KR20010073962A - Monitoring method and light source module for wavelength locking - Google Patents

Abstract

PURPOSE: A method for detecting and stabilizing wavelength and a wavelength stabilizing optical source module by using thereof are provided to stabilize the wavelength by using the wavelength dependence of reflection and transmission efficiently with using a Fabry-Perot structure filter element in an optical route. CONSTITUTION: In the method for detecting and stabilizing wavelength and the wavelength stabilizing optical source module by using the same, a single mode optical source(10), a lens(12), a Fabry-Perot filter(11), an array optical detector(20) and optical detectors(31, 32) are included. The lens(12) controls the radiation angle of the laser beam radiated from the single mode optical source(10). The array optical detector(20) detects the beam reflected in the F-P filter(11). The optical detectors(31, 32) detect the beam, which is transmitted the F-P filter(11). Because the incident angle to the first and second Photo Detectors(PD)(21, 22) is different, the strength of the optical detection is compared.

Description

Wavelength detection and stabilization method for wavelength stabilization and wavelength stabilization light source module using the same {Monitoring method and light source module for wavelength locking}

The present invention relates to a wavelength detection and stabilization method that can be used in all optical communication systems requiring wavelength stability, including WDM optical communication systems and analog optical communication systems.

The present invention also relates to a small wavelength stabilized light source module using the wavelength detection and stabilization method and a method of manufacturing the same.

As predicted by the large-scale exchange of information using the Internet, the next 21C will require real-time transmission and reception of large-capacity multimedia information from the minimum unit user level, and in order to meet the demand due to the explosive increase of such unit users. Technology will need more and more speed.

Optical communication technology has developed from the gigabit (Gbps) era to the terabit (Tbps) era, and a transmission device using a wavelength division multiplexing (WDM) method is studied as a large-capacity, high-speed optical communication technology. have. One of the factors that determine the capacity in WDM is to reduce the wavelength grid of the optical signal. Currently, WDM wavelength division interval adopts 1.6nm (200GHz Grid), but 0.8nm (100GHz) is used for ultra-large capacity in the future. Grid) and 0.4nm (50GHz Grid) are expected to shrink. As the wavelength division interval becomes narrower, wavelength stabilization, in which the wavelength of the optical transmission module is kept constant, becomes the most essential requirement. In addition, even in time division multiplexing (hereinafter referred to as TDM) optical communication or analog optical communication, wavelength stability is required for smooth transmission and reception of a high speed optical modulation signal.

At present, a detailed technique for monitoring the wavelength is to use a diffraction grating structure such as crystal grating and fiber grating to take advantage of the wavelength dependence of Bragg diffraction angle. Technology and wavelength selectivity of Fabry-Perot Interferometers such as narrow bandpass filers and etalons.

In addition, the module for wavelength stabilization includes an external type manufactured by some companies including Snatac. For the wavelength selection and stabilization of the WDM system, the signal from the light source is diverged from the optical fiber to monitor the change of the wavelength in an external wavelength locker, and the wavelength is kept constant by adjusting the temperature of the light source using the monitoring signal again. have. Therefore, since separate wavelength stabilization module and light source module are used, the size of the system can not be miniaturized and more cost is required.

Another light source module with built-in wavelength stabilization is being manufactured at Nortel, which arrays light with wavelength dependence when the beam from the rear of the laser diode passes through Fabri-Perot. It uses a method of detecting wavelength changes by detecting it with an array pin-photo detector. This light source module performs wavelength stabilization using only transmission characteristics, and multi-channel wavelength stabilization is impossible.

On the other hand, in order to satisfy the wavelength gap of 0.8 nm or 0.4 nm required in the WDM system, at least picometer wavelength control is required, and wavelengths of several tens of nanometers (nm) are centered around 1550 nm. There is a need for a wavelength stabilization technique that can satisfy the region. For this purpose, it is necessary to use a wavelength selection optical system that has excellent wavelength selection characteristics, can be used in a wide wavelength range, and is easy to manufacture and economical.

In addition, in order to manufacture a compact and economical wavelength stabilizer that satisfies the reliability required by the system, a light source module having a wavelength stabilizer function is desirable.

The present invention is applicable to both internal and external types, using a single Fabry-Perot structure filter element in the optical path from a single mode light source. It is an object of the present invention to provide a wavelength detection and stabilization method capable of stabilizing wavelengths for a plurality of selected wavelengths having a predetermined interval as well as a stabilization function of a single wavelength.

Another object of the present invention is to provide a wavelength stabilizing light source module using the wavelength detection and stabilization method to achieve the above object and a manufacturing method thereof.

1 is a schematic diagram of a wavelength detection system for wavelength stabilization of three wavelengths having a predetermined interval using reflection and transmission characteristics of an optical system having periodic wavelength sensitivity according to the present invention.

2 is a schematic diagram of a wavelength detection system for single channel wavelength stabilization using only reflection characteristics of an optical system having periodic wavelength sensitivity according to the present invention.

