on a fiber optic system, and a single optical fiber polarization plate 144' is interposed between a pair of optical fiber wave plates 142 'and 146'.

The pulse shaping unit 150 is a part that prevents the mode locked pulse from spreading by the internal dispersion of the resonator 100 and allows the resonator 100 to generate the ultrashort pulses. The pulse shaping section 150 is a part forming a dispersion opposite to the sum dispersion of the optical fibers constituting the resonator 100 and may be a dispersion compensating fiber or a chirped fiber Bragg grating or a grating pair (Grating pair) or a prism pair. The pulse shaping unit 150 can narrow the pulse widths by filtering and removing the frequencies forming the front and rear ends of the chirp pulses. The pulse shaping unit 150 includes a bulk type optical fiber type optical filter or a fiber Bragg grating .

The gain medium 130 may be a rare earth doped optical fiber that absorbs the pump light to generate a light spectrum in a wide frequency band. For example, the gain medium 130 may include a Ytterbium doped fiber, an Erbium doped fiber, Doped fiber, and doped fiber (Nd doped fiber).

The pump light can be output using the diode laser 120, and a continuous wave laser having the wavelength of the absorption band of each rare earth element can be used. The rare earth doped optical fiber generates a spectrum of several to several tens nanometer (nm) wavelength band at a wavelength corresponding to the emission band.

The resonator 100 according to the present embodiment configured as described above can generate a mode lock pulse or a noise pulse in a single resonator 100.

When the frequency modes that are multiples of the repetition rate frequency corresponding to the resonator length among the frequencies corresponding to the wide emission spectrum band of the gain medium 130 survive and their phases coincide, the mode locked pulse of the fs Can be generated. In the resonator 100, a condition for generating such a mode lock should be formed. If considered in terms of the time axis, an ultrarapid pulse may be formed if the time required for the gain to become larger than the loss is equal to the pico in the femto .

Nonlinear polarization evolution, nonlinear amplifying (optic) loop mirror, and saturable absorber are the methods of forming such a mode lock, and the mode applied according to the resonator structure The locking method is different.

Frequency modes that are multiples of the repetition rate frequency corresponding to the resonator length among the frequencies corresponding to the wide emission spectrum band of the gain medium 130 are survived but the wide spectrums composed of random frequency modes May be formed to be a noise pulse. A method of forming a noise pulse can be found by adjusting the polarization in a mode-lockable device and a resonator having a structure.

In the ring resonator 100 according to the present embodiment, a mode locking method of a nonlinear polarization rotation method can be applied.

Referring to FIG. 1, the driving process of the selective pulse generator 10 according to the present embodiment will be described.

First, when the resonator 100 is turned on, the laser diode 120 is turned on and a mode lock pulse or noise pulse generation is selected in the application program unit 250. The polarization control unit 140 is driven in the application program unit 250 to start the polarization control of the inner side of the resonator 100. [

Next, the light sensing unit 210 senses a pulse generated in the resonator 100, and detects the intensity or the intensity of the pulse of the pulse sensed by the photosensor included in the light sensing unit 210 and the frequency and intensity of the repetition rate RF signal . Therefore, the light sensing unit 210 can sense whether the incident pulse is a mode lock pulse or a noise pulse. The detailed structure of the light sensing unit 210 and the pulse sensing method will be described in detail below with reference to FIGS. 4A to 9E.

Next, the control signal generator 240 generates a control signal for controlling the polarization controller 140 according to the type of the pulse sensed by the light sensing unit 210, and transmits the control signal through the application program unit 250 And transmits the control signal to the polarization controller 140.

Accordingly, when the application program 250 detects that the selected pulse is generated, the control signal generator 240 generates and transmits a control signal for stopping the polarization controller 140. If it is not confirmed that the selected pulse is generated, the polarization control unit 140 is driven again through the application program unit 250 to resume polarization control in the resonator 100.

3A to 3C are graphs showing spectral energy densities of the respective wavelengths according to the types of light. FIG. 3A shows the spectral energy density of each wavelength of the continuous wave, FIG. 3B shows the spectral energy density of Q-switching by wavelength, FIG. 3C shows the spectral energy density of the mode lock pulse and the noise pulse, .

The spectrum before the mode lock pulse is generated is either a continuous wave or a Q-switched state and has a wavelength bandwidth within a few nanometers of the gain medium.

