JP5435447B2 - Laser element and laser module - Google Patents

Description

  The present invention relates to a laser element and a laser module that are signal light sources for optical communication, and more particularly to a laser element and a laser module that perform wavelength lock control.

  2. Description of the Related Art Conventionally, as a WDM (Wavelength Division Multiplexing) optical communication device, a wavelength tunable laser apparatus that makes the wavelength of output laser light variable is known. Among these wavelength tunable laser devices, the wavelength selective type tunable laser device is attracting attention because it has excellent wavelength stability and can obtain a wide wavelength tunable characteristic by changing the operating temperature (Patent Document). 1).

  Here, when performing the wavelength lock control, a part of the laser beam outputted forward from the variable wavelength laser element is separated by the first beam splitter provided on the optical axis, and the output of the laser beam is monitored by the output monitor. Further, a part of the laser beam is separated by a second beam splitter provided on the optical axis, a predetermined wavelength component of the separated laser beam is filtered, and the laser beam having the filtered wavelength is monitored by a wavelength monitor. The wavelength is locked based on the monitor results of the output monitor and the wavelength monitor (see Patent Document 2).

Japanese Patent Application Laid-Open No. 2004-34992 JP 2005-101039 A

  However, in a laser module in which a wavelength lock control mechanism such as a variable wavelength laser module in which a wavelength lock control mechanism is mounted on the above-described wavelength tunable laser element is mounted, two beam splitters (first and first) are arranged on the optical axis. 2), the wavelength lock control mechanism occupies a large capacity, which increases the size of the laser module, and increases the size of the temperature adjustment mechanism such as a Peltier element, which increases power consumption. There was a problem.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a laser element and a laser module that can promote downsizing.

  In order to solve the above-described problems and achieve the object, a laser element according to the present invention includes a laser unit, and an end surface from which an output laser beam output from the laser unit or an output laser beam of the laser unit is emitted. Is integrated with a branching part for branching a part of the rear laser light outputted from the opposite end face, and through the branching part, a part of the output laser light and the remaining output laser light or the rear laser light. A part and the remaining rear laser light are output in different directions.

  According to another aspect of the present invention, there is provided a laser module comprising: a laser unit; and an output laser beam output from the laser unit or a rear laser beam output from an end surface opposite to an end surface from which the output laser beam of the laser unit is emitted. And a part of the output laser beam and the remaining output laser beam or a part of the rear laser beam and the remaining rear laser beam through the branch unit in different directions. A laser element to be output to, a branching means for branching a part of the remaining output laser light or rear laser light output from the branching unit, and a part of the output laser light or rearward branching by the branching means A wavelength filter for filtering a predetermined wavelength of the laser light; a wavelength monitor for monitoring a wavelength component filtered by the wavelength filter; An output monitor that monitors the output of the part of the output laser light or the rear laser light output from the unit, and performs wavelength lock control of the laser element based on the measurement results of the wavelength monitor and the output monitor. It is characterized by performing.

  According to this invention, the laser unit and a part of the output laser beam output from the laser unit or the rear laser beam output from the end surface opposite to the end surface from which the output laser beam of the laser unit is emitted A branching unit that branches is integrated, and a part of the output laser beam and the remaining output laser beam or a part of the rear laser beam and the remaining rear laser beam are output in different directions via the branching unit. Therefore, it is possible to directly monitor the output of a part of light, and only one optical branching means such as a beam splitter necessary for wavelength monitoring is required, the number of optical elements provided on the optical axis is reduced, and the laser module Miniaturization can be promoted, and a temperature adjustment mechanism such as a Peltier element can be miniaturized, and power consumption can be suppressed. Furthermore, the length of the optical axis until it is guided to the optical fiber can be shortened, and the optical axis shift can be suppressed. Optical elements such as a beam splitter are expensive, but the number of optical elements can be reduced, so that an inexpensive laser module can be realized.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a variable wavelength laser element and a variable wavelength laser module according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment)
FIG. 1 is a schematic diagram showing a configuration of a variable wavelength laser module including a variable wavelength laser element according to an embodiment of the present invention. In FIG. 1, the variable wavelength laser module 1 includes a variable wavelength laser element 10 inside. The variable wavelength laser element 10 includes a variable wavelength laser unit 11 that outputs a variable wavelength laser beam, and a semiconductor optical amplifier unit 12 that is realized by an SOA (Semiconductor Optical Amplifier) that optically amplifies the variable wavelength laser beam. And a branching unit 15 realized by a directional coupler that separates the laser light amplified by the semiconductor optical amplifier 12 and outputs the laser light in different directions.