3 is a schematic diagram of a wavelength detection system for single channel wavelength stabilization using reflection and transmission characteristics of an optical system having periodic wavelength sensitivity according to the present invention.

4 is a schematic diagram of a wavelength detection system for single channel wavelength stabilization using only transmission characteristics of an optical system having periodic wavelength sensitivity according to the present invention.

FIG. 5 is a graph showing wavelength stabilization at three different wavelengths by reflection and transmission characteristics according to the wavelength of an optical system having periodic wavelength sensitivity measured by four photodetectors in the wavelength detection system of FIG. 1.

FIG. 6 is a graph showing reflection characteristics of wavelengths of an optical system having periodic wavelength sensitivity measured by two PDs of an array photodetector in the wavelength detection system of FIG.

FIG. 7 is a graph showing reflection and transmission characteristics according to the wavelength of an optical system having periodic wavelength sensitivity measured by two photodetectors in the wavelength detection system of FIG.

FIG. 8 is a graph showing transmission characteristics according to wavelengths of an optical system having periodic wavelength sensitivity measured by two PDs of an array photodetector or two PDs of individual devices in the wavelength detection system of FIG. 4.

9 is a block diagram of a light source module having a multi-channel wavelength stabilization function to which the present invention is applied

10 is a block diagram of a light source module having a single channel wavelength stabilization function to which the present invention is applied

Explanation of symbols on the main parts of the drawings

10: single mode light source

11: Optical / Fabric-Perot Filter with Periodic Wavelength Sensitivity

12 rear lens 13 thermistor

14 front lens 15 ceramic substrate

16: thermoelectric cooling element (TEC)

17: wavelength meter

20: Array Photo Detector

21, 22: PD1, 2 (Photo Detector) of array photodetector for detecting reflected beam

23 PD for reflected beam detection

24: PD for transmission beam detection

31, 32: PD for transmission beam detection

51, 51a, 51b: light detection curves for the reflected beam according to the wavelength of the PD 21

52, 52a: light detection curve for the reflected beam according to the wavelength of the PD (22)

53, 53a, 53b: light detection curves for transmitted beams according to the wavelength of the PD 31

54, 54a: Photodetection curves for the transmitted beam according to the wavelength of the PD 32

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a wavelength detection system for wavelength stabilization of three wavelengths having a predetermined interval by using reflection and transmission characteristics of an optical system having periodic wavelength sensitivity according to the present invention. Lens 12 for appropriately adjusting the divergence angle of the laser beam emitted from the mode light source 10, Fabry-Perot filter 11 having a wavelength selection characteristic for the laser beam incident through the lens 12 FP filter), an array photodetector 20 for detecting a beam reflected from the FP filter 11, and two photodetectors for detecting a beam transmitted through the FP filter 11 (hereinafter referred to as PD). It consists of (31, 32).

In such a configuration, the beam reflected when the laser beam from the single mode light source 10 is incident on the FP filter 11 having a wavelength divergence characteristic with an appropriate divergence angle by the lens 12 is array light. The two PDs 21 and 22 of the detector 20 detect light in the form of photocurrent, and the transmitted beams are detected by the PD 31 and the PD 32.

The single mode light source 10 emits a beam of a single mode wavelength at a predetermined angle, such as a distributed feedback (DFB) laser diode, a distributed bragg reflection (DBR) laser diode, and a single mode optical fiber. The lens 12 functions to control the divergence angle of the beam from the single mode light source 10, which plays an important role in relation to the size and alignment distance of the photodetector and the photodetection output. However, the lens 12 may not be used depending on the characteristics of the light source.

The FP filter 11 is a Fabry-Perot resonator such as a solid etalon filter or a narrow bandpass filter. The transmittance and the reflectance of the FP filter have periodic wavelengths as shown in FIG. 5. It has the same characteristics with respect to the incident angle of the incident beam. For example, in the case of a solid etalon filter coated on both sides of fused silica with the same reflectivity, the free spectral range and peak FWHM ( The size of FullWidth Half Maximum depends on the thickness of the etalon, the refractive index, the size of the coating reflectivity, the wavelength of the beam and the angle of incidence. Therefore, when the thickness of the etalon, the refractive index, and the size of the coating reflectance are determined, the transmission and the reflectance of the incident beam at a specific wavelength vary depending on the incident angle, and the wavelength depends on the incident angle. This is a general characteristic of the F-P filter, and the present invention uses the characteristic of this F-P filter.

PD1, 2 (21, 22) is for detecting the wavelength dependence of the reflection output of the F-P filter 11, PD (31, 32) serves to detect the transmission output of the F-P filter (11).

The wavelength detection system of FIG. 1 may be mounted on a thermoelectric cooling device (TEC) to stabilize at least three wavelengths.

Prior to the detailed description of the wavelength detection system of FIG. 1, wavelength detection and wavelength stabilization method using the three wavelength detection systems of FIGS. 2 to 4 for single wavelength locking are described first.

