JP2016099595A - Three-terminal optical signal control element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-terminal optical signal control element having a sandwich-type configuration formed by connecting two semiconductor optical amplifiers by an AWG (Arrayed Waveguide Grating) optical filter and capable of providing wavelength-converted optical AND/optical NOT signals.SOLUTION: An AWG optical filter 16 disposed between a first semiconductor optical amplification element 14 and a second semiconductor optical amplification element 18 has a plurality of crests and troughs where a transmission factor is changed with respect to the wavelength. The AWG optical filter transmits first output light Iout1 as signal light with a second wavelength λ2, output from the first semiconductor optical amplification element 14 to the second semiconductor optical amplification element 18, reflects first input light Iin1 with a first wavelength λ1 from the first semiconductor optical amplification element 14, to the first semiconductor optical amplification element 14, and reflects control light Ic input from the output side of the second semiconductor optical amplification element 18, to the second semiconductor optical amplification element 18. Consequently, the second output light Iout2 as the wavelength-converted optical AND signal and the first output light Iout1 as the optical NOT signal can be acquired from the output side of the second semiconductor optical amplification element 18.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a three-terminal optical signal control element that amplifies, controls, or switches an optical signal, and in particular, optoelectronics such as optical communication, optical image processing, optical computer, optical measurement, and optical integrated circuit capable of advanced information processing. The present invention relates to a three-terminal optical signal control element that can constitute an optical AND gate, an optical NOT gate, an optical flip-flop circuit, or an optical operational amplifier suitable for an optical digital circuit or an optical analog circuit. Further, in the current optical communication technology, the communication capacity is greatly widened by using wavelength division multiplexing (WDM) technology for transmitting optical signals of a plurality of wavelengths through one optical fiber. In this case, the wavelength conversion uses a wavelength conversion technique in which an optical signal is once converted into an electrical signal and a laser of another wavelength is generated again by the electrical signal. The present invention relates to an all-optical three-terminal optical signal control element that performs wavelength conversion simultaneously with switching. Furthermore, in the future photonic network, a multicasting technique for converting an optical signal of one wavelength into many other wavelengths will be indispensable. The present invention relates to a three-terminal optical signal control element having a multicasting function of converting and outputting each wavelength when multiple wavelengths are input as control light.

  Widespread development of new broadband services such as video communication and video distribution using optical fiber communication capable of broadband and high-speed transmission is expected. However, for example, in terms of electronics, a function (signal amplification function) element equivalent to a three-terminal transistor, an optical function element that directly controls an optical signal with another optical signal, and amplifies the signal, that is, an optical signal. An element that controls an optical signal is extremely useful because it converts an optical signal into an electrical signal and does not need to convert the electrical signal into an optical signal. Further, since it is not necessary to convert the signal once into an electric signal in the wavelength conversion technique, it is useful as a next generation all-optical multiple wavelength conversion technique capable of reducing power consumption and cost.

  In contrast, in an optical amplifying element such as a semiconductor optical amplifying element or a rare earth element-doped fiber amplifier, spontaneous emission light (ambient light) having an ambient wavelength of input light having a predetermined wavelength λ1 responds to a change in the intensity of the input light. The intensity changes in the opposite direction with respect to the signal intensity change of the input light, and the laser light having the other wavelength λ2 within the wavelength range of the spontaneous emission light, that is, the wavelength range around the input light is transmitted to the input light. When the light is superimposed and incident, the change in the signal (amplitude) of the spontaneous emission light is maintained and the overall intensity rapidly increases, and a phenomenon to be referred to as mutual gain modulation is obtained as a wavelength conversion function from wavelength λ1 to λ2. It is known that The inventor has conceived an element that controls light with an optical signal based on a tandem wavelength conversion element that connects the wavelength conversion in two stages, and has found an optical signal three-terminal control element. This is what is described in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4.

  In these patent documents, the first input light having the first wavelength as the optical signal and the second input light having the second wavelength as the continuous light are received and converted into the second wavelength by mutual gain modulation, and A first semiconductor optical amplifying element that outputs a first optical output signal whose intensity is inverted; and a wavelength selecting element that selects a first optical output signal having a second wavelength from the light output from the first semiconductor optical amplifying element; The first optical output signal of the second wavelength output from the first semiconductor optical amplifier and the control light of the third wavelength are combined, converted into the third wavelength by mutual gain modulation, and the intensity is inverted. An optical signal three-terminal control element is configured by including a second semiconductor optical amplification element that outputs two optical output signals.

