WO2002047217A1

WO2002047217A1 - Wavelength multiplexing light source and wavelength multiplexing device

Info

Publication number: WO2002047217A1
Application number: PCT/JP2001/010716
Authority: WO
Inventors: Takeshi Ota
Original assignee: Photonixnet Kabushiki Kaisha
Priority date: 2000-12-08
Filing date: 2001-12-07
Publication date: 2002-06-13
Also published as: AU2002221079A1; JPWO2002047217A1

Abstract

Multiple grating cavity laser has the upper limit of a modulable speed been restricted by the shuttling time of light within a resonator due to an elongated resonance optical system. An optical amplifier (1), a looped optical fiber (2), an optical coupler (4), a passive wavelength multiplexer (5), and looped optical fibers (7-1 to 7-n) and optical fibers (6-1 to 6-n) corresponding to respective branching outputs of the passive wavelength multiplexer (5) are provided to form closed loops for laser beams of individual wavelengths, and laser beams of individual wavelengths can be extracted to the outside from output terminals (11-1 to 11-n) and modulated by an optical modulator, thereby providing a high-speed-modulated wavelength multiplexing signal.

Description

Description Wavelength multiplexed light source and wavelength multiplexing device

The present invention relates to a wavelength division multiplexer (WDM). In particular, the present invention relates to a light source that generates light of a plurality of wavelengths used as a light source of a wavelength multiplexing device. The present invention relates to a low-density wavelength multiplexing device (DWDM). The present invention relates to optical fiber communication. Background art

Conventionally, a multiple grating cavity laser (MGC) having a structure shown in FIG. 10 is known (US Pat. No. 5,570,226, “Optica 1 Link Amplifier and a Wavelength”). h Mu 1 tip 1 ex Laser Oscillator ", JP-A-62-229891," Multi-wavelength semiconductor light source ", JP-A-5-198893," Wavelength multiplexed laser-one oscillator "," Wave l engt h— select ab lel as ere mi ssionfr om a mu ltistripe ar ray gratingin nt e gr at ed c av itylaser, "J. S oole, K. Pogunt ke, A. S che rer, H. LeB lanc, C. Chang—Has na in, J. Hayes, C. Canaeau, R. Bhat, and M. Koza, A pp 1. Phys. Lett., Pp. 2750- 2752, December, 1992).

On the semiconductor laser array 101, a laser 102 and lasers 103-1 to 103-n are arranged. The first end face 104a of the semiconductor laser array 101 is coated with a coating having a reflectance of about several tens percent. On the other hand, the second end face 104b of the semiconductor laser array 101 is provided with an anti-reflection coating, and its reflectance is almost zero percent. The laser 102 and the laser 103-1 or 103-n are coupled via the concave diffraction grating 106 at respective wavelengths. For example, laser 102 and laser 103-1 are coupled at wavelength 1, —The 102 and the Laser 103 — n are coupled at wavelength; L n. Therefore, the two lasers are combined to form an external resonator type laser resonator, and laser oscillation occurs.

A modulation current is applied to the lasers 103_1 to 103_n from a current modulation circuit (not shown), and the laser light is modulated by a signal. The modulated laser beams having wavelengths of 1 to n are collected by the laser 102 and then coupled to the optical fiber 105. In other words, the multiple grating cavity laser described above has the function of simultaneously oscillating a large number of wavelengths, the function of individually modulating a large number of oscillated wavelengths, and the coupling of an optical signal consisting of these many wavelengths into a single optical fiber. Function.

Furthermore, the laser optical system has the advantage that the line width of the oscillated laser light is narrow due to the long cavity optical system, and high quality laser light can be generated. Disclosure of the invention

However, since the multiple grating cavity laser has a long resonant optical system length, the upper limit of the modulatable speed is limited by the round-trip time of light in the resonator, and the modulation is at most about 622 Mb ps. There was a disadvantage. In this case, the transmission of 2.5 G bps (OC-48), lO Gb ps (O C_1 92), or 40 Gb ps (OC-768) required for current wavelength multiplexing equipment It cannot respond to speed.

