Electric signal output device

Abstract

The present invention reduces a frequency interval between laser beams of two different wavelengths.　An electric signal output device 1 comprises: a first laser beam output unit 10 that receives a first stabilized laser beam SL1 of a prescribed wavelength λ1 and outputs a first laser beam L1 having a component of a wavelength equal to the prescribed wavelength λ1+m×(first resonance wavelength interval λFSR1); a second laser beam output unit 20 that receives a second stabilized laser beam SL2 of the prescribed wavelength λ1 and outputs a second laser beam L2 having a component of a wavelength equal to the prescribed wavelength λ1+n×(second resonance wavelength interval λFSR2); and a UTC-PD 8 that receives the first laser beam L1 and the second laser beam L2 and outputs an electric signal ES of the frequency of the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2. In this context, m and n are positive integers. The first resonance wavelength interval λFSR1 and the second resonance wavelength interval λFSR2 are different values.

Description

Electrical signal output device

[0001] This invention relates to the output of an electrical signal of any frequency, such as a subterahertz wave.

[0002] Conventionally, a technique has been known in which three ring resonators are used to output laser light of two different wavelengths (see, for example, Patent Document 1). In this case, the frequencies of the two types of laser light are f ＦＳＲ They are separated by a certain distance. However, f ＦＳＲ The Free Spectrum Range (Free Spectrum Range) is the interval between the resonant frequencies of one of the three ring resonators.

[0003] Japanese Patent No. 6327342, Japanese Unexamined Patent Publication No. 2015-225328, Japanese Unexamined Patent Publication No. 2021-092740, Japanese Unexamined Patent Publication No. 2017-022247

[0004] However, according to the conventional technology described above, the frequency interval of two types of laser light wavelengths is determined by the f of a single ring resonator. ＦＳＲ It cannot be less than that.

[0005] Let's assume we are applying laser light of two different wavelengths to a single-traveling carrier photodiode (UTC-PD) and attempting to obtain an electrical signal with the same frequency as the difference Δf between the optical frequencies of the two lasers. In this case, the frequency of that electrical signal is measured by the f of a single ring resonator. ＦＳＲ This means it cannot be reduced below a certain value. This also means a decrease in the frequency resolution of electrical signals.

[0006] Therefore, the present invention aims to reduce the frequency interval between two types of laser light wavelengths.

[0007] The electrical signal output device according to the present invention includes: a first laser light output unit that receives a first stabilized laser light of a predetermined wavelength and outputs a first laser light having a wavelength component of predetermined wavelength + m × (first resonant wavelength interval); a second laser light output unit that receives a second stabilized laser light of a predetermined wavelength and outputs a second laser light having a wavelength component of predetermined wavelength + n × (second resonant wavelength interval); and an electrical signal output unit that receives the first laser light and the second laser light and outputs an electrical signal with a frequency of the difference between the optical frequency of the first laser light and the optical frequency of the second laser light, where m and n are positive integers, the first resonant wavelength interval is the interval of the resonant wavelengths of the first laser light output unit, and the second resonant wavelength interval is the interval of the resonant wavelengths of the second laser light output unit, and the first resonant wavelength interval and the second resonant wavelength interval are configured to be different values.

[0008] According to the electrical signal output device configured as described above, the first laser light output unit receives a first stabilized laser light of a predetermined wavelength and outputs a first laser light having a wavelength component of predetermined wavelength + m × (first resonant wavelength interval). The second laser light output unit receives a second stabilized laser light of a predetermined wavelength and outputs a second laser light having a wavelength component of predetermined wavelength + n × (second resonant wavelength interval). The electrical signal output unit receives the first laser light and the second laser light and outputs an electrical signal with a frequency equal to the difference between the optical frequency of the first laser light and the optical frequency of the second laser light. Hereinafter, m and n are positive integers. The first resonant wavelength interval is the interval of the resonant wavelengths of the first laser light output unit. The second resonant wavelength interval is the interval of the resonant wavelengths of the second laser light output unit. The first resonant wavelength interval and the second resonant wavelength interval are different values.

[0009] Furthermore, the electrical signal output device according to the present invention may be configured such that the electrical signal output unit is UTC-PD.

[0010] Furthermore, the electrical signal output device according to the present invention may be configured such that the first laser beam and the second laser beam further have components of the predetermined wavelength.

[0011] Furthermore, the electrical signal output device according to the present invention may include a reduction unit that reduces the predetermined wavelength components in the first laser light and the second laser light and supplies them to the electrical signal output unit.

[0012] Furthermore, in the electrical signal output device according to the present invention, the reduction unit may be a notch filter.

[0013] Furthermore, in the electrical signal output device according to the present invention, the reduction unit may be a low-pass filter.

[0014] Furthermore, the electrical signal output device according to the present invention may have the following configuration: the first laser light output unit includes a first ring resonator whose resonant wavelength is the predetermined wavelength; a second ring resonator whose resonant wavelength is the predetermined wavelength + m × (first resonant wavelength interval); and a third ring resonator that receives the first stabilized laser light, the first ring resonator, and the second ring resonator, and whose resonant wavelengths are the predetermined wavelength and the predetermined wavelength + m × (first resonant wavelength interval).

[0015] Furthermore, the electrical signal output device according to the present invention may have a second laser light output unit that includes a first ring resonator whose resonant wavelength is the predetermined wavelength, a second ring resonator whose resonant wavelength is the predetermined wavelength + n × (second resonant wavelength interval), and a third ring resonator that receives the second stabilized laser light, the first ring resonator, and the second ring resonator, and whose resonant wavelengths are the predetermined wavelength and the predetermined wavelength + n × (second resonant wavelength interval).

[0016] Furthermore, in the electrical signal output device according to the present invention, the third ring resonator may receive the outputs of the first ring resonator and the second ring resonator from separate locations.

[0017] Furthermore, in the electrical signal output device according to the present invention, the third ring resonator may be configured to receive the outputs of the first ring resonator and the second ring resonator from the same location.

[0018] Furthermore, the electrical signal output device according to the present invention includes, in the first laser light output unit, a first intermediate laser light output unit that receives the first stabilized laser light and outputs a first intermediate laser light having a predetermined wavelength and the predetermined wavelength + m × (first resonant wavelength interval), and a first final laser light output unit that receives the output of the first intermediate laser light output unit and outputs a first final laser light having a wavelength of the predetermined wavelength + m × (first resonant wavelength interval); and in the second laser light output unit, a second intermediate laser light output unit that receives the second stabilized laser light and outputs a second intermediate laser light having a predetermined wavelength and the predetermined wavelength + n × (second resonant wavelength interval), and a second final laser light output unit that receives the output of the second intermediate laser light output unit and outputs a second final laser light having a wavelength of the predetermined wavelength + n × (second resonant wavelength interval), wherein the first final laser light may be the first laser light and the second final laser light may be the second laser light.

[0019] Furthermore, in the electrical signal output device according to the present invention, the first stabilized laser beam and the second stabilized laser beam may be output from the same light source.

[0020] Furthermore, in the electrical signal output device according to the present invention, the first stabilized laser light may be obtained from the output of the second intermediate laser light output unit.

[0021] Furthermore, in the electrical signal output device according to the present invention, the second stabilized laser light may be obtained from the output of the first intermediate laser light output unit.

[0022] Furthermore, in the electrical signal output device according to the present invention, one or both of the first intermediate laser light output unit and the second intermediate laser light output unit may be ring oscillators.

[0023] Furthermore, in the electrical signal output device according to the present invention, one or both of the first intermediate laser light output unit and the second intermediate laser light output unit may be DBR.

[0024] This is a functional block diagram showing the configuration of an electrical signal output device 1 according to the first embodiment of the present invention. This is a diagram showing the configuration of the first laser light output unit 10 according to the first embodiment. This is a diagram showing the configuration of the second laser light output unit 20 according to the first embodiment. This is a diagram showing the configuration of the first laser light output unit 10 according to the second embodiment. This is a diagram showing the configuration of the second laser light output unit 20 according to the second embodiment. This is a functional block diagram showing the configuration of an electrical signal output device 1 according to the third embodiment of the present invention. This is a functional block diagram showing the configuration of an electrical signal output device 1 according to the fourth embodiment of the present invention. This is a functional block diagram showing the configuration of an electrical signal output device 1 according to the fifth embodiment of the present invention. This is a functional block diagram showing the configuration of an electrical signal output device 1 according to the sixth embodiment of the present invention.

[0025] Embodiments of the present invention will be described below with reference to the drawings.

[0026] Figure 1 of the first embodiment is a functional block diagram showing the configuration of an electrical signal output device 1 according to the first embodiment of the present invention. The electrical signal output device 1 according to the first embodiment comprises a stabilized laser light source 2, couplers 3a and 3b, circulators 4a and 4b, a notch filter (reduction unit) 6, a UTC-PD (UTC-PD: Uni-Traveling Carrier Photodiode) (electrical signal output unit) 8, a first laser light output unit 10, and a second laser light output unit 20.