Referring to FIG. 3C, a mode locking pulse forms a spectrum having a wavelength bandwidth of several to several tens of nanometers centered on a center wavelength, and a noise pulse has a spectrum having a wavelength bandwidth of several tens to several hundreds of nanometers or more .

4A and 4B are schematic diagrams for explaining a configuration and a sensing method of the optical sensing unit in the apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to an embodiment of the present invention. FIG. 4B is a schematic diagram showing the division of pulses according to the area of the optical sensor to which the dispersion optical system emission light is incident. FIG.

4A, the light sensing unit 210 includes a dispersion optical system 212 for spatially dispersing incident light and an optical sensor 214 for sensing the degree of dispersion of a spectrum dispersed therefrom do.

The dispersion optics 212 spatially disperses the output beam of the resonator 100 (see FIG. 1), at which time the dispersed spectra diverge at different angles for each frequency. That is, when the continuous wave or the Q-switching is transmitted or reflected, the degree of spreading is the smallest in the case (c), the degree of spreading is the largest when the noise pulse is transmitted or reflected, (D), the degree of spreading becomes intermediate.

4B, the optical sensor 214 includes a first region A in which the center of the dispersed light is incident from the dispersion optical system 212, a second region A formed in a predetermined area outside the first region A, (B) which is set on the outer side of the second region (B), and a third region (C) which is set on the outer side of the second region (B). The optical sensor 214 may detect the light scattered from the dispersion optical system 212 for each of the regions by using the optical sensor for each region. That is, the light in which the continuous wave and the Q-switching are dispersed is contained in the first area A of the optical sensor 214, and the light in which the mode lock pulse is dispersed is emitted from the first area A of the optical sensor 214 And the noise pulses are dispersed in the second area B so that the light is dispersed from the first area A and the second area B of the photosensor 214 to the third area C Can be set in advance.

The optical sensor 214 thus configured outputs an electrical signal corresponding to the mode lock pulse when the light is detected over the first area A and the second area B, When the light is detected over the region C, an electrical signal corresponding to a noise pulse may be output.

The dispersion optics 212 may include, for example, a grating or a prism that spreads the light into space by frequency.

In this embodiment, the optical sensor 212 may include a plurality of optical sensors. The plurality of photo-sensors may be arranged in a linear or planar manner so that the optical signal can be converted into an electrical signal only in a portion corresponding to the length or area where the light is spatially sensed.

5A and 5B are schematic diagrams for explaining the configuration and sensing method of the optical sensing unit in the apparatus for generating a selective pulse for a mode locking pulse and a noise pulse according to another embodiment of the present invention. FIG. 5B is a table showing distinctions of pulses according to detection conditions of a photodiode to which the dispersion optical system emission light is incident. FIG.

Referring to FIG. 5A, the optical sensor of the light sensing unit 211 according to the present embodiment includes a photodiode 217. The photodiode 217 may be located outside the first region A in a common region between the second region B and the third region C. [

Referring to FIG. 5B, when the light is detected by the photodiode 217, the incident light is a mode lock pulse or a noise pulse. If the light is not detected by the photodiode 217, the incident light may be judged to be continuous wave or Q-switching.

6A and 6B are schematic diagrams illustrating an optical sensing unit in an apparatus for generating a selective pulse for a mode lock pulse and a noise pulse according to another embodiment of the present invention. FIG. 6A shows a light sensing unit based on a bulk optical system, and FIG. 6B shows a light sensing unit based on an optical fiber.

Referring to FIG. 6A, the light sensing portion 212 according to the present embodiment includes an optical filter 223 and a photodiode 227, based on a bulk optical system.

6A, the optical filter 223 receives light output from the resonator 100 (see FIG. 1), and the photodiode 227 transmits the optical filter 223 or detects the reflected light .

Referring to FIG. 6B, the optical sensing unit 213 according to the present embodiment may include an optical filter 233 and a photodiode 237, based on an optical fiber optical system.

As shown in FIG. 6B, the optical filter 233 receives light output from the resonator 100, and the photodiode 237 can transmit the optical filter 233 or sense the reflected light.

On the other hand, the optical filters 223 and 233 can block the continuous wave and the Q-switching spectral region and transmit the mode locking pulse spectral region. Each of the optical filters 223 and 233 may be, for example, a bulk filter or a fiber-based filter or a fiber Bragg grating (FBG).