In order to solve the above problems, a wavelength multiplexed light source according to one aspect of the present invention includes at least two components: an optical amplifier, a first loop-shaped optical fiber, a first optical power bra, a passive wavelength multiplexer. A second optical power bra, comprising at least two second loop optical fibers, branching only one wavelength of laser light out of the laser light oscillated at a plurality of wavelengths from the second optical power bra; It is characterized by outputting to the outside.

According to the above configuration, since a closed loop optical circuit including the optical amplifier and the passive wavelength multiplexer is formed, the laser of the optical signal of each wavelength selected by the passive wavelength multiplexer is formed. Oscillation occurs. Then, only the optical signals of the individual wavelengths are branched out to the outside through the plurality of second optical power blurs and output. After this optical signal is modulated by an optical modulator, it can be wavelength-multiplexed into one optical fiber by a wavelength multiplexer. The above-described one aspect of the present invention and other aspects of the present invention are described in the claims and are described in detail below. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a schematic configuration of a wavelength multiplexed light source according to a first embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of a wavelength multiplexing device configured using the wavelength multiplexing light source according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a partial reflection element used in the wavelength multiplexed light source i_QJ according to the first embodiment of the present invention and an alternative means thereof.

FIG. 4 is a diagram showing a schematic configuration of a wavelength multiplexed light source according to a second embodiment of the present invention. FIG. 5 is a diagram showing a schematic configuration of a wavelength multiplexed light source 30 according to a third embodiment of the present invention. FIG. 6 is a diagram showing a schematic configuration of a wavelength multiplexed light source according to a fourth embodiment of the present invention. FIG. 7 is a diagram showing a schematic configuration of a wavelength multiplexed light source 60 according to a fifth embodiment of the present invention. FIG. 8 is a diagram showing a schematic configuration of a wavelength-division multiplexed light source: L according to a sixth embodiment of the present invention. FIG. 9 is a diagram showing a schematic configuration of a wavelength multiplexed light source A according to a seventh embodiment of the present invention. FIG. 10 is a diagram showing a schematic configuration of a conventionally known multiple grating cavity laser. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to Examples.

[First embodiment]

FIG. 1 shows the establishment of the wavelength multiplexed light source according to the first embodiment of the present invention. On this wavelength multiplexed light source, there are an optical amplifier 1, a looped optical fiber 2, a variable optical attenuator 3, an optical power blur 4, a passive wavelength multiplexer (spectroscope) 5, and an optical power blur 6-1 to 6- n, loop optical fiber 7-1 to 7-n, and automatic power control (APC) 8.

Specifically, the optical amplifier 1 uses an L-band (amplifiable wavelength band: 1535 to 1565 nm) erbium-doped optical fiber amplifier (EDFA). Type of fiber optic amplifier or semiconductor laser fiber optic amplifier Or a Raman optical fiber amplifier. A normal optical amplifier has an optical isolator inside, and light is amplified only in one direction.

For the optical power bra 4 or the optical power bras 6-1 to 6_n, a fusion type optical fiber optical plastic was used. This is a waveguide type optical power bra or a free space optical type optical power bra. Is also good.

As the passive wavelength multiplexer (spectrometer) 5, an arrayed waveguide grating (AWG) was used, but other types of passive wavelength multiplexers (AWGs) were used. Spectrometer), for example, a free-space optical wavelength multiplexer using a diffraction grating, a free-space optical wavelength multiplexer using a dielectric filter, or an optical waveguide using a diffraction grating or a dielectric filter Type wavelength multiplexer.

Further, as described later, in the present invention, the wavelength of the laser light oscillated by the passive wavelength multiplexer is determined, so that the passive wavelength multiplexer (spectroscope) 5 is controlled to a predetermined temperature by a temperature control mechanism (not shown). Is controlled. This mechanism can be omitted depending on the accuracy of wavelength multiplexing.

