JP5016571B2 - Optical spectrum monitor - Google Patents

Description

  The present invention relates to a spectroscope that splits light and an optical spectrum monitor that is used to measure the wavelength and power of light to be measured using the spectroscope.

  FIG. 8 is a diagram showing a schematic configuration of an optical spectrum monitor using a Littman type spectroscope. The optical spectrum monitor 101 shown in FIG. 8 includes an incident means 102, a diffracting means 103, and a diffracted light receiving means 104. The incident means 102 includes a light input port 102a through which light to be measured is incident and a collimator 102b that converts light incident from the light input port 102a into collimator light. The diffracting means 103 includes a diffraction grating 103a that diffracts the collimator light, and a reflecting mirror 103b that causes the diffracted light diffracted by the diffraction grating 103a to enter the diffraction grating again. Further, the diffracted light receiving means 104 receives the light collected by the light collector 104a and the light collected by the light collector 104a, and converts the received light signal into an electrical signal. And the photoreceiver 104b for outputting.

As an optical spectrum analyzer using the optical spectrum monitor 101 of FIG. 8, for example, the one disclosed in FIG. 3 of the following Patent Document 1 is known, and an object to be measured is measured using an electrical signal output from a spectrometer. It measures the wavelength and power of light.
JP 2003-114149 A

  By the way, with the recent increase in capacity of optical communication, the density of WDM (Wavelength Division Multiplexing) communication has increased, and DWDM (Dense Wavelength Division Multiplexing: high density wavelength division multiplexing) that performs WDM at narrow wavelength intervals. System), and there is an increasing demand for high wavelength accuracy.

  However, a conventionally known optical spectrum monitor has not been able to obtain sufficient wavelength accuracy.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an optical spectrum monitor capable of measuring an optical spectrum such as DWDM transmission with high wavelength accuracy.

In order to achieve the above object, an optical spectrum monitor according to claim 1 of the present invention has diffractive means 3 for diffracting measured light at a diffraction angle corresponding to the sweep of the optical spectrum. In the optical spectrum monitor that receives the next diffracted light and converts it into an electrical signal corresponding to the amount of light received
An incident means 2 including a wavelength monitor light source 22 that emits light in the vicinity of a half wavelength of the wavelength of the light to be measured; and a multiplexer 23 that combines the light to be measured and the light from the wavelength monitor light source; ,
A demultiplexing unit 61 for demultiplexing the first-order diffracted light of the light to be measured and the second-order diffracted light of the light source for wavelength monitoring, and inputs the second-order diffracted light of the light source for wavelength monitoring demultiplexed by the demultiplexing unit And wavelength monitoring means 6 for monitoring the wavelength.

The optical spectrum monitor according to claim 2 is the optical spectrum monitor according to claim 1,
The wavelength monitoring light source 22 emits a broadband light including a half wavelength of the wavelength of the light to be measured.

The optical spectrum monitor according to claim 3 is the optical spectrum monitor according to claim 2,
The wavelength monitoring unit 6 transmits the second-order diffracted light of the wavelength monitoring light source demultiplexed by the demultiplexing unit 61, and the transmitted light causes a light intensity change with respect to the wavelength, and the transmission of the transmission element. And a light receiver 64c that receives the light and converts the light intensity change into an electrical signal with respect to the wavelength.

The optical spectrum monitor according to claim 4 is the optical spectrum monitor according to claim 3,
The wavelength monitoring means 6 is disposed in an optical path between the demultiplexing unit 61 and the transmission element 64a, and a spectral unit 62 that splits light directed toward the transmission element and light not directed toward the transmission element, It further includes a light receiver 63b that receives the light not directed to the transmissive element dispersed by the spectroscopic unit.

The optical spectrum monitor according to claim 5 is the optical spectrum monitor according to claim 1,
The wavelength monitoring light source 22 includes at least one light having a known wavelength.

The optical spectrum monitor according to claim 6 is the optical spectrum monitor according to claim 1,
The wavelength monitoring light source 22 emits light of a narrow band having a known wavelength.

