KR100944959B1 - Wavelength conversion laser system - Google Patents

Abstract

The present invention relates to a wavelength conversion laser system, comprising: a semiconductor optical amplifier, an optical condenser for condensing light emitted from the optical amplifier, a diffraction grating plate for guiding each wavelength component of light passing through the optical concentrator in a different direction, A wavelength converting laser system having a VLSI processor is provided.

Semiconductor Optical Amplifiers, Optical-VLSI, Opto-VLSI

Description

Wavelength Laser System {Tunable Laser System}

The present invention relates to a wavelength conversion laser system, and more particularly, to a wavelength conversion laser system using an optical-VLSI (Very Large Scale Integration) processor.

The source of the wavelength conversion laser is a major component for building an optical communication network based on wavelength division modulation (WDM). This is because wavelength convertible laser sources have greater flexibility in wavelength selection and more efficient utility as wavelength resources.

Wavelength conversion lasers have been widely used in wavelength division modulation (WDM) based optical communications because of their wavelength selectivity. Conventional wavelength conversion lasers have been used for solid-state lasers and chemical dye lasers.However, noise changes due to fluctuations in pump power are very large and complex pumping systems are required. Is difficult.

Therefore, in the design of a wavelength conversion laser system, a lot of efforts have been made to find laser media that enable a broad emission band. In fact, CW (Continous Wave) wavelength convertible solid state and Chemical dye lasers have been developed to meet some practical requirements.

However, a drawback of these systems is that they require complex noise pumps and inherent loud noises caused by variations in pump power or dye jets, which increases the volume of the system and responds to environmental impacts. There was a problem causing (susceptibility).

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to convert a wavelength into a very simple configuration using a semiconductor optical amplifier, an SLD, an optical VLSI processor, etc. It is to provide a conversion laser system.

A first aspect of the invention is a semiconductor optical amplifier; An optical condenser for condensing light emitted from the optical amplifier; A diffraction grating plate for guiding each wavelength component of light passing through the light condenser in a different direction; And an optical-VLSI processor for returning light of each of the wavelength components only to a specific wavelength back to a semiconductor optical amplifier, and applying a current through a data decoder and an address decoder to form a desired hologram pattern. To provide.

Preferably, the light having the specific wavelength returned to the light collector further includes an output port for amplifying through the semiconductor optical amplifier and emitted to the outside.

A second aspect of the invention is a light emitting diode; A photocondenser for condensing light emitted from the light emitting diodes; A diffraction grating plate for guiding each wavelength component of light passing through the light condenser in a different direction; An optical-VLSI processor for returning light of each of the wavelength components only to a specific wavelength back to the light emitting diode, and applying a current through a data decoder and an address decoder to form a desired hologram pattern; And an optical coupler disposed between the light emitting diode and the photocondenser and separating the light returned from the photo-VLSI processor.

Preferably, the optocoupler has one input port, the input port is connected to the photocondenser, two output ports, one output port is connected to a light emitting diode, and the other is the actual output Is added.

Preferably, a plurality of light emitting diodes having different wavelength ranges are connected to one output port.

On the other hand, the light emitting diode is preferably SLD (Super luminescent diode).

According to the present invention, since the wavelength conversion is possible with a very simple configuration using a semiconductor optical amplifier and an optical VLSI processor, it is possible to manufacture a low-cost, small size, and very precise wavelength conversion by allowing only a specific wavelength of light to be emitted through the optical VLSI processor. Done.

According to the present invention, in order to realize wavelength variability, any narrow waveband of the wide ASE spectrum generated by the semiconductor optical amplifier is combined with the active resonant structure of the SOA, which is an optimized phase loaded on the optical-VLSI processor. For amplification using holograms.

In addition, the present invention changes the phase hologram of the optical VLSI processor, for example, the stable laser performance by the wavelength variable range of 10nm has the effect that can be achieved.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do. The present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, only the embodiments of the present invention to make the disclosure of the present invention complete and complete the scope of the invention to those skilled in the art. It is provided to inform you.

(Wavelength conversion system using semiconductor optical amplifier and optical-VLSI)

1 is a schematic configuration diagram of a wavelength conversion system according to a first embodiment of the present invention.

Referring to FIG. 1, the wavelength conversion laser system 10 includes an optical spectrum analyzer 110, a semiconductor optical amplifier 120, an optical collimator 140, a diffraction grating plate 150, and an optical-VLSI processor 160. ).

