Optical device and wavelength-variable laser

Abstract

This optical device comprises, for example: a base; a plurality of optical components fixed to the base; an etalon filter serving as an optical component; and a heater wiring layer that is provided in a position outside a light passage region on the surface of the etalon filter and that generates heat when energized. In the optical device, the heater wiring layer may be provided to an end surface constituting a surface and through which light passes, may be provided to a lateral surface constituting a surface and through which light does not pass, may have a bent portion on the surface, or may extend so as to at least partially surround the passage region.

Description

Optical Devices and Tunable Lasers

[0001] The present invention relates to optical devices and tunable lasers.

[0002] This application is a patent application filed in FY2022 under the "Commissioned Research for Research and Development of Innovative Information and Communications Technology / Research and Development of Bandwidth-Extended Optical Node Technology to Realize Beyond 5G Ultra-High-Speed ​​and Large-Capacity Networks - Research and Development of Bandwidth-Extended Optical Node Technology for Expanding the Bit Rate-Distance Product of Optical Networks" by the National Institute of Information and Communications Technology, a National Research and Development Agency, and subject to Article 17, Paragraph 1 of the Industrial Technology Enhancement Act.

[0003] A chip-integrated wavelength tunable laser is known (see Patent Document 1). The wavelength tunable laser disclosed in Patent Document 1 integrates an amplifier unit that emits and amplifies light and an optical filter that has predetermined wavelength characteristics.

[0004] Patent No. 2687464

[0005] In the configuration of Patent Document 1, for example, when the amount of current to the amplifier is increased to increase the laser output, heat generated in the amplifier may be transferred to the optical filter, affecting the wavelength characteristics of the optical filter. Therefore, it is preferable that the temperature of the optical filter can be individually adjusted. In addition, it is preferable that the temperature of the optical filter can be adjusted with greater precision.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a novel and improved optical device and tunable laser that allows, for example, the temperature of optical filters to be adjusted individually and with greater precision.

[0007] The optical device of the present invention includes, for example, a base, a plurality of optical components fixed to the base, an etalon filter as the optical component, and a heater wiring layer that is located outside the light passage area on the surface of the etalon filter and generates heat when electricity is applied.

[0008] In the optical device, the heater wiring layer may be provided on an end surface, which serves as the surface, through which the light passes.

[0009] In the optical device, the heater wiring layer may be provided on a side surface of the surface through which the light does not pass.

[0010] In the optical device, the heater wiring layer may extend so as to at least partially surround the passage area.

[0011] In the optical device, the etalon filter may have a body and reflective films provided on the entrance end and exit end of the body, and the body may be made of glass or silicon.

[0012] In the optical device, the heater wiring layer may have a laminated structure made of any one of Ti, Pt, Au, Ni, TaN, TiW, and indium tin oxide, or a material containing any one of them.

[0013] In the optical device, the heater wiring layer may be used for temperature detection.

[0014] In the optical device, the heater wiring layer used for temperature detection may include a Ti / Pt laminated structure.

[0015] In the optical device, the heater wiring layer may be capable of changing the temperature of a light passing region of the etalon filter within a range of room temperature to 150° C. by changing the power supplied thereto.

[0016] The optical device may include a plurality of etalon filters provided with the heater wiring layer as the optical component.

[0017] The optical device may include a temperature detector provided on the surface.

[0018] In the optical device, the temperature detection section may be a temperature sensing resistance wiring layer whose resistance value changes in response to a change in temperature.

[0019] In the optical device, the temperature sensing resistance wiring layer may be located closer to the passing region than the heater wiring layer.

[0020] In the optical device, the heater wiring layer may be longer than the temperature sensing resistance wiring layer.

[0021] In the optical device, the temperature sensing resistance wiring layer may be located farther from the passing region than the heater wiring layer.

[0022] In the optical device, the heater wiring layer may extend in a circumferential direction while reciprocating in a radial direction relative to an optical axis of light passing through the passage region.

[0023] In the optical device, the heater wiring layer may extend so as to surround the passage area at least partially and in multiple layers.

[0024] The wavelength tunable laser of the present invention includes, for example, an optical amplifier unit that generates and amplifies light and outputs the light from a first end and a second end opposite the first end, a first mirror that reflects the light output from the first end, a second mirror that reflects the light output from the second end, an etalon filter that is provided between the optical amplifier unit and the first mirror or the second mirror, has predetermined wavelength characteristics, and passes the light output from the optical amplifier unit, and a heater wiring layer that is provided on the surface of the etalon filter at a position outside the light passing area and generates heat when current is applied.

[0025] The wavelength tunable laser may include a lens that is provided between the optical amplifier and the etalon filter and through which light traveling between the optical amplifier and the etalon filter passes.