  According to the present invention, an optical spectrum monitor capable of measuring an optical spectrum with high wavelength accuracy can be provided. Moreover, even if the light intensity of the light source for wavelength monitoring is not constant with respect to the wavelength, it is possible to provide an optical spectrum monitor that can be similarly measured with high wavelength accuracy.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a diagram illustrating a first embodiment of an optical spectrum monitor according to the present invention, FIGS. 2A to 2C are schematic diagrams illustrating configuration examples of a demultiplexing unit, and FIG. FIG. 4 is a diagram showing a relationship between diffraction angles of diffracted light, FIG. 4 is a diagram showing a second embodiment of an optical spectrum monitor according to the present invention, and FIG. 5 is a diagram showing a third embodiment of the optical spectrum monitor according to the present invention. 6 is a diagram showing a fourth embodiment of the optical spectrum monitor according to the present invention, and FIG. 7 is a diagram showing a fifth embodiment of the optical spectrum monitor according to the present invention.

  First, the configuration of the first embodiment of the optical spectrum monitor according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the optical spectrum monitor 1 (1A) of the first embodiment is roughly configured to include an incident means 2, a diffraction means 3, a diffraction control means 4, a measurement light receiving means 5, and a wavelength monitor means 6. The

  The incident means 2 includes an optical input port 21, a wavelength monitor light source 22, a multiplexer 23, and a collimator 24.

  The light input port 21 receives light under measurement (for example, a 1.5 μm band) to be measured. The light to be measured input to the optical input port 21 is input to one input port of the multiplexer 23 via the optical fiber 21a.

  The wavelength monitoring light source 22 includes a broadband light source (LED) that emits broad light (white light) in the vicinity of half the wavelength of the light to be measured. For example, when the light to be measured is 1.4 μm to 1.6 μm, the wavelength monitoring light source 22 is configured by a broadband light source having a wavelength component of 0.7 μm to 0.8 μm. The monitor light emitted from the wavelength monitoring light source 22 is input to the other input port of the multiplexer 23 via the optical fiber 22a.

  The multiplexer 23 is composed of an optical coupler having two input ports and one output port. The light to be measured input from the optical input port 21 to one input port via the optical fiber 21a, and the wavelength monitor The monitor light input from the light source 22 to the other input port via the optical fiber 22 a is combined, and the combined light is incident on the collimator 24.

  The collimator 24 includes a collimator lens that converts incident light into parallel light. The light from the multiplexer 23 (combined light of the light to be measured and the monitor light) is converted into parallel light and incident on the diffraction unit 3. ing.

  The diffractive means 3 includes a diffraction grating 31 and a reflector 32. The diffraction grating 31 is fixedly arranged behind the collimator 24 on the outgoing light path with the diffraction surface 31a formed with parallel engraving lines (groove spacing d) at predetermined intervals facing the collimator 24 side. The diffraction grating 3 diffracts the light incident from the collimator 24 and outputs the diffracted light to the reflector 32.

  The reflector 32 is configured by a mirror in which the reflecting surface 32a is disposed so as to face the diffraction surface 31a of the diffraction grating 31 and can be rotated around an axis parallel to the engraving direction of the diffraction grating 31 according to the sweep of the optical spectrum. Is done. The reflector 32 reflects the diffracted light from the diffraction grating 31 to the diffraction grating 31 again.

  The diffraction control unit 4 includes a control unit 41 and a drive unit 42. The control unit 41 outputs information on the rotation angle θλ of the reflector 32 to the drive unit 42 in order to control the diffraction angle of the diffracting means 3. Further, the diffraction control means 4 outputs information on the designated wavelength λ for performing wavelength calibration to the wavelength calibration unit 67 described later.

  The drive unit 42 rotates the reflector 32 of the diffractive unit 3 so that the rotation angle θλ = 0 ° is set to a predetermined initial position so that the rotation angle θλ is input from the diffraction control unit 4.