Japanese Patent No. 3182426 Japanese Patent No. 3989374 Japanese Patent No. 4084994 Japanese Patent No. 4485745

  However, in the conventional optical signal three-terminal control element, the first optical output signal whose intensity is inverted from the first semiconductor optical amplifying element and the control light of the third wavelength are combined and input to the second semiconductor optical amplifying element. Therefore, an optical multiplexer providing a separate optical path is required, and it is difficult to integrate the elements. Here, the term “integrated” means that the semiconductor optical amplifying element is inherently a two-terminal element, and connecting the two semiconductor optical amplifying elements by providing a separate optical path is strictly integrated. It is difficult to say that there are two terminals. In the present invention, the first semiconductor optical amplifying element and the second semiconductor optical amplifying element are coupled to each other by a two-terminal element of an optical filter that transmits and reflects depending on the wavelength, and the first wavelength first light is transmitted from one end. An element structure in which input light and second input light having a second wavelength that is continuous light is input, control light having a third wavelength is input from the other end, and output light is output from the other end is realized. Integration was possible. The optical filter is designed to suppress transmission of the first input light having the first wavelength, transmit the second input light having the second wavelength, which is continuous light, and reflect the control light having the third wavelength. Here, the third wavelength control light input from the other end may be input with multiple wavelengths.

  The present invention has been made against the background of the above circumstances. The object of the present invention is to convert the first output light whose intensity is inverted from the first semiconductor optical amplifier and the control light having the third wavelength into the second semiconductor light. To provide a three-terminal optical signal control element that eliminates the need for an optical multiplexer that provides a separate optical path for input to an amplifying element, integrates the elements, and can be configured by only two input / output ports of an input terminal and an output terminal. It is in. Another object of the present invention is to provide a three-terminal optical signal control element that obtains a first output light having a second wavelength whose intensity is inverted simultaneously with a second output light having a third wavelength from the output terminal of the second semiconductor optical amplification element.

  The present inventor made various studies on the background of the above situation, and when the AWG optical filter is configured by removing the slab waveguide from a general array optical waveguide type diffraction grating (AWG), the first semiconductor light In order to input the first output light of the second wavelength and the control light of the third wavelength whose intensity is inverted from the amplifying element to the second semiconductor optical amplifying element, an optical multiplexer providing a separate optical path is not necessary. I found the fact that it is possible. Then, the present inventor reflects the third wavelength control light input from the output end to the second semiconductor optical amplifying element by the AWG type optical filter, and performs mutual gain modulation in the second semiconductor optical amplifying element. It was found that the second output light converted to the third wavelength and inverted in intensity again can be output from the output end. It has also been found that it is possible to obtain first output light whose intensity is inverted simultaneously with the second output light of the third wavelength from the output end of the second semiconductor optical amplifier. The present invention has been made based on such knowledge.

  That is, the gist of the present invention is that (a) first input light having a first wavelength that is an optical signal and second input light having a second wavelength that is continuous light are received by mutual gain modulation. A first semiconductor optical amplifying element that outputs first output light that has been converted into two wavelengths and whose intensity is inverted; and (b) a first output light having a second wavelength and a third wavelength that are output from the first semiconductor optical amplifying element. A three-terminal optical signal control element comprising: a second semiconductor optical amplifying element that receives the control light and outputs a second output light that has been converted to a third wavelength by mutual gain modulation and whose intensity is inverted again. (C) The first semiconductor light amplifying element is provided between the first semiconductor light amplifying element and the second semiconductor light amplifying element, and the first output light having the second wavelength output from the first semiconductor light amplifying element is supplied to the second semiconductor. A first input of the first wavelength from the first semiconductor optical amplifier element. An optical filter that reflects light toward the first semiconductor optical amplifying element and reflects the control light input from the output side of the second semiconductor optical amplifying element toward the second semiconductor optical amplifying element; It is in.

  According to this configuration, the optical filter disposed between the first semiconductor optical amplification element and the second semiconductor optical amplification element has the first output light having the second wavelength output from the first semiconductor optical amplification element. Is transmitted to the second semiconductor optical amplifier element side, the first input light having the first wavelength from the first semiconductor optical amplifier element is reflected to the first semiconductor optical amplifier element side, and the second semiconductor Since the control light input from the output side of the optical amplifying element is reflected to the second semiconductor optical amplifying element side, the second output light of the third wavelength integrates the signal of the first input light and the signal of the control light. Signal can be obtained. That is, an optical AND circuit is realized. Further, since the first output light having the second wavelength obtained by inverting the input signal is output to the output side, an inversion signal indispensable in the optoelectronic circuit is obtained, and an optical NOT circuit is realized. The first output light having the second wavelength and the second output light having the third wavelength can be simultaneously output by using an AWG as the optical demultiplexer. Further, when continuous light is used as the control light, the second output light having the third wavelength rotated in the same manner as the first output light is obtained, and the wavelength conversion element from the first wavelength to the third wavelength is obtained. Function. Further, when multi-wavelength continuous light is used as the control light, it has a multicasting function for converting a single wavelength signal into a multi-wavelength optical signal and transmitting it.