Spontaneous emission light with a wide wavelength spectrum emitted from an optical amplifier (EDFA) 1 passes through a loop-shaped optical fiber 2, a variable optical attenuator 3, and a light power bra 4, and a passive wavelength multiplexer (AWG) Reach five. The passive wavelength multiplexer (AWG) 5 splits the spontaneous emission light into discrete wavelengths 1 to n and outputs them to each output terminal. The split light of wavelength λΐ or η is transmitted to the passive wavelength multiplexer (AWG) 5 again through the loop optical fiber 7-1 to 7 _ η and the optical power coupler 6-1 to 6-η, respectively. And return. The passive wavelength multiplexer (AWG) 5 combines the light of wavelengths 1 to η into one and sends it to the optical amplifier (EDFA) 1 via the optical power bra 4. Η is amplified by an optical amplifier (EDFA) 1, and then looped optical fiber 2, variable optical attenuator 3, optical power bra 4, passive wavelength multiplexer (AWG) 5, Power Brass 6-1 to 6_n, Looped Optical Fibers 7-1 to 7-n, Passive Wavelength Multiplexer (AWG) 5, Optical Brassier 4, and then sent back to Optical Amplifier (EDFA) 1 . As a result, a closed loop is formed, and discrete wavelengths 1 to n cause laser oscillation.

The optical power 4 splits a part of the laser light of Send to Force Control Unit (AP C) 8. An automatic output control device (APC) 8 controls the variable optical attenuator 3 so that the laser light oscillation output becomes constant. The automatic output control device (APC) 8 can be omitted. This is because the optical amplifier has a saturation output characteristic, and the laser output is stabilized at a predetermined output. However, the stability of the laser output is better when the automatic power controller (APC) 8 is used.

The optical power plugs 6-1 to 6-n branch off part of the laser light with discrete wavelengths 1 to η and send them to the output terminals 11-1 to 11-η, respectively.

In the optical fiber on the optical amplifier (EDFA) 1 side with respect to the passive wavelength multiplexer (AWG) 5, discrete wavelengths 1 to λη are mixed and transmitted. On the other hand, on the optical power 6-1 to 6-η side with respect to the passive wavelength multiplexer (AWG) 5, discrete wavelengths 1 to η are separately transmitted to each optical fiber. .

As described above, according to the configuration of FIG. 1, an arbitrary number of wavelengths of laser light determined by the passive wavelength multiplexer (AWG) 5 for wavelengths within the amplifying wavelength band of the optical amplifier (EDFA) 1 Can be oscillated.

FIG. 2 is a diagram showing a configuration of a wavelength multiplexing device using the wavelength multiplexing light source of FIG. Wavelength multiplexed light source 出力 _0_ output terminal 1 1 1 1 to 1 1 _n The laser light of different wavelengths passes through the transmitting module 14-1 to 14-1 n and the passive wavelength multiplexer (AWG) 15 a Are combined into one optical fiber. The transmission modules 141-1 to 14-n are composed of electric signal units 12-1 to 12-n and optical modulators 13-1 to 13-n. The optical modulators 13-1 to 13 _n modulate the laser light from the wavelength multiplexed light source 10 by the electric signal added from the electric signal units 12-1 to 12-n. Therefore, the laser light that has passed through the transmission modules 1411 to 1411n is an optical signal modulated at a speed of, for example, 10 Gbp / s (10 gigabits per second). Known light modulators 13-1 to 13-n include lithium-niobate-based electro-optic modulators and semiconductor-based electro-optic absorption modulators (QCS E modulators: Quantum Confined St ark Effect: Quantum) For example, a confined Stark effect modulator can be used.

The optical signals 18a having a plurality of wavelengths multiplexed by the passive wavelength multiplexer (AWG) 15a are guided to the communication optical fiber 17 through the optical circuit 16. Light One terminal of Kyure Izuya 16 is connected to a passive wavelength division multiplexer (AWG) 15b for reception. It should be noted that a light bra and an optical isolator can be used in combination instead of the optical circuit.

The wavelength multiplexed optical signal 18b received through the communication optical fiber 17 is transmitted only to the passive passive wavelength multiplexer (AWG) 15b by the optical circulator 16. You. The received wavelength-division multiplexed optical signal is separated into respective wavelengths by a passive wavelength multiplexer (AWG) 15b for reception and transmitted to the reception units 19-1 to 19-n .