  The light receiving means for measurement 5 includes a light collector for measurement 51 and a light receiver for measurement 52. The measurement condenser 51 condenses the first-order diffracted light of the light to be measured, which has passed through a demultiplexing unit (high-pass filter) 61 described later from the diffraction grating 31, on the measurement light receiver 52.

  The light receiver for measurement 52 receives the first-order diffracted light of the light to be measured collected by the light collector for measurement 51, and an electrical signal (light intensity) corresponding to the light intensity of the first-order diffracted light of the received light to be measured. Is output to a spectrum display unit 68 which will be described later.

  The wavelength monitoring means 6 includes a demultiplexing unit 61, a spectroscopic unit 62, a monitor light first light receiving unit 63, a monitor light second light receiving unit 64, a transmittance calculating unit 65, a storage unit 66, a wavelength calibration unit 67, and a spectrum display unit 68. It has.

  The demultiplexing unit 61 demultiplexes the diffracted light incident from the diffracting means 3 into the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitor light source 22, and is constituted by a high-pass filter, for example. When the diffracted light from the diffracting means 3 is incident on the high-pass filter constituting the demultiplexing unit 61, the first-order diffracted light of the light to be measured is transmitted to the measuring light-receiving means 5, and the second-order diffracted light from the wavelength monitor light source 22. Is reflected by the second branch part 62.

  In addition, as the branching part 61, the structure shown to Fig.2 (a)-(c) is employable, for example. In the example of FIG. 2A, the demultiplexing unit 61 is configured by a beam splitter that demultiplexes the diffracted light from the diffracting means 3 into a long wave and a short wave. In this configuration, of the diffracted light from the diffracting means 3, the first-order diffracted light of the light to be measured that is a long wave is transmitted to the measurement light-receiving means 5 side, and the second-order diffracted light of the wavelength monitor light source 22 that is a short wave is transmitted to the spectroscopic unit. Reflected toward the 62 side.

  In the example of FIG. 2B, the demultiplexing unit 61 is configured by a half mirror and a filter provided in the subsequent stage of the half mirror. In this configuration, the diffracted light from the diffracting means 3 is divided into two by a half mirror, and the diffracted light from the diffracting means 3 is converted into the second-order diffracted light of the measured light and the wavelength monitoring light source 22 by the subsequent filter. And are separated.

  In the example of FIG. 2C, a light splitting unit 61 is configured by a light receiver (measurement light receiver 51, monitor light first light receiver 63b, monitor light second light receiver 64c) described later. In this configuration, the diffracted light from the diffracting means 3 is separated into the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitor light source 22 by the light receiving sensitivity characteristic of the light receiver.

  The spectroscopic unit 62 is composed of, for example, a beam splitter, and splits the second-order diffracted light of the wavelength monitoring light source 22 demultiplexed by the demultiplexing unit 61 at a predetermined ratio (for example, a ratio of 50%: 50%), The light is reflected by the monitor light first light receiving unit 63 and the other is transmitted by the monitor light second light receiving unit 64.

  The monitor light first light receiving unit 63 includes a monitor light first light collector 63a and a monitor light first light receiver 63b. The monitor light first condenser 63a condenses the second-order diffracted light of the wavelength monitoring light source 22 that has been split and reflected by the spectroscopic unit 62 onto the monitor light first light receiver 63b.

  The monitor light first light receiver 63b is made of, for example, Si-PD, receives the second-order diffracted light of the wavelength monitor light source 22 collected by the monitor light first light collector 63a, and receives the received wavelength monitor light source. An electrical signal corresponding to the light intensity of the 22nd-order diffracted light (spectrum data represented by an intensity data string for each wavelength included in the received light) is output.

  The monitor light second light receiving unit 64 includes a transmission element 64a, a monitor light second light collector 64b, and a monitor light second light receiver 64c. The transmissive element 64a is an element having a transmission characteristic in which the transmittance with respect to light varies depending on the wavelength. The etalon 64a has a transmission characteristic in which the transmittance periodically increases and decreases at a constant wavelength interval with respect to a monotonous change in wavelength, and the second-order diffracted light of the wavelength monitor light source 22 spectrally separated by the spectroscopic unit 62 is obtained. In response to this, light of a plurality of known wavelengths arranged at equal intervals is transmitted, and the transmitted light causes a change in light intensity with respect to the wavelength.