  Here, the optical filter is a grating type filter composed of an optical waveguide type diffraction grating having at least one high transmission region and low transmission region whose transmittance varies on the wavelength axis. It is characterized by reflection. If it does in this way, the 1st output light of the 2nd wavelength output from the 1st semiconductor optical amplification element will be permeate | transmitted to the 2nd semiconductor optical amplification element side, and the 1st wavelength from the 1st semiconductor optical amplification element will be transmitted. The first input light is reflected to the first semiconductor optical amplifier element side, and the control light from the second semiconductor optical amplifier element is reflected to the second semiconductor optical amplifier element side. The optical amplifying element and the second semiconductor optical amplifying element are directly connected by two terminals to integrate the elements, and the second output light having the second wavelength obtained by inverting the input signal is output simultaneously with the second output light having the third wavelength. Further, it can be manufactured monolithically on the same substrate as the semiconductor optical amplifier. The optical filter is constituted by a waveguide type optical filter made of, for example, a semiconductor. According to this, a refractive index modulation type grating is formed in the cladding layer of the optical waveguide that couples the two first and second semiconductor optical amplifying elements, the wavelength component called the Bragg wavelength is reflected, and the remaining wavelength components Can form a transmissive optical filter. As described above, since the optical filter that couples the first and second semiconductor optical amplifying elements can be formed linearly, a space-saving and simple three-terminal optical signal control element can be obtained as compared with the case of the AWG type filter.

  Preferably, the optical filter is an AWG type filter composed of an arrayed optical waveguide type diffraction grating having one input waveguide and one output waveguide, and has a plurality of transmittances that change with respect to wavelength. It is characterized by having a transmission characteristic having individual peaks and valleys. If it does in this way, since it has a plurality of peaks and valleys, the first wavelength and the third wavelength can be easily set to the low transmission range, and the second wavelength can be set to the high transmission range. Further, it can be manufactured monolithically on the same substrate as the semiconductor optical amplifier. An AWG type filter is an optical filter that performs multiplexing / demultiplexing according to wavelength by causing mutual propagation of light propagating through a plurality of waveguides having different optical path lengths. Monolithic is possible. In addition, since there are a plurality of peaks and valleys, a plurality of control lights of the third wavelength are set, and a second output light of a plurality of wavelengths can be obtained (multicasting function).

  Preferably, the AWG filter has a plurality of high transmission regions having a central wavelength of 400 nm, 800 nm, 1300 nm, 1500 nm, 1550 nm, or 1600 nm and a wavelength interval of 10 nm or less, and a plurality of high transmission regions between the plurality of high transmission regions. And a transmission characteristic in which a difference between the plurality of low transmission regions and the plurality of low transmission regions is 5 dB or more. If it does in this way, in each center wavelength, the 1st wavelength and the 3rd wavelength can be set as a low transmission region, and the 2nd wavelength can be set as a high transmission region.

  Preferably, the structures of the first semiconductor optical amplifier and the second semiconductor optical amplifier are asymmetric. For example, if the length of the element is made longer for the second semiconductor optical amplifier than for the first semiconductor optical amplifier, the longer one increases the gain of the element and increases the intensity of the second output light. Is possible. That is, an element that obtains high output power with low input power is realized.

  Preferably, the active layer of the first semiconductor optical amplifier and the second semiconductor optical amplifier is composed of quantum dots. The switching speed of the device is determined by the carrier recovery time depending on the semiconductor structure of the active layer. The carrier recovery time of an ordinary quantum well structure semiconductor optical amplifying device is about several tens of picoseconds. However, in the case of quantum dots, the device can be increased in speed because of its high speed of several picoseconds.

  Preferably, an optical multiplexer that multiplexes the first input light and the second input light is provided on an input side of the first semiconductor optical amplifier element, and an output of the second semiconductor optical amplifier element is provided. An optical demultiplexer for separating and outputting the first output light of the second wavelength or the second output light of the third wavelength and the control light is provided on the side. If it does in this way, the 1st input light of the 1st wavelength and the 2nd input light of the 2nd wavelength will be combined in the input side of the 1st semiconductor optical amplification element, and the output side of the 2nd semiconductor optical amplification element will be carried out. The third wavelength control light, the second output light of the third wavelength modulated by the control light, and the first output light of the first wavelength are demultiplexed and output.

  Preferably, the optical multiplexer comprises an optical waveguide coupler or an array optical waveguide type diffraction grating, and the optical demultiplexer comprises an optical waveguide coupler, an array optical waveguide type diffraction grating or a circulator. It is. In this way, there is an advantage that an optical multiplexer and an optical demultiplexer can be easily configured.

  Preferably, the control light has a third wavelength. However, if the transmission characteristic of the optical filter can sufficiently suppress the transmission of the first input light to the second semiconductor optical amplifier, the first light is used. The first wavelength may be the same as the input light. In this case, since the wavelength of the input signal light of the three-terminal optical signal control element and the wavelength of the output signal modulated by the three-terminal optical signal control element are common, a large number of three-terminal optical signal control elements are provided. Since optical signals having the same wavelength are used in a large-scale optical circuit, there is an advantage that wavelength conversion is reduced.