[0027] The stabilized laser light source 2 outputs stabilized laser light SL with a predetermined wavelength λ1. In the drawings (Figure 1, etc.), the wavelength (λ1, etc.) is shown in parentheses following the symbol for light (SL, etc.).

[0028] The coupler 3a receives stabilized laser light SL from the stabilized laser light source 2 and outputs it as a first stabilized laser light SL1 with a predetermined wavelength λ1 and a second stabilized laser light SL2 with a predetermined wavelength λ1.

[0029] The circulator 4a receives the first stabilized laser beam SL1 (wavelength λ1) from the coupler 3a and supplies it to the first laser beam output unit 10. The circulator 4a also receives the first laser beam L1 output by the first laser beam output unit 10 and supplies it to the coupler 3b.

[0030] The first laser light output unit 10 receives the first stabilized laser light SL1 with a predetermined wavelength λ1 and outputs the first laser light L1. The first laser light L1 has a component with a wavelength of a predetermined wavelength λ1 + m × (first resonance wavelength interval λ FSR1 ) and a component with a predetermined wavelength λ1.

[0031] However, m is a positive integer. Also, the first resonance wavelength interval λ FSR1 is the interval between the resonance wavelengths of the first laser light output unit 10.

[0032] The circulator 4b receives the second stabilized laser light SL2 (wavelength λ1) from the coupler 3a and supplies it to the second laser light output unit 20. The circulator 4b also receives the second laser light L2 output from the second laser light output unit 20 and supplies it to the coupler 3b.

[0033] The second laser light output unit 20 receives the second stabilized laser light with a predetermined wavelength λ1 and outputs the second laser light L2. The second laser light L2 has a component with a wavelength of a predetermined wavelength λ1 + n × (second resonance wavelength interval λ FSR2 ) and a component with a predetermined wavelength λ1.

[0034] However, n is a positive integer. Also, the second resonance wavelength interval λ FSR2 is the interval between the resonance wavelengths of the second laser light output unit 20. Also, the first resonance wavelength interval λ FSR1 and the second resonance wavelength interval λ FSR2 are different values.

[0035] The coupler 3b receives the first laser light L1 and the second laser light L2, combines them, and supplies them to the notch filter (reduction unit) 6.

[0036] The notch filter (reduction unit) 6 reduces the component with the predetermined wavelength λ1 in the first laser light L1 and the second laser light L2 and supplies it to the electrical signal output unit 8. The notch filter 6 is a filter that reduces and outputs the component with the predetermined wavelength λ1 and wavelengths in its vicinity. Instead of the notch filter 6, a low-pass filter (reduction unit) that reduces the predetermined wavelength λ1 but does not significantly reduce the components with wavelengths higher than the predetermined wavelength λ1 (i.e., lower frequencies) may be used.

[0037] The UTC-PD (Uni-Traveling Carrier Photodiode) (electrical signal output unit) 8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0038] Figure 2 shows the configuration of the first laser light output unit 10 according to the first embodiment. The first laser light output unit 10 according to the first embodiment includes a first ring resonator 12, a second ring resonator 14, a third ring resonator 16, gain chips 11 and 18, half mirrors 13 and 17, input / output terminals 10a and 10b, and optical waveguides WG1, WG2, WG3 and WG4.

[0039] Input / output terminals 10a and 10b are connected to the circulator 4a. Input / output terminal 10a receives the first stabilized laser beam SL1 and outputs the first laser beam L1 (where the component with wavelength λ1 is present). Input / output terminal 10b receives the first stabilized laser beam SL1 and outputs the first laser beam L1 (where λ1 + m × λ FSR1 It outputs the wavelength components.

[0040] Half mirror 13 has one end connected to input / output terminal 10a and the other end connected to optical waveguide WG2. Half mirror 17 has one end connected to input / output terminal 10b and the other end connected to optical waveguide WG3.

[0041] The first ring resonator 12 has a resonant wavelength of λ1. The first ring resonator 12 is connected to the gain chip 18 via an optical waveguide WG4. The gain chip 18 has one end connected to the optical waveguide WG4 and the other end has a reflector 18a.

[0042] In the drawings (Figure 2, etc.), the resonant wavelength (λ1, etc.) is indicated in parentheses following the reference numeral (12, etc.) indicating components such as the ring resonator.

[0043] The second ring resonator 14 is λ1 + m × λ FSR1This is defined as the resonant wavelength. The second ring resonator 14 is connected to the gain chip 11 via the optical waveguide WG1. The gain chip 11 has one end connected to the optical waveguide WG1 and the other end has a reflector 11a.

[0044] The third ring resonator 16 receives the output of the first ring resonator 12 at part 16a and the output of the second ring resonator 14 at part 16b. In this way, the third ring resonator 16 receives the outputs of the first ring resonator 12 and the second ring resonator 14 from separate parts 16a and 16b. The third ring resonator 16 also receives the first stabilized laser beam SL1 input from input / output terminals 10a and 10b.

[0045] The third ring resonator 16 is composed of λ1 and λ1 + m × λ FSR1 This is defined as the resonant wavelength. The third ring resonator 16 is connected to the optical waveguide WG3 at part 16a and to the optical waveguide WG2 at part 16b.

[0046] Optical waveguide WG2 is connected to the second ring resonator 14 between the half mirror 13 and section 16b. Optical waveguide WG3 is connected to the first ring resonator 12 between the half mirror 17 and section 16a.

[0047] The resonant wavelength intervals of the first ring resonator 12, the second ring resonator 14, and the third ring resonator 16 are all different values.

[0048] Figure 3 shows the configuration of the second laser light output unit 20 according to the first embodiment. The second laser light output unit 20 according to the first embodiment includes a first ring resonator 22, a second ring resonator 24, a third ring resonator 26, gain chips 21 and 28, half mirrors 23 and 27, input / output terminals 20a and 20b, and optical waveguides WG1, WG2, WG3 and WG4.

[0049] Input / output terminals 20a and 20b are connected to the circulator 4b. Input / output terminal 20a receives the second stabilized laser beam SL2 and outputs the second laser beam L2 (where the component with wavelength λ1). Input / output terminal 20b receives the second stabilized laser beam SL2 and outputs the second laser beam L2 (where λ1 + n × λ FSR2It outputs the wavelength components.

[0050] Half mirror 23 has one end connected to input / output terminal 20a and the other end connected to optical waveguide WG2. Half mirror 27 has one end connected to input / output terminal 20b and the other end connected to optical waveguide WG3.

[0051] The first ring resonator 22 has a resonant wavelength of λ1. The first ring resonator 22 is connected to the gain chip 28 via an optical waveguide WG4. The gain chip 28 has one end connected to the optical waveguide WG4 and the other end has a reflector 28a.

[0052] The second ring resonator 24 is λ1 + n × λ FSR2 This is defined as the resonant wavelength. The second ring resonator 24 is connected to the gain chip 21 via the optical waveguide WG1. The gain chip 21 has one end connected to the optical waveguide WG1 and the other end has a reflector 21a.

[0053] The third ring resonator 26 receives the output of the first ring resonator 22 at part 26a and the output of the second ring resonator 24 at part 26b. In this way, the third ring resonator 26 receives the outputs of the first ring resonator 22 and the second ring resonator 24 from separate parts 26a and 26b. The third ring resonator 26 also receives the second stabilized laser beam SL2 input from input / output terminals 20a and 20b.

[0054] The third ring resonator 26 is composed of λ1 and λ1 + n × λ FSR2 This is defined as the resonant wavelength. The third ring resonator 26 is connected to the optical waveguide WG3 at part 26a and to the optical waveguide WG2 at part 26b.

[0055] Optical waveguide WG2 is connected to the second ring resonator 24 between the half mirror 23 and section 26b. Optical waveguide WG3 is connected to the first ring resonator 22 between the half mirror 27 and section 26a.

[0056] The resonant wavelength intervals of the first ring resonator 22, the second ring resonator 24, and the third ring resonator 26 are all different values.

[0057] Next, the operation of the first embodiment will be described.

[0058] First, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 is split by the coupler 3a into a first stabilized laser light SL1 (wavelength λ1) and a second stabilized laser light SL2 (wavelength λ1).

[0059] The first stabilized laser beam SL1 is supplied to the first laser beam output unit 10 via the circulator 4a. The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20 via the circulator 4b.

[0060] The first laser light output unit 10 outputs the first laser light L1. The first laser light L1 is λ1 + m × λ FSR1 It has a wavelength component and a component at a predetermined wavelength λ1.