  The monitor light second light collector 64b condenses the transmitted light from the transmission element (etalon) 64a on the monitor light second light receiver 64c.

  The monitor light second light receiver 64c receives the transmitted light from the transmission element 64a collected by the monitor light second light collector 64b, and an electrical signal (transmission element 64a) corresponding to the light intensity of the received transmitted light. (Spectrum data represented by a data string of intensities for each wavelength included in the light affected by the transmission characteristics).

  The transmittance calculating unit 65 is based on an electrical signal (spectrum data) corresponding to the intensity of light received and detected by the monitor light first light receiving unit 63 and the monitor light second light receiving unit 64 and wavelength information associated therewith. Thus, the light transmittance of the monitor light transmission element (etalon) 64b is calculated.

  The storage unit 66 stores in advance transmission characteristics (transmission profile) of the transmission element (etalon) 64a. The transmission profile of the etalon 64a has a shape in which Laurentian peaks are arranged at equal intervals on the wavelength axis for each free spectral range (FSR). And each peak wavelength is memorize | stored in the memory | storage part 67 as a transmission characteristic of the known wavelength (For example, ... 1535nm, 1540nm, 1545nm ... and the like).

  The wavelength calibration unit 67 is based on the transmittance calculated by the transmittance calculation unit 65, the transmission characteristics of the transmission element (etalon) 64 a stored in advance in the storage unit 66, and the designated wavelength λ from the control unit 41. Thus, the wavelength of each sample value of the monitor light first light receiving unit 63 is obtained, and the wavelength of each sample value of the monitor light first light receiving unit 64 is calibrated based on the obtained wavelength.

  More specifically, an error between each wavelength detected for each wavelength detection target value and the wavelength information stored in association with each wavelength detection target value is obtained, and the error of the specified wavelength λ from the control unit 41 is calculated. A change characteristic is obtained, and each wavelength information of the spectrum data of the monitor light first light receiving unit 63 is subtracted and corrected based on the change characteristic.

  When an etalon is used as the transmissive element 64a, the wavelength cannot be uniquely determined from the calculated transmittance. Therefore, among the plurality of wavelengths obtained from the transmission characteristics for the calculated one transmittance, The wavelength closest to the wavelength associated with the designated wavelength λ and stored in the storage unit 66 is selected as an accurate wavelength corresponding to the wavelength detection target value.

  The spectrum display unit 68 is composed of a display device such as a liquid crystal display, reads spectrum data based on the wavelength information calibrated by the wavelength calibration unit 66, and displays the horizontal axis as the wavelength axis and the vertical axis as the orthogonal coordinate of the power axis. The waveform of the read spectrum data is displayed on the Cartesian coordinates. Since the wavelength axis of this spectrum waveform is calibrated by the wavelength calibration unit 66, the wavelength and intensity of each spectrum can be accurately grasped.

  In the optical spectrum monitor 1 </ b> A according to the first embodiment configured as described above, light (measured light) input from the optical input port 21 is converted into collimated light by the collimator 24 and is incident on the diffraction grating 31. The light incident on the diffraction grating 31 is diffracted by the diffraction surface, and the first-order diffracted light resulting from this diffraction is output to the reflector 32. The reflector 32 can be rotated according to the sweep of the optical spectrum on an axis parallel to the direction of the engraving line of the diffraction grating 31, and the light reflected by the reflector 32 is diffracted by the diffraction grating 31 again. The first-order diffracted light is condensed by the measurement condenser 51 and received by the measurement light receiver 52. The spectrum can be measured by rotating the reflector 32 according to the designated wavelength λ under the control of the control unit 41 and observing the intensity signal that has been photoelectrically converted by the measurement light receiver 52.