FIGS. 7A to 7C are schematic diagrams showing a configuration of an interferometer unit in a mode pulse generating apparatus and a noise pulse generating apparatus according to an embodiment of the present invention. FIG. 7A shows a bulk optical system based interferometer unit, 7c shows an optical fiber based interferometer unit, and FIG. 7d is a table showing distinction of pulses according to detection conditions of a photodiode and an interferometer unit of the light sensing unit.

7A, the bulk optical system based interferometer unit 270 includes a light splitter 271, a first mirror 273, a second mirror 276, and a photodiode 278, and the first mirror 273 And an actuator 274 connected to the actuator 274 and driving the same. That is, the length of the optical path spaced from the light splitter 271 by the actuator 274 can be varied in the first mirror 273.

The light splitter 271 divides the light output from the resonator 100 (see FIG. 1) into at least two divided lights of the first divided light and the second divided light, and the first mirror 273 separates the light output from the light splitter 271 And the second mirror 276 reflects the pulse repetition rate length (resonator length) from the optical splitter 271. The first optical splitter 271 is formed by a first optical splitter 271, The length of the second optical path corresponding to a multiple of twice the length of the second optical path, and the second divided light can be reflected. The photodiode 278 can detect whether an interference signal is generated by receiving the first split light reflected from the first mirror 273 and the second split light reflected from the second mirror 276. [ The sensing signal of the photodiode 278 passes through a low pass filter (LPF) having a frequency band that is less than the resonator repetition rate frequency.

7B, the optical fiber based interferometer unit 270 'includes a first optical coupler 270 for dividing the light output from the resonator 100 and forming a first optical path L1 and a second optical path L2 271 'and a second optical coupler 275', and includes an optical path difference delay (OPD delay) 273 'on the second optical path L2. A photodiode 278 'is connected to the second optical coupler 275'.

The light output from the resonator 100 is split into a first split light passing through the first optical path L1 and a second split light passing through the second optical path L2, A path delay is generated as it passes through the path 273 '. An interference signal may be generated while the first split light and the second split light coupled again in the second optical coupler 275 'are incident on the photodiode 278'.

Referring to FIG. 7C, the optical fiber based interferometer unit 270 'of another example includes an optical coupler 270' for dividing the light output from the resonator 100 to form the first optical path L1 and the second optical path L2 271 "is connected to the first optical path L1 and an optical path delay 273" is connected to the first optical path L1 and a mirror 276 "is connected to the second optical path L2. A photodiode 278 "is also coupled to the optocoupler 271 ".

The light output from the resonator 100 is divided into a first divided light passing through the first optical path L1 and a second divided light passing through the second optical path L2, The path delay is generated while passing through the mirror 273 ", and the second split light is reflected by the mirror 276 ". The first split light and the second split light combined again in the optical coupler 271 " may be incident on the photodiode 278 "to generate an interference signal.

When the light output from the resonator 100 is a mode locking pulse, an interference signal is detected by the photodiodes 278, 278 ', and 278'. When the light output from the resonator 100 is a noise pulse, 278, 278 ', and 278'. That is, the generation of the mode lock pulse and the noise pulse can be distinguished according to the detection of the interference signal in the photodiodes 278, 278 ', and 278'.

Therefore, in the pulse generating apparatus according to the present embodiment, the generation of the mode lock pulse or the noise pulse can be classified and controlled by combining the signal detected by the photodiode of the photo sensing unit and the interference signal detected by the interferometer.

7D, when the light is detected by the photodiode 217 and the interferometer 270 simultaneously, the incident light is a mode lock pulse. If the light is detected by the photodiode 217 but not detected by the interferometer 270, If the light is a noise pulse and is not detected by both the photodiode 217 and the interferometer unit 270, the incident light may be judged to be continuous wave or Q-switching.

Meanwhile, in the pulse generating apparatus according to the present embodiment, the light sensing unit may include a plurality of photodiodes along the region.

8A and 8B are schematic diagrams for explaining the configuration and sensing method of the optical sensing unit in the apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention. FIG. 8B is a table showing distinctions of pulses according to detection conditions of the photodiodes to which the dispersion optical system emission light is incident. FIG.

Referring to FIG. 8A, the optical sensor of the light sensing unit 210 'according to the present embodiment includes a plurality of photodiodes 217 and 218. A plurality of photodiodes 217 and 218 are formed on the first photodiode 217 located outside the first region A and the third photodiode 217 located outside the second region B, And a second photodiode 218 located in the second photodiode.