In Fig. 2, a passive wave for reception, a long multiplexer and a passive wavelength multiplexer for transmission are provided.However, only one wavelength multiplexer is provided, and the optical It is also possible to construct a wavelength multiplexing apparatus so that the transmission optical signal and the reception optical signal are coupled to one optical fiber and then wavelength-multiplexed by this wavelength multiplexer. In this case, it is necessary to provide the number of optical circuits and the number of optical power bras as many as the wavelengths to be used.

Although FIG. 2 shows a wavelength multiplexing device for bidirectional optical transmission, the present invention can be applied to unidirectional optical transmission in which a transmitting optical fiber and a receiving optical fiber are provided separately. In this case, there is no need for an optical filter or optical power coupler for coupling the transmission signal and the reception signal.

In FIG. 2, a passive wavelength multiplexer is provided on the transmitting side, but this can be replaced by an optical coupling means having no wavelength selectivity, such as a linear optical power blur. An optical amplifier can be added to the configuration of FIG. A preamplifier is installed between the passive wavelength multiplexer 15b on the receiving side and the optical circuit 16 or between the passive wavelength multiplexer 15a on the transmitting side and the optical circuit 16 An amplifier can be installed in the booth.

It should be noted that the partial reflection element including the optical power blur 6-1 to 6-n and the loop optical fiber 7-1 to 7-n in the wavelength multiplexed light source 10 can be replaced with a half mirror. FIG. 3 (a) shows a partial reflection element composed of an optical power bra 6 and a loop optical fiber 7. FIG. In the figure, light incident from the left side is partially reflected in the incident direction (left side in the figure) by the optical power bra 6 and the loop-shaped optical fiber 7, and the rest is guided to the output terminal 11 on the right side. As shown in FIG. 3 (b), such a function can be realized by a partially reflecting element including a lens 46, a half mirror 47, and a lens 48. The optical signal from the optical fiber 45 is converted into substantially parallel light by a lens 46 and guided to an optical fiber 49 via a half mirror 47 and a lens 48. At this time, part of the light incident from the right side of the figure is reflected by the half mirror and sent to the optical fiber 45 side, and the rest is sent to the optical fiber 49 side. Therefore, according to the configuration of FIG. 3 (b), a function substantially equivalent to the configuration of FIG. 3 (a) can be realized.

Since the wavelength multiplexed light source _ _Q_ shown in FIG. 1 has the above-mentioned partial reflection element (optical power bra 6 and loop optical fiber 7 or half mirror 47) near the output terminal, the wavelength Reflection occurs when an optical signal is externally applied to the output terminal of the multiplexed light source. However, since the wavelength multiplexing device shown in FIG. 2 is provided with the optical circuit 16, no optical signal is externally applied to the output terminal of the wavelength multiplexing light source. [Second embodiment]

FIG. 4 shows the configuration of a wavelength multiplexed light source according to a second embodiment of the present invention. The wavelength multiplexed light source ϋ is an optical amplifier (EDFA) 22, the first passive wavelength multiplexer (AWG) 23, the optical power blur 28-1 to 28-η, and the second passive wavelength multiplexer (AWG). ) 24, variable optical attenuator 26, optical power bra 25, and automatic power control (APC) 27. Note that the first passive wavelength multiplexer (AWG) 23 and the second passive wavelength multiplexer (AWG) 24 have substantially the same characteristics.

The spontaneous emission light from the optical amplifier (EDFA) 22 is separated by the first passive wavelength multiplexer (AWG) 23 into discrete wavelengths 1 or η, and the corresponding light After passing through the power brass 28-1 to 28-η, they are combined again into one optical fiber by the second passive wavelength multiplexer (ΑWG) 24. Then, the light is sent to the optical amplifier (EDFA) 22 again through the variable optical attenuator 26 and the optical power bra 25. The discrete wavelengths 1 to n are amplified by the optical amplifier (EDFA) 22 and return to the optical amplifier (EDFA) 22 again along the same path as described above. That is, a closed loop is formed, and laser oscillation occurs. Laser light oscillated at discrete wavelengths 1 to n is partially branched by the optical power plugs 28-1 to 28_n and guided to the output terminals 21-1 to 21-n. .