  When wavelength calibration is performed, the monitor light emitted near the half wavelength of the wavelength of the measured light from the wavelength monitor light source 22 that emits near the wavelength of the measured light is multiplexed. 23. For example, when the light to be measured is 1.4 μm to 1.6 μm, the monitor light from the wavelength monitor light source 22 having a wavelength component of 0.7 μm to 0.8 μm and the light to be measured to the multiplexer 23. input.

  A demultiplexing unit 61 that demultiplexes the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitor light source 22 is disposed in the optical path between the diffraction grating 31 and the measurement condenser 51. The second-order diffracted light from the wavelength monitor light source 22 is input to the wavelength monitor means 6 to monitor the wavelength.

  That is, in the first embodiment, the monitor light from the wavelength monitor light source 22 that emits light in the vicinity of half the wavelength of the light to be measured and the light to be measured are combined by the multiplexer 23 to the diffraction unit 3. The diffracted light from the diffracting means 3 is demultiplexed into the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitor light source 22 by the demultiplexing unit 61, and the demultiplexed second-order diffracted light is used as the transmission element 64a. The transmittance of the transmitted light is calculated, and wavelength calibration is performed based on the calculated transmittance, the specified wavelength λ, and the etalon transmittance profile of the storage unit 66.

  Here, as shown in FIG. 3, when light having a wavelength λ is incident on the diffraction grating 31 having the groove interval d at an incident angle α, the diffraction angle β of the diffracted light is expressed by the equation Nλ = d (sin α + sin β). be able to. However, N = 0, ± 1, ± 2,...

  For example, when light of λ = 1550 nm is incident on the diffraction grating 31 having an incident angle of 85 ° and a groove interval of 1/1100 mm, β is 44.6 ° (N = 1). When light having a wavelength of 775 nm is incident, the light with N = 2 is also diffracted in the direction of 44.6 °.

  As described above, the diffraction angle of the first-order diffracted light of the diffraction grating 31 having an arbitrary wavelength of the light to be measured matches the diffraction angle of the second-order diffracted light of the diffraction grating 31 of the wavelength monitor light source 22, so The light path toward the light receiving means 5 for measurement and the light of the wavelength monitoring light source 22 having a half wavelength of the light to be measured have the same light path.

  Accordingly, a correlation is obtained between the wavelength to be measured and the light from the wavelength monitoring light source 22, that is, the light from the wavelength monitoring light source 22 having a half wavelength of the measured light wavelength, and the light wavelength of the wavelength monitoring light source 22 is monitored. Thus, the wavelength of the light to be measured can be specified.

  Since the light to be measured and the light from the wavelength monitoring light source 22 have different wavelengths, they can be easily demultiplexed by the demultiplexing unit 61.

  In the first embodiment, the second-order diffracted light of the wavelength monitor light source 22 demultiplexed by the demultiplexing unit 61 is transmitted as the monitor light second light receiving unit 64, and the transmitted light causes a change in light intensity with respect to the wavelength. An element (etalon) 64a, a monitor light second condenser 64b that condenses the transmitted light of the transmission element 64a, and a monitor light that receives the collected transmitted light and converts a change in light intensity into an electrical signal with respect to the wavelength. The second light receiver 64c is used. Then, by obtaining the wavelength of the wavelength monitor light source 22 from the output signal of the monitor light second light receiver 64c, that is, the light intensity change signal of the light of the wavelength monitor light source 22 after passing through the transmission element 64a, the wavelength of 2 is obtained. A wavelength to be measured that is a double wavelength can be specified.

  Further, in the first embodiment, a half mirror that forms the spectroscopic unit 62 is disposed in the optical path between the demultiplexing unit 61 that demultiplexes the second-order diffracted light of the wavelength monitoring light source 22 having the above configuration and the transmission element 64a, and the transmission element A part of the light directed to the transmissive element 64a is extracted by splitting the light toward the light 64a and the light not directed to the transmissive element 64a, and the half-mirror light (light not directed to the transmissive element 64a) is used as the monitor light first light receiving unit 63. ) And a monitor light first light receiving unit 63 including a monitor light first light receiver 63b that receives the collected light.

