JP5028240B2 - Output light pulse width control device, method, program, and recording medium - Google Patents

Description

  The present invention relates to optical pulse compression using an optical fiber.

  Conventionally, it is known to compress an optical pulse (see, for example, the summary of Patent Document 1). Moreover, it is possible to compress an optical pulse using an optical fiber.

  In addition, when using the compressed optical pulse for measurement (for example, when using for optical sampling), it is preferable to make the pulse width of the compressed optical pulse constant.

Japanese Patent Laid-Open No. 11-298076

  Accordingly, an object of the present invention is to make the pulse width of an optical pulse compressed using an optical fiber constant.

  An output optical pulse width control device according to the present invention includes a compressed optical fiber that outputs an output optical pulse obtained by compressing a pulse width of an input optical pulse, a first optical pulse and a second optical branch that are branched from the output optical pulse. An optical pulse branching unit that outputs an optical pulse; a first power measuring unit that measures the power of the first branched optical pulse; a filter that receives the second branched optical pulse and passes a wavelength component in a passband; A power ratio that is a ratio of the second power measurement unit that measures the power of the optical pulse that has passed through the filter, the measurement result of the first power measurement unit, and the measurement result of the second power measurement unit, A power control unit that controls the power of the input light pulse so as to match the value, and when the output light pulse has a desired pulse width, a part of the passband, and the second branched light Pulse signal And a portion overlaps the minute wavelength region, the target value, when the output light pulse is the desired pulse width, configured to be the power ratio.

  According to the output light pulse width control device configured as described above, the compressed optical fiber outputs an output light pulse in which the pulse width of the input light pulse is compressed. The optical pulse branching unit branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse. The first power measurement unit measures the power of the first branched light pulse. The filter receives the second branched light pulse and passes the wavelength component in the passband. The second power measurement unit measures the power of the optical pulse that has passed through the filter. The power control unit controls the power of the input optical pulse so that a power ratio, which is a ratio between the measurement result of the first power measurement unit and the measurement result of the second power measurement unit, matches a target value. . Furthermore, when the output light pulse has a desired pulse width, a part of the passband and a part of the wavelength region of the signal component of the second branch light pulse overlap. Moreover, the target value is the power ratio when the output light pulse has the desired pulse width.

  In the output light pulse width control device according to the present invention, the filter may be a short pass filter, and a wavelength in the pass band may be equal to or less than a cutoff wavelength of the filter.

  In the output light pulse width control device according to the present invention, the filter may be a long pass filter, and a wavelength in the pass band may be equal to or greater than a cutoff wavelength of the filter.

  The output optical pulse width control device according to the present invention includes an optical fiber amplifier that outputs the input optical pulse, and the power control unit controls the amplification degree of the optical fiber amplifier according to the power ratio. You may make it have an amplification degree control part.

  In the output optical pulse width control device according to the present invention, the optical pulse branching unit branches the output optical pulse to acquire a partial output optical pulse, and the partial output optical pulse. And a branched light pulse output unit for outputting the first branched light pulse and the second branched light pulse.

  In the output light pulse width control device according to the present invention, the power control unit increases the power of the input light pulse when the power ratio is increased, and the input power when the power ratio is decreased. The power of the light pulse may be reduced.

  The present invention relates to a compressed optical fiber that outputs an output optical pulse in which the pulse width of an input optical pulse is compressed, and an optical pulse branch that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse A first power measuring unit for measuring the power of the first branched optical pulse, a filter for receiving the second branched optical pulse and passing a wavelength component in a pass band, and an optical pulse passing through the filter An output optical pulse width control method for controlling a pulse width of the output optical pulse in an output optical pulse width control device comprising a second power measuring unit for measuring the power of the first optical power measurement unit A power control step of controlling the power of the input optical pulse so that the power ratio, which is the ratio of the result and the measurement result of the second power measurement unit, matches the target value, When the pulse width is desired, a part of the passband and a part of the wavelength region of the signal component of the second branched light pulse overlap, and the target value is the desired value of the output light pulse. This is an output light pulse width control method that is the power ratio when the pulse width is the same.