[0061] Referring to Figure 2, the first stabilized laser beam SL1 (wavelength λ1) input to the input / output terminal 10a passes through the half mirror 13, travels through the optical waveguide WG2, and reaches portion 16b of the third ring resonator 16. Since the third ring resonator 16 has λ1 as its resonant wavelength, a drop of light with wavelength λ1 is output from portion 16a and travels through the optical waveguide WG3. When the drop of light with wavelength λ1 that has traveled through the optical waveguide WG3 reaches the first ring resonator 12 (resonant wavelength λ1), the drop of light with wavelength λ1 is output from the first ring resonator 12, travels through the optical waveguide WG4, reaches the gain tip 18, and is reflected by the reflector 18a. The reflected drop light of wavelength λ1 travels through the optical waveguide WG4 and reaches the first ring resonator 12. Thereupon, drop light of wavelength λ1 is output from the first ring resonator 12, travels through the optical waveguide WG3, and reaches part 16a of the third ring resonator 16. Then, drop light of wavelength λ1 is output from part 16b, travels through the optical waveguide WG2, passes through the half mirror 13, and is output from the input / output terminal 10a as the first laser light L1 (with a component of wavelength λ1).

[0062] The first stabilized laser beam SL1 (wavelength λ1) input to the input / output terminal 10b passes through the half mirror 17, propagates through the optical waveguide WG3, passes through the first ring resonator 12, is supplied to the optical waveguide WG4, and is emitted to the outside. As described above, the first stabilized laser beam SL1 (wavelength λ1) input to the input / output terminal 10a contributes to the stabilization of the third ring resonator 16. The third ring resonator 16 is λ1 + m × λ FSR1 To make this the resonant wavelength, the wavelength λ1 + m × λ is set from part 16b. FSR1 A drop of light is emitted and propagates through the optical waveguide WG2. The wavelength of light propagating through the optical waveguide WG2 is λ1 + m × λ FSR1 The drop light is transmitted to the second ring resonator 14 (resonance wavelength λ1 + m × λ). FSR1 When it reaches ), the wavelength λ1 + m × λ is emitted from the second ring resonator 14. FSR1 The resulting drop light is output, travels through the optical waveguide WG1, reaches the gain tip 11, and is reflected by the reflector 11a. The reflected wavelength is λ1 + m × λ FSR1 The dropped light travels through the optical waveguide WG1 and, upon reaching the second ring resonator 14, emits light at a wavelength of λ1 + m × λ from the second ring resonator 14. FSR1 A drop of light is emitted, and this drop of light propagates through the optical waveguide WG2 and reaches part 16b of the third ring resonator 16. Then, from part 16a, the wavelength λ1 + m × λ FSR1 The drop light is output, passes through the optical waveguide WG3 and the half mirror 17, and the first laser beam L1 (where λ1 + m × λ) is emitted from the input / output terminal 10b. FSR1 It is output as a component of the wavelength.

[0063] The second laser light output unit 20 outputs the second laser light L2. The second laser light L2 is λ1 + n × λ FSR2 It has a wavelength component and a component at a predetermined wavelength λ1.

[0064] Referring to Figure 3, the first stabilized laser beam SL2 (wavelength λ1) input to the input / output terminal 20a passes through the half mirror 23, travels through the optical waveguide WG2, and reaches portion 26b of the third ring resonator 26. Since the third ring resonator 26 has λ1 as its resonant wavelength, a drop of light with wavelength λ1 is output from portion 26a and travels through the optical waveguide WG3. When the drop of light with wavelength λ1 that has traveled through the optical waveguide WG3 reaches the first ring resonator 22 (resonant wavelength λ1), a drop of light with wavelength λ1 is output from the first ring resonator 22, travels through the optical waveguide WG4, reaches the gain tip 28, and is reflected by the reflector 28a. The reflected drop light of wavelength λ1 travels through the optical waveguide WG4 and reaches the first ring resonator 22. Thereupon, drop light of wavelength λ1 is output from the first ring resonator 22, travels through the optical waveguide WG3, and reaches part 26a of the third ring resonator 26. Then, drop light of wavelength λ1 is output from part 26b, travels through the optical waveguide WG2, passes through the half mirror 23, and is output from the input / output terminal 20a as the second laser light L2 (with a component of wavelength λ1).

[0065] The second stabilized laser beam SL2 (wavelength λ1) input to the input / output terminal 20b passes through the half mirror 27, propagates through the optical waveguide WG3, passes through the first ring resonator 22, is supplied to the optical waveguide WG4, and is emitted to the outside. As described above, the first stabilized laser beam SL2 (wavelength λ1) input to the input / output terminal 20a contributes to the stabilization of the third ring resonator 26. The third ring resonator 26 is λ1 + n × λ FSR2 To make this the resonant wavelength, the wavelength λ1 + n × λ is set from part 26b. FSR2 A drop of light is emitted and propagates through the optical waveguide WG2. The wavelength of light propagating through the optical waveguide WG2 is λ1 + n × λ FSR2 The drop light is transmitted to the second ring resonator 24 (resonance wavelength λ1 + n × λ). FSR2 When it reaches ), the wavelength λ1 + n × λ is emitted from the second ring resonator 24. FSR2 The resulting drop light is output, travels through the optical waveguide WG1, reaches the gain tip 21, and is reflected by the reflector 21a. The reflected wavelength is λ1 + n × λ FSR2The dropped light travels through the optical waveguide WG1 and, upon reaching the second ring resonator 24, emits light at a wavelength of λ1 + n × λ from the second ring resonator 24. FSR2 A drop of light is emitted, and this drop of light propagates through the optical waveguide WG2 and reaches part 26b of the third ring resonator 26. Then, from part 26a, the wavelength λ1 + m × λ FSR1 The resulting drop light is output, passes through the optical waveguide WG3 and the half mirror 27, and exits the input / output terminal 20b as the second laser beam L2 (where λ1 + n × λ FSR2 It is output as a component of the wavelength.

[0066] The first laser beam L1 and the second laser beam L2 are combined by the coupler 3b and supplied to the UTC-PD8 via the notch filter 6. The first laser beam L1 and the second laser beam L2 supplied to the UTC-PD8 have a reduced wavelength component λ1. That is, the first laser beam L1 supplied to the UTC-PD8 has a wavelength component of λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0067] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0068] By setting m appropriately, the first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 The interval between the optical frequencies of the wavelength components can be set to a predetermined interval (e.g., 10 GHz). For example, λ¹ + m × λ FSR1 The optical frequencies of the wavelength components can be set to f0 + 10 GHz, f0 + 20 GHz, f0 + 30 GHz, ..., f0 + 110 GHz. Note that f0 is a predetermined optical frequency.

[0069] By setting n appropriately, the second laser beam L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 The interval between the optical frequencies of the wavelength components can be set to a predetermined interval (for example, 11 GHz). For example, λ¹ + n × λ FSR2The optical frequencies of the wavelength components can be set to f0 + 11 GHz, f0 + 22 GHz, f0 + 33 GHz, ..., f0 + 121 GHz.

[0070] In this case, the first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 The optical frequency of the wavelength component and the λ1 + n × λ of the second laser beam L2 supplied to UTC-PD8 FSR2 The difference between the wavelength component and the optical frequency can be set to 1GHz intervals as follows: (f0 + 11GHz) - (f0 + 10GHz) = 1GHz (f0 + 22GHz) - (f0 + 20GHz) = 2GHz (f0 + 33GHz) - (f0 + 30GHz) = 3GHz ... (f0 + 121GHz) - (f0 + 110GHz) = 11GHz (f0 + 22GHz) - (f0 + 10GHz) = 12GHz (f0 + 33GHz) - (f0 + 20GHz) = 13GHz ... (f0 + 121GHz) - (f0 + 10GHz) = 111GHz In this case, the frequency of the electrical signal ES output by UTC-PD8 can be changed from 1GHz to 111GHz in 1GHz intervals.

[0071] According to the first embodiment, by using two types of laser light output units, such as a first laser light output unit 10 and a second laser light output unit 20, the frequency interval between two types of laser light wavelengths can be reduced. For example, the frequency interval between the first laser light L1 and the second laser light L2 can be set to a value of 1 GHz, which is smaller than the resonant frequency interval of the first laser light output unit 10 (10 GHz) and the resonant frequency interval of the second laser light output unit 20 (11 GHz).

[0072] The second embodiment of the electrical signal output device 1 differs from the first embodiment in that, in the first laser light output unit 10 and the second laser light output unit 20, the third ring resonator 16 receives the outputs of the first ring resonator 12 and the second ring resonator 14 from the same part 16a (see Figure 4), and the third ring resonator 26 receives the outputs of the first ring resonator 22 and the second ring resonator 24 from the same part 26a (see Figure 5).

[0073] The configuration of the electrical signal output device 1 according to the second embodiment is the same as that of the first embodiment (see Figure 1). However, the first laser light output unit 10 according to the second embodiment is a replacement of the first laser light output unit 10 according to the first embodiment (see Figure 2) with the configuration shown in Figure 4. Also, the second laser light output unit 20 according to the second embodiment is a replacement of the second laser light output unit 20 according to the first embodiment (see Figure 3) with the configuration shown in Figure 5.