Fig. 2 is a schematic diagram of a wavelength detection system using the wavelength-dependent characteristics of the reflected beam by the FP filter. In the case of using this wavelength detection system, the beam from the single mode light source 10 is PD1 of the array photodetector 20. Since the angles incident on 2 (21, 22) are different, wavelength stabilization is achieved by controlling the wavelength by comparing the light detection intensity due to the difference in wavelength dependence of PD1, 2 (21, 22).

That is, as a method using the characteristic that the reflectance of the F-P filter 11 depends on the wavelength and the reflection angle of an incident beam simultaneously, the reflectance changes periodically with respect to the incident angle of a specific wavelength. Since the beam from the light source 10 is approximated as a Gaussian beam, the angle of the FP filter 11 in FIG. 2 is such that the arrangement of the array photodetector 20 does not block the intensity of the maximum incident beam of the Gaussian beam. Should be greater than

When the inclination angle of the FP filter 11 is fixed, the wavelength dependence of FIG. 6 is shifted while the PD 1 21 and the PD 2 22 of the array photodetector 20 are moved in a state where light intensity can be detected. Align it with and fix it with epoxy or solder. In FIG. 6, curve 51a shows the wavelength dependence of the photocurrent measured by PD 1 (21), and curve 52a shows the wavelength dependence of the photocurrent sensed by PD 2 (22). The photocurrents of the two PDs 21 and 22 are aligned at the wavelength λ _L so that the difference in the currents becomes zero. At this time, the equivalent point of the two currents should ideally be in the middle of the linear part of the photocurrent difference of each PD (21, 22), and the slope of the linear part is related to the precision of the wavelength stability.

In FIG. 6, when the wavelength changes to the short wavelength λ ₁ , the photocurrent of the PD1 21 decreases and the photocurrent of the PD2 22 increases, and when the wavelength changes to the long wavelength λ ₂ , the opposite is detected. In addition, by controlling the temperature controller of the light source to change the wavelength of the light source according to the temperature so that the difference in the photo current of the two PD (21, 22) to zero by controlling the wavelength to stabilize.

FIG. 3 is a schematic diagram of a wavelength detection system in which the intensity of the reflected beam and the transmitted beam is sensed by the PD 23 and the PD 24 to control the wavelength, and the beam incident on the FP filter 11 at a specific angle is shown in FIG. 7. It has the same wavelength dependency as In this case, since the divergence characteristic of the incident beam is not used, the beam from the single-mode light source 10 is converted to the balanced light by the lens 12 and used as compared to the case of FIG. 2 or FIG. 4 to be described later. There is little restriction on the size and alignment distance of, and the input light of sufficient intensity can be guaranteed. Of course, even in the case of divergent beams other than balanced light, the same characteristics may be obtained by aligning the PD 23 and the PD 24 at specific incident angles.

Curve 51b in FIG. 7 is the intensity of the reflected beam of F-P filter 11 measured by PD 23, and curve 53b is the intensity of the transmitted beam of F-P filter 11 measured by PD 24.

In the alignment method of FIG. 3, in the case of balanced light, the position of the PD 24 in the state where photodetection is possible at the stabilization wavelength λ _L is performed while finding and fixing the maximum intensity point, and then the FP filter 11 is inserted. The angle is adjusted and fixed so that the light output of the PD 24 is in the middle of the linear region between the maximum and minimum. In consideration of the arrangement of the PD 23 among various angles of the FP filter 11 satisfying such a condition, an angle having an appropriate size may be obtained. Next, the PD 23 is fixed while the PD 23 is moved in a state where photodetection is possible to find a point having the same light detection intensity as the PD 24.

7 shows the wavelength dependence of the light detection intensity of each PD at this time. Even if there is a slight deviation due to the misalignment, the wavelength stabilization function remains unchanged unless it is outside the linear region of each curve. In this method, the PD 23 and the PD 24 should be made of the same substrate in consideration of the wavelength response characteristic.

4 is a schematic diagram of a wavelength detection system using transmission characteristics of an F-P filter.

PD 31 and PD 32 for detecting the beam passing through the FP filter 11 are efficient to use an array photodetector, in which case the FP filter 11 is placed together with the PD so as to be above the light receiving portion of the PD element. It is attached to a ceramic mount and is simultaneously fixed with epoxy and solder at the point and angle where the light detection characteristics are as shown in FIG. 8 while controlling the angle and position.

In FIG. 8, curve 53a shows the wavelength dependence of the photocurrent measured by the PD 31, and curve 54a shows the wavelength dependence of the photocurrent detected by the PD 32. The photocurrents of the two PDs 31 and 32 are aligned at the wavelength λ _L so that the difference in the currents becomes zero. At this time, the equivalent point of the two currents should ideally be in the middle of the linear portion of the photocurrent difference of each PD (31, 32), and the slope of the linear portion is related to the precision of the wavelength stability.