  The present invention relates to a compressed optical fiber that outputs an output optical pulse in which the pulse width of an input optical pulse is compressed, and an optical pulse branch that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse A first power measuring unit for measuring the power of the first branched optical pulse, a filter for receiving the second branched optical pulse and passing a wavelength component in a pass band, and an optical pulse passing through the filter A program for causing a computer to execute an output light pulse width control process for controlling the pulse width of the output light pulse in an output light pulse width control device comprising a second power measuring unit for measuring the power of The output light pulse width control process is performed so that a power ratio, which is a ratio between a measurement result of the first power measurement unit and a measurement result of the second power measurement unit, matches a target value. A power control step for controlling the power of the input optical pulse, wherein when the output optical pulse has a desired pulse width, a part of the passband and a wavelength region of the signal component of the second branched optical pulse The target value is a program that is the power ratio when the output light pulse has the desired pulse width.

  The present invention relates to a compressed optical fiber that outputs an output optical pulse in which the pulse width of an input optical pulse is compressed, and an optical pulse branch that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse A first power measuring unit for measuring the power of the first branched optical pulse, a filter for receiving the second branched optical pulse and passing a wavelength component in a pass band, and an optical pulse passing through the filter And a second power measurement unit for measuring the power of the output optical pulse width control device comprising: a computer recorded with a program for causing the computer to execute an output optical pulse width control process for controlling the pulse width of the output optical pulse The output light pulse width control process includes a measurement result of the first power measurement unit and a measurement result of the second power measurement unit. A power control step for controlling the power of the input optical pulse so that the power ratio, which is a ratio of the output light pulse, is adjusted to a target value, and when the output optical pulse has a desired pulse width, And a part of the wavelength region of the signal component of the second branched light pulse overlap, and the target value is a recording of the power ratio when the output light pulse has the desired pulse width. It is a medium.

  Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a functional block diagram showing a configuration of an output light pulse width control device 1 according to a first embodiment of the present invention. The output optical pulse width control device 1 according to the first embodiment includes an optical fiber amplifier 10, a compressed optical fiber 12, a partial output optical pulse acquisition unit 14a, a branched optical pulse output unit 14b, a filter 15, photodiodes 16a and 16b, A / D converters 18a and 18b and a power control unit 20 are provided.

  The optical fiber amplifier 10 amplifies the optical pulse P1 and outputs an input optical pulse P2 input to the compressed optical fiber 12. The optical fiber amplifier 10 is, for example, an EDFA (Erbium-doped Fiber Amplifier). By giving a control signal to the optical fiber amplifier 10, the amplification degree (power of the input optical pulse P2 / power of the optical pulse P1) of the optical fiber amplifier 10 can be controlled.

  The compressed optical fiber 12 receives the input light pulse P2 and outputs an output light pulse P3. The output light pulse P3 is a light pulse obtained by compressing the pulse width of the input light pulse P2. The compressed optical fiber 12 is composed of, for example, a highly nonlinear fiber and a single mode fiber (SMF). In this case, linear compression is performed by the compressed optical fiber 12. The compressed optical fiber 12 is, for example, a dispersion reducing fiber. In this case, soliton compression is performed by the compressed optical fiber 12.

  The partial output optical pulse acquisition unit 14a and the branched optical pulse output unit 14b constitute an optical pulse branching unit. The optical pulse branching unit branches the output light pulse P3 and outputs the first branched light pulse P6 and the second branched light pulse P7.

  The partial output light pulse acquisition unit 14a branches the output light pulse P3 to acquire the measuring instrument light pulse P4 and the partial output light pulse P5. The power of the measuring instrument light pulse P4 is set to be about 9 times the power of the partial output light pulse P5.

  The measuring instrument light pulse P4 is applied to the measuring instrument. The measuring instrument performs optical sampling using, for example, a measuring instrument optical pulse P4. In order to use for optical sampling, the pulse width of the measuring instrument optical pulse P4 needs to be kept constant. This is because the pulse width of the measuring instrument optical pulse P4 is equivalent to the sampler frequency band. Since the pulse widths of the output light pulse P3 and the measuring instrument light pulse P4 are the same, the pulse width of the output light pulse P3 may be kept at a desired constant value. Since the pulse widths of the output light pulse P3 and the partial output light pulse P5 are the same, the pulse width of the partial output light pulse P5 may be maintained at a desired constant value.