Broad amplified spontaneous emission light emitted and amplified by the semiconductor optical amplifier 120 is incident on the light condenser 140. The light collected through the light condenser 140 is applied to the light-VLSI processor 160 through the diffraction grating plate 150.

The diffraction grating plate 150 serves to send each wavelength component of the collected light in different directions of the photo-VLSI processor 160. The photo-VLSI processor 160 forms a desired diffraction grating pattern to direct only light of a particular wavelength back through the light condenser 140. Optical-VLSI processor 160 is described in detail below.

On the other hand, the specific wavelength passing through the light condenser 140 is amplified through the semiconductor optical amplifier 120 is emitted to the outside. Therefore, wavelength conversion is possible by allowing only light of a desired wavelength to be emitted. At this time, the optical spectrum analyzer 110 (OSA; Optical spectrum analyzer) serves to analyze the light emitted to the outside.

The optical-VLSI processor 160 is for returning the light of each wavelength component induced only to a specific wavelength back to the semiconductor optical amplifier. The function of returning a specific wavelength is made possible by applying a current through the data decoder and the address decoder to form the desired hologram pattern.

Meanwhile, the polarization controller 130 may be selectively added and adjusts the polarization required for the system.

2 is a detailed view of the optical-VLSI processor 160 of FIG. 1.

Referring to FIG. 2, an aluminum mirror, a gotter wave plate, a liquid crystal material (LC material), an indium tin oxide (ITO), and a glass are sequentially stacked on a silicon substrate, and a desired hologram is applied by applying current through a data decoder and an address decoder. Allows you to form patterns.

When light is applied to the optical-VLSI processor 160 configured as described above, the light is diffracted by the hologram pattern formed in the optical-VLSI processor 160 and the angle of the light is determined by θ = λ / (qxd). Where λ is the wavelength of incident light, q is the number of pixels per unit interval, and d is the pixel diameter.

In more detail, the optical-VLSI processor 160 generates digital holographic diffraction gratings capable of adjusting the direction of the optical beam and / or shaping the optical beam. Each pixel is assigned to a predetermined memory element for storing digital values, and also to a multiplexer for selecting a particular input voltage value or for applying the selected voltage value to an aluminum mirror plate.

The optical-VLSI processor 160 is electronically controlled, software-configured, polarization independent, connected by a personal computer 170 and the like, and can simultaneously control a plurality of optical beams, as well as a VLSI chip. It is inexpensive because it can be produced in large quantities. It is also very reliable because the beam steering is provided without mechanically moving parts. In this regard, optical-VLSI technology has attracted attention as a technology for reconfigurable optical networks.

2 shows a preferred structure of an optical-VLSI processor. In this case, an indium-tin oxide (ITO) layer is used as a transparent electrode, and an aluminum mirror is used as a reflective electrode. Inserting a thin quarter-wave plate (QWP) between the liquid crystal and the backside of the VLSI can result in a polarization-insensitive optical-VLSI processor. The ITO layer is generally grounded, and voltage is applied to the reflective electrode by the VLSI circuit under the liquid crystal material, to create a staged brazed grating for optical beam steering.

Meanwhile, FIGS. 3A-3C show the steering performance of an optical-VLSI processor of pixel size d, which is driven by the braze grating according to the phase hologram (FIG. 3B). Figure 3a is a phase level for the number of pixels for braze grating analysis by the optical-VLSI processor of Figure 2, Figure 3b is a view for explaining the steering of the blaze hologram of the various pixel blocks corresponding to Figure 3c is an optical-VLSI processor A diagram for explaining the principle of the beam steering using.

If the pitch of the braze grating is q × d (where q refers to the number of pixels per pitch), the optical beam is proportional to the wavelength of light λ and inversely proportional to q × d, as shown in FIG. Is steered by the angle θ.

An arbitrary pitch braze grating can be generated, for example using MATLAB or LabView software, by varying the voltage applied to each pixel, thereby digitally driving one block of pixels to the appropriate phase levels. Also, the incident optical beam is emitted dynamically along any direction.

Experimental Example

Figure 4 shows the configuration of the actual experiment according to the first embodiment of the present invention, Figure 5 is a photograph showing a picture of the experimental configuration.

It can be seen that the wavelength conversion laser system of FIG. 4 includes a semiconductor optical amplifier, a collimator, a diffraction grating plate, and an optical-VLSI processor.