  In this configuration, the monitor light second light receiver 64c detects the signal after transmission through the transmission element 64a, and the monitor light first light receiver 63b detects the signal before transmission through the transmission element 64a. Light that does not depend on the change of the wavelength-light power of the light of the wavelength monitor light source 22 by determining the ratio of the light-electric conversion signal intensity of the light detector 64c and the light-electric conversion signal intensity of the monitor light first light receiver 63b A signal serving as a wavelength scale of the spectrum monitor can be obtained.

  Then, by generating a sampling trigger based on a signal having a wavelength scale obtained from the transmitted light intensity of the transmission element (etalon) 64a described above, high-speed and high-accuracy measurement can be performed.

  Furthermore, in order to increase the accuracy, it is possible to phase-divide the signal that becomes the wavelength scale to generate a position signal at fine wavelength steps.

  Next, the configuration of the second embodiment of the optical spectrum monitor according to the present invention will be described with reference to FIG.

  In addition, in the optical spectrum monitor 1 (1B) of the second embodiment shown in FIG. 4, the same reference numerals are given to substantially the same components as those of the optical spectrum monitor 1A of the first embodiment, and the configuration with the first embodiment. Only the differences will be described.

  In the optical spectrum monitor 1B of the second embodiment, the monitor light first light receiving unit 63 and the transmittance calculating unit 65 of the wavelength monitoring unit 6 of the first embodiment are deleted, and the transmission element 64a of the monitor light second light receiving unit 64 is replaced. This is a configuration provided in the incident means 2. That is, the known wavelength transmitting portion 25 is provided between the wavelength monitoring light source 22 of the incident means 2 and the multiplexer 23.

  The known wavelength transmission unit 25 has a configuration in which a condenser lens 25a, a transmission element (etalon) 25b, and a condenser lens 25c are arranged in this order from the wavelength monitor light source 22 side. In the known wavelength transmission unit 25, the monitor light from the wavelength monitoring light source 22 is condensed on the transmission element 25b by the condenser lens 25a. The transmissive element 25b receives the light collected by the condenser lens 25a and transmits light of a plurality of known wavelengths arranged at equal intervals, and the other input port of the multiplexer 23 by the condenser lens 25c. The light is condensed and input. As the transmission element 25b, for example, an etalon of an optical comb filter having a stable transmission characteristic is used, similarly to the transmission element 64a of the monitor light second light receiving unit 64 described above.

  Further, in the optical spectrum monitor 1B of the second embodiment, the wavelength monitoring means 6 has a simpler configuration than that of the first embodiment, and includes a demultiplexing unit 61, a monitor light second light receiving unit 64, a storage unit 66, and a wavelength. A calibration unit 67 and a spectrum display unit 68 are provided.

  In the optical spectrum monitor 1B of the second embodiment, the diffracted light from the diffracting means 3 is demultiplexed by the demultiplexing unit 61 into the first-order diffracted light of the measured light and the second-order diffracted light of the wavelength monitor light source 22. . Then, the first-order diffracted light of the light under measurement is received and detected by the measurement light receiving means 5, and a spectrum waveform based on the result of this light reception detection is displayed on the spectrum display unit 68. Further, the second-order diffracted light of the wavelength monitor light source 22 is received and detected by the monitor light second light receiving unit 64, and an electrical signal corresponding to the light intensity detected and detected (the light affected by the transmission characteristics of the transmission element 25b). (Spectrum data represented by an intensity data string for each wavelength included) is input to the wavelength calibration unit 67. Then, the wavelength calibration unit 67 determines the wavelength of the electrical signal input from the monitor light second light receiving unit 64 based on the designated wavelength λ from the control unit 41 and the wavelength-level information stored in the storage unit 66 in advance. The spectrum waveform that has been calibrated and wavelength-calibrated is displayed on the spectrum display unit 68.

  Next, the configuration of the third embodiment of the optical spectrum monitor according to the present invention will be described with reference to FIG.