[0074] The electrical signal output device 1 according to the second embodiment (see Figure 1) comprises a stabilized laser light source 2, couplers 3a and 3b, circulators 4a and 4b, a notch filter (reduction unit) 6, a UTC-PD (UTC-PD: Uni-Traveling Carrier Photodiode) (electrical signal output unit) 8, a first laser light output unit 10, and a second laser light output unit 20. The stabilized laser light source 2, couplers 3a and 3b, circulators 4a and 4b, notch filter (reduction unit) 6, and UTC-PD (UTC-PD: Uni-Traveling Carrier Photodiode) (electrical signal output unit) 8 are the same as in the first embodiment, so their description is omitted.

[0075] Figure 4 shows the configuration of the first laser light output unit 10 according to the second embodiment. The first laser light output unit 10 according to the second embodiment includes a first ring resonator 12, a second ring resonator 14, a third ring resonator 16, a gain chip 18, a half mirror 13, input / output terminals 10a, and optical waveguides WG2, WG3, and WG4.

[0076] The input / output terminal 10a is connected to the circulator 4a. The input / output terminal 10a receives the first stabilized laser beam SL1 and the first laser beam L1 (component of wavelength λ1 and λ1 + m × λ FSR1 It outputs (which has wavelength components).

[0077] One end of the half-mirror 13 is connected to the input / output terminal 10a, and the other end is connected to the optical waveguide WG2.

[0078] The first ring resonator 12 has a resonant wavelength of λ1. The first ring resonator 12 is connected to the gain chip 18 via an optical waveguide WG4. The gain chip 18 has one end connected to the optical waveguide WG4 and the other end has a reflector 18a. The reflectivity of the reflector 18a may be set to transmit some of the incident light from the optical waveguide WG4. In this case, the light transmitted through the reflector 18a is directed to the circulator 4a as the output of the first laser light output unit 10.

[0079] The second ring resonator 14 is λ1 + m × λ FSR1 This is defined as the resonant wavelength. The second ring resonator 14 is connected to the gain chip 18 via the optical waveguide WG4.

[0080] The third ring resonator 16 receives the outputs of the first ring resonator 12 and the second ring resonator 14 at part 16a. In this way, the third ring resonator 16 receives the outputs of the first ring resonator 12 and the second ring resonator 14 from the same part 16a. The third ring resonator 16 also receives the first stabilized laser beam SL1 input from the input / output terminal 10a.

[0081] The third ring resonator 16 is composed of λ1 and λ1 + m × λ FSR1 This is defined as the resonant wavelength. The third ring resonator 16 is connected to the optical waveguide WG3 at part 16a and to the optical waveguide WG2 at part 16b.

[0082] The optical waveguide WG3 is connected to the first ring resonator 12 and the second ring resonator 14. The first ring resonator 12 is connected to the optical waveguide WG3 between portion 16a and the second ring resonator 14.

[0083] The resonant wavelength intervals of the first ring resonator 12, the second ring resonator 14, and the third ring resonator 16 are all different values.

[0084] Figure 5 shows the configuration of the second laser light output unit 20 according to the second embodiment. The first laser light output unit 20 according to the second embodiment includes a first ring resonator 22, a second ring resonator 24, a third ring resonator 26, a gain chip 28, a half mirror 23, an input / output terminal 20a, and optical waveguides WG2, WG3, and WG4.

[0085] The input / output terminal 20a is connected to the circulator 4b. The input / output terminal 20a receives the second stabilized laser light SL2 and the second laser light L2 (component of wavelength λ1 and λ1 + n × λ FSR2 It outputs (which has wavelength components).

[0086] One end of the half-mirror 23 is connected to the input / output terminal 20a, and the other end is connected to the optical waveguide WG2.

[0087] The first ring resonator 22 has a resonant wavelength of λ1. The first ring resonator 22 is connected to the gain chip 28 via an optical waveguide WG4. The gain chip 28 has one end connected to the optical waveguide WG4 and the other end has a reflector 28a. The reflectivity of the reflector 28a may be set to transmit some of the incident light from the optical waveguide WG4. In this case, the light transmitted through the reflector 28a is directed to the circulator 4b as the output of the second laser light output unit 20.

[0088] The second ring resonator 24 is λ1 + n × λ FSR2 This is defined as the resonant wavelength. The second ring resonator 24 is connected to the gain chip 28 via the optical waveguide WG4.

[0089] The third ring resonator 26 receives the outputs of the first ring resonator 22 and the second ring resonator 24 at part 26a. In this way, the third ring resonator 26 receives the outputs of the first ring resonator 22 and the second ring resonator 24 from the same part 26a. The third ring resonator 26 also receives the second stabilized laser beam SL2 input from the input / output terminal 20a.

[0090] The third ring resonator 26 is composed of λ1 and λ1n × λ FSR2This is defined as the resonant wavelength. The third ring resonator 26 is connected to the optical waveguide WG3 at part 26a and to the optical waveguide WG2 at part 26b.

[0091] The optical waveguide WG3 is connected to the first ring resonator 22 and the second ring resonator 24. The first ring resonator 22 is connected to the optical waveguide WG3 between portion 26a and the second ring resonator 24.

[0092] The resonant wavelength intervals of the first ring resonator 22, the second ring resonator 24, and the third ring resonator 26 are all different values.

[0093] Next, the operation of the second embodiment will be described.

[0094] First, referring to Figure 1, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 is split by the coupler 3a into a first stabilized laser light SL1 (wavelength λ1) and a second stabilized laser light SL2 (wavelength λ1).

[0095] The first stabilized laser beam SL1 is supplied to the first laser beam output unit 10 via the circulator 4a. The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20 via the circulator 4b.

[0096] The first laser light output unit 10 outputs the first laser light L1. The first laser light L1 is λ1 + m × λ FSR1 It has a wavelength component and a component at a predetermined wavelength λ1.

[0097] Referring to Figure 4, the first stabilized laser beam SL1 (wavelength λ1) input to the input / output terminal 10a passes through the half mirror 13, propagates through the optical waveguide WG2, and reaches the portion 16b of the third ring resonator 16. The third ring resonator 16 is composed of λ1 and λ1 + m × λ FSR1 To make this the resonant wavelength, wavelength λ1 and wavelength λ1 + m × λ FSR1 The resulting drop light is emitted from part 16a and propagates through the optical waveguide WG3.

[0098] The drop light of wavelength λ1 that travels through the optical waveguide WG3 reaches the first ring resonator 12 (resonance wavelength λ1), where it is output from the first ring resonator 12, travels through the optical waveguide WG4, reaches the gain tip 18, and is reflected by the reflector 18a. The reflected drop light of wavelength λ1 travels through the optical waveguide WG4, and when it reaches the first ring resonator 12, it is output from the first ring resonator 12, travels through the optical waveguide WG3, and reaches part 16a of the third ring resonator 16. Then, drop light of wavelength λ1 is output from part 16b, and this drop light travels through the optical waveguide WG2, passes through the half mirror 13, and is output from the input / output terminal 10a as the first laser beam L1 (however, the component with wavelength λ1).

[0099] Wavelength λ1 + m × λ propagated through optical waveguide WG3 FSR1 The drop light is transmitted to the second ring resonator 14 (resonance wavelength λ1 + m × λ). FSR1 When it reaches the wavelength λ1 + m × λ, FSR1 The drop light is output from the second ring resonator 14, travels through the optical waveguide WG4, reaches the gain tip 18, and is reflected by the reflector 18a. The reflected wavelength is λ1 + m × λ FSR1 The dropped light travels through the optical waveguide WG4 and, upon reaching the second ring resonator 14, emits light at a wavelength of λ1 + m × λ from the second ring resonator 14. FSR1 A drop of light is emitted, propagates through the optical waveguide WG3, and reaches part 16a of the third ring resonator 16. Then, from part 16b, a wavelength λ1 + m × λ FSR1 A drop of light is output, and this drop of light travels through the optical waveguide WG2, passes through the half mirror 13, and is emitted from the input / output terminal 10a as the first laser beam L1 (where the wavelength is λ1 + m × λ FSR1 It is output as a component of [the product].

[0100] However, if the reflectivity of the reflecting portion 18a is such that it transmits incident light from the optical waveguide WG4 to a certain extent, the light transmitted through the reflecting portion 18a may be used as the first laser beam L1.

[0101] The second laser light output unit 20 outputs the second laser light L2. The second laser light L2 is λ1 + n × λ FSR2It has a wavelength component and a component at a predetermined wavelength λ1.

[0102] Referring to Figure 5, the second stabilized laser beam SL2 (wavelength λ1) input to the input / output terminal 20a passes through the half mirror 23, propagates through the optical waveguide WG2, and reaches the portion 26b of the third ring resonator 26. The third ring resonator 26 is composed of λ1 and λ1 + n × λ FSR2 To make this the resonant wavelength, wavelength λ1 and wavelength λ1 + n × λ FSR2 The resulting drop light is emitted from part 26a and propagates through the optical waveguide WG3.