A part of the collective light of the laser light having discrete wavelengths 1 to n is branched by the optical power bra 25 and sent to the automatic power control device (APC) 27. An automatic output controller (APC) 27 controls the variable optical attenuator 26 so that the laser oscillation has a constant intensity. The wavelength multiplexed light source of the second embodiment has a ring laser structure and does not use a partial reflection element. Therefore, when an optical signal is input from the outside to the output terminals 21_1 to 21-n. However, there is an advantage that reflected light is not returned. On the other hand, it has the disadvantage of using two more expensive passive wavelength multiplexers (AWGs) than the first embodiment.

The light incident on the output terminals 21-1 to 21-1n is attenuated by the optical amplifier provided in the optical amplifier (EDFA) 22.

The wavelength multiplexed light source of this embodiment can be used in place of the wavelength multiplexed light source 10 of the wavelength multiplexing apparatus shown in FIG.

[Third embodiment]

FIG. 5 shows a configuration of the wavelength multiplexed light source A according to the third embodiment of the present invention. The wavelength multiplexed light source 30 is an erbium-doped optical fiber 39, an excitation light source (semiconductor laser) 33, an optical isolator 32, a WDM type optical power plug 40, an optical power bra 41, a loop optical fiber 42, an optical power bra 34, passive wavelength division multiplexer (AWG) 35, optical power bra 36-1 or

It consists of 36-n, looped optical fiber 37-1 to 37-n, and automatic power control (APC) 38.

The excitation light source (semiconductor laser) 33 generates laser light with a wavelength of 980 nm or 1480 nm. The WDM optical power plug 40 is composed of a fusion type optical fiber cover that also has a wavelength multiplexing mechanism. The WDM-type optical power bra 40 couples pump light having a wavelength of 980 nm (or 1480 nm) and C-band signal light (wavelength: 1535 to 1565 nm) into one optical fiber. Or conversely, a wavelength of 980 nm (or 1

It has a function to separate the 480 nm excitation light and the C-band signal light (wavelength: 1535-1565 nm) into two optical fibers and combine them. Since the erbium-doped optical fiber 39 pumped by the pumping light source 33 has the function of amplifying light, the reflective element consisting of the optical power bra 41 and the loop optical fiber 42, the passive wavelength multiplexer (AWG) 35 A closed loop is formed by the optical power bra 36-1 to 36-n and the partially reflecting element group consisting of the loop-shaped optical fibers 37-1 to 37-n, which is determined by the passive wavelength multiplexer (AWG) 35. Laser oscillation occurs at a plurality of discrete wavelengths 1 to n. Then, a part of the laser light of discrete wavelengths 1 to n is output to the output terminal 31-1 or 31-η via the optical power blur 36-1 to 36-n.

It should be noted that a reflecting element such as a reflecting mirror or a fiber Bragg grating filter may be used instead of the reflecting element including the optical power bra 41 and the loop-shaped optical fiber. A part of the laser beam split by the optical power bra 34 is sent to an automatic power controller (APC) 38. An automatic output control device (APC) 38 controls the drive current of the excitation light source 33 so that the laser oscillation output becomes constant.

Excitation light from the excitation light source 33 excites the erbium-doped optical fiber 39 by the WDM type optical bra 40, and is reflected by the optical bra 41 and the loop optical fiber 42 to excite the erbium-doped optical fiber 39 again. After that, the light is sent to the excitation light source 33 through the WDM type optical power bra 40. However, the reflected excitation light is absorbed by the optical isolator 32, which prevents the excitation light from returning to the excitation light source 33.

According to the present embodiment, the laser oscillation light output control is performed by controlling the drive current of the pump light source 33, so that the variable optical attenuator can be omitted.

[Fourth embodiment]