[0026] The wavelength-tunable laser may include a temperature control mechanism that adjusts the temperature of the optical amplification unit, and a heat-shielding member that is interposed between the temperature control mechanism and the etalon filter and that suppresses heat conduction between the temperature control mechanism and the etalon filter.

[0027] The present invention provides novel and improved optical devices and tunable lasers that, for example, allow the temperature of optical filters to be individually and more precisely adjusted.

[0028] FIG. 1 is an exemplary and schematic plan view showing an optical device of a first embodiment with its top cover removed. FIG. 2 is an exemplary and schematic side view of a portion of the optical device of the first embodiment. FIG. 3 is an exemplary and schematic front view of an etalon filter included in the optical device of the first embodiment. FIG. 4 is an exemplary and schematic plan view showing an optical device of a second embodiment with its top cover removed. FIG. 5 is an exemplary and schematic plan view showing an optical device of a third embodiment with its top cover removed. FIG. 6 is an exemplary and schematic plan view showing an optical device of a fourth embodiment with its top cover removed. FIG. 7 is an exemplary and schematic plan view showing an optical device of a fifth embodiment with its top cover removed. FIG. 8 is an exemplary and schematic side view of a portion of the optical device of the fifth embodiment. FIG. 9 is an exemplary and schematic plan view showing an optical device of a sixth embodiment with its top cover removed. FIG. 10 is an exemplary and schematic plan view showing an optical device of a seventh embodiment with its top cover removed. FIG. 11 is an exemplary and schematic plan view showing a state in which the top cover of the optical device of the eighth embodiment is removed. FIG. 12 is an exemplary and schematic plan view showing a state in which the top cover of the optical device of the ninth embodiment is removed. FIG. 13 is an exemplary and schematic plan view showing a state in which the top cover of the optical device of the tenth embodiment is removed. FIG. 14 is an exemplary and schematic front view of an etalon filter included in an optical device of the eleventh embodiment. FIG. 15 is an exemplary and schematic front view of an etalon filter included in an optical device of the twelfth embodiment. FIG. 16 is an exemplary and schematic front view of an etalon filter included in an optical device of the thirteenth embodiment. FIG. 17 is an exemplary and schematic front view of an etalon filter included in an optical device of the fourteenth embodiment. FIG. 18 is an exemplary and schematic front view of an etalon filter included in an optical device of the fifteenth embodiment. FIG. 19 is an exemplary and schematic front view of an etalon filter included in an optical device of the sixteenth embodiment. Fig. 20 is an exemplary schematic front view of an etalon filter included in an optical device according to a seventeenth embodiment. Fig. 21 is an exemplary schematic front view of an etalon filter included in an optical device according to an eighteenth embodiment. Fig. 22 is an exemplary schematic perspective view of an etalon filter included in an optical device according to a nineteenth embodiment.FIG. 23 is an exemplary and schematic front view of an etalon filter included in the optical device of the twentieth embodiment. FIG. 24 is an exemplary and schematic front view of an etalon filter included in the optical device of the twenty-first embodiment. FIG. 25 is an exemplary and schematic front view of an etalon filter included in the optical device of the twenty-second embodiment. FIG. 26 is an exemplary and schematic perspective view of an etalon filter included in the optical device of the twenty-third embodiment. FIG. 27 is an exemplary and schematic front view of a modified etalon filter included in the optical device of the embodiment. FIG. 28 is an exemplary and schematic front view of a modified etalon filter included in the optical device of the embodiment. FIG. 29 is an exemplary and schematic rear view of a modified etalon filter included in the optical device of the embodiment. FIG. 30 is an exemplary and schematic rear view of a modified etalon filter included in the optical device of the embodiment. FIG. 31 is an exemplary and schematic rear view of a modified etalon filter included in the optical device of the embodiment. FIG. 32 is an exemplary schematic rear view of a modified example of the etalon filter included in the optical device of the embodiment.

[0029] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments described below, as well as the actions and results (effects) brought about by the configurations, are merely examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0030] The following embodiments have similar configurations. Therefore, according to the configurations of each embodiment, similar actions and effects based on the similar configurations can be obtained. Furthermore, in the following, similar configurations are given similar reference numerals, and duplicated descriptions may be omitted.

[0031] In this specification, ordinal numbers may be assigned for convenience to distinguish between parts, members, parts, directions, lights, etc. Note that ordinal numbers do not indicate priority or order, nor do they specify a number.

[0032] In each drawing, the X direction is represented by an arrow X, the Y direction is represented by an arrow Y, and the Z direction is represented by an arrow Z. The X direction, Y direction, and Z direction intersect with each other and are perpendicular to each other.