  In the optical spectrum monitor 1 (1C) of the third embodiment shown in FIG. 5, the same reference numerals are given to substantially the same components as those of the optical spectrum monitors 1A and 1B of the first and second embodiments described above. A description of the same components as those of the embodiment described above will be omitted.

  In the optical spectrum monitor 1C of the third embodiment, the monitor light first light receiving unit 63 of the wavelength monitor unit 6 of the first embodiment, the transmission element 64a of the monitor light second light receiving unit 64, and the transmittance calculation unit 65 are deleted. The wavelength monitoring light source 22 of the incident means 2 is composed of a narrow band light source that emits monitor light having a known wavelength (for example, 0.7 μm band) that is ½ of the wavelength of the light to be measured. .

  Further, in the optical spectrum monitor 1C of the third embodiment, the wavelength monitoring means 6 has a simplified configuration compared to the first embodiment, and has the same configuration as that of the second embodiment, that is, the demultiplexing unit 61 and the second monitor light. A light receiving unit 64, a storage unit 66, a wavelength calibration unit 67, and a spectrum display unit 68 are provided. The operation after the diffracted light from the diffracting means 3 is demultiplexed into the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitor light source 22 is the same as in the second embodiment. Description is omitted.

  Next, the configuration of the fourth embodiment of the optical spectrum monitor according to the present invention will be described with reference to FIG.

  In addition, in the optical spectrum monitor 1 (1D) of the fourth embodiment in FIG. 6, the same reference numerals are given to substantially the same components as the optical spectrum monitors 1A to 1C of the first to third embodiments described above. A description of the same components as those described above will be omitted.

  In the optical spectrum monitor 1 </ b> D of the fourth embodiment, the reflector (mirror) 32 of the diffractive means 3 is fixed, and the diffraction grating 31 can be rotated by driving the drive unit 42 based on the control of the control unit 41. The configuration is adopted. In addition, about another structure and operation | movement of each structure, it is the same as 1st Embodiment.

  Next, the configuration of the fifth embodiment of the optical spectrum monitor according to the present invention will be described with reference to FIG.

  In addition, in the optical spectrum monitor 1E of the fifth embodiment shown in FIG. 7, the same reference numerals are given to substantially the same components as those of the optical spectrum monitors 1A to 1D of the first to fourth embodiments described above, and the components described above. Description of the same components as those in FIG.

  In the optical spectrum monitor 1E of the fifth embodiment, the positional relationship between the diffraction grating 31 and the reflector (mirror) 32 constituting the diffractive means 3 is opposite to that of the first embodiment. The configuration is adopted. In addition, about another structure and operation | movement of each structure, it is the same as 1st Embodiment.

  Thus, according to the optical spectrum monitor of the present invention, it is possible to provide a spectrum monitor that measures the optical spectrum with high wavelength accuracy. Further, even if the light intensity for wavelength monitoring is not constant with respect to the wavelength, a spectrum monitor with high wavelength accuracy can be provided similarly.

  By the way, as the diffraction means 3 of the above-described embodiment, the diffraction grating and the reflector are combined, one is fixed, and the other rotates around an axis parallel to the score line. Omitting, the diffraction means 3 may be composed of only a concave diffraction grating that can rotate around an axis parallel to the score line, and a single-pass spectroscope may be configured.

  In the above-described embodiment, the collimator 24 is described as being included in the incident means 2, but the collimator 24 may be omitted. The wavelength monitoring light source 22 is not limited to the emission wavelength of ½ wavelength of the light to be measured. For example, the wavelength monitoring light source 22 is a broadband light source that emits light in the vicinity of ３ wavelength of the light to be measured. Can also be configured. In that case, it is desirable that the diffraction efficiency of the light to be measured in the diffractive means 3 and the diffraction efficiency of the monitor light from the wavelength monitoring light source 22 are substantially equal.