[0103] The drop light of wavelength λ1 that travels through the optical waveguide WG3 reaches the first ring resonator 22 (resonance wavelength λ1), where it is output from the first ring resonator 22, travels through the optical waveguide WG4, reaches the gain tip 28, and is reflected by the reflector 28a. The reflected drop light of wavelength λ1 travels through the optical waveguide WG4, and when it reaches the first ring resonator 22, it is output from the first ring resonator 22, travels through the optical waveguide WG3, and reaches part 26a of the third ring resonator 26. Then, drop light of wavelength λ1 is output from part 26b, and this drop light travels through the optical waveguide WG2, passes through the half mirror 23, and is output from the input / output terminal 20a as the second laser beam L2 (however, the component with wavelength λ1).

[0104] The wavelength λ1 + n × λ propagated through the optical waveguide WG3 FSR2 The drop light is transmitted to the second ring resonator 24 (resonance wavelength λ1 + n × λ). FSR2 When it reaches the wavelength λ1 + n × λ, FSR2 The drop light is output from the second ring resonator 24, travels through the optical waveguide WG4, reaches the gain tip 28, and is reflected by the reflector 28a. The reflected wavelength is λ1 + n × λ FSR2 The dropped light travels through the optical waveguide WG4 and, upon reaching the second ring resonator 24, emits wavelength λ1 + n × λ from the second ring resonator 24. FSR2 A drop of light is emitted, propagates through the optical waveguide WG3, and reaches part 26a of the third ring resonator 26. Then, from part 26b, a wavelength λ1 + n × λ FSR2A drop of light is output, and this drop of light propagates through the optical waveguide WG2, passes through the half mirror 23, and exits the input / output terminal 20a as the second laser beam L2 (where the wavelength is λ1 + n × λ FSR2 It is output as a component of [the product].

[0105] However, if the reflectivity of the reflecting portion 28a is such that it transmits incident light from the optical waveguide WG4 to a certain extent, the light transmitted through the reflecting portion 28a may be used as the second laser beam L2.

[0106] The first laser beam L1 and the second laser beam L2 are combined by the coupler 3b and supplied to the UTC-PD8 via the notch filter 6. The first laser beam L1 and the second laser beam L2 supplied to the UTC-PD8 have a reduced wavelength component λ1. That is, the first laser beam L1 supplied to the UTC-PD8 has a wavelength component of λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0107] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0108] The frequency of the electrical signal ES is the same as in the first embodiment, so its explanation is omitted.

[0109] The second embodiment also produces the same effects as the first embodiment.

[0110] Third Embodiment The electrical signal output device 1 according to the third embodiment differs from the first embodiment in that the first laser light output unit 10 has a first intermediate laser light output unit 102 and a first final laser light output unit 104, and the second laser light output unit 20 has a second intermediate laser light output unit 202 and a second final laser light output unit 204.

[0111] Figure 6 is a functional block diagram showing the configuration of an electrical signal output device 1 according to a third embodiment of the present invention. The electrical signal output device 1 according to the third embodiment comprises a stabilized laser light source 2, an isolator 5, a coupler 7, a UTC-PD (electrical signal output unit) 8, a half mirror 9, a first laser light output unit 10, a second laser light output unit 20, and an optical waveguide WG0.

[0112] The stabilized laser light source 2 outputs stabilized laser light SL with a predetermined wavelength λ1.

[0113] The isolator 5 receives the stabilized laser beam SL and supplies it to the coupler 7. The isolator 5 is intended to prevent light from returning to the stabilized laser light source 2.

[0114] The coupler 7 receives the stabilized laser beam SL and outputs it as a first stabilized laser beam SL1 with a predetermined wavelength λ1 and a second stabilized laser beam SL2 with a predetermined wavelength λ1. This means that the first stabilized laser beam L1 and the second stabilized laser beam L2 are output from the same light source (stabilized laser light source 2).

[0115] The first laser light output unit 10 receives a first stabilized laser light SL1 with a predetermined wavelength λ1 and outputs a first laser light L1. The first laser light L1 has a predetermined wavelength λ1 + m × (first resonant wavelength interval λ FSR1 It has components with wavelengths of ).

[0116] However, m is a positive integer. Also, the first resonant wavelength interval λ FSR1 This is the interval of the resonant wavelengths of the first laser light output unit 10.

[0117] The second laser light output unit 20 receives a second stabilized laser light of a predetermined wavelength λ1 and outputs a second laser light L2. The second laser light L2 is calculated as follows: predetermined wavelength λ1 + n × (second resonant wavelength interval λ FSR2 It has components with wavelengths of ).

[0118] However, n is a positive integer. Also, the second resonant wavelength interval λ FSR2 λ is the interval of the resonant wavelengths of the second laser light output unit 20. FSR1 and the second resonance wavelength interval λ FSR2 These two values ​​are different.

[0119] The optical waveguide WG0 is connected to the first laser light output unit 10 and the second laser light output unit 20, through which the first laser light L1 and the second laser light L2 propagate. The half mirror 9 is connected to one end of the optical waveguide WG0 and receives the first laser light L1 and the second laser light L2 and supplies them to the UTC-PD (electrical signal output unit) 8.

[0120] The UTC-PD (electrical signal output unit) 8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0121] The coupler 7, the first laser light output unit 10, the second laser light output unit 20, the optical waveguide WG0, and the half mirror 9 are all integrated into a single optical integrated circuit.

[0122] The first laser light output unit 10 includes optical waveguides WG11 and WG12, a gain chip 101, a first intermediate ring oscillator (first intermediate laser light output unit) 102, a mirror 103, and a first final ring oscillator (first final laser light output unit) 104.

[0123] One end of the optical waveguide WG11 is connected to the coupler 7. The gain chip 101, the first intermediate ring oscillator 102, and the first final ring oscillator 104 are also connected to the optical waveguide WG11.

[0124] The gain chip 101 receives the first stabilized laser beam SL1 and supplies it to the first intermediate ring oscillator 102.

[0125] The first intermediate ring oscillator (first intermediate laser light output unit) 102 receives the first stabilized laser light SL1 via the gain chip 101. The first intermediate ring oscillator 102 receives a predetermined wavelength λ1 and a predetermined wavelength λ1 + m × (first resonant wavelength interval λ FSR1 The first intermediate laser beam is output at a predetermined wavelength λ1 and a predetermined wavelength λ1 + m × (first resonant wavelength interval λ). FSR1 ) is defined as the resonant wavelength.

[0126] Mirror 103 reflects the output of the first intermediate ring oscillator 102 back to the first intermediate ring oscillator 102. One end of the optical waveguide WG12 is connected to the mirror 103. The first intermediate ring oscillator 102 is connected to the optical waveguide WG12.

[0127] The first final ring oscillator (first final laser light output unit) 104 receives the output of the first intermediate ring oscillator (first intermediate laser light output unit) 102 and outputs a predetermined wavelength λ1 + m × (first resonant wavelength interval λ FSR1 The first final laser beam has a wavelength of λ1 + m × (first resonant wavelength interval λ). FSR1 ) is defined as the resonant wavelength.

[0128] The resonant wavelength intervals of the first intermediate ring oscillator 102 and the first final ring oscillator 104 are different values.

[0129] The second laser light output unit 20 includes optical waveguides WG21 and WG22, a gain chip 201, a second intermediate ring oscillator (second intermediate laser light output unit) 202, a mirror 203, and a second final ring oscillator (second final laser light output unit) 204.

[0130] One end of the optical waveguide WG21 is connected to the coupler 7. The gain chip 201, the second intermediate ring oscillator 202, and the second final ring oscillator 204 are also connected to the optical waveguide WG21.

[0131] The gain chip 201 receives the second stabilized laser beam SL2 and supplies it to the second intermediate ring oscillator 202.

[0132] The second intermediate ring oscillator (second intermediate laser light output section) 202 receives the second stabilized laser light SL2 via the gain chip 201. The second intermediate ring oscillator 202 receives a predetermined wavelength λ1 and a predetermined wavelength λ1 + n × (second resonant wavelength interval λ) FSR2 The second intermediate laser beam is output at a predetermined wavelength λ1 and a predetermined wavelength λ1 + n × (second resonant wavelength interval λ). FSR2 ) is defined as the resonant wavelength.

[0133] Mirror 203 reflects the output of the second intermediate ring oscillator 202 back to the second intermediate ring oscillator 202. One end of the optical waveguide WG22 is connected to the mirror 203. The first intermediate ring oscillator 202 is connected to the optical waveguide WG22.