  The branched light pulse output unit 14b branches the partial output light pulse P5 and outputs a first branched light pulse P6 and a second branched light pulse P7. It is assumed that the power of the first branched light pulse P6 is equal to the power of the second branched light pulse P7.

  Since the pulse widths of the first branch light pulse P6, the second branch light pulse P7, and the partial output light pulse P5 are the same, in order to keep the pulse width of the partial output light pulse P5 at a desired constant value, the first branch light pulse The pulse widths of P6 and the second branched light pulse P7 may be maintained at a desired constant value.

  In general, there is a correspondence between the pulse width of an optical pulse and the spectrum width of the signal component of the optical pulse. Therefore, in order to keep the pulse widths of the first branched light pulse P6 and the second branched light pulse P7 at a desired constant value, the spectrum widths of the signal components of the first branched light pulse P6 and the second branched light pulse P7 are set. Just keep it constant. The width of the spectrum is, for example, a half width.

  That is, in order to keep the pulse widths of the output light pulse P3 and the measuring instrument light pulse P4 constant, the spectrum widths of the signal components of the first branch light pulse P6 and the second branch light pulse P7 may be kept constant. .

  FIG. 2 shows the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the first embodiment (FIG. 2A), and the transmission of the filter 15 according to the first embodiment. The characteristics (FIG. 2B), the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the first embodiment, and the transmission characteristics of the filter 15 are superimposed (FIG. 2). 2 (c)).

  FIG. 2A is a diagram showing the relationship between the wavelength and power of the first branched light pulse P6 (second branched light pulse P7) when the pulse width of the output light pulse P3 is a desired constant value. . The first branched light pulse P6 (second branched light pulse P7) has a signal component and a noise component. The power spectrum of the first branched light pulse P6 (second branched light pulse P7) has a wavelength region S (corresponding to the signal component) of the signal component and a noise portion N (corresponding to the noise component). The wavelength region S of the signal component is a region where the signal component of the power spectrum exists. It can be said that the width of the spectrum of the signal component of the first branched light pulse P6 and the second branched light pulse P7 is the width of the wavelength region S of the signal component.

  The filter 15 receives the second branched light pulse P7 and passes the wavelength component in the passband. In the first embodiment, the filter 15 is a short pass filter.

  Referring to FIG. 2B, the filter 15 transmits light having a short wavelength with a transmittance of approximately 100% (gain 0 dB), but the transmittance decreases as the wavelength of the light increases. Here, the cutoff wavelength of the filter 15 (the wavelength at which the gain is −3 dB) is λc. Furthermore, the filter 15 transmits light having a wavelength shorter than the cutoff wavelength better than light having a wavelength longer than the cutoff wavelength. Here, a region having a wavelength equal to or shorter than the cutoff wavelength is referred to as a pass region, and a region having a wavelength exceeding the cutoff wavelength is referred to as an attenuation region. That is, the filter 15 transmits the light in the pass band better than the light in the attenuation band. The cutoff wavelength λc can be changed.

  Referring to FIG. 2C, when the pulse width of output light pulse P3 (measuring device light pulse P4) is a desired constant value (that is, signals of first branch light pulse P6 and second branch light pulse P7). When the width of the component spectrum takes a certain value), a part of the passband (≦ λc) and a part of the wavelength region S of the signal component of the second branched light pulse overlap. A region where the passband and the wavelength region S of the signal component overlap is referred to as an overlapping region H.

  However, in FIG. 2C, for convenience of illustration, 0 [dB] in the transmission characteristic of the filter 15 is arranged at a position slightly higher than the height of the wavelength region S of the signal component (FIG. 3, FIG. 4 and FIG. 5). Further, in FIG. 2C, for convenience of illustration, the transmission characteristics of the filter 15 are illustrated by a broken line that is bent at the cutoff wavelength λc (the same applies to FIG. 3).