The wavelength detection using the wavelength detection system of FIGS. 2 to 4 described above is a very useful method of supporting wavelength stabilization at a single wavelength. However, the fixed use of the wavelength stabilizer at one wavelength not only requires an extra number of light source modules for each wavelength in actual WDM system, but also has a disadvantage in terms of efficient use of expensive light sources. Thus, if one wavelength stabilization module can be used to stabilize at more than two wavelengths, this would be a very economical module.

1 is a schematic configuration diagram of a wavelength detection system for enabling such multi-channel wavelength stabilization.

To illustrate the basic principle with practical examples, in the wavelength stabilizer for a WDM system requiring a wavelength interval of 0.8 nm, the PD 21 and PD 22 of FIG. 1 stabilize the wavelength of 1552.52 nm by the method of FIG. If acting as a photodetector for, the PD 21 and PD 31 are aligned to enable photodetection for wavelength stabilization of 1551.72 nm by the method of FIG. 3, and the PD 22 and PD 32 are also By the method of FIG. 3, alignment is made to enable photodetection for wavelength stabilization of 1553.32 nm.

That is, in FIG. 1, the two PDs 21 and 22 of the array photodetector 20 perform photodetection to stabilize the center wavelength, and the PD 21 and PD 31, the PD 22, and the PD 32. ) Performs photodetection for stabilizing neighboring wavelengths each having a predetermined distance from the center wavelength.

FIG. 5 is a diagram illustrating all these wavelength characteristics, showing that wavelength stabilization is possible at three wavelengths λ _L1 , λ _L2 , and λ _L3 .

9 is a block diagram of a multi-channel wavelength stabilized light source module according to an embodiment of the present invention, except for a butterfly package.

The multi-channel wavelength stabilizing light source module of the present embodiment is characterized in that the multi-channel wavelength detection system of FIG. 1 is mounted on a thermoelectric cooling element (TEC), and as shown in the drawing, a thermoelectric cooling element for controlling the temperature of the light source 10 ( 16); A ceramic substrate 15 mounted on the thermoelectric cooling element 16, mounted with a later wavelength detection system and thermistor 13, and having a metal pad pattern required for driving a module; A light source 10, a lens 12 for appropriately adjusting the divergence angle of the laser beam emitted from the light source 10, the FP filter having a wavelength selection characteristic for the laser beam incident through the lens 12 ( 11), an array photodetector 20 having two PDs 21 and 22 for detecting a beam reflected by the FP filter 11 and two PDs for detecting a beam transmitted through the FP filter 11 31, 32) wavelength detection for wavelength stabilization wavelength detection system; A thermistor 13 which continuously senses the temperature of the ceramic substrate 15; And a lens 14 for controlling a spot size of the beam emitted from the light source 10.

The lens 14 is required when the light source 10 is a laser diode, but may not be used in the case of a laser beam in which the light source 10 is transferred to an optical space or free space from the outside.

Before describing a method of manufacturing a multi-channel wavelength stabilized light source module having such a configuration, the two PDs 21 and 22 and the PD 31 of the FP filter 11 and the array photodetector 20 constituting the wavelength detection system 20 may be described. The method of setting and aligning 32 will be described.

First, in the case where the light source 10 is a laser diode oscillating at a single mode wavelength, when the center control wavelength is operated at λ _L2 (for example, 1552.52 nm) at a specific temperature (for example, 25 ° C.), the method of FIG. By aligning the FP filter 11, PD 21 and PD 22 in the same way as, and measuring the light detection intensity at this time by detecting the wavelength change by the external control circuit to the light source 10 by the thermoelectric cooling element By changing the temperature of the laser diode (), the wavelength change is corrected to maintain the wavelength of λ _L2 continuously. At this time, the wavelength dependence of the photocurrent of PD 21 and PD 22 is represented by curve 51 and curve 52 in FIG.

Now, the temperature of the thermoelectric cooling element 16 is artificially adjusted to perform stabilization at a neighboring wavelength of λ _L1 (for example, 1551.72 nm) so that the wavelength of the laser diode is λ _L1 . In general, in case of DFB laser diode, temperature dependence of wavelength is about 0.1nm / ℃, so temperature change of about 8 ℃ is required for wavelength change of 0.8nm. For example, when the wavelength of the laser diode is exactly λ _L1 (for example, 1551.72 nm) in the temperature region around 17 ° C., the wavelength characteristics of the photocurrent by the PD 21 and the PD 31 are compared with the curve 51 of FIG. 5. Likewise, λ _L1 (eg 1551.72 nm) is in the linear region on the opposite slope.

This can be controlled by coating reflectance or resonance distance when the FP filter 11 is manufactured. An easy method that can be applied at various wavelengths is to control the angle of the FP filter 11 to reduce the resonated distance. How to change. Accordingly, FP is controlled so that the width of the FWHM is approximately equal to (λ _L2 -λ _L1 ) in the wavelength dependent characteristic of the PD 21 while simultaneously controlling the inclination angle of the FP filter 11 when the PD 21 and the PD 22 are aligned. It is important to determine the inclination angle of the filter 11. At this angle, the FWHM width of the PD 22 may be different from the FWHM width of the PD 21, but since the angle difference between the two PDs 21 and 22 is not large, the value is almost close to (λ _L2 -λ _L1 ). The wavelength of λ _L3 (eg, 1553.32 nm) adjacent to _L2 is also located on the right inclined plane of the wavelength characteristic curve of the PD 22 as shown in FIG.