1 is a schematic diagram for schematically explaining the main part of the configuration of a three-terminal optical signal control element of an embodiment of the present invention used in an experiment. It is a figure which shows the monolithic structure which implement | achieved the principal part of the 3 terminal optical signal control element of FIG. 1 on the semiconductor chip. It is a graph which shows the transmission characteristic of the optical filter of FIG. 1 or FIG. 2 in the two-dimensional coordinate of a wavelength axis and a transmittance | permeability axis | shaft. FIG. 3 is a diagram showing a spectrum of second output light of a second semiconductor optical amplification element observed from the output side of the second semiconductor optical amplification element in the three-terminal optical signal control element of FIG. 1 or FIG. 2. In the three-terminal optical signal control element of FIG. 1 or FIG. 2, the spectrum of the reflected light from the optical filter 16 is observed from the third port of the circulator provided between the optical multiplexer and the first semiconductor optical amplifying element. It is a figure shown. FIG. 3 is a diagram showing an eye pattern of a 10 Gbps non-zero return pseudo-random bit sequence signal input as the first input light in the three-terminal optical signal control element of FIG. 1 or FIG. 2. In the three-terminal optical signal control element of FIG. 1 or FIG. 2, when the first input light shown in FIG. 6 is input, the reflected optical signal of the second wavelength λ2 that is cross-gain modulated in the first semiconductor optical amplifier element It is a figure which shows the eye pattern of (the reflected light of the 1st output light Iout1 observed in the 3rd port of a circulator). It is a figure explaining the action | operation as a 3 terminal optical signal control element which is one Example of this invention. The second semiconductor optical amplifying element has an asymmetric structure with a longer element length than the first semiconductor optical amplifying element. In the three-terminal optical signal control element of FIG. 8, the first input light that is the signal light having the first wavelength of 1560.8 nm and the second input light that is the continuous light having the second wavelength of 1543.2 nm are combined with the optical multiplexer. FIG. 6 is a diagram showing waveforms observed from the output side when control light having a third wavelength of 1531.0 nm is input from the optical demultiplexer by 0.5 mW. FIG. 9 is a diagram illustrating an eye pattern of a 10 Gbps non-zero return pseudo-random bit sequence signal input as first input light (signal light) having a first wavelength (1560.8 nm) in the three-terminal optical signal control element of FIG. 8. . FIG. 9 is a diagram showing an eye pattern of the first output light of the second wavelength (1543.2 nm) obtained by inverting the signal by the mutual gain modulation of the first semiconductor optical amplification element in the three-terminal optical signal control element of FIG. 8. FIG. 9 is a diagram showing an eye pattern of the second output light of the third wavelength (1531.0 nm) obtained by inverting the signal again by the mutual gain modulation of the second semiconductor optical amplifier in the three-terminal optical signal control element of FIG. 8. FIG. 9 is a diagram illustrating signal waveforms when a modulated signal is used as control light instead of continuous light in the three-terminal optical signal control element of FIG. 8.

  Hereinafter, a three-terminal optical signal control element 10 according to an embodiment of the present invention will be described in detail with reference to the drawings.

  The operation principle will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram for explaining the main part of the configuration of the three-terminal optical signal control element 10 used in the experiment. FIG. 2 shows the main part of the three-terminal optical signal control element 10 on the semiconductor chip 11 with a monolithic structure. The realized experimental device is shown. In FIG. 1 and FIG. 2, an input-side circulator C1 for taking out an observation waveform is interposed on the input side. This is for experimentally observing the waveform, and is a three-terminal optical signal control element 10. This is not a mandatory configuration.

  The three-terminal optical signal control element 10 in FIG. 1 multiplexes the first input light Iin1 that is signal light having the first wavelength λ1 and the second input light Iin2 that is continuous light having the second wavelength λ2. And an input-side circulator C1 for taking out reflected light from the optical filter 16 and observing it from the input side, a first input light Iin1 having a first wavelength λ1, and a second input light Iin2 having a second wavelength λ2. The first semiconductor optical amplifying element 14 that outputs the first output light Iout1 converted into the second wavelength λ2 by the mutual gain modulation and having the intensity inverted with respect to the first input light Iin1, and the first output of the second wavelength λ2 A high transmission region that transmits the light Iout1 with high transmittance, and the first input light Iin1 of the first wavelength λ1 and the control light Ic of the third wavelength λc are transmitted at a relatively low low transmission region of at least 5 dB and are not transmitted. The remaining light is converted into the first semiconductor optical amplifying element 1. 4 and an optical filter 16 having a low transmission region reflected to the second semiconductor optical amplifying element 18, and the first output light Iout1 of the second wavelength λ2 and the control light Ic of the third wavelength λc, and by mutual gain modulation The second semiconductor optical amplifying element 18 that outputs the second output light Iout2 that has been converted to the third wavelength λc and whose intensity is inverted again, and the control light Ic having the third wavelength λc are input and from the second semiconductor optical amplifying element 18 The optical demultiplexer 20 that outputs the second output light Iout2 having the third wavelength of the light is connected in series by the optical waveguide 22.