  The photodiode 16a receives the first branched light pulse P6 and outputs an analog electric signal indicating a voltage corresponding to the power of the first branched light pulse P6. The A / D converter 18a converts the analog electric signal output from the photodiode 16a into a digital signal. The value of this digital signal (a value that digitally represents a voltage value corresponding to the power of the first branch light pulse P6) is Va. The photodiode 16a and the A / D converter 18a correspond to a first power measuring unit (measuring the power of the first branched light pulse P6).

  The photodiode 16 b receives the light pulse that has passed through the filter 15, and outputs an analog electrical signal indicating a voltage corresponding to the power of the light pulse that has passed through the filter 15. The A / D converter 18b converts the analog electric signal output from the photodiode 16b into a digital signal. The value of this digital signal (the value that digitally represents the value of the voltage corresponding to the power of the optical pulse that has passed through the filter 15) is defined as Vb. The photodiode 16b and the A / D converter 18b correspond to a second power measuring unit (measuring the power of the light pulse that has passed through the filter 15).

  The power control unit 20 includes a measurement result Va of the first power measurement unit (the photodiode 16a and the A / D converter 18a) and a measurement result Vb of the second power measurement unit (the photodiode 16b and the A / D converter 18b). The power of the input optical pulse P2 is controlled so that the power ratio Vb / Va, which is the ratio, matches the target value.

  However, the target value is the power ratio Vb / Va when the output light pulse P3 (measurement device light pulse P4) has a desired pulse width.

  The power control unit 20 includes a power ratio deriving unit 22, a target value recording unit 24, and an amplification degree control unit 26.

  The power ratio deriving unit 22 derives the power ratio Vb / Va. The target value recording unit 24 records the target value.

  The amplification degree control unit 26 controls the amplification degree of the optical fiber amplifier 10 according to the power ratio by giving a control signal to the optical fiber amplifier 10. Specifically, the amplification degree control unit 26 receives the power ratio Vb / Va from the power ratio deriving unit 22. The amplification degree control unit 26 receives the target value from the target value recording unit 24. Here, when the power ratio Vb / Va is smaller (larger) than the target value, the amplification factor of the optical fiber amplifier 10 is increased (decreased), and the power of the input optical pulse P2 is increased (decreased). Increase (decrease) Vb / Va.

  Here, if the output light pulse P3 (measurement device light pulse P4) has a desired pulse width, the spectrum width of the signal components of the first branch light pulse P6 and the second branch light pulse P7 takes a certain value ( (See FIG. 2 (a)). However, when the output light pulse P3 (measurement device light pulse P4) does not have a desired pulse width, the spectrum width of the signal components of the first branch light pulse P6 and the second branch light pulse P7 is too narrow (FIG. 3 ( a)) or too wide (see FIG. 3B).

  FIG. 3 is a diagram showing the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 and the transmission characteristics of the filter 15 according to the first embodiment. It is a figure which shows the case where the width | variety of the spectrum of the signal component of the one branch light pulse P6 and the 2nd branch light pulse P7 is too narrow (refer Fig.3 (a)), and when it is too wide (refer FIG.3 (b)).

  Referring to FIG. 3A, when the spectrum widths of the signal components of the first branched light pulse P6 and the second branched light pulse P7 are too narrow, the overlapping region H (see FIG. 2C) disappears. (Or smaller). In this case, the light passing through the filter 15 is almost only a noise component. Therefore, Vb decreases and the power ratio Vb / Va also decreases.

  Referring to FIG. 3B, when the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7 is too wide, the overlapping region H (see FIG. 2C) becomes large. . In this case, the power of the light passing through the filter 15 is larger than that in the case of FIG. Therefore, Vb increases and the power ratio Vb / Va also increases.

  When the power ratio Vb / Va is smaller than the target value, the amplification degree control unit 26 widens the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7, and increases the power ratio Vb. Increase / Va. In order to widen the spectrum width of the signal component of the first branch light pulse P6 and the second branch light pulse P7 (that is, to widen the spectrum width of the signal component of the output light pulse P3), Just increase the power. When the power of the input light pulse P2 is increased, the spectrum width of the signal component of the output light pulse P3 is widened due to the self-phase modulation effect. Therefore, the amplification degree control unit 26 performs control so as to increase the amplification degree of the optical fiber amplifier 10.