Therefore, the PD 31 is lighted at a wavelength of 17 ° C. and λ _L1 (1551.72 nm) as an example in which the inclination angle of the FP filter 11 and the positions of the PD 21 and the PD 22 are fixed so that these conditions are satisfied. Align in a state where it can be detected and fix it so that it has wavelength dependency as shown in curve 53 in Fig. 2. At this time, the intersection point of curves 51 and 53 becomes the stabilization wavelength of λ _L1 . In view of the alignment error, the wavelength stabilization is possible if the intersection occurs within the linear region even when not in the center of the linear curve as in the case of λ _L2 . Done.

The thermoelectric cooling element is again controlled for the wavelength of λ _L3 (1553.32 nm) to induce an accurate oscillation wavelength at a temperature near 33.9 ° C., and the PD 32 is aligned near the PD 31 to obtain a curve 54 as shown in FIG. 5. By fixing the wavelength characteristics at visible points, it is possible to stabilize the three wavelengths adjacent to each other at regular intervals. Finally, in the completed module, PD (21, 22, 31, 32) is selected and used for each wavelength to be stabilized at three wavelengths.

In addition, if the light source 10 is a light source that is input from the outside, such as an optical fiber, not a laser diode, the temperature of the wavelength detection system only needs to maintain a specific temperature, and only a signal for the wavelength change of the input light is transmitted to the original light source through a control circuit. The feedback is controlled to restore the wavelength by controlling the temperature of the light source. Also in this case, the optical alignment method is the same as before except that the temperature of the thermoelectric cooling element 16 equipped with the wavelength stabilizer is kept constant.

Hereinafter, a manufacturing process of the multi-channel wavelength stabilized light source module will be described.

In this embodiment, after the core module is manufactured separately, it is assembled into a butterfly package, and a single wavelength laser diode is used.

First, a single mode light source 10 having a heat sink, a diode, and a thermistor 13 are attached to a ceramic substrate 15 having a metal pad pattern, and then a lens 14 is attached to the front of the ceramic substrate 15. The ceramic substrate 15 is mounted on and attached to the thermoelectric cooling element 16.

Next, the current is driven by the single mode light source 10, and the lens 12 is measured by aligning the lens 12 to control the divergence angle of the laser beam, and measuring the far field angle using a PD lamp from the rear. ) Use the epoxy etc to attach in the optimized position. When the output intensity of the rear portion of the single mode light source 10 is sufficiently large, the assembly of the lens 12 may be omitted.

In addition, the thermoelectric cooling device 16 is controlled and fixed to a specific wavelength to be locked by monitoring the wavelength through the wavelength analyzer 17 by an external alignment method while driving the single mode light source 10. , FP filter 11 and array photodetectors 21, 22 and PD 31, PD 32 are fixed in position according to the requirements described above.

After checking the characteristics of the partial module at each wavelength, the partial module is attached to a butterfly package and the wavelength stabilizing light source module is completed by laser welding.

In this way, the pre-assembly process of the partial module makes it easier to control each part, thereby providing space for aligning the parts in the correct position.

FIG. 10 is a schematic diagram of a single channel wavelength stabilized light source module according to an embodiment of the present invention, except for a butterfly package.

In the present embodiment, the wavelength detection system of FIG. 3 is used as the most efficient method in the case where the output of the light source is weak or the reception output needs to be high among the wavelength detection and stabilization methods of the present invention.

The single channel wavelength stabilized light source module of the present embodiment includes a thermoelectric cooling element 16 for controlling the temperature of the light source 10 as shown in the drawing; A ceramic substrate 15 mounted on the thermoelectric cooling element 16, mounted with a later wavelength detection system and thermistor 13, and having a metal pad pattern required for driving a module; A light source 10, a lens 12 for converting a beam incident from the light source 10 into balanced light, an FP filter 11 having a wavelength selection characteristic with respect to a laser beam incident through the lens 12, and A wavelength detection system comprising a PD (23) for detecting a beam reflected by the FP filter (11) and a PD (24) for detecting a beam transmitted through the FP filter (11); A thermistor 13 which continuously senses the temperature of the ceramic substrate 15; And a lens 14 for controlling a spot size of the beam emitted from the light source 10.

Like the multi-channel wavelength stabilized light source module described above, the lens 14 is required when the light source 10 is a laser diode, but may not be used when the light source 10 is an optical fiber or a laser beam transmitted from outside to free space. Can be.