  In the three-terminal optical signal control element 10 of FIG. 2, a three-dimensional optical waveguide WG that transmits light while confining light three-dimensionally is formed on one surface of the semiconductor chip 11 by locally increasing the refractive index. Yes. An optical multiplexer 12 and an input-side circulator C1 are connected to the input side of the three-dimensional optical waveguide WG via an optical fiber F, for example, and an optical demultiplexer 20 is connected to the output side of the three-dimensional optical waveguide WG, for example. They are connected via an optical fiber F. In FIG. 2, the optical path between the optical filter 16 and the second semiconductor optical amplification element 18 is shorter than the optical path between the optical filter 16 and the first semiconductor optical amplification element 14. This shortens the optical path of the reflected light and further increases the switching speed.

  The circulator C1 has, for example, a Faraday element and a half-wave plate. Light incident from the first port is output from the second port, and light input from the second port is output from the third port. The light incident from the third port is well known to be output from the first port. The circulator C1 emits the first input light Iin1 that is the signal light having the first wavelength λ1 incident from the first port, from the second port to the first semiconductor optical amplifying element 14, and from the first semiconductor optical amplifying element 14 It is used so that light incident on the second port is emitted from the third port and observed.

  The optical multiplexer 12 is composed of, for example, an optical waveguide coupler or an array optical waveguide type diffraction grating that joins a three-dimensional optical waveguide in a Y shape to multiplex two input lights into one output light. Further, when the optical waveguide is constituted by an optical fiber, an optical waveguide coupler is also constituted by joining the optical fiber in a Y shape. Since the optical multiplexer 12 has reversibility, the optical demultiplexer 20 may be configured in the same manner as that or a circulator.

  The first semiconductor optical amplifying element 14 and the second semiconductor optical amplifying element 18 have an InGaAsP quantum well structure formed with a width of about 2 μm and a length of about 1 mm in a compound semiconductor layer stacked by crystal growth on an InP substrate. When the active layer is excited with an injection current of about 150 mA between the bottom electrode and the top electrode of the InP substrate, the optical signal is amplified with an optical amplification gain peak of about 1530 nm and about ± 40 nm. In this embodiment, the active layer has a quantum well structure, but a quantum dot structure having a carrier recovery time of several picoseconds and a high speed may be used. In that case, the switching speed of the three-terminal optical signal control element is increased.

  The optical filter 16 is composed of an AWG type filter composed of an arrayed optical waveguide type diffraction grating in which both ends of a plurality of waveguide arrays having slightly different optical path lengths are used as one input section and one output section. . An ordinary arrayed waveguide grating (AWG) has a plurality of output ports, one input port, a plurality of waveguide arrays having slightly different optical path lengths, and the number of waveguide arrays. A plurality of corresponding output ports and slab waveguides provided between the input port and the waveguide array and between the waveguide array and the output port, respectively. However, the AWG type filter used in the present embodiment is different from the normal arrayed optical waveguide type diffraction grating in that it does not have a slab waveguide and has one output port. To do. FIG. 3 shows the transmission characteristics of the AWG filter used in this embodiment. The reason why the transmission characteristics are generally lowered to the right is that the characteristics were measured using the spontaneous emission light of the semiconductor optical amplifier. In other words, this is because the gain peak of this semiconductor optical amplifier is around 1530 nm. This transmission characteristic has a plurality of high transmission regions having a wavelength interval of about 10 nm and a plurality of low transmission regions between the plurality of high transmission regions, and a plurality of low transmission regions between the plurality of high transmission regions. Is 5 dB or more (up to about 10 dB). In addition, when the center wavelength is 400 nm, 800 nm, 1300 nm, 1500 nm, 1550 nm, or 1600 nm, a similar wavelength interval of 10 nm or less, a plurality of high transmission regions, and a plurality of low transmission regions between the plurality of high transmission regions are provided. An AWG filter having a difference between the plurality of low transmission regions and the plurality of low transmission regions of 5 dB or more can be manufactured.

  In this experimental example, the first input light Iin1 that is signal light having a first wavelength λ1 of 1560.8 nm and the second input light Iin2 that is continuous light having a second wavelength λ2 of 1546.2 nm are each 1 mW. Although input, the control light Ic is not input. Thereby, in the first semiconductor optical amplifying element 14, the first output light Iout1 that is the signal light having the second wavelength λ2 (1546.2 nm) whose intensity is inverted with respect to the first input light Iin1 is generated by the mutual gain modulation action. To do. At this time, the spectrum of the second output light Iout2 observed from the second semiconductor optical amplifier 18 side is FIG. 4, and the spectrum of the reflected light from the optical filter 16 is observed from the third port of the circulator C1. FIG. 4 and 5 are compared, the intensities of the first input light Iin1 that is the signal light having the first wavelength λ1 and the second input light Iin2 that is the continuous light having the second wavelength λ2 are the filter characteristics of the optical filter 16. It turns out that it is influenced by. That is, in FIG. 4, the intensity of the second input light Iin2 is greater than that of the first input light Iin1 (having higher transmittance), whereas in FIG. 5, the intensity of the second input light Iin2 is higher than that of the first input light Iin2. It is smaller than one input light Iin1. This has a plurality of high transmission regions having a wavelength interval of 10 nm or less and a plurality of low transmission regions between the plurality of high transmission regions, and a plurality of low transmission regions between the plurality of high transmission regions, In the optical filter 16 having a difference of 5 dB or more, the second wavelength λ2 light (the first output light Iout1 that is signal light) is transmitted in a high transmission region, and the light of the first wavelength λ1 (the first input that is signal light). The light Iin1) is transmitted through a low transmission region that is at least 5 dB or more and has a relatively low transmittance, and the light that does not transmit is reflected toward the first semiconductor optical amplification element 14 side.