[0033] 1 is a plan view showing an optical module 100A (100) according to a first embodiment with its top cover removed. The optical module 100A (100) is an example of an optical device having a tunable laser.

[0034] 1, the optical module 100A includes a housing 1. The housing 1 includes an output port 1a, four side walls 1b, a bottom wall 1c, and a top cover (not shown).

[0035] The bottom wall 1c is a plate-shaped member located at the end opposite the Z direction. The bottom wall 1c intersects the Z direction and is perpendicular to it, and extends in the X and Y directions with a substantially constant thickness in the Z direction. The bottom wall 1c is made of a material with high thermal conductivity, such as copper tungsten (CuW), copper molybdenum (CuMo), or aluminum oxide (Al2O3).

[0036] Each of the side walls 1b is a plate-shaped member, and extends in the Z direction, substantially perpendicular to the bottom wall 1c, and perpendicular to the X direction or the Y direction.

[0037] The output port 1a is provided on the side wall 1b located at the end in the X direction. The lens 2 is housed within the output port 1a. The output port 1a also supports an optical fiber 3 that outputs output light to the outside.

[0038] The top cover is a plate-shaped member located at the end in the Z direction. The top cover intersects and is perpendicular to the Z direction, extends in the X and Y directions with a substantially constant thickness in the Z direction, and is substantially parallel to the bottom wall 1c.

[0039] The output port 1a, side wall 1b, and top cover are made of a material with a low coefficient of thermal expansion, such as an Fe-Ni-Co alloy or aluminum oxide (Al2O3).

[0040] The storage chamber in the housing 1 is, for example, hermetically sealed. An inert gas such as nitrogen gas may be stored in the housing 1. In this case, nitrogen gas is an example of the gas.

[0041] The housing 1 contains components such as the chip-on submount 4, lenses 51 and 52, etalon filter 11, mirror 10a, optical isolator 6, beam splitter 23, photodiode 24, and carrier 60. These components are fixed to the housing 1 directly or indirectly via other members or components. Among these components, the chip-on submount 4, lenses 51 and 52, mirror 10a, etalon filter 11, optical isolator 6, beam splitter 23, and photodiode 24 are examples of optical components. Optical components are, for example, components that output light, receive light, transmit light, or affect light. Note that the housing 1 may contain and support optical components other than the above-mentioned components, as well as components such as electronic and electrical components different from optical components. The housing 1 is an example of a base.

[0042] In this embodiment, the chip-on submount 4, lenses 51 and 52, etalon filter 11, mirror 10a, optical isolator 6, beam splitter 23, and photodiode 24 are supported on a carrier 60 directly or indirectly via other members. The carrier 60 is, for example, a Peltier module with a temperature adjustment function. In this case, the carrier 60 is an example of a temperature adjustment mechanism capable of adjusting the temperature of the laser element 4a. The Peltier module will be described in detail later. Note that a temperature adjustment mechanism other than a Peltier module, such as a heater as a resistance heating module, may be provided corresponding to the chip-on submount 4.

[0043] The chip-on submount 4 has a laser element 4a, a submount 4b, and a thermistor 4c. The laser element 4a is a semiconductor laser element. The laser element 4a has an optical amplifier 4a1. The chip-on submount 4 may also be called a light-emitting unit.

[0044] The optical amplifier 4a1 has a laser medium such as a semiconductor active layer, and generates and amplifies light in response to a supplied current. The optical amplifier 4a1 outputs light from one end 4a11 and another end 4a12 opposite the end 4a11. The end 4a11 is an example of a first end, and the end 4a12 is an example of a second end.

[0045] A mirror 10b is provided at the end 4a12. The mirror 10b reflects at least a portion of the incoming light. In this embodiment, the mirror 10b reflects a portion of the light output from the optical amplifier 4a1 and inputs it to the optical amplifier 4a1, while also transmitting a portion of the light output from the optical amplifier 4a1. The mirror 10b is, for example, a dielectric multilayer film mirror. The mirror 10b is an example of a second mirror.

[0046] The submount 4b supports the laser element 4a. The submount 4b is made of an insulating material with high thermal conductivity. The thermistor 4c is an example of a temperature sensor. The thermistor 4c is mounted on, for example, the submount 4b.

[0047] The light output from the end 4a11 of the optical amplifier 4a1 passes through the lens 51. The lens 51 is, for example, a collimator lens.

[0048] The light passing through the lens 51 passes through the etalon filter 11 and reaches the mirror 10a.

[0049] The etalon filter 11 has predetermined wavelength characteristics and transmits light of a wavelength corresponding to the wavelength characteristics. A heater 12 is provided on an end face 11a of the etalon filter 11. The heater 12 changes the optical path length of the etalon filter 11, thereby changing the wavelength characteristics of the etalon filter 11. The heater 12 will be described in detail later.