As a practical example, in the case of using a laser diode as the light source 10, the front mirror is coated with AR (Anti Reflection) and the rear face is coated with at least 90% of HR (Hard Reflection) to increase the output characteristics. In this case, since the wavelength stabilized light source module uses the output from the rear mirror of the laser diode, the weakly diverging beams are collected into one spot using the lens 12 as shown in FIG. 10, and the FP filter 11 at that point. ) And align the PD 23 and PD 24 back and forth to measure the intensity of the reflected and transmitted beams, respectively.

At this time, the angle of the FP filter 11 is such that the intensity of the reflected and transmitted beams with respect to the stabilization wavelength λ _L has the wavelength dependency described in FIG. 7, and the two PDs 23 and 24 have the same response characteristics. PDs 23 and 24 are used.

Hereinafter, a manufacturing process of the single channel wavelength stabilized light source module will be described.

In this embodiment, as in the manufacturing process of the multi-channel wavelength stabilized light source module described above, after separately manufacturing the partial module shown in FIG. 10, it is assembled into a butterfly package, and manufactured as a light source. Diodes were used.

First, a single mode light source 10 having a heat sink, a diode, and a thermistor 13 are attached to a ceramic substrate 15 having a metal pad pattern, and then a lens 14 is attached to the front of the ceramic substrate 15. The ceramic substrate 15 is mounted on and attached to the thermoelectric cooling element 16.

Next, the single mode light source 10 is driven by current and attached using an epoxy lamp while optimizing the alignment position of the lens 12 that changes the incident laser beam into balanced light.

In addition, the thermoelectric cooling device 16 is controlled and fixed to a specific wavelength to be locked by monitoring the wavelength through the wavelength analyzer 17 by an external alignment method while driving the single mode light source 10. The FP filter 11 and the PD 23 and the PD 24 are aligned as described above with reference to FIG. 3.

After checking the characteristics of the final partial module, attach the partial module to the butterfly package and complete the wavelength stabilization light source module using laser welding.

This embodiment does not need to consider the interval between PDs because it is efficient when the intensity of the light source is weak and does not use an array photodetector, and has a merit that a sufficient reception output can be ensured by relatively increasing the size of PDs.

The present invention as described above uses a pair of array photodetectors or individual PDs having the same characteristics, and provides a method for fabricating a wavelength stabilization module that operates at a single wavelength in various ways by one FP filter. It is possible to manufacture wavelength stabilized light source module with high reliability. In addition, reliable single-channel wavelength stabilized light source modules can be manufactured even when the light intensity of the light source is weak or the reception output needs to be high.

In addition, it detects the reflected and transmitted beams through one FP filter using four PDs. It is possible to stabilize the wavelength at three wavelengths that satisfy the WDM wavelength gap with one module. Multi-channel wavelength stabilized light source module can be manufactured.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only and not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (16)