  At this time, when a pseudo random bit sequence (PRBS) signal of 10 Gbps non return zero (NRZ) shown in the eye pattern of FIG. 6 is input as the first input light Iin1, the eye of FIG. As shown in the pattern, the reflected light signal (the reflected light of the first output light Iout1 observed at the third port of the circulator C1) that has been subjected to the mutual gain modulation with respect to the second wavelength λ2 is compared with the first input light Iin1. The signal was inverted in intensity, and it was confirmed that the waveform was excellent in high quality as shown in the eye pattern of FIG. According to this experimental example, it was confirmed that an intensity inversion signal can be obtained even in the reflected light by inputting the laser light from the input end of the first semiconductor optical amplifying element 14 and reflecting it by the optical filter 16.

  So far, the characteristics of the optical filter 16 and the intensity inversion signal reflected by the optical filter 16 have been described. The operation as the three-terminal optical signal control element 10 will be described below. In FIG. 8, the three-terminal optical signal control element 10 includes a first input light Iin1 that is signal light having a first wavelength λ1 of 1560.8 nm and a second input light Iin2 that is continuous light having a second wavelength λ2 of 1543.2 nm. The control light Ic having the third wavelength λc of 1531.0 nm is input from the optical demultiplexer 20 by 0.5 mW. The element length of the second semiconductor optical amplifying element 18 in FIG. 8 is longer than the first semiconductor optical amplifying element and is asymmetric. FIG. 9 shows the waveform observed from the output side of the three-terminal optical signal control element 10 at this time, as in FIG. 1 or FIG. From FIG. 9, since the second input light Iin2 that is continuous light of the second wavelength λ2 is set at the top of the high transmission region (peak of the mountain formed in the spectrum) in the transmission spectrum of the optical filter 16, The first input light Iin1 having the first wavelength λ1 is observed at a low intensity because it is set at the lowest point of the low transmission region (the valley bottom formed in the spectrum) in the transmission spectrum of the optical filter 16. ing. Further, since the third wavelength λc of the control light Ic is also set at the lowest point of the low transmission region (the valley bottom formed in the spectrum) in the transmission spectrum of the optical filter 16, reflection is obtained with high intensity. .

  The operation of signals in the three-terminal optical signal control element 10 is as follows. First, when the first input light Iin1 that is signal light having the first wavelength λ1 and the second input light Iin2 that is continuous light having the second wavelength λ2 are input, mutual gain modulation in the first semiconductor optical amplifier 14 is performed. The first output light Iout1 that is an inverted signal of the second wavelength λ2 is obtained. Next, when the first output light Iout1 of the second wavelength, which is the inverted signal, passes through the optical filter 16 and the control light Ic of the third wavelength λc is input, the mutual gain modulation of the second semiconductor optical amplifier 18 is performed. , Modulated by the first output light Iout1 having the second wavelength, which is an inverted signal, and the intensity is inverted again, and the second signal which is the normal signal light, which is the optical signal having the same phase as the first input light Iin1, but having the third wavelength λc. Output light Iout2 is obtained. At the same time, the first input light having the first wavelength λ 1 that has passed through the optical filter 16 has a low intensity due to reflection by the optical filter 16, and therefore hardly affects the control light Ic. This is because the mutual gain modulation action in the first semiconductor optical amplifying element 14 and the second semiconductor optical amplifying element 18 is a non-linear phenomenon that occurs at a high intensity on the order of mW, and does not occur in low-intensity light. In addition, since the element length of the second semiconductor optical amplifying element 18 is longer than that of the first semiconductor optical amplifying element 14, a large optical output signal intensity can be obtained with a small optical input signal intensity.