FIG. 6 shows the configuration of a wavelength multiplexed light source according to a fourth embodiment of the present invention. This wavelength-multiplexed light source ϋ is composed of a first optical amplifier (EDFA-C) 59a, a second optical amplifier (EDF Α-L) 59b, a first optical power 54a, and a second optical power 54b, Third optical power bra 54c, Variable optical attenuator 53, Passive wavelength multiplexer (spectroscope) 55, Optical power bra 56-1 or 56-n, Loop optical fiber 57-1 to 57 — N, consisting of an automatic power control (APC) 58. This embodiment is a modification of the first embodiment shown in FIG. The main difference is that the first optical amplifier (EDFA-C) 59a and the second optical amplifier (EDFA-L) 59b are provided, the second optical power bra 54b and the third optical power bra 54c. Are arranged in parallel. The first optical amplifier (EDFA-C) 59a has gain in the wavelength band of the C band (1535-1565 nm), and the second optical amplifier (EDFA-L) 59b has the gain in the L band (1565-1 (595 nm). As a result, it is possible to cause laser oscillation in both the C band and the L band (wavelength: 1535 to 1595 nm). In this case, the passive wavelength multiplexer (division device) 55 is different from those of the other embodiments, and is designed to be capable of wavelength multiplexing over this wide wavelength band. . The oscillated laser light of each wavelength is output from output terminals 51-1 to 51-n.

[Fifth embodiment]

FIG. 7 shows a configuration of a wavelength multiplexed light source according to a fifth embodiment of the present invention. The wavelength multiplexing light source is an optical amplifier (ED FA) 62, a passive wavelength multiplexer (AWG) 63, an optical power 68-1-1 to 68_n, a linear optical power 64, a variable optical attenuator 66. , Optical power 65 and automatic power control (APC) 67. The oscillated laser light of each wavelength is output from the output terminals 61-1 to 61-n.

This embodiment is a modification of the second embodiment shown in FIG. In the second embodiment, two passive wavelength multiplexers (AWGs) 23 to 24 are used. However, a perimeter optical power bra 64 is used instead of the passive wavelength multiplexers (AWG) 24. Is different. The passive wavelength multiplexer (AWG) 63 of this embodiment corresponds to the passive wavelength multiplexer (AWG) 23 of the second embodiment.

The linear optical power plastic has the advantage of being less expensive than the arrayed waveguide grating (AWG). On the other hand, if the number of wavelengths at which laser oscillation is to be increased is to be increased, the loss in the case of a tree-shaped optical power sharply increases. Therefore, this embodiment is suitable for oscillating a relatively small number of wavelengths at low cost.

[Sixth embodiment] FIG. 8 shows the configuration of the wavelength multiplexed light source L according to the sixth embodiment of the present invention. The wavelength multiplexing light source 70 is a semiconductor laser 79, a lens 72, an optical power blur 74, a passive wavelength multiplexer (AWG) 75, an optical power blur 76-1 to 76-n, and no loop optical fiber 77-1. 77-n, consisting of an automatic output controller (APC) 78.

The first end face 79a of the semiconductor laser has a 髙 reflectivity (HR) coat, and the second end face 79b has an antireflection (AR) coat. The semiconductor laser 79 cannot oscillate by itself because the second end face 79b has an anti-reflection (AH) coat, but can oscillate by feedback of light from an external optical system. A so-called external resonance optical system is formed.

Spontaneous emission light from the semiconductor laser 79 is coupled to the optical fiber 73 by the lens 72. 'The light coupled to the optical fiber 73 is a part consisting of an optical power 74, a passive wavelength multiplexer (AWG) 75, an optical power 76-1 to 76-n, and a loop optical fiber 77-1 to 77-n. After passing through the reflecting element group, the light enters the semiconductor laser 79 again via the passive wavelength multiplexer (AWG) 75, the optical power bra 74, the optical fiber 73, and the lens 72. That is, a closed loop is formed as a whole, and laser oscillation occurs.

The laser light of 1 to n which oscillated the laser is partly branched by the optical power plugs 76-1 to 76-n and output from the output terminals 71-1 to 71_n. Further, a part of the laser light is branched by the optical power bra 74 and sent to the automatic output control device (APC) 78. The automatic output control device (APC) 78 controls the drive current of the semiconductor laser 79 so that the laser oscillation output becomes constant.

The semiconductor laser 79 has the advantage that the wavelength selection range is wider than that of rare-earth-doped optical fibers such as erbium-doped optical fibers, and that the optical amplifiable wavelength band as an optical amplifier is wider. It is also generally low cost.

Therefore, according to the present embodiment, there is an advantage that the range of wavelength selection and the number of selectable channels can be increased at low cost.