  When the power ratio Vb / Va is larger than the target value, the amplification degree control unit 26 narrows the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7, and the power ratio Vb Reduce / Va. In order to narrow the spectrum width of the signal component of the first branch light pulse P6 and the second branch light pulse P7 (that is, to narrow the spectrum width of the signal component of the output light pulse P3), You only need to reduce the power. Therefore, the amplification degree control unit 26 performs control so that the amplification degree of the optical fiber amplifier 10 is reduced.

  Next, the operation of the first embodiment will be described.

  The optical pulse P1 is amplified by the optical fiber amplifier 10 and becomes an input optical pulse P2. The input optical pulse P2 has a pulse width compressed by the compressed optical fiber 12, and becomes an output optical pulse P3. The output light pulse P3 is branched by the partial output light pulse acquisition unit 14a into a measuring instrument light pulse P4 (given to the measuring instrument) and a partial output light pulse P5. The partial output light pulse P5 is branched by the branch light pulse output unit 14b into a first branch light pulse P6 and a second branch light pulse P7.

  The first branched light pulse P6 is converted into an analog electric signal (indicating a voltage corresponding to the power of the first branched light pulse P6) by the photodiode 16a, and digitized by the A / D converter 18a (value is Va). ).

  The second branch light pulse P7 is given to the filter 15. The light pulse that has passed through the filter 15 is converted into an analog electrical signal (indicating a voltage corresponding to the power of the light pulse that has passed through the filter 15) by the photodiode 16b, and digitized by the A / D converter 18b (value). Vb).

  The power ratio deriving unit 22 of the power control unit 20 receives Va and Vb and derives the power ratio Vb / Va. The amplification degree control unit 26 receives the power ratio Vb / Va from the power ratio deriving unit 22. The amplification degree control unit 26 receives the target value from the target value recording unit 24. Here, when the power ratio Vb / Va is smaller (larger) than the target value, the amplification factor of the optical fiber amplifier 10 is increased (decreased), and the power of the input optical pulse P2 is increased (decreased). Increase (decrease) Vb / Va.

  According to the first embodiment, by setting the spectrum width of the signal components of the first branch light pulse P6 and the second branch light pulse P7 to a certain constant value, the output light pulse P3 (measurement instrument light pulse P4) is obtained. A desired pulse width can be taken.

  Moreover, the power ratio Vb / Va is measured in order to make the spectrum widths of the signal components of the first branch light pulse P6 and the second branch light pulse P7 constant, and the amplification factor of the optical fiber amplifier 10 is based on the measurement result. To control. The output light pulse width control device 1 can be simplified compared to a method in which the spectrum width itself of the signal components of the first branch light pulse P6 and the second branch light pulse P7 is measured by an optical spectrum analyzer.

Second Embodiment The output light pulse width control device 1 according to the second embodiment is obtained by replacing the filter 15 of the output light pulse width control device 1 according to the first embodiment with a long pass filter.

  The configuration of the output light pulse width control device 1 according to the second embodiment is the same as that of the first embodiment (see FIG. 1). The output optical pulse width control device 1 according to the second embodiment includes an optical fiber amplifier 10, a compressed optical fiber 12, a partial output optical pulse acquisition unit 14a, a branched optical pulse output unit 14b, a filter 15, photodiodes 16a and 16b, A / D converters 18a and 18b and a power control unit 20 are provided. The optical fiber amplifier 10, the compressed optical fiber 12, the partial output optical pulse acquisition unit 14a, the branched optical pulse output unit 14b, the photodiodes 16a and 16b, and the A / D converters 18a and 18b are the same as those in the first embodiment, and will be described. Omitted.

  FIG. 4 shows the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the second embodiment (FIG. 4A), and the transmission of the filter 15 according to the second embodiment. Characteristic (FIG. 4B), the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the second embodiment, and the transmission characteristic of the filter 15 (see FIG. 4 (c)).

  Since FIG. 4A is the same as FIG. 2A, description thereof is omitted.

  The filter 15 receives the second branched light pulse P7 and passes the wavelength component in the passband. In the second embodiment, the filter 15 is a long pass filter.