The semiconductor optical amplifier used in the experiment was an off-the-self semiconductor optical amplifier manufactured by Qphotonics. The semiconductor optical amplifier is driven by the Newport modular controllar model 8000 and the drive current is 400mA.

6 is a graph illustrating the spectrum of a wideband ASE generated by a semiconductor optical amplifier. The broadband ASE is collected using a fiber collimator with a diameter of 1 mm, and the collected beam is oscillated with a 1200 lines / mm diffraction grating. The diffraction grating plate diffuses the wavelength components of the focused beam along different directions and maps the wavelength components onto the active window of the photo-VLSI processor.

The optical-VLSI processor used in this experiment has one-dimensional 1 ㅧ 4096 pixels and 256 phase levels with a pixel size of 1 μm, with a dead spacing of 0.8 μm between each pixel.

LabView software was used to generate optimized digital holograms that independently steer the incident wavelength component along any direction.

In order to prove the principle of the proposed wavelength convertible laser structure, three scenarios were investigated. The optical-VLSI processor loads the digital phase hologram, which minimizes the attenuation and couples the collimator back to wavelengths of 1524.8 nm, 1527.1 nm and 1532.5 nm, respectively.

7A, 7B, and 7C show digital phase holograms for selecting specific wavelengths and are semiconductor optical amplifier output spectra measured for each selected wavelength.

7A, 7B, and 7C demonstrate the concept of laser wavelength conversion using the characteristics of an optical-VLSI processor, showing that it is possible to steer a specific wavelength and combine that wavelength with an optical amplifier active resonant structure. Referring to FIGS. 7A, 7B, and 7C, it can be seen that an output of 20 dB or less is generated at 1529 nm in addition to the output wavelengths, which is a low power zeroth order diffraction amplified by a semiconductor optical amplifier cavity. Due to the beam.

8 shows the measured output spectrum to realize single wavelength selection through hologram optimization. The wavelength conversion range of 10 nm is obtained from the optical-VLSI processor used, which has an active window of approximately 7.3 mm size.

6 shows that it is important that the 3-dB bandwidth measured in the ASE spectrum of the semiconductor optical amplifier is about 40 nm. It should be noted that the scalability of the wavelength conversion range depends on the broadband spectrum of the semiconductor optical amplifier, the size of the active window and the pitch of the grating. Thus, by using an optical-VLSI processor having an active window of size 20 nm and a braze grating of 600 lines / mm, a wavelength conversion range of 40 nm can be achieved.

To realize wavelength conversion, any narrow waveband of the wideband ASE spectrum generated by the semiconductor optical amplifier is combined with the active resonant structure of the semiconductor optical amplifier, which uses an optimized phase hologram mounted on the optical-VLSI processor. Is for amplification.

The present invention has shown that by varying the phase hologram of an optical-VLSI processor, stable laser performance can be achieved, for example with a wavelength tunable range of 10 nm.

As shown in Fig. 1, the wavelength conversion laser system according to the present embodiment is based on the use of an optical-VLSI processor as a wavelength convertible optical filter and a semiconductor optical amplifier as a gain medium.

An optimal digital hologram is generated for independently steering the incident wavelength components along any direction. Certain wavelengths can be combined with the fiber light concentrator to minimize attenuation through beam steering. On the other hand, all other wavelengths are off the path and attenuate.

The combined wavelength is injected into the semiconductor optical amplifier and amplified to produce a high amplitude output optical signal. Wavelength conversion is achieved by varying the phase hologram uploaded onto the optical-VLSI processor.

(Wavelength-variable laser system using SLD and photo-VLSI)

9 is a schematic structural diagram of a wavelength conversion laser system according to a second embodiment of the present invention.

Referring to FIG. 9, the wavelength conversion laser system 20 may include a light emitting diode 220, an optocoupler 235, a collimator 240, a diffraction grating plate 250, and an optical-VLSI processor 260. Equipped.

The difference from the first embodiment will be mainly described. In the second embodiment, a light emitting diode is used instead of the semiconductor optical amplifier 120, and an optical coupler 235 is used. The light emitting diode preferably uses a super luminescent diode (SLD) 220. The SLD 220 is a light emitting device having high luminance of a laser diode and low coherence of an LED.

According to the present embodiment, the optocoupler 235 is provided between the light emitting diodes 220 and the light concentrator 240 and separates the light returned from the photo-VLSI processor 260. The optocoupler 235 preferably uses a 2 by 1 coupler, and when light is input into the input port, light is divided and passed at a desired ratio such as 5:95 or 50:50. In the configuration according to the present embodiment, light is input through one of two output ports. That is, when light is input at output 1, the light does not enter output 2 but is mostly incident on the input. The light returned through the optical-VLSI processor 260 then enters part of output1 and part of output2. If you configure the configuration to go a lot to output2 (for example, 95 for output2, 5 for output1), most of the light goes to output2.