Referring to FIG. 8B, when the first photodiode 217 and the second photodiode 218 are simultaneously detected, the incident light is a noise pulse, which is detected by the first photodiode 217 but is detected by the second photodiode 218, The incident light is a mode lock pulse. If the first and second photodiodes 217 and 218 are not detected, the incident light may be determined to be continuous wave or Q-switching.

9A to 9E are schematic diagrams illustrating an optical sensing unit in an apparatus for generating a selective pulse for a mode lock pulse and a noise pulse according to another embodiment of the present invention. FIGS. 9A and 9B show a light sensing unit based on a bulk optical system, FIGS. 9C and 9D show an optical fiber based optical sensing unit, and FIG. 9E is a table showing whether or not a photodiode signal is detected according to a pulse state.

9A and 9B, the light sensing units 220 and 220 'according to the present embodiment include a light splitter 221, a first optical filter 223, a second optical filter 224 ), A first photodiode (227), and a second photodiode (228).

9A, the optical splitter 221 divides the light output from the resonator 100 (see FIG. 1) into at least two split lights, and the first optical filter 223 divides the light output from the optical splitter 221 And the second optical filter 224 causes the second split light output from the optical splitter 221 to enter. The first photodiode 227 can either pass the first optical filter 223 or sense the reflected light and the second photodiode 228 can either pass the second optical filter 224 or sense the reflected light have.

9B, in the optical sensing unit 220 'according to the modification of the present embodiment, the first optical filter 223 may be positioned to cause the light output from the resonator 100 to be incident, The second optical filter 224 may divide the reflected light into the first split light and the second split light and the second optical filter 224 may divide the reflected light into the first split light and the second split light, And can be positioned so as to make the two-split light incident thereon. The first photodiode 227 senses the second split light output from the optical splitter 221 and the second photodiode 228 can either pass the second optical filter 224 or sense the reflected light .

9C and 9D, the optical sensing units 230 and 230 'according to the present embodiment include an optical coupler 231, a first optical filter 233, a second optical filter 234 ), A first photodiode 237, and a second photodiode 238.

9C, the optical coupler 231 divides the light output from the resonator 100 into at least two divided lights, and the first optical filter 233 divides the light output from the resonator 100 into the first And the second optical filter 234 causes the second split light output from the optical coupler 231 to enter. The first photodiode 237 can either pass the first optical filter 233 or sense the reflected light and the second photodiode 238 can either pass the second optical filter 234 or sense the reflected light have.

9D, in the optical sensing unit 230 'according to the modification of the present embodiment, the first optical filter 233 may be positioned so as to cause the light output from the resonator 100 to be incident, The second optical filter 234 may divide the reflected light into the first split light and the second split light and the second optical filter 234 may divide the reflected light into the first split light and the second split light, And can be positioned so as to make the two-split light incident thereon. The first photodiode 237 senses the second split light output from the optocoupler 231 and the second photodiode 238 can either pass the second optical filter 234 or sense the reflected light .

On the other hand, the first optical filters 223 and 233 block the continuous wave and the Q-switching spectral region as shown in Fig. 10A, and the second optical filters 224 and 234, The lock pulse spectrum area can be blocked. Each of the optical filters 223, 224, 233, and 234 may be, for example, a bulk filter or a fiber-based filter or fiber Bragg grating (FBG).

Referring to FIG. 9E, when the first photodiodes 227 and 237 and the second photodiodes 228 and 238 are simultaneously detected, the incident light is a noise pulse, and the first photodiodes 227 and 237 detect 237 and the second photodiodes 228, 238 are not detected, the incident light is a mode locking pulse, and if the first photodiodes 227, 237 and the second photodiodes 228, 238 are not both detected, Or Q-switching.

11 is a schematic diagram showing a state in which an 8-shaped optical fiber resonator is applied to an apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention.

11, the 8-shaped optical fiber resonator 30 includes a gain medium 330 connected to the laser diode 320 and a first polarization controller 340 forming a first loop, The first and second loops 360 and 350 form a second loop, and the first loop and the second loop are connected through an optical coupler 345. [ An isolator is disposed between the second polarization controller 360 and the pulse shaping unit 350 and an optical coupler 365 is connected to the rear end of the second polarization controller 350 to form an 8- And may be connected to the input of the signal sense controller 200 (see Figure 1).