  The variable wavelength laser unit 11 includes a laser array in which a plurality of DFB (Distributed Feedback) lasers having different oscillation wavelengths are arranged in an array, and an MMI coupler that combines laser beams output from the plurality of laser arrays. A DFB laser that oscillates at a desired wavelength is selected from a plurality of DFB lasers and output.

  Each DFB laser can be tunable by about 3 to 4 nm per one DFB laser by controlling the element temperature by a Peltier element, a heater, or the like. The lower limit of the wavelength variable range by this element temperature control is limited by the factor of the power consumption of the Peltier element, and the upper limit is limited by the factor of the light output decrease, the drive current increase, and the laser reliability due to the temperature increase. The diffraction gratings included in the respective DFB lasers are designed so that the oscillation wavelengths of the respective DFB lasers are arranged at intervals of about 3 to 4 nm. By switching the driving DFB laser and controlling the element temperature, it becomes possible to cover a continuous wavelength band that is wider than that of a single DFB laser. Here, in order to cover the entire wavelength band for WDM optical communication, for example, the C band of 1.53 to 1.56 μm or the L band of 1.57 to 1.61 μm with one variable wavelength laser element 10, It is conceivable to increase the number of laser elements. For example, if it is possible to change the wavelength of 3 to 4 nm per DFB laser by adjusting the element temperature, if 10 or more such DFB lasers are integrated, the wavelength can be varied over a wavelength range of 30 nm or more. The tunable wavelength laser element 10 can be obtained.

  As described above, the branching unit 15 is realized by a directional coupler. For example, the branching unit 15 guides the main laser beam and is disposed in parallel in the vicinity of the waveguide 13 so that a part of the laser beam is predetermined. And a waveguide 14 for branching out at a branching ratio of. Laser light is output from the output end of the waveguide 13 and the output end of the waveguide 14 in different directions.

  The variable wavelength laser element 10 is disposed on a base 23 having good thermal conductivity, and an output monitor PD1 for monitoring the output of the laser light output from the waveguide 14 is disposed on the base 23 in the vicinity.

  On the other hand, the main laser light output from the waveguide 13 is guided to the optical fiber 7 via the condenser lens 2, the isolator 3, and the beam splitter 4, and is output to the outside. The beam splitter 4 branches a part of the laser light on the optical axis, and the branched laser light is output to the wavelength monitor PD2 via the wavelength filter 5 realized by an etalon. The wavelength monitor PD2 monitors the output of the laser light having the wavelength filtered by the wavelength filter 5.

  The condenser lens 2 is disposed on a base 23 having good thermal conductivity on which the base 23 and the condenser lens 2 are disposed, and a temperature adjusting means realized by a Peltier element or the like is disposed below the base 22. Is done. The isolator 3 is disposed on the base 20 having good thermal conductivity. A base 21 with good thermal conductivity is further disposed on the base 20, and a beam splitter 4, a wavelength filter 5, a wavelength monitor PD 2, and a thermistor 6 are disposed on the base 21. Note that temperature adjusting means realized by a Peltier element or the like is disposed below the base 20.

  The monitoring results of the output monitor PD1, the wavelength monitor PD2, and the thermistor 6 are output to the control unit C provided outside the variable wavelength laser module 1. The control unit C performs wavelength lock control based on the monitor results of the output monitor PD1 and the wavelength monitor PD2. That is, the control unit C selects the DFB laser in the variable wavelength laser unit 11 and adjusts the temperature of the temperature adjusting unit disposed at the bottom of the base 22. Further, the control unit C adjusts the temperature of the temperature adjusting means arranged at the lower part of the base 10 in order to change the wavelength selected by the wavelength monitor based on the monitoring result of the thermistor 6. Further, the control unit C controls the optical amplification factor by the semiconductor optical amplification unit 12 based on the monitoring result of the output monitor PD1.

  In this embodiment, since the output monitor PD1 directly monitors the output of a part of the laser beam branched by the branching unit 15 integrated in the wavelength tunable laser element 10, the branching means is used for wavelength monitoring. Therefore, the number and volume of the optical elements for performing wavelength lock control in the variable wavelength laser module 1 can be reduced, and the variable wavelength laser module 1 can be reduced. Downsizing can be promoted. Further, since only one beam splitter 4 needs to be provided on the optical axis, the length of the optical axis from the waveguide 13 to the input end of the optical fiber 7 can be shortened, and the optical axis deviation can be reduced. it can. Further, with the miniaturization of the variable wavelength laser module 1, the miniaturization of the temperature adjusting means realized by a Peltier element or the like is promoted, and the power consumption can be suppressed. Moreover, since optical components such as the beam splitter 4 are expensive, an inexpensive variable wavelength laser module can be realized.