In the wavelength detection and stabilization method for the multi-channel wavelength stabilization of the laser beam having a divergence characteristic from the light source, Place one F-P filter at a certain distance from the light source and align it with an angle with respect to the axis of the Gaussian beam of the laser beam so that the laser beam incident on the F-P filter is reflected and transmitted. The intensity of the reflected beam is photodetected using two PDs, the intensity of the transmitted beam is photodetected using two other aligned PDs, In order to detect the center wavelength for wavelength stabilization, the reflected beams are detected so that the intensity of the reflected beams detected by the two PDs detecting the reflected beams is the same, and to detect other neighboring center wavelengths separated by a predetermined distance from the center wavelengths. The intensity of the reflected beam detected in one PD detecting the, the intensity of the transmitted beam detected in one PD detecting the transmitted beam, and the intensity of the reflected beam detected in the other PD detecting the reflected beam; Arranging the light source, the FP filter, and the PDs so that the intensity of the transmitted beams detected by the other PD detecting the transmitted beams is the same, respectively, Detecting the intensity of the reflected beam in the two PDs detecting the reflected beam using only the wavelength dependency of the reflected intensity of the FP filter on the divergence angle of the laser beam emitted from the light source, and comparing the detected reflected beam intensities To stabilize the center wavelength by controlling the light source so that the difference is zero, The wavelength dependence of the reflection and transmission intensity of the FP filter is detected using one PD for detecting the reflected beam and one PD for detecting the transmitted beam, and the intensity of each detected reflected beam is compared with that of the transmitted beam. The wavelength detection and stabilization method for multi-channel wavelength stabilization, characterized in that for stabilizing the wavelength at three wavelengths by controlling the light source so that the difference is equal to zero by stabilizing the two adjacent wavelengths separated from the center wavelength. The method of claim 1, In detecting the transmission beam by arranging two individual PDs so that wavelength stabilization is possible with respect to two other neighboring wavelengths with a predetermined interval at the center wavelength, FWHM (Full Width) in the wavelength-dependent curve of transmission and reflectance of the FP filter Half Maximum) so as to coincide with the neighboring wavelength intervals, and the FWHM of the FP filter is controlled by adjusting the angle of the FP filter. The method according to claim 1 or 2, And all PDs having the same response characteristics, and selectively using the PDs in combination with the desired wavelengths for stabilization. In the wavelength detection and stabilization method for single channel wavelength stabilization, Place one F-P filter at a distance from the light source, Detecting the reflected beams of the F-P filter by using two PDs having a predetermined interval, and arranging the light source, the F-P filter, and the PDs so that the intensity of the reflected beams detected by the two PDs in the wavelength stabilization state is the same; Using only the reflection intensity dependence of the FP filter and its wavelength dependence on the divergence angle of the laser beam emitted from the light source, the intensity of the reflected beams is stabilized by comparing the intensities of the reflected beams detected by the two PDs so that the difference is zero. A wavelength detection and stabilization method for single channel wavelength stabilization, characterized in that. In the wavelength detection and stabilization method for single channel wavelength stabilization, Place one F-P filter at a distance from the light source, Detecting the reflected beams of the F-P filter by using two PDs having a constant interval, and arranging the light source, the F-P filter, and the PDs so that the intensity of the transmitted beams detected by the two PDs in the wavelength stabilization state is the same; Using only the wavelength dependence of the FP filter on the divergence angle of the laser beam emitted from the light source and comparing the intensities of the transmitted beams detected by the two PDs, the wavelength is stabilized by controlling the light source so that the difference is zero. Wavelength detection and stabilization method for the single channel wavelength stabilization, characterized in that. In the wavelength detection and stabilization method for single channel wavelength stabilization, Place one F-P filter at a distance from the light source, Detecting the reflection beam and the transmission beam of the F-P filter by using two separate PDs, and arranging the light source, the F-P filter, and the PDs so that the intensity of the reflection beam and transmission beam detected in the wavelength stabilization state is the same; By using the wavelength dependence of the reflection and transmission intensity of the FP fill to compare the intensity of the reflected beam and the intensity of the transmitted beam detected by the two individual PD and control the light source so that the difference is 0 to stabilize the wavelength Wavelength Detection and Stabilization Method for Channel Wavelength Stabilization. The method of claim 6, Using a condenser lens, the diverging beam from the light source is collected into one spot and the F-P filter is placed at that position to reinforce the weak light source intensity, A method for detecting and stabilizing wavelengths for single channel wavelength stabilization, characterized by ensuring a sufficient detection intensity by detecting beams reflected and transmitted by the F-P filter using individual PDs whose size is not restricted. In the multi-channel wavelength stabilized light source module to enable a multi-channel wavelength stabilization, A thermoelectric cooling element for controlling the temperature of the light source; A ceramic substrate mounted on the thermoelectric cooling element, mounted with a later wavelength detection system and thermistor, and having a metal pad pattern necessary for driving a module; A light source, a lens for appropriately adjusting the divergence angle of the laser beam emitted from the light source, an FP filter having a wavelength selection characteristic with respect to the laser beam incident through the lens, and two PDs for detecting the beam reflected from the FP filter A multi-channel wavelength detection system consisting of an array photodetector having two and two PDs for detecting the beam passing through the FP filter; And The multi-channel wavelength stabilized light source module, characterized in that it comprises a thermistor for continuously sensing the temperature of the ceramic substrate. In the single channel wavelength stabilized light source module to enable the single channel wavelength stabilization, A thermoelectric cooling element for controlling the temperature of the light source; A ceramic substrate mounted on the thermoelectric cooling element, mounted with a later wavelength detection system and thermistor, and having a metal pad pattern necessary for driving a module; A light source, a lens for converting a beam incident from the light source into balanced light, a FP filter having a wavelength selection characteristic with respect to a laser beam incident through the lens, a PD for detecting a beam reflected from the FP filter, and the FP filter A single channel wavelength detection system comprising a PD for detecting the transmitted beam; And Single channel wavelength stabilized light source module comprising a thermistor for continuously sensing the temperature of the ceramic substrate. The method according to claim 8 or 9, And a lens provided in front