Light modulation device and light modulation method
A light modulation device and light modulation technology are applied in the direction of modulation carrier system, optics, nonlinear optics, etc., and can solve problems such as difficulty in detecting drift
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no. 1 approach ）
[0044] Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0045] figure 1 It is a block diagram showing a schematic configuration of the light modulation device 500 according to the first embodiment of the present invention. Here, an optical modulation device that outputs 16-value QAM is described, but an optical modulation device that generates a QAM signal of a different multi-value number by changing the multi-value number of a drive signal to a value other than 4 can also be used.
[0046] In the light modulation device 500, the IQ light modulator 100 has figure 2 The internal structure shown includes: an input optical waveguide (optical waveguide) 101, an optical coupler 1, an optical modulator 2, an optical modulator 3, an optical waveguide 104 and an optical waveguide 105, an optical coupler 5, and an optical phase shifter4. A CW optical signal is supplied to the input optical waveguide 101 . Optical coupler 1 is ...
no. 2 approach ）
[0092] image 3 It is a block diagram showing the configuration of the light modulation device 500a according to the second embodiment of the present invention. In 2nd Embodiment, the same code|symbol is attached|subjected to the same structure as 1st Embodiment, and a different structure is demonstrated below. In the second embodiment, the bias control circuit 210 , synthesizer 211 , controller 212 , and synchronous detection circuit 202 of the control circuit 200 of the first embodiment are integrated into a digital circuit 300 . The digital circuit 300 may also be a personal computer, and may also be formed of an FPGA (Field Programmable Gate Array, field programmable gate array) or a DSP (Digital Signal Processor, digital signal processor). In addition, the light modulation device 500 a of the second embodiment includes an A / D (Analog Digital, analog-to-digital) converter 301 and D / A (Digital Analog, digital-to-analog) converters 305 , 306 . The A / D converter 301 is conn...
no. 3 approach ）
[0097] Figure 4 It is a block diagram showing the configuration of the IQ light modulator 100b included in the light modulation device according to the third embodiment of the present invention. In the third embodiment, the same reference numerals are assigned to the same configurations as those in the first embodiment, and different configurations will be described below.
[0098] The IQ optical modulator 100b of the third embodiment includes an optical coupler 5b and an optical power monitoring unit 12b. That is, in the IQ optical modulator 100b, the I-component optical modulation unit 2, the Q-component optical modulation unit 3, the optical phase shifter 4, and the optical power monitoring unit 12b are provided on the same optical integrated circuit. Optical coupler 5 b is connected to optical waveguide 104 and optical waveguide 105 , and combines (combines) the CW optical signal propagating through optical waveguide 104 and optical waveguide 105 to output to output opti...
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