  In the above-described embodiment, the branching unit 15 is realized by using a directional coupler. However, the present invention is not limited to this. For example, as in the variable wavelength laser element 30 shown in FIG. It is also possible to branch the output to different waveguides 34 and 35.

  Furthermore, in the above-described embodiment, the variable wavelength laser element selects a plurality of DFB lasers. However, the present invention is not limited to this, and the variable wavelength laser unit 11 can be changed using a single semiconductor laser 46 instead of the variable wavelength laser unit 11. Wavelength output may be performed. In this case, the semiconductor laser 46 is provided with a variable wavelength section 47 like a DBR laser. In this case, the wavelength control may be performed on the variable wavelength unit 47, or the wavelength control may be performed by a temperature adjusting unit.

  The variable wavelength laser element described above may be an element that does not have an amplification unit. The amplification factor in this case is determined by controlling the current injection amount. Further, in this case, as shown in FIG. 3, a branching portion 45 is provided for the monitor light leaking from the rear of the semiconductor laser 46, and the monitor light is respectively output from the output monitor waveguide 44 and the wavelength monitor waveguide 43. Branch output may be performed in different directions.

It is a schematic diagram which shows the structure of the variable wavelength laser module containing the variable wavelength laser element which is embodiment of this invention. It is a schematic diagram which shows the modification of a variable wavelength laser element. It is a schematic diagram which shows the other modification of a variable wavelength laser element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable wavelength laser module 2 Condensing lens 3 Isolator 4 Beam splitter 5 Wavelength filter 6 Thermistor 7 Optical fiber 10, 30, 40 Variable wavelength laser element 11 Variable wavelength laser part 12 Semiconductor optical amplification part 13, 14, 33, 34, 42 , 43, 44 Waveguide 15, 45 Branching unit 20 Base 21-23 Base 35 MMI coupler 46 Semiconductor laser 47 Wavelength tuning unit PD1 Output monitor PD2 Wavelength monitor C Control unit

Claims (3)

A laser unit, an optical amplifying section for the laser beam to the optical amplifying said laser unit is outputted, it is optically amplified by the output from the laser unit the optical amplification unit, the output laser beam or the output laser beam of the laser unit emits And a branch portion made of a waveguide for branching a part of the rear laser beam outputted from the end surface opposite to the end surface, and a part of the output laser beam and the remaining output through the branch portion. A laser element for outputting a laser beam or a part of the rear laser beam and the remaining rear laser beam in different directions in which both are separated from each other;
Branching means for branching a part of the remaining output laser beam or rear laser beam output from the branching unit;
A wavelength filter for filtering a predetermined wavelength of the part of the output laser beam or the rear laser beam branched by the branching unit;
A wavelength monitor for monitoring a wavelength component filtered by the wavelength filter;
An output monitor disposed close to the laser element for monitoring the output of the part of the output laser light or the rear laser light output from the branching unit;
With
The branching portion is disposed in parallel in the vicinity of the first waveguide for guiding the remaining output laser light or rear laser light and the first waveguide, and the partial output laser light or rear laser A second waveguide for branching and outputting light at a predetermined branching ratio, wherein the first waveguide and the second waveguide are a part of the output laser light and the remaining output laser light or It is configured to output a part of the rear laser beam and the remaining rear laser beam in different directions in which both are separated from each other,
The part of the output laser beam or the rear laser beam branched by the branching unit is monitored by the wavelength monitor via a condenser lens,
The part of output laser light or rear laser light output from the branching unit is directly monitored by the output monitor,
A laser module that performs wavelength lock control of the laser element based on measurement results of the wavelength monitor and the output monitor. The branch portion includes a first waveguide that guides the remaining laser light,
2. A directional coupler comprising: a second waveguide disposed in parallel adjacent to the first waveguide, and having a second waveguide for branching and outputting the part of the laser light at a predetermined branching ratio. Item 2. The laser module according to Item 1. The remaining output laser light or rear laser light output from the branch portion is from the partial output laser light or rear laser light output from the branch portion with respect to the longitudinal axis of the laser element. The output is tilted away.
The part of the output laser beam or the rear laser beam output from the branch unit is from the remaining output laser beam or the rear laser beam output from the branch unit with respect to the longitudinal axis of the laser element. The laser module according to claim 1, wherein the laser module is output with an inclination in a direction away from the laser module.

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