of the light source to control a mode size of a beam emitted from the light source. In the method of manufacturing a multi-channel wavelength stabilized light source module to enable a multi-channel wavelength stabilization, Attaching a light source with a heat sink and a thermistor to the ceramic substrate on which the metal pad pattern is formed, and then mounting and attaching the ceramic substrate on the thermoelectric cooling element; A second process of driving a light source and aligning the lens to control the divergence angle of the laser beam while measuring a far field angle using a PD lamp from the rear to fix the lens in an optimized position; An array photodetector that accurately monitors the wavelengths through a wavelength analyzer by an external alignment method while driving the light source, controls the thermoelectric cooling elements, and accurately fixes them to a specific wavelength to be stabilized, and detects the FP filter and the reflected beams of the FP filters. A third step of fixing the two PDs and the two PDs for detecting the transmission beams of the FP filters in the proper positions according to the requirements; And a fourth step of attaching the partial module produced by the above processes to the butterfly package and laser welding the respective modules after the characteristic checking at each wavelength. The method of claim 11, In the second step, when the light source is a laser diode oscillating at a single mode wavelength, after attaching the light source and thermistor to the ceramic substrate, a lens for controlling the mode size of the beam emitted from the light source is attached to the front of the light source. Method of manufacturing a multi-channel wavelength stabilized light source module. The method of claim 12, The third process is when the light source is a laser diode oscillating at a single mode wavelength, After the thermoelectric cooling element is controlled by an external control circuit to operate at the optical center wavelength λ _L2 , the FP filter is positioned at a spot where a lens spot for controlling the divergence angle of the beam is formed, and the array photodetector is arranged. The angle of inclination larger than the maximum incident beam intensity of the Gaussian beam is fixed, and then the two PDs of the array photodetector are moved in a state where the light intensity can be detected so that the photocurrents detected by the two PDs are the same. At this time, the angle of inclination of the FP filter is simultaneously controlled during two PD alignment, and the angle of inclination of the FP filter is finally determined so that the width of the FWHM is almost equal to the interval between neighboring wavelengths in the wavelength dependency characteristic of the two PDs. The thermoelectric cooling element is controlled by an external control circuit so that the light source operates at a neighboring wavelength λ _L1 that is shorter than the center wavelength λ _L2 and has a predetermined distance from the center wavelength, and then detects the transmission beam for the wavelength λ _L1 . While moving the PD in a state where the transmission beam can be detected, the intensity of the transmission beam is aligned at the same position as that detected by the PD detecting the reflection beam with respect to the wavelength λ _L1 , The thermoelectric cooling element is controlled by an external control circuit so that the light source operates at a neighboring wavelength λ _L3 longer than the center wavelength λ _L2 and at a predetermined distance from the center wavelength, and then detects the transmission beam for the wavelength λ _L3 . Moving the PD in a state in which the transmission beam can be detected while the intensity of the transmission beam is aligned at the same position as that detected by the PD detecting the reflection beam with respect to the wavelength λ _L3 . How to make. The method of claim 11, In the third step, when the light source is a light source input from the outside, such as an optical fiber, The thermoelectric cooling element is controlled by an external control circuit to maintain the temperature of the entire system at a specific temperature. With respect to the center wavelength λ _L2 , place the FP filter at the point where the spot of the lens controlling the divergence angle of the beam is formed, and the arrangement of the array photodetector is larger than not blocking the maximum incident beam intensity of the Gaussian beam. After fixing to the inclination angle, the two PDs of the array photodetector are moved while the light intensity is detected, and the photocurrents detected by the two PDs are aligned to be the same. While controlling, the angle of inclination of the FP filter is finally determined so that the width of the FWHM is almost equal to the interval between neighboring wavelengths in the wavelength dependent characteristics of the two PDs. With respect to the neighboring wavelength λ _L1 that is shorter than the center wavelength λ _L2 and has a predetermined distance from the center wavelength, the PD that detects the transmission beam for the wavelength λ _L1 is moved while the transmission beam can be detected. The intensity is aligned at the same position as the intensity detected by the PD detecting the reflected beam for wavelength λ _L1 , With respect to the neighboring wavelength λ _L3 that is longer than the center wavelength λ _L2 and has a predetermined distance from the center wavelength, the PD that detects the transmission beam for the wavelength λ _L3 is moved while the detection of the transmission beam is possible. A method of fabricating a multi-channel wavelength stabilized light source module, wherein the intensity is aligned at the same position as that detected by the PD detecting the reflected beam with respect to the wavelength [lambda] _L3 . In the method of manufacturing a single channel wavelength stabilized light source module to enable a single channel wavelength stabilization, Attaching a light source and a thermistor with a heat sink to the ceramic substrate on which the metal pad pattern is formed, and attaching a lens for controlling the mode size of the beam emitted from the light source to the front of the light source, and then mounting the ceramic substrate on the thermoelectric cooling element. 1 step; A second step of driving a light source in a current state and fixing it in an optimized state in which an alignment position of a lens for changing an incident laser beam into balanced light; With the light source driven, the thermoelectric cooling element is controlled while the wavelength is monitored by a wavelength analyzer by an external alignment method, so that it is fixed to the stabilization wavelength λ _L accurately, and the FP filter and the PD and transmission beams for detecting the reflected beam are detected. A third step of aligning the PD to detect; And And a fourth step of attaching and laser welding the partial module manufactured by the above processes through a characteristic verification test at the stabilization wavelength λ _L. . The method of claim 15, The third step, Find and fix the maximum intensity point by shifting the position of PD to detect the transmission beam at the stabilization wavelength λ _L in a state where photodetection is possible, Next, insert the FP filter to adjust the angle so that the light output of the PD detecting the transmitted beam is fixed in the middle of the linear region between the maximum and the minimum, and the reflected beam is among the various angles of the FP filter satisfying this condition. In consideration of the arrangement of the PD to be detected to have an appropriate size angle, A method of manufacturing a single channel wavelength stabilized light source module, wherein the intensity of the reflected beam is aligned at the same position as the intensity detected by the PD detecting the transmitted beam while the PD detecting the reflected beam is moved in a state where photodetection is possible.