Accordingly, referring to FIG. 9, since there is one input port of the optical coupler 235, and this input port is connected to the optical condenser 240, and the output port is composed of two, only one of them is connected to the light emitting diode 220. It is connected.

10 is a schematic structural diagram of another modification of the wavelength conversion laser system according to the second embodiment of the present invention. Referring to FIG. 10, the light emitting diode 220 has a structure in which a plurality of light emitting diodes are tied to an input of the optical coupler 235.

In this case, the input coupler of the optical coupler 235 is one, the optical concentrator 240 is connected to the input port, the output port is composed of a plurality of each output port is a plurality of light emitting diodes, a plurality of light emitting diodes At least two may be configured to have different wavelength ranges.

This structure can be more effective in the wavelength conversion laser system because there is an effect that can be configured to a wider wavelength band.

According to this embodiment, the input unit and the output unit can be separated, the structure is simplified, and the attachment and detachment of the light source can be easily performed.

In the case of using an optical amplifier, the input unit and the output unit may be the same, but it may feel as if there is no difference in the drawing. However, if the actual configuration of this configuration is a system, the input unit and the output unit can be further simplified. In addition, since the input / output unit is divided, the light source can be detachable, and the light emitting diode (eg, SLD) having a desired wavelength can be mounted.

In addition, when multiple SLDs are mounted at the same time, there is an advantage that the wavelength can be varied for a wider wavelength. When using optical-VLSI, how wide the range of wavelength variation is due to the spectral distribution of the SLD or optical amplifier (see FIG. 6). I can have it.

1 is a schematic configuration diagram of a wavelength conversion system according to a first embodiment of the present invention.

2 is a detailed view of the optical-VLSI processor 160 of FIG. 1.

Figure 3a is a phase level for the number of pixels for braze grating analysis by the optical-VLSI processor of Figure 2, Figure 3b is a view for explaining the steering of the blaze hologram of the various pixel blocks corresponding to Figure 3c is an optical-VLSI processor A diagram for explaining the principle of the beam steering using.

Figure 4 shows the configuration of the actual experiment according to the first embodiment of the present invention, Figure 5 is a photograph showing a picture of the experimental configuration.

6 is a graph illustrating the spectrum of a wideband ASE generated by a semiconductor optical amplifier.

7A, 7B, and 7C are diagrams illustrating digital phase holograms for selecting specific wavelengths.

8 shows the measured output spectrum to realize single wavelength selection through hologram optimization.

9 is a schematic structural diagram of a wavelength conversion laser system according to a second embodiment of the present invention.

10 is a schematic structural diagram of another modification of the wavelength conversion laser system according to the second embodiment of the present invention.

Claims (6)

Semiconductor optical amplifiers; An optical condenser for condensing light emitted from the optical amplifier; A diffraction grating plate for guiding each wavelength component of light passing through the light condenser in a different direction; And A wavelength conversion laser system comprising an optical-VLSI processor for returning the light of each of the wavelength components to a semiconductor optical amplifier only by a specific wavelength and applying a current through a data decoder and an address decoder to form a desired hologram pattern. . According to claim 1, And the light having the specific wavelength returned to the optical condenser is further amplified through the semiconductor optical amplifier and output to the outside. Light emitting diodes; A photocondenser for condensing light emitted from the light emitting diodes; A diffraction grating plate for guiding each wavelength component of light passing through the light condenser in a different direction; An optical-VLSI processor for returning light of each of the wavelength components only to a specific wavelength back to the light emitting diode, and applying a current through a data decoder and an address decoder to form a desired hologram pattern; And And a photocoupler disposed between the light emitting diode and the photocondenser and separating the light returned from the photo-VLSI processor. The method of claim 3, wherein The optical coupler has one input port, and the input port is connected to the optical condenser, 2 output ports, the output port is connected to the light emitting diode, the other is a wavelength conversion laser system. The method of claim 3, wherein The light emitting diode is a wavelength conversion laser system having a structure in which a plurality of light emitting diodes having different wavelength ranges are connected. The wavelength conversion laser system of claim 3, wherein the light emitting diode is a super luminescent diode (SLD).

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