The signal detection controller 200 can detect the mode lock pulse or the noise pulse by receiving the light output from the 8-shaped optical fiber resonator 30, and the signal detection controller 200 includes the 8- The polarization control units 340 and 360 may control the polarization control units 340 and 360 by transmitting control signals according to the detected pulse signals.

12 is a schematic diagram showing a state in which a nine-character optical fiber resonator is applied to an apparatus for generating a selective pulse of a mode locking pulse and a noise pulse according to another embodiment of the present invention.

12, a nine-figure optical fiber resonator 50 includes a gain medium 530 connected to a laser diode 520 and a first polarization controller 540 forming a loop, and an optical coupler The pulse shaping unit 550 and the mirror 570 are sequentially connected through the first polarization control unit 560, the second polarization control unit 560, The optical coupler 545 can output the light generated by the nine-fiber optical resonator 50 and can be connected to the input of the signal detection controller 200 (see FIG. 1).

The signal detection controller 200 can detect the mode lock pulse or the noise pulse by receiving the light output from the nine-figure-shaped optical fiber resonator 50. The signal detection controller 200 includes a nine-shaped optical fiber resonator 50 540 and 560 of the polarization control unit 540 and 560, and transmit the control signal according to the detected pulse signal to control the polarization control units 540 and 560.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

10, 30, 50: selective pulse generating apparatus 100, 300, 500: resonator
200, 400, 600: signal detection control unit 120: laser diode
130: gain medium 135: isolator
140: polarization controller 150: pulse shaping unit
210: light sensing unit 240: control signal generating unit
250: Application program

Claims

A laser diode for outputting light; and a polarization controller for adjusting a polarization of the pulse to generate a mode lock pulse or a noise pulse; And
And a light source that is optically connected to an output terminal of the resonator and is electrically connected to the polarization controller to sense and disperse the light output from the resonator and to divide and interfere with light output from the resonator to detect whether an interference signal is generated, A signal detection controller for transmitting a control signal to stop the operation of the polarization controller when it is confirmed that the mode lock pulse or the noise pulse is generated,
Lt; / RTI >
The signal-
A light sensing unit for sensing a pulse output from the resonator; And
And an interferometer unit for detecting whether an interference signal is generated according to the type of the pulse output from the resonator,
Wherein the mode lock pulse or the noise pulse is generated by combining the signal detected by the optical sensing unit and the interference signal detected by the interferometer unit.

The method according to claim 1,
The signal-
A control signal generator connected to the light sensing unit and generating a signal for controlling the polarization controller according to the pulse sensed by the light sensing unit; And
An application program unit connected to the control signal generator and the interferometer unit and connected to the polarization controller to transmit the control signal generated by the control signal generator and the signal detected by the interferometer unit to the polarization controller,
Further comprising: means for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The interferometer unit,
A light splitter for splitting the light output from the resonator into a first split light and a second split light;
A first mirror that is spaced apart from the optical splitter by a length of a first optical path corresponding to a pulse repetition rate length and reflects the first split light;
A second mirror spaced apart from the optical splitter by a length of a second optical path corresponding to a multiple of twice the pulse repetition rate length and reflecting the second split light; And
A second mirror for reflecting the first split light reflected from the first mirror and the second split light reflected from the second mirror to detect whether an interference signal is generated,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The interferometer unit,
An optical coupler for dividing the light output from the resonator to form a first optical path and a second optical path;
An optical path difference retarder formed on the second optical path to generate a path delay;
A second optical coupler coupling the first optical path and the second optical path; And
A photodiode connected to the second optical coupler for receiving a first split beam passing through the first optical path and a second split beam passing through the second optical path to detect whether an interference signal is generated,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The interferometer unit,
An optical coupler for dividing the light output from the resonator to form a first optical path and a second optical path;
An optical path difference delayer connected to the first optical path to generate a path delay;
A mirror coupled to the second optical path and reflecting the incident light; And
A photodiode connected to the optical coupler for detecting whether an interference signal is generated by receiving a first split beam passing through the first optical path and a second split beam passing through the second optical path,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The photo-
A dispersion optical system for spatially dispersing light output from the resonator by frequency; And
A first region where a center of scattered light from the dispersion optical system is incident, and a second region that is formed in a predetermined area on an outer periphery of the first region, wherein a photo-sensing sensor is positioned for each of the regions, And a light sensor
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 6,
The optical sensor includes:
And outputs an electric signal corresponding to a mode lock pulse or a noise pulse when the light is detected over the first area and the second area.