[Seventh embodiment]

FIG. 9 shows a configuration of a wavelength multiplexed light source A according to a seventh embodiment of the present invention. The wavelength multiplexed light source 80 is a semiconductor laser 89, a concave diffraction grating 82, and an optical fiber 83-1 to 8 It consists of 3-n, optical power plugs 86-1 to 86-n, and loop optical fiber 87-1 to 87_n. Laser light of each wavelength is output from output terminals 81_1 through 81-n.

The first end face 89a of the semiconductor laser has a high reflectivity (HR) coat, and the second end face 89b has an anti-reflection (AR) coat. The semiconductor laser 89 cannot oscillate by itself because the second end face 89b has an anti-reflection (AR) coat, but it can oscillate by feedback of light from an external optical system. A so-called external resonance optical system is formed.

This embodiment is a modification of the sixth embodiment. The present embodiment is characterized in that a spectroscopic optical system including a concave diffraction grating 82 and a free space optical system is used instead of the arrayed waveguide diffraction grating (AWG).

The spontaneous emission light from the semiconductor laser 89 is coupled by the concave diffraction grating 82 to the optical fibers 83 1 1 to 83-n at specific wavelengths 1 to n, respectively. The light coupled to the optical fiber 83-1 through 83-n passes through the partial reflection element group consisting of the optical power plugs 76-1 through 76-n and the loop optical fiber 77-1 through 77-n. The light enters the semiconductor laser 89 through 83-1 to 83-n and the concave diffraction grating 82. That is, a closed loop is formed as a whole, and laser oscillation occurs. Concave gratings have the advantage of lower cost compared to arrayed waveguide gratings (AWGs).

In addition, instead of the concave diffraction grating, a combination of a transmission diffraction grating and a lens, or a combination of a dielectric film and a lens, or the like can be used as a known spectral optical system. Also, instead of the partial reflection element group consisting of the optical power bras 76_1 to 76-n and the loop-shaped optical fibers 77-1 to 77-1n, the partial reflection consisting of the half mirror and the lens shown in Fig. 3 (b) Elements can also be used. Industrial applicability

According to the present invention, a plurality of wavelengths can be simultaneously laser-oscillated, and laser light signals having individual wavelengths can be separated and extracted.

Claims

The scope of the claims

1. Optical amplifier, first loop optical fiber, first optical power bra, passive wavelength multiplexer, at least two second optical bra, at least two second loop optical fiber A wavelength-division multiplexed light source comprising: a laser beam having a single wavelength out of a plurality of wavelengths of laser light;

2. The wavelength multiplexed light source according to claim 1, wherein the light having passed through the optical amplifier is sent to the passive wavelength multiplexer through a first loop-shaped optical fiber and a first optical power bra. After being separated for each wavelength, the light is again sent to the passive wavelength multiplexer via a second optical power blur and a second loop optical fiber corresponding to each light of each wavelength, and is sent to the passive wavelength multiplexer again. The wavelength is characterized in that an optical system is provided to form a closed loop so that the light is collected into one optical fiber and then sent again to the optical amplifier through the first optical power plug. Multiplexed light source.

3. The wavelength multiplexed light source according to claim 1, further comprising: an automatic output control means for measuring the intensity of the oscillated laser light and controlling the laser light intensity to be kept constant; and a signal from the automatic output control means. A wavelength-division multiplexed light source comprising variable attenuation means for attenuating the intensity of laser light.

4. The wavelength-division multiplexed light source according to claim 1, further comprising: an automatic output control means for measuring the intensity of the oscillated laser light and controlling the laser light intensity to be kept constant; and a signal from the automatic output control means. A wavelength multiplexed light source comprising means for controlling an excitation means of an optical amplifier.

5. The wavelength-division multiplexed light source according to claim 1, wherein a partial reflection means is used instead of the second optical power bra and the second loop-shaped optical fiber.

6. The wavelength-division multiplexed light source according to claim 1, wherein the optical amplifier is replaced with a configuration in which a plurality of optical amplifiers having different amplifiable wavelength bands are connected in parallel.

7. The wavelength multiplexing light source according to claim 1, a plurality of optical modulators corresponding to the number of wavelengths to be used, and a transmission optical signal coupling unit, wherein the optical signal of a plurality of wavelengths from the wavelength multiplexing light source is described. A wavelength multiplexing device, wherein after being modulated by an optical modulator, optical signals of a plurality of wavelengths are coupled to one optical fiber by the transmission optical signal coupling means.