[0134] The second final ring oscillator (second final laser light output unit) 204 receives the output of the second intermediate ring oscillator (second intermediate laser light output unit) 202 and outputs a predetermined wavelength λ1 + n × (second resonant wavelength interval λ FSR2 The second final laser beam has a wavelength of λ1 + n × (second resonant wavelength interval λ). This second final laser beam is the second laser beam L2. The second final ring oscillator 204 outputs a predetermined wavelength λ1 + n × (second resonant wavelength interval λ). FSR2 ) is defined as the resonant wavelength.

[0135] The resonant wavelength intervals of the second intermediate ring oscillator 202 and the second final ring oscillator 204 are different values.

[0136] In addition, one or both of the first intermediate laser light output unit and the second intermediate laser light output unit may be ring oscillators (first intermediate ring oscillator 102, second intermediate ring oscillator 202).

[0137] Next, the operation of the third embodiment will be described.

[0138] First, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 passes through the isolator 5 and is split by the coupler 7 into a first stabilized laser light SL1 (wavelength λ1) and a second stabilized laser light SL2 (wavelength λ1).

[0139] The first stabilized laser beam SL1 is supplied to the first laser beam output unit 10. The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20.

[0140] The first laser light output unit 10 outputs the first laser light L1. The first laser light L1 is λ1 + m × λ FSR1 It has components of the wavelength.

[0141] The first stabilized laser beam SL1 travels through the optical waveguide WG11 of the first laser beam output unit 10 and is applied to the first intermediate ring oscillator 102 via the gain chip 101. The first intermediate ring oscillator 102 has resonance wavelengths of λ1 and λ1 + m×λ FSR1 Therefore, the drop beams with wavelengths of λ1 and λ1 + m×λ FSR1 are output from the first intermediate ring oscillator 102, travel through the optical waveguide WG12, are reflected by the mirror 103, and return to the first intermediate ring oscillator 102. As a result, the drop beams with wavelengths of λ1 and λ1 + m×λ FSR1 are output from the first intermediate ring oscillator 102, travel through the optical waveguide WG11, and are applied to the first final ring oscillator 104.

[0142] Since the first final ring oscillator 104 has a resonance wavelength of λ1 + m×λ FSR1 the drop beam with the wavelength of λ1 + m×λ FSR1 is output from the first final ring oscillator 104 as the first final laser beam (the first laser beam L1) and travels through the optical waveguide WG0.

[0143] The second laser beam output unit 20 outputs the second laser beam L2. The second laser beam L2 has a component with a wavelength of λ1 + n×λ FSR2

[0144] The second stabilized laser beam SL2 travels through the optical waveguide WG21 of the second laser beam output unit 20 and is applied to the second intermediate ring oscillator 202 via the gain chip 201. The second intermediate ring oscillator 202 has resonance wavelengths of λ1 and λ1 + n×λ FSR2 Therefore, the drop beams with wavelengths of λ1 and λ1 + n×λ FSR2 are output from the second intermediate ring oscillator 202, travel through the optical waveguide WG22, are reflected by the mirror 203, and return to the second intermediate ring oscillator 202. As a result, the drop beams with wavelengths of λ1 and λ1 + n×λ FSR2 are output from the second intermediate ring oscillator 202, travel through the optical waveguide WG21, and are applied to the second final ring oscillator 204.

[0145] Since the second final ring oscillator 204 has a resonance wavelength of λ1 + n×λ FSR2 the drop beam with the wavelength of λ1 + n×λFSR2 The resulting drop light is output from the second final ring oscillator 204 as the second final laser beam (second laser beam L2) and travels through the optical waveguide WG0.

[0146] The first laser beam L1 and the second laser beam L2 both travel through the optical waveguide WG0 and are supplied to UTC-PD8 via the half mirror 9. The first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0147] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0148] The frequency of the electrical signal ES is the same as in the first embodiment, so its explanation is omitted.

[0149] The third embodiment also produces the same effects as the first embodiment. Furthermore, according to the third embodiment, the notch filter 6 in the first embodiment is unnecessary.

[0150] The fourth embodiment of the electrical signal output device 1 differs from the third embodiment in that the first laser light output unit 10 obtains the first stabilized laser light SL1 from the output of the second intermediate laser light output unit 202 via a ring oscillator 30.

[0151] Figure 7 is a functional block diagram showing the configuration of an electrical signal output device 1 according to a fourth embodiment of the present invention. The electrical signal output device 1 according to the fourth embodiment comprises a stabilized laser light source 2, an isolator 5, a coupler 7, a UTC-PD (electrical signal output unit) 8, a half mirror 9, a first laser light output unit 10, a second laser light output unit 20, a ring oscillator 30, and an optical waveguide WG0. Hereinafter, parts the same as those in the third embodiment are denoted by the same reference numerals and their description is omitted.

[0152] The stabilized laser light source 2, isolator 5, UTC-PD (electrical signal output unit) 8, half mirror 9, and second laser light output unit 20 are the same as in the third embodiment and will not be described.

[0153] The coupler 7 receives the stabilized laser beam SL and outputs it as a second stabilized laser beam SL2 with a predetermined wavelength λ1.

[0154] The first laser light output unit 10 includes optical waveguides WG11 and WG12, a gain chip 101, a first intermediate ring oscillator (first intermediate laser light output unit) 102, a mirror 103, and a first final ring oscillator (first final laser light output unit) 104. The first laser light output unit 10 is the same as in the third embodiment and will not be described further.

[0155] However, the optical waveguide WG11 is connected to the ring oscillator 30.

[0156] Furthermore, the optical waveguide WG21 of the second laser light output unit 20 is also connected to the ring oscillator 30.

[0157] The ring oscillator 30 has a resonant wavelength of a predetermined wavelength λ1.

[0158] Next, the operation of the fourth embodiment will be described.

[0159] First, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 passes through the isolator 5 and is output as the second stabilized laser light SL2 (wavelength λ1) by the coupler 7.

[0160] The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20. The second laser beam output unit 20 outputs the second laser beam L2. The second laser beam L2 is λ1 + n × λ FSR2 It has components of the wavelength.

[0161] The operation of the second laser light output unit 20 is the same as in the third embodiment, and therefore will not be described. However, the second intermediate ring oscillator 202 outputs wavelengths λ1 and λ1 + n × λ FSR2 When the drop light is output and travels through the optical waveguide WG21 and is supplied to the second final ring oscillator 204, the through light of wavelength λ1 travels through the optical waveguide WG21 and heads toward the ring oscillator 30.

[0162] The through-light of wavelength λ1 that travels through the optical waveguide WG21 of the second laser light output unit 20 is supplied to the ring oscillator 30. Since the resonant wavelength of the ring oscillator 30 is wavelength λ1, the drop light of wavelength λ1 is supplied to the optical waveguide WG11 of the first laser light output unit 10 as the first stabilized laser light SL1. This means that the first stabilized laser light SL1 is obtained from the output of the second intermediate laser light output unit 202 via the second final ring oscillator 204 and the ring oscillator 30. Conversely, it is also conceivable to obtain the second stabilized laser light SL2 from the output of the first intermediate ring oscillator 102 via the first final ring oscillator 104 and the ring oscillator 30.

[0163] The operation of the first laser light output unit 10 is the same as in the third embodiment, and therefore will not be described.

[0164] The first laser beam L1 and the second laser beam L2 both travel through the optical waveguide WG0 and are supplied to UTC-PD8 via the half mirror 9. The first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0165] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0166] The frequency of the electrical signal ES is the same as in the first embodiment, so its explanation is omitted.

[0167] The fourth embodiment also produces the same effects as the third embodiment.

[0168] Fifth Embodiment The electrical signal output device 1 according to the fifth embodiment differs from the fourth embodiment in that the first intermediate laser light output unit (first intermediate DBR 106) and the second intermediate laser light output unit (second intermediate DBR 206) are DBRs (distributed Bragg reflectors).

[0169] Figure 8 is a functional block diagram showing the configuration of an electrical signal output device 1 according to the fifth embodiment of the present invention. The electrical signal output device 1 according to the fifth embodiment comprises a stabilized laser light source 2, an isolator 5, a coupler 7, a UTC-PD (electrical signal output unit) 8, a half mirror 9, a first laser light output unit 10, a second laser light output unit 20, a ring oscillator 30, and an optical waveguide WG0. Hereinafter, parts the same as those in the fourth embodiment are denoted by the same reference numerals and their description is omitted.

[0170] The stabilized laser light source 2, isolator 5, coupler 7, UTC-PD (electrical signal output unit) 8, half mirror 9, ring oscillator 30, and optical waveguide WG0 are the same as in the fourth embodiment and will not be described.

[0171] The first laser light output unit 10 includes an optical waveguide WG 11, a gain chip 101, a first intermediate DBR (first intermediate laser light output unit) 106, and a first final ring oscillator (first final laser light output unit) 104.