  10, FIG. 11, and FIG. 12 show the first input light, which is the signal light of the first wavelength λ1, with eye patterns cut out by the bandpass filters of the respective wavelengths of FIG. 9 and measured in the same manner as FIG. 6 and FIG. Iin1, an inverted signal of the second wavelength λ2 (first output light Iout1) (optical NOT circuit), and a second output light of the third wavelength λc that is in-phase signal light with the first input light Iin1 due to signal inversion again Iout2 is shown respectively. 10, FIG. 11 and FIG. 12 show signal waveforms with good quality, so that the second output light Iout2 can obtain a signal with a transmission speed of at least 10 Gbps modulated in phase with the first input light Iin1. Is clear. FIG. 13 shows signal waveforms when a modulated signal is used as the control light Ic instead of continuous light. According to this, the second output light Iout2 that is the same phase signal light as the first input light Iin1 of the third wavelength λc and modulated by the control light Ic is obtained (optical AND circuit). Further, when the optical filter 16 can sufficiently suppress the transmission of the first input light Iin1, the control light Ic having the first wavelength λ1 can be used. In this case, the second output light Iout2 having the first wavelength λ1 that is the same phase signal light as the first input light Iin1 and is modulated by the control light Ic is obtained. In addition, the waveform shown to the continuous line, broken line, dashed-dotted line, and dashed-two dotted line shown in (c) of FIG. 13 has shown the case where the control light Ic is 0 mW, 0.1 mW, 0.3 mW, and 0.5 mW. From FIG. 13, it can be seen that the output light intensity increases as the intensity of the control light Ic increases, and a waveform obtained by integrating the first input light Iin1 and the control light Ic is obtained (optical AND circuit).

  When the arrayed optical waveguide grating AWG is used as the optical demultiplexer 20, the first output light Iout1 having the second wavelength λ2 having the phase inverted from the first input light Iin1 as the signal light and the third wavelength λc It is possible to simultaneously obtain the first input light Iin1 and the second output light Iout2 that is an in-phase signal. For example, as in an electronic circuit, a NOT circuit is indispensable simultaneously with an AND circuit, and its inverted signal has an important role in signal control technology. Further, when the array optical waveguide grating AWG is used as the optical demultiplexer 20, the second output light Iout2 controlled for each wavelength can be obtained by using the multi-wavelength control light Ic.

  As described above, according to the present embodiment, the optical filter 16 disposed between the first semiconductor optical amplification element 14 and the second semiconductor optical amplification element 18 is output from the first semiconductor optical amplification element 14. The first output light Iout1 that is the signal light having the second wavelength λ2 is transmitted to the second semiconductor optical amplifier 18 side, and the first input light Iin1 having the first wavelength λ1 from the first semiconductor optical amplifier 14 is the first. The first semiconductor optical amplifying element 14 is reflected from the side of the semiconductor optical amplifying element 14 and the control light Ic having the third wavelength from the second semiconductor optical amplifying element 18 is reflected to the second semiconductor optical amplifying element 18 side. The second output light Iout2 (optical AND circuit) and the first output light Iout1 (optical NOT circuit) modulated by the control light Ic from the output side of the second semiconductor optical amplification element 18 are directly connected to each other. ) Can be obtained.

  Further, according to the present embodiment, the optical filter 16 is a grating type filter composed of an optical waveguide type diffraction grating having at least one high transmission region and low transmission region whose transmittance varies on the wavelength axis, Since light having a wavelength that does not pass through is reflected to the input side, the first output light having the second wavelength λ2 output from the first semiconductor optical amplification element 14 is transmitted to the second semiconductor optical amplification element 18 side, and the first The first input light Iin1 having the first wavelength λ1 from the semiconductor optical amplifier 14 is reflected to the first semiconductor optical amplifier 14 side, and the control light Ic from the second semiconductor optical amplifier 18 is amplified by the second semiconductor optical amplifier. Since the light is reflected to the element 18 side, the first semiconductor light amplification element 14 and the second semiconductor light amplification element 18 are directly connected, and the second output light Iout2 and the first output light Iout1 are output from the output side of the second semiconductor light amplification element 18. Can get Kill. The grating filter can be manufactured monolithically on the same substrate as the semiconductor optical amplifier.

  Further, according to the present embodiment, the optical filter 16 is an AWG type filter composed of an arrayed optical waveguide type diffraction grating having one input waveguide and one output waveguide, and has a transmittance with respect to the wavelength. It has a transmission characteristic having a plurality of changing peaks and valleys. Since it has a transmission characteristic having a plurality of peaks and valleys, the first wavelength λ1 and the third wavelength λc can be easily set to a low transmission range, and the second wavelength λ2 can be set to a high transmission range. Are input to obtain a plurality of second output lights Iout2. The AWG filter can be manufactured monolithically on the same substrate as the semiconductor optical amplifier.

  Further, according to the present embodiment, the AWG type filter constituting the optical filter 16 includes a plurality of high transmission regions having a center wavelength of 400 nm, 800 nm, 1300 nm, 1500 nm, 1550 nm, or 1600 nm and a wavelength interval of 10 nm or less, and a plurality of them. And a plurality of low transmission regions between the high transmission regions, and a difference between the plurality of high transmission regions and the plurality of low transmission regions is 5 dB or more. Therefore, the first wavelength λ1 and the third wavelength λc can be easily set to the low transmission region and the second wavelength λ2 can be set to the high transmission region in each central wavelength band.