  Referring to FIG. 4B, the filter 15 transmits light having a long wavelength with a transmittance of approximately 100% (gain 0 dB), but the transmittance is reduced when the wavelength of the light is shortened. Here, the cutoff wavelength of the filter 15 (the wavelength at which the gain is −3 dB) is λc. Furthermore, the filter 15 transmits light having a wavelength longer than or equal to the cutoff wavelength better than light having a wavelength shorter than or equal to the cutoff wavelength. Here, a region having a wavelength greater than or equal to the cutoff wavelength is referred to as a pass region, and a region having a wavelength less than the cutoff wavelength is referred to as an attenuation region. That is, the filter 15 transmits the light in the pass band better than the light in the attenuation band. The cutoff wavelength λc can be changed.

  Referring to FIG. 4C, when the pulse width of the output light pulse P3 (measuring device light pulse P4) is a desired constant value (that is, signals of the first branch light pulse P6 and the second branch light pulse P7). When the width of the component spectrum takes a certain value), a part of the passband (≧ λc) and a part of the wavelength region S of the signal component of the second branched light pulse overlap. A region where the passband and the wavelength region S of the signal component overlap is referred to as an overlapping region H.

  However, in FIG. 4C, for convenience of illustration, 0 [dB] in the transmission characteristic of the filter 15 is arranged at a position slightly higher than the height of the wavelength region S of the signal component (the same applies to FIG. 5). ). Further, in FIG. 4C, for the convenience of illustration, the transmission characteristics of the filter 15 are illustrated by a broken line that is bent at the cutoff wavelength λc (the same applies to FIG. 5).

  The power control unit 20 includes a measurement result Va of the first power measurement unit (the photodiode 16a and the A / D converter 18a) and a measurement result Vb of the second power measurement unit (the photodiode 16b and the A / D converter 18b). The power of the input optical pulse P2 is controlled so that the power ratio Vb / Va, which is the ratio, matches the target value.

  However, the target value is the power ratio Vb / Va when the output light pulse P3 (measurement device light pulse P4) has a desired pulse width.

  The power control unit 20 includes a power ratio deriving unit 22, a target value recording unit 24, and an amplification degree control unit 26.

  The power ratio deriving unit 22 derives the power ratio Vb / Va. The target value recording unit 24 records the target value.

  The amplification degree control unit 26 controls the amplification degree of the optical fiber amplifier 10 according to the power ratio by giving a control signal to the optical fiber amplifier 10. Specifically, the amplification degree control unit 26 receives the power ratio Vb / Va from the power ratio deriving unit 22. The amplification degree control unit 26 receives the target value from the target value recording unit 24. Here, when the power ratio Vb / Va is smaller (larger) than the target value, the amplification factor of the optical fiber amplifier 10 is increased (decreased), and the power of the input optical pulse P2 is increased (decreased). Increase (decrease) Vb / Va.

  Here, if the output light pulse P3 (measurement device light pulse P4) has a desired pulse width, the spectrum width of the signal components of the first branch light pulse P6 and the second branch light pulse P7 takes a certain value ( (See FIG. 4 (a)). However, when the output light pulse P3 (measurement device light pulse P4) does not have a desired pulse width, the spectrum width of the signal components of the first branch light pulse P6 and the second branch light pulse P7 is too narrow (FIG. 5 ( a)) or too wide (see FIG. 5B).

  FIG. 5 is a diagram showing the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 and the transmission characteristics of the filter 15 according to the second embodiment. It is a figure which shows the case where the width | variety of the spectrum of the signal component of the one branch light pulse P6 and the 2nd branch light pulse P7 is too narrow (refer Fig.5 (a)), and when it is too wide (refer FIG.5 (b)).

  Referring to FIG. 5A, when the spectrum widths of the signal components of the first branched light pulse P6 and the second branched light pulse P7 are too narrow, the overlapping region H (see FIG. 4C) disappears. (Or smaller). In this case, the light passing through the filter 15 is almost only a noise component. Therefore, Vb decreases and the power ratio Vb / Va also decreases.

  Referring to FIG. 5B, when the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7 is too wide, the overlapping region H (see FIG. 4C) becomes large. . In this case, the power of the light passing through the filter 15 becomes larger than that in the case of FIG. Therefore, Vb increases and the power ratio Vb / Va also increases.