[0172] The optical waveguide WG11 is connected to the ring oscillator 30. The gain chip 101, the first intermediate DBR 106, and the first final ring oscillator 104 are also connected to the optical waveguide WG11.

[0173] The gain tip 101 receives the first stabilized laser beam SL1 and supplies it to the first intermediate DBR 106.

[0174] The first intermediate DBR 106 receives the first stabilized laser light SL1 via the gain tip 101. The first intermediate DBR 106 receives a predetermined wavelength λ1 and a predetermined wavelength λ1 + m × (first resonant wavelength interval λ) FSR1 The first intermediate laser beam is output. The first intermediate DBR 106 is, for example, an SG-DBR, SSG-DBR, or DS-DBR. The first intermediate DBR 106 can be considered a mirror that can reflect a specific wavelength.

[0175] The first final ring oscillator (first final laser light output unit) 104 receives the output of the first intermediate DBR 106 and outputs a predetermined wavelength λ1 + m × (first resonant wavelength interval λ FSR1The first final laser beam has a wavelength of λ1 + m × (first resonant wavelength interval λ). FSR1 ) is defined as the resonant wavelength.

[0176] The second laser light output unit 20 includes an optical waveguide WG 21, a gain chip 201, a second intermediate DBR (second intermediate laser light output unit) 206, and a second final ring oscillator (second final laser light output unit) 204.

[0177] The optical waveguide WG21 is connected to the ring oscillator 30. The gain chip 201, the second intermediate DBR 206, and the second final ring oscillator 204 are also connected to the optical waveguide WG21.

[0178] The gain chip 201 receives the second stabilized laser beam SL2 and supplies it to the second intermediate DBR 206.

[0179] The second intermediate DBR 206 receives the second stabilized laser light SL2 via the gain chip 201. The second intermediate DBR 206 receives a predetermined wavelength λ1 and a predetermined wavelength λ1 + n × (second resonant wavelength interval λ) FSR2 The second intermediate laser beam is output. The second intermediate DBR206 is, for example, SG-DBR, SSG-DBR, or DS-DBR. The second intermediate DBR206 can be thought of as a mirror that can reflect a specific wavelength.

[0180] The second final ring oscillator (second final laser light output section) 204 receives the output of the second intermediate DBR 206 and generates a predetermined wavelength λ1 + n × (second resonant wavelength interval λ FSR2 The second final laser beam has a wavelength of λ1 + n × (second resonant wavelength interval λ). This second final laser beam is the second laser beam L2. The second final ring oscillator 204 outputs a predetermined wavelength λ1 + n × (second resonant wavelength interval λ). FSR2 ) is defined as the resonant wavelength.

[0181] Next, the operation of the fifth embodiment will be described.

[0182] First, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 passes through the isolator 5 and is output as the second stabilized laser light SL2 (wavelength λ1) by the coupler 7.

[0183] The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20. The second laser beam output unit 20 outputs the second laser beam L2. The second laser beam L2 is λ1 + n × λ FSR2 It has components of the wavelength.

[0184] The operation of the second laser light output unit 20 is the same as in the fourth embodiment, and therefore its explanation is omitted. However, wavelengths λ1 and λ1 + n × λ are emitted from the second intermediate DBR 206. FSR2 When light is output and travels through the optical waveguide WG21, and is supplied to the second final ring oscillator 204, through light of wavelength λ1 travels through the optical waveguide WG21 and heads towards the ring oscillator 30.

[0185] The through-light of wavelength λ1 that travels through the optical waveguide WG21 of the second laser light output unit 20 is supplied to the ring oscillator 30. Since the resonant wavelength of the ring oscillator 30 is wavelength λ1, the drop light of wavelength λ1 is supplied to the optical waveguide WG11 of the first laser light output unit 10 as the first stabilized laser light SL1. This means that the first stabilized laser light SL1 is obtained from the output of the second intermediate laser light output unit 202 via the second final ring oscillator 204 and the ring oscillator 30. Conversely, it is also conceivable to obtain the second stabilized laser light SL2 from the output of the first intermediate ring oscillator 102 via the first final ring oscillator 104 and the ring oscillator 30.

[0186] The operation of the first laser light output unit 10 is the same as in the fourth embodiment, and therefore the explanation is omitted. However, the wavelengths λ1 and λ1 + m × λ are emitted from the first intermediate DBR 106. FSR1 The light is output, travels through the optical waveguide WG11, and is supplied to the first final ring oscillator 104.

[0187] The first laser beam L1 and the second laser beam L2 both travel through the optical waveguide WG0 and are supplied to UTC-PD8 via the half mirror 9. The first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0188] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0189] The frequency of the electrical signal ES is the same as in the first embodiment, so its explanation is omitted.

[0190] The fifth embodiment also produces the same effects as the fourth embodiment.

[0191] The sixth embodiment of the electrical signal output device 1 differs from the fifth embodiment in that the first final laser beam (first laser beam L1) and the second final laser beam (second laser beam L2) pass through separate optical waveguides WG01 and WG02 before being supplied to the UTC-PD 8.

[0192] Figure 9 is a functional block diagram showing the configuration of an electrical signal output device 1 according to the sixth embodiment of the present invention. The electrical signal output device 1 according to the sixth embodiment comprises a stabilized laser light source 2, an isolator 5, a coupler 7, a UTC-PD (electrical signal output unit) 8, a first laser light output unit 10, a second laser light output unit 20, a ring oscillator 30, a gain chip 32, a coupler 34, and optical waveguides WG01 and WG02. Hereinafter, parts the same as those in the fifth embodiment are denoted by the same reference numerals and their description is omitted.

[0193] The stabilized laser light source 2, isolator 5, coupler 7, UTC-PD (electrical signal output unit) 8, and ring oscillator 30 are the same as in the fifth embodiment and will not be described.

[0194] The first laser light output unit 10 includes optical waveguides WG01 and WG11, a semi-reflective gain chip 108, a first intermediate DBR (first intermediate laser light output unit) 106, and a first final ring oscillator (first final laser light output unit) 104.

[0195] The optical waveguide WG01 connects the first final ring oscillator 104, the semi-reflective gain chip 108, and the coupler 34.

[0196] The optical waveguide WG11 is connected to the ring oscillator 30. The optical waveguide WG11 is also connected to the first intermediate DBR 106 and the first final ring oscillator 104.

[0197] The first intermediate DBR 106 is the same as in the fifth embodiment. However, the first intermediate DBR 106 receives the first stabilized laser light SL1.

[0198] The first final ring oscillator (first final laser light output unit) 104 is the same as in the fifth embodiment. However, the output of the first final ring oscillator 104 is supplied to the semi-reflective gain chip 108 via the optical waveguide WG01.

[0199] The semi-reflective gain chip 108 receives the first final laser beam (first laser beam L1) output from the first final ring oscillator 104 and transmits it to the coupler 34 via the optical waveguide WG01. The semi-reflective gain chip 108 has a half-mirror at the end facing the coupler 34.

[0200] The second laser light output unit 20 includes optical waveguides WG02 and WG21, a semi-reflective gain chip 208, a second intermediate DBR (second intermediate laser light output unit) 206, and a second final ring oscillator (second final laser light output unit) 204.

[0201] The optical waveguide WG02 connects the second final ring oscillator 204, the semi-reflective gain chip 208, and the coupler 34.

[0202] The optical waveguide WG21 is connected to the ring oscillator 30. The optical waveguide WG21 is also connected to the second intermediate DBR 206 and the second final ring oscillator 204.

[0203] The second intermediate DBR206 is the same as in the fifth embodiment, except that the second intermediate DBR206 receives the second stabilized laser light SL2.

[0204] The second final ring oscillator (second final laser light output section) 204 is the same as in the fifth embodiment. However, the output of the second final ring oscillator 204 is supplied to the semi-reflective gain chip 208 via the optical waveguide WG02.

[0205] The semi-reflective gain chip 208 receives the second final laser beam (second laser beam L2) output from the second final ring oscillator 204 and transmits it to the coupler 34 via the optical waveguide WG02. The semi-reflective gain chip 208 has a half-mirror at the end facing the coupler 34.

[0206] The gain chip 32 is connected between the ring oscillator 30 and the optical waveguides WG11 and WG21.

[0207] The coupler 34 combines the first laser beam L1 and the second laser beam L2 and supplies them to the UTC-PD (electrical signal output unit) 8. The UTC-PD (electrical signal output unit) 8 is the same as in the first embodiment.

[0208] Next, the operation of the sixth embodiment will be described.

[0209] First, the stabilized laser light SL (wavelength λ1) output from the stabilized laser light source 2 passes through the isolator 5 and is output as the second stabilized laser light SL2 (wavelength λ1) by the coupler 7.

[0210] The second stabilized laser beam SL2 is supplied to the second laser beam output unit 20. The second laser beam output unit 20 outputs the second laser beam L2. The second laser beam L2 is λ1 + n × λ FSR2 It has components of the wavelength.