  Furthermore, in the first, fourth, and fifth embodiments (FIGS. 1, 6, and 7), the configurations of the spectroscopic unit 62, the monitor light first light receiving unit 63, and the transmittance calculating unit 65 may be omitted. In this case, the storage unit 66 stores information indicating a wavelength-level relationship in advance. Then, similarly to the second and third embodiments, the wavelength calibration unit 67 is based on the designated wavelength λ from the control unit 41 and the wavelength-level information in the storage unit 66, and the electrical signal from the monitor light second light receiving unit 64. Wavelength calibration will be performed for.

It is a figure which shows 1st Embodiment of the optical spectrum monitor which concerns on this invention. (A)-(c) It is the schematic which shows each structural example of a demultiplexing part. It is a figure which shows the relationship between the incident angle in a diffraction grating, and the diffraction angle of diffracted light. It is a figure which shows 2nd Embodiment of the optical spectrum monitor which concerns on this invention. It is a figure which shows 3rd Embodiment of the optical spectrum monitor which concerns on this invention. It is a figure which shows 4th Embodiment of the optical spectrum monitor which concerns on this invention. It is a figure which shows 5th Embodiment of the optical spectrum monitor which concerns on this invention. It is a schematic block diagram of the conventional optical spectrum monitor.

Explanation of symbols

1 (1A to 1E) Optical spectrum monitor 2 Incident means 3 Diffraction means 4 Diffraction control means 5 Measurement light receiving means 6 Wavelength monitoring means 21 Optical input port 22 Wavelength monitoring light source 23 Multiplexer 24 Collimator 25 Known wavelength transmission part 31 Diffraction Lattice 32 Reflector 41 Control unit 42 Drive unit 51 Measuring concentrator 52 Measuring light receiver 61 Demultiplexing unit 62 Spectroscopic unit 63 Monitor light first light receiving unit 63a Monitor light first light collector 63b Monitor light first light receiver 64 Monitor light second light receiving part 64a Etalon (transmission element)
64b Monitor light second light collector 64c Monitor light second light receiver 65 Transmittance calculation unit 66 Storage unit 67 Wavelength calibration unit 68 Spectrum display unit

Claims (6)

An optical spectrum monitor having a diffracting means (3) for diffracting the light to be measured at a diffraction angle corresponding to the sweep of the optical spectrum, receiving the first-order diffracted light by the diffracting means, and converting it into an electrical signal corresponding to the amount of received light In
A wavelength monitor light source (22) that emits light in the vicinity of a half wavelength of the wavelength of the light to be measured; and a multiplexer (23) that combines the light to be measured and the light from the wavelength monitor light source. Incident means (2);
A demultiplexing unit (61) for demultiplexing the first-order diffracted light of the light to be measured and the second-order diffracted light of the wavelength monitoring light source; and the second-order diffracted light of the wavelength monitoring light source demultiplexed by the demultiplexing unit An optical spectrum monitor comprising wavelength monitor means (6) for monitoring the wavelength by inputting. The optical spectrum monitor according to claim 1, wherein the wavelength monitor light source (22) emits broadband light including a half wavelength of the wavelength of the light to be measured. The optical spectrum monitor according to claim 2,
The wavelength monitoring means (6) transmits the second-order diffracted light of the wavelength monitoring light source demultiplexed by the demultiplexing unit (61), and the transmitted light (64a) generates a change in light intensity with respect to the wavelength. An optical spectrum monitor comprising: a light receiver (64c) that receives light transmitted through the transmissive element and converts the light intensity change into an electrical signal with respect to wavelength. The optical spectrum monitor according to claim 3.
The wavelength monitoring means (6) is disposed in an optical path between the demultiplexing unit (61) and the transmissive element (64a), and splits the light toward the transmissive element and the light not directed to the transmissive element. An optical spectrum monitor, further comprising: a spectroscopic unit (62); and a light receiver (63b) that receives light that is split by the spectroscopic unit and does not travel toward the transmission element. The optical spectrum monitor according to claim 1, characterized in that the wavelength monitoring light source (22) contains light of at least one known wavelength. The optical spectrum monitor according to claim 1, wherein the wavelength monitor light source (22) emits light of a narrow band having a known wavelength.

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