[0050] The mirror 10a reflects at least a portion of the light that reaches it. In this embodiment, the mirror 10a reflects all of the light that reaches the mirror 10a so that the light returns to the etalon filter 11. The mirror 10a is, for example, a dielectric multilayer mirror. The mirror 10a is an example of a first mirror.

[0051] The light output from the end 4a12 of the optical amplifier 4a1 and transmitted through the mirror 10b reaches the optical isolator 6 via the lens 52. The lens 52 is, for example, a collimating lens.

[0052] The optical isolator 6 transmits the incoming light, in this case the light coming from the lens 52 , towards the beam splitter 23 and blocks the light from returning from the beam splitter 23 .

[0053] The beam splitter 23 outputs most of the light to the lens 2 and outputs a portion of the light to the photodiode 24. The lens 2 collects the light from the beam splitter 23 and couples it into the optical fiber 3.

[0054] The photodiode 24 receives the light from the beam splitter 23 and outputs a detection signal corresponding to the intensity of the received light. The detection signal is input to a controller (not shown) via wiring (not shown). The controller controls the operation of the laser element 4 a based on the detection signal from the photodiode 24.

[0055] In this configuration, the optical amplifier 4a1 and the etalon filter 11 are interposed between the mirrors 10a and 10b, and a resonant mechanism is formed in which light resonates by reciprocating between the mirrors 10a and 10b at a predetermined wavelength. In this resonant mechanism, the resonant wavelength can be changed by changing the temperature of the etalon filter 11 to change the optical path length.

[0056] Furthermore, in this configuration, by providing the lens 51 between the laser element 4a and the etalon filter 11, the distance between the optical amplifier 4a1 of the laser element 4a and the etalon filter 11 can be increased. The optical amplifier 4a1 generates heat when in operation. Therefore, if the distance between the optical amplifier 4a1 and the etalon filter 11 were short, the heat generated by the optical amplifier 4a1 could make it difficult to accurately adjust the temperature of the etalon filter 11 using the heater 12. In this regard, in this embodiment, by providing the lens 51, the distance between the optical amplifier 4a1 and the etalon filter 11 can be increased. Therefore, the thermal effect of the optical amplifier 4a1 on the etalon filter 11 can be suppressed, thereby enabling more accurate temperature adjustment of the etalon filter 11 using the heater 12, and therefore wavelength control.

[0057] FIG. 2 is a side view of a portion of the optical module 100A. As described above, in this embodiment, the carrier 60 is configured as a Peltier module 60P. As shown in FIG. 2, the Peltier module 60P includes a first substrate 60a, a second substrate 60b, and multiple thermoelectric elements 60c. The thermoelectric elements 60c are columnar semiconductor elements disposed between the first substrate 60a and the second substrate 60b. The thermoelectric elements 60c are made of a P-type or N-type semiconductor, such as a bismuth telluride-based semiconductor. The multiple thermoelectric elements 60c are connected in series to form a PN junction via wiring patterns (not shown) provided on the first substrate 60a and the second substrate 60b. Electric power is supplied from wiring (not shown) to a circuit including the multiple thermoelectric elements 60c connected in series via the wiring patterns. As a result, the Peltier module 60P absorbs or generates heat depending on the direction of the power current. The Peltier module 60P is capable of adjusting the temperature of the laser element 4a in accordance with a value detected by, for example, the thermistor 4c, and is an example of a temperature adjustment mechanism.

[0058] In this embodiment, the etalon filter 11, heater 12, and mirror 10a are supported by the Peltier module 60P via a heat shield 70 having a lower thermal conductivity than the housing 1, the Peltier module 60P, metal materials, etc. In other words, the heat shield 70 is interposed between the etalon filter 11, heater 12, and mirror 10a and the optical amplifier 4a1 or the Peltier module 60P, suppressing heat conduction therebetween. The heat shield 70 is made of, for example, glass. The etalon filter 11 and mirror 10a are fixed to the heat shield 70 with, for example, a bonding material 90. This configuration can suppress a decrease in the accuracy of the heater 12's temperature adjustment function of the etalon filter 11, which may be caused by heat from the Peltier module 60P during temperature adjustment or heat transferred from the optical amplifier 4a1 via the Peltier module 60P. Note that the heat shield 70 has a block shape, but is not limited thereto. For example, the heat shield 70 may be provided with a hollow portion.

[0059] Furthermore, the etalon filter 11 and the mirror 10a are supported on the Peltier module 60P together with the chip-on submount 4 and the lenses 51 and 52. With this configuration, the temperature adjustment function of the Peltier module 60P can suppress, for example, a decrease in the coupling efficiency between the optical