  Further, according to the present embodiment, an optical multiplexer 12 that multiplexes the first input light Iin1 and the second input light Iin2 is provided on the input side of the first semiconductor optical amplification element 14, and the second semiconductor optical amplification element is provided. 18 is provided with an optical demultiplexer 20 that separates and outputs the second output light Iout2 having the first wavelength λ1 or the third wavelength λc and the control light Ic. Therefore, on the input side of the first semiconductor optical amplifying element 14, the first input light Iin1 having the first wavelength λ1 and the second input light Iin2 having the second wavelength λ2 are combined, On the output side, the control light Ic having the third wavelength λc and the second output light Iout2 and the first output light Iout1 having the third wavelength λc modulated by the control light Ic are demultiplexed and output.

  According to the present embodiment, the optical multiplexer 12 includes an optical waveguide coupler or an array optical waveguide type diffraction grating, and the optical demultiplexer 20 includes the optical waveguide coupler, the array optical waveguide type diffraction grating, or Since it consists of a circulator, there is an advantage that the optical multiplexer 12 and the optical demultiplexer 20 are easily configured.

  Further, according to the present embodiment, the control light Ic has the third wavelength λc, but may be the same first wavelength λ1 as the first input light Iin1. In this case, since the wavelength of the input signal light of the three-terminal optical signal control element 10 and the wavelength of the output signal modulated by the three-terminal optical signal control element 10 are common, a number of three-terminal optical signal control elements are There is an advantage that wavelength conversion is reduced in a large-scale optical circuit.

  Further, according to the three-terminal optical signal control element 10 of the present embodiment, the optical filter 16 composed of, for example, an AWG filter is interposed between the two first semiconductor optical amplifying elements 14 and 18. Because of the sandwich structure inserted, a very simple basic structure can be constructed. For example, in the semiconductor field, the transistor also has a PNP or NPN sandwich structure, and the Josephson element in the superconducting field also has a sandwich structure in which a superconductor is sandwiched between normal conductors. 10 becomes their similar structure.

  The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit of the present invention.

10: 3-terminal optical signal control element 12: optical multiplexer 14: first semiconductor optical amplifier 16: optical filter 18: second semiconductor optical amplifier 20: optical demultiplexer

Claims (8)

The first output light having the first wavelength of the first wavelength that is the optical signal and the second input light of the second wavelength that is the continuous light is converted into the second wavelength and the intensity is inverted by the mutual gain modulation. The first semiconductor optical amplifying element to be output, the first output light having the second wavelength output from the first semiconductor optical amplifying element, and the control light having the third wavelength are received and changed to the third wavelength by mutual gain modulation. A three-terminal optical signal control element comprising: a second semiconductor optical amplification element that outputs a second output light that has been converted and has an inverted intensity;
Provided between the first semiconductor optical amplification element and the second semiconductor optical amplification element, the first output light of the second wavelength output from the first semiconductor optical amplification element is the second semiconductor optical amplification element side. The first input light of the first wavelength from the first semiconductor optical amplifier is reflected to the first semiconductor optical amplifier and input from the output side of the second semiconductor optical amplifier An optical filter for reflecting the control light toward the second semiconductor optical amplifier element;
A three-terminal optical signal control element comprising:   The optical filter is a grating type filter composed of an optical waveguide type diffraction grating having at least one high transmission region and low transmission region whose transmittance varies on the wavelength axis, and reflects light having a wavelength that does not transmit. The three-terminal optical signal control element according to claim 1.   The optical filter is an AWG type filter composed of an arrayed optical waveguide type diffraction grating having one input waveguide and one output waveguide, and has a plurality of peaks and valleys whose transmittance varies with wavelength. 3. A three-terminal optical signal control device according to claim 1, wherein said device has transmission characteristics.   The AWG filter has a plurality of high transmission regions having a central wavelength of 400 nm, 800 nm, 1300 nm, 1500 nm, 1550 nm, or 1600 nm and a wavelength interval of 10 nm or less, and a plurality of low transmission regions between the plurality of high transmission regions. 4. The three-terminal optical signal control element according to claim 3, wherein the three-terminal optical signal control element has a transmission characteristic in which a difference between the plurality of low transmission areas and the plurality of low transmission areas is 5 dB or more.   5. The three-terminal optical signal control element according to claim 1, wherein the first semiconductor optical amplifying element and the second semiconductor optical amplifying element have asymmetric structures.   6. The three-terminal optical signal control element according to claim 1, wherein an active layer of the first semiconductor optical amplifying element and the second semiconductor optical amplifying element is composed of quantum dots. An optical multiplexer for multiplexing the first input light and the second input light is provided on the input side of the first semiconductor optical amplification element,
An optical demultiplexer for separating and outputting the first output light of the second wavelength or the second output light of the third wavelength and the control light is provided on the output side of the second semiconductor optical amplification element. The three-terminal optical signal control element according to claim 1, wherein 8. The three-terminal light according to claim 7, wherein the optical multiplexer comprises an optical waveguide coupler or an array optical waveguide type diffraction grating, and the optical demultiplexer comprises an optical waveguide coupler, an array optical waveguide type diffraction grating, or a circulator. Signal control element.