[0211] The operation of the second laser light output unit 20 is the same as in the fifth embodiment, and therefore its explanation is omitted. However, wavelengths λ1 and λ1 + n × λ are emitted from the second intermediate DBR 206. FSR2 When light is output and travels through the optical waveguide WG21 and is supplied to the second final ring oscillator 204, through light of wavelength λ1 travels through the optical waveguide WG21 and is directed toward the ring oscillator 30 via the gain chip 32. Also, the drop light from the second final ring oscillator 204 becomes the second final laser light (second laser light L2 (wavelength λ1 + n × λ) FSR2 The signal is then supplied to the coupler 34 via the semi-reflective gain chip 208.

[0212] The through-light of wavelength λ1 that travels through the optical waveguide WG21 of the second laser light output unit 20 is supplied to the ring oscillator 30. Since the resonant wavelength of the ring oscillator 30 is wavelength λ1, the drop light of wavelength λ1 is supplied as the first stabilized laser light SL1 to the optical waveguide WG11 of the first laser light output unit 10 via the gain chip 32. This means that the first stabilized laser light SL1 is obtained from the output of the second intermediate laser light output unit 202 via the second final ring oscillator 204 and the ring oscillator 30. Conversely, it is also conceivable to obtain the second stabilized laser light SL2 from the output of the first intermediate ring oscillator 102 via the first final ring oscillator 104 and the ring oscillator 30.

[0213] The operation of the first laser light output unit 10 is the same as in the fifth embodiment, and therefore its explanation is omitted. However, the wavelengths λ1 and λ1 + m × λ are emitted from the first intermediate DBR 106. FSR1 When light is output and travels through the optical waveguide WG11 and is supplied to the first final ring oscillator 104, the drop light from the first final ring oscillator 104 becomes the first final laser beam (first laser beam L1 (wavelength λ1 + m × λ) FSR1 The signal is then supplied to the coupler 34 via the semi-reflective gain chip 108.

[0214] The first laser beam L1 and the second laser beam L2 are combined by the coupler 34 and supplied to UTC-PD8. The first laser beam L1 supplied to UTC-PD8 is λ1 + m × λ FSR1 It has wavelength components. The second laser light L2 supplied to UTC-PD8 is λ1 + n × λ FSR2 It has components of the wavelength.

[0215] The UTC-PD8 receives the first laser beam L1 and the second laser beam L2, and outputs an electrical signal ES with a frequency equal to the difference between the optical frequency of the first laser beam L1 and the optical frequency of the second laser beam L2.

[0216] The frequency of the electrical signal ES is the same as in the first embodiment, so its explanation is omitted.

[0217] The sixth embodiment also produces the same effects as the fifth embodiment.

[0218] Furthermore, replacing the first intermediate DBR 106 in the sixth embodiment with the first intermediate ring oscillator 102 and mirror 103 of the third embodiment (see Figure 6), and replacing the second intermediate DBR 206 in the sixth embodiment with the second intermediate ring oscillator 202 and mirror 203 of the third embodiment (see Figure 6), will produce the same effects as the fifth embodiment.

[0219] 1 Electrical signal output device 2 Stabilized laser light source 3a, 3b Coupler 4a, 4b Circulator 6 Notch filter (reduction section) 8 UTC-PD (UTC-PD: Uni-Traveling Carrier Photodiode) (electrical signal output section) 10 First laser light output section 10a, 10b Input / output terminals 12 First ring resonator 14 Second ring resonator 16 Third ring resonator 16a, 16b Section 11, 18 Gain chip 13, 17 Half mirror 101 Gain chip 102 First intermediate ring oscillator (first intermediate laser light output section) 103 Mirror 104 First final ring oscillator (first final laser light output section) 106 First intermediate DBR (first intermediate laser light output section) WG1, WG2, WG3, WG4, WG11, WG12 Optical waveguide 20 Second laser light output section 20a, 20b Input / output terminals 22 First ring resonator 24 Second ring resonator 26 Third ring resonator 26a, 26b Sections 21, 28 Gain chip 23, 27 Half mirror 201 Gain chip 202 Second intermediate ring oscillator (second intermediate laser light output section) 203 Mirror 204 Second final ring oscillator (second final laser light output section) 206 Second intermediate DBR (second intermediate laser light output section) WG1, WG2, WG3, WG4, WG21, WG22 Optical waveguide 5 Isolator 7 Coupler 9 Half mirror 30 Ring oscillator 32 Gain chip 34 Coupler WG0, WG01, WG02 Optical waveguide SL Stabilized laser light SL1 First stabilized laser light SL2 Second stabilized laser light λ1 predetermined wavelength λ FSR1 First resonance wavelength interval λ FSR2Second resonant wavelength interval L1 First laser beam L2 Second laser beam ES Electrical signal

Claims

1. An electrical signal output device comprising: a first laser light output unit that receives a first stabilized laser light of a predetermined wavelength and outputs a first laser light having a wavelength component of predetermined wavelength + m × (first resonant wavelength interval); a second laser light output unit that receives a second stabilized laser light of a predetermined wavelength and outputs a second laser light having a wavelength component of predetermined wavelength + n × (second resonant wavelength interval); and an electrical signal output unit that receives the first laser light and the second laser light and outputs an electrical signal with a frequency of the difference between the optical frequency of the first laser light and the optical frequency of the second laser light, wherein m and n are positive integers, the first resonant wavelength interval is the interval of the resonant wavelengths of the first laser light output unit, the second resonant wavelength interval is the interval of the resonant wavelengths of the second laser light output unit, and the first resonant wavelength interval and the second resonant wavelength interval are different values.

2. An electrical signal output device according to claim 1, wherein the electrical signal output unit is UTC-PD.

3. An electrical signal output device according to claim 1, wherein the first laser light and the second laser light further have components of the predetermined wavelength.

4. An electrical signal output device according to claim 3, comprising a reduction unit that reduces the predetermined wavelength component in the first laser light and the second laser light and provides it to the electrical signal output unit.

5. An electrical signal output device according to claim 4, wherein the reduction unit is a notch filter.

6. An electrical signal output device according to claim 4, wherein the reduction unit is a low-pass filter.

7. An electrical signal output device according to claim 3, wherein the first laser light output unit comprises: a first ring resonator having a predetermined wavelength as its resonant wavelength; a second ring resonator having a predetermined wavelength + m × (first resonant wavelength interval) as its resonant wavelength; and a third ring resonator that receives the output of the first stabilized laser light, the first ring resonator, and the second ring resonator, and has a predetermined wavelength and a predetermined wavelength + m × (first resonant wavelength interval) as its resonant wavelengths.

8. An electrical signal output device according to claim 3, wherein the second laser light output unit comprises: a first ring resonator having a predetermined wavelength as its resonant wavelength; a second ring resonator having a predetermined wavelength + n × (second resonant wavelength interval) as its resonant wavelength; and a third ring resonator that receives the second stabilized laser light, the first ring resonator, and the second ring resonator, and has a predetermined wavelength and a predetermined wavelength + n × (second resonant wavelength interval) as its resonant wavelengths.

9. An electrical signal output device according to claim 7 or 8, wherein the third ring resonator receives the outputs of the first ring resonator and the second ring resonator from separate locations.

10. An electrical signal output device according to claim 7 or 8, wherein the third ring resonator receives the outputs of the first ring resonator and the second ring resonator from the same location.

11. An electrical signal output device according to claim 1, wherein the first laser light output unit includes: a first intermediate laser light output unit that receives the first stabilized laser light and outputs a first intermediate laser light having a predetermined wavelength and the predetermined wavelength + m × (first resonant wavelength interval); a first final laser light output unit that receives the output of the first intermediate laser light output unit and outputs a first final laser light having a wavelength of the predetermined wavelength + m × (first resonant wavelength interval); the second laser light output unit includes: a second intermediate laser light output unit that receives the second stabilized laser light and outputs a second intermediate laser light having a predetermined wavelength and the predetermined wavelength + n × (second resonant wavelength interval); a second final laser light output unit that receives the output of the second intermediate laser light output unit and outputs a second final laser light having a wavelength of the predetermined wavelength + n × (second resonant wavelength interval); the first final laser light is the first laser light, and the second final laser light is the second laser light.

12. An electrical signal output device according to claim 11, wherein the first stabilized laser beam and the second stabilized laser beam are output from the same light source.

13. An electrical signal output device according to claim 11, wherein the first stabilized laser light is obtained from the output of the second intermediate laser light output unit.

14. An electrical signal output device according to claim 11, wherein the second stabilized laser light is obtained from the output of the first intermediate laser light output unit.

15. An electrical signal output device according to claim 11, wherein one or both of the first intermediate laser light output unit and the second intermediate laser light output unit are ring oscillators.

16. An electrical signal output device according to claim 11, wherein one or both of the first intermediate laser light output unit and the second intermediate laser light output unit are DBRs.

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