  When the power ratio Vb / Va is smaller than the target value, the amplification degree control unit 26 widens the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7, and increases the power ratio Vb. Increase / Va. In order to widen the spectrum width of the signal component of the first branch light pulse P6 and the second branch light pulse P7 (that is, to widen the spectrum width of the signal component of the output light pulse P3), Just increase the power. When the power of the input light pulse P2 is increased, the spectrum width of the signal component of the output light pulse P3 is widened due to the self-phase modulation effect. Therefore, the amplification degree control unit 26 performs control so as to increase the amplification degree of the optical fiber amplifier 10.

  When the power ratio Vb / Va is larger than the target value, the amplification degree control unit 26 narrows the spectrum width of the signal components of the first branched light pulse P6 and the second branched light pulse P7, and the power ratio Vb Reduce / Va. In order to narrow the spectrum width of the signal component of the first branch light pulse P6 and the second branch light pulse P7 (that is, to narrow the spectrum width of the signal component of the output light pulse P3), You only need to reduce the power. Therefore, the amplification degree control unit 26 performs control so that the amplification degree of the optical fiber amplifier 10 is reduced.

  Since the operation of the second embodiment is the same as the operation of the first embodiment, description thereof is omitted.

  According to the second embodiment, there are the same effects as the first embodiment.

  Moreover, said embodiment is realizable as follows. A computer having a CPU, a hard disk, and a medium (floppy (registered trademark) disk, CD-ROM, etc.) reader reads a medium on which a program for realizing each of the above-described parts (for example, the power control unit 20) is recorded. Install it on your hard disk. Such a method can also realize the above functions.

It is a functional block diagram which shows the structure of the output light pulse width control apparatus 1 concerning 1st embodiment of this invention. The relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the first embodiment (FIG. 2A), the transmission characteristics of the filter 15 according to the first embodiment (FIG. 2). (B)), the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the first embodiment, and the transmission characteristics of the filter 15 (FIG. 2C). ). It is a figure which shows what overlapped the relationship between the wavelength and power of the 1st branch light pulse P6 and 2nd branch light pulse P7 concerning 1st embodiment, and the transmission characteristic of the filter 15, and is the 1st branch light pulse. It is a figure which shows the case where the width | variety of the spectrum of the signal component of P6 and the 2nd branch optical pulse P7 is too narrow (refer Fig.3 (a)), and the case where it is too wide (refer Fig.3 (b)). The relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 according to the second embodiment (FIG. 4A), the transmission characteristics of the filter 15 according to the second embodiment (FIG. 4). (B)), the relationship between the wavelength and power of the first branched light pulse P6 and the second branched light pulse P7 and the transmission characteristics of the filter 15 according to the second embodiment (FIG. 4C). ). It is a figure which shows what overlapped the relationship between the wavelength and power of the 1st branch light pulse P6 and 2nd branch light pulse P7 concerning 2nd embodiment, and the transmission characteristic of the filter 15, and is shown in FIG. It is a figure which shows the case where the width | variety of the spectrum of the signal component of P6 and the 2nd branch optical pulse P7 is too narrow (refer Fig.5 (a)), and when it is too wide (refer FIG.5 (b)).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Output light pulse width control apparatus 10 Optical fiber amplifier 12 Compression optical fiber 14a Partial output light pulse acquisition part 14b Branching light pulse output part 15 Filter 16a, 16b Photodiode 18a, 18b A / D converter 20 Power control part 22 Power ratio derivation Unit 24 target value recording unit 26 amplification degree control unit P2 input light pulse P3 output light pulse P4 measuring device light pulse P5 partial output light pulse P6 first branched light pulse P7 second branched light pulse S signal component wavelength region N noise part H overlap area

Claims (9)