The method according to claim 6,
The optical sensor includes:
And a first photodiode located in the second region outside of the first region.

9. The method of claim 8,
The optical sensor includes:
Further comprising a second photodiode located outside of the second region. &Lt; Desc / Clms Page number 13 >

The method according to claim 1,
The photo-
A first optical filter that receives light output from the resonator and blocks a continuous wave and a Q-switching spectral region; And
A first photodiode that transmits the first optical filter or senses reflected light,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The photo-
A light splitter for splitting the light output from the resonator into at least two divided lights;
A first optical filter that receives the first split light output from the optical splitter and blocks the continuous wave and the Q-switched spectral range;
A second optical filter that receives the second split light output from the optical splitter and blocks the mode locking pulse spectrum region;
A first photodiode that transmits the first optical filter or detects the reflected light; And
A second photodiode that transmits the second optical filter or detects the reflected light,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The photo-
A first optical filter that receives light output from the resonator and blocks a continuous wave and a Q-switching spectral region;
A light splitter for splitting the light transmitted through or reflected by the first optical filter into a first split light and a second split light;
A first photodiode sensing a second split light output from the optical splitter;
A second optical filter that receives the second split light output from the optical splitter and blocks the mode locking pulse spectrum region;
A second photodiode that transmits the second optical filter or detects the reflected light,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

delete

The method according to claim 1,
The photo-
An optical coupler for dividing the light output from the resonator into at least two divided lights;
A first optical filter that receives the first split light output from the optical coupler and blocks the continuous wave and the Q-switching spectral range;
A second optical filter that receives the second split light output from the optical coupler and blocks the mode locking pulse spectrum region;
A first photodiode that transmits the first optical filter or detects the reflected light; And
A second photodiode that transmits the second optical filter or detects the reflected light,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

The method according to claim 1,
The photo-
A first optical filter that receives light output from the resonator and blocks a continuous wave and a Q-switching spectral region;
An optical coupler for splitting the light that has passed through the first optical filter or reflected by the first split light and the second split light;
A first photodiode sensing a second split light output from the optical coupler;
A second optical filter that receives the second split light output from the optical coupler and blocks the mode locking pulse spectrum region;
A second photodiode that transmits the second optical filter or detects the reflected light,
And a mode lock pulse generator for generating a mode lock pulse and a noise pulse.

delete

The method according to claim 1,
Wherein the resonator is a ring-shaped optical fiber resonator,
Wherein the ring-shaped optical fiber resonator comprises a gain medium connected to the laser diode and a pulse shaping unit connected to the polarization control unit to form a loop, wherein the mode lock pulse and the noise pulse are generated in the form of a loop.

A laser diode for outputting light; and a polarization controller for adjusting a polarization of the pulse to generate a mode lock pulse or a noise pulse; And
And a light source that is optically connected to an output terminal of the resonator and is electrically connected to the polarization controller to sense and disperse the light output from the resonator and to divide and interfere with light output from the resonator to detect whether an interference signal is generated, A signal detection controller for transmitting a control signal to stop the operation of the polarization controller when it is confirmed that the mode lock pulse or the noise pulse is generated,
/ RTI >
Wherein the resonator is an 8-shaped optical fiber resonator,
Wherein the polarization controller includes a first polarization controller and a second polarization controller,
Wherein the 8-shaped optical fiber resonator forms a gain medium connected to the laser diode and the first polarization control unit form a first loop, the second polarization control unit and the pulse shaping unit form a second loop,
Wherein the first loop and the second loop are coupled through an optical coupler.

A laser diode for outputting light; and a polarization controller for adjusting a polarization of the pulse to generate a mode lock pulse or a noise pulse; And
And a light source that is optically connected to an output terminal of the resonator and is electrically connected to the polarization controller to sense and disperse the light output from the resonator and to divide and interfere with light output from the resonator to detect whether an interference signal is generated, A signal detection controller for transmitting a control signal to stop the operation of the polarization controller when it is confirmed that the mode lock pulse or the noise pulse is generated,
/ RTI >
Wherein the resonator is a nine-figure-shaped optical fiber resonator,
Wherein the polarization controller includes a first polarization controller and a second polarization controller,
The 9-shaped optical fiber resonator includes a gain medium connected to the laser diode and the first polarization control unit forming a loop, and the second polarization control unit, the pulse shaping unit, and the mirror are sequentially A mode lock pulse and a noise pulse.