8. An optical amplifier, a passive wavelength multiplexer, an optical signal coupling unit, and at least two second optical power bras. A wavelength multiplexed light source characterized in that only a laser beam having a wavelength is branched and output to the outside.

9. The wavelength-division multiplexed light source according to claim 8, wherein the optical signal coupling means is of a passive wavelength-division multiplex type.

10. The wavelength multiplexed light source according to claim 8, wherein said optical signal coupling means is a tree-shaped optical power blur.

11. The wavelength multiplexing light source according to claim 8, wherein the light output from the optical amplifier is a first passive wavelength multiplexer, at least a second optical power blur, and a second passive wavelength multiplexer. A wavelength-division multiplexed light source comprising an optical system forming a closed loop so that it can be sent to the optical amplifier again through the optical amplifier.

12. The wavelength multiplexed light source according to claim 8, a plurality of optical modulators corresponding to the number of wavelengths to be used, a transmission optical signal coupling unit, and an optical signal having a plurality of wavelengths from the wavelength multiplexed light source. After being modulated by the optical modulator, a plurality of waves are transmitted by the transmitting optical signal coupling means. A wavelength multiplexing device for combining a modulated optical signal with a single optical fiber.

13 3. A semiconductor laser coated with an end face so that one end face has high reflectivity and the other end face has low reflectivity, coupling means between the optical fiber and the low reflectivity end face of the semiconductor laser, passive wavelength multiplexing A second optical fiber brassier comprising at least two optical fibers, and a second loop optical fiber comprising at least two optical fibers. A wavelength-division multiplexed light source characterized by branching out from a power bra and outputting to the outside.

14. The wavelength multiplexed light source according to claim 13, a plurality of optical modulators corresponding to the number of wavelengths to be used, an optical signal coupling means for transmission, and an optical signal of a plurality of wavelengths from the wavelength multiplexed light source. A wavelength multiplexing apparatus for modulating a plurality of wavelengths by the optical modulator, and then coupling optical signals having a plurality of wavelengths modulated by the transmission optical signal coupling means to one optical fiber.

15. A semiconductor laser coated with an end face so that one end face has high reflectivity and the other end face has low reflectivity, and a spectroscopy that couples the low reflectivity end face of the semiconductor laser and a plurality of optical fibers by changing the wavelength. An optical coupling means, at least two second optical power brass, and at least two second loop-shaped optical fibers, wherein only laser light of one wavelength is emitted from laser light oscillated at a plurality of wavelengths. A wavelength-division multiplexed light source characterized by branching off from a second optical power bra and outputting to the outside.

16. The wavelength multiplexed light source according to claim 15, a plurality of optical modulators corresponding to the number of wavelengths to be used, an optical signal coupling means for transmission, and an optical signal of a plurality of wavelengths from the wavelength multiplexed light source. A wavelength multiplexing apparatus for modulating a plurality of wavelengths by the optical modulator, and then coupling optical signals having a plurality of wavelengths modulated by the transmission optical signal coupling means to one optical fiber.

17. A first optical fiber and a first optical power bra that constitute a multiplexed path with respect to optical loops of a plurality of wavelengths, and an optical amplifier disposed in the first optical fiber; A plurality of second optical fibers and a plurality of second optical power brass constituting paths for optical loops of a plurality of wavelengths are connected to the first optical fiber and the second optical fiber. A wavelength multiplexing light source that outputs laser light of a corresponding wavelength via the second optical fiber.

18. A first optical fiber and a first optical power bra that constitute a multiplexed path with respect to optical loops of a plurality of wavelengths; an optical amplifier disposed in the first optical fiber; A plurality of second optical fibers and a plurality of second optical power brass constituting paths for each of a plurality of wavelength optical loops are connected to the first optical fiber and the second optical fiber. And a plurality of optical modulators provided corresponding to each of the second optical fibers and modulating a laser beam of a corresponding wavelength guided through the second optical fiber. An optical signal combiner for combining laser lights of different wavelengths modulated by the optical modulator.