A compressed optical fiber that outputs an output optical pulse obtained by compressing the pulse width of the input optical pulse;
An optical pulse branching unit that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse;
A first power measuring unit for measuring the power of the first branched light pulse;
A filter that receives the second branched light pulse and passes a wavelength component in a passband;
A second power measurement unit for measuring the power of the optical pulse that has passed through the filter;
A power control unit that controls the power of the input optical pulse so that a power ratio that is a ratio between a measurement result of the first power measurement unit and a measurement result of the second power measurement unit matches a target value;
With
When the output light pulse has a desired pulse width, a part of the passband and a part of the wavelength region of the signal component of the second branch light pulse overlap,
The target value is the power ratio when the output light pulse has the desired pulse width.
Output light pulse width controller. The output light pulse width control device according to claim 1,
The filter is a short pass filter;
The wavelength in the passband is equal to or less than the cutoff wavelength of the filter.
Output light pulse width controller. The output light pulse width control device according to claim 1,
The filter is a long pass filter;
The wavelength in the passband is not less than the cutoff wavelength of the filter.
Output light pulse width controller. The output light pulse width control device according to claim 1,
An optical fiber amplifier that outputs the input light pulse;
The power control unit is
An output light pulse width control device having an amplification degree control unit that controls the amplification degree of the optical fiber amplifier according to the power ratio. The output light pulse width control device according to claim 1,
The optical pulse branching unit is
A partial output optical pulse acquisition unit for branching the output optical pulse to acquire a partial output optical pulse;
Branching the partial output light pulse, a branched light pulse output unit that outputs a first branched light pulse and a second branched light pulse;
An output light pulse width control device. The output light pulse width control device according to claim 1,
The power control unit is
When increasing the power ratio, increase the power of the input light pulse,
When reducing the power ratio, reduce the power of the input light pulse,
Output light pulse width controller. A compressed optical fiber that outputs an output optical pulse obtained by compressing the pulse width of the input optical pulse;
An optical pulse branching unit that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse;
A first power measuring unit for measuring the power of the first branched light pulse;
A filter that receives the second branched light pulse and passes a wavelength component in a passband;
A second power measurement unit for measuring the power of the optical pulse that has passed through the filter;
An output light pulse width control method for controlling a pulse width of the output light pulse in an output light pulse width control device comprising:
A power control step of controlling the power of the input optical pulse so that a power ratio, which is a ratio between a measurement result of the first power measurement unit and a measurement result of the second power measurement unit, matches a target value; ,
When the output light pulse has a desired pulse width, a part of the passband and a part of the wavelength region of the signal component of the second branch light pulse overlap,
The target value is the power ratio when the output light pulse has the desired pulse width.
Output light pulse width control method. A compressed optical fiber that outputs an output optical pulse obtained by compressing the pulse width of the input optical pulse;
An optical pulse branching unit that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse;
A first power measuring unit for measuring the power of the first branched light pulse;
A filter that receives the second branched light pulse and passes a wavelength component in a passband;
A second power measurement unit for measuring the power of the optical pulse that has passed through the filter;
A program for causing a computer to execute an output light pulse width control process for controlling a pulse width of the output light pulse in an output light pulse width control device comprising:
The output light pulse width control process is:
A power control step of controlling the power of the input optical pulse so that a power ratio, which is a ratio between a measurement result of the first power measurement unit and a measurement result of the second power measurement unit, matches a target value; ,
When the output light pulse has a desired pulse width, a part of the passband and a part of the wavelength region of the signal component of the second branch light pulse overlap,
The target value is the power ratio when the output light pulse has the desired pulse width.
program. A compressed optical fiber that outputs an output optical pulse obtained by compressing the pulse width of the input optical pulse;
An optical pulse branching unit that branches the output optical pulse and outputs a first branched optical pulse and a second branched optical pulse;
A first power measuring unit for measuring the power of the first branched light pulse;
A filter that receives the second branched light pulse and passes a wavelength component in a passband;
A second power measurement unit for measuring the power of the optical pulse that has passed through the filter;
A computer-readable recording medium storing a program for causing a computer to execute an output light pulse width control process for controlling a pulse width of the output light pulse in an output light pulse width control device comprising:
The output light pulse width control process is:
A power control step of controlling the power of the input optical pulse so that a power ratio, which is a ratio between a measurement result of the first power measurement unit and a measurement result of the second power measurement unit, matches a target value; ,
When the output light pulse has a desired pulse width, a part of the passband and a part of the wavelength region of the signal component of the second branch light pulse overlap,
The target value is the power ratio when the output light pulse has the desired pulse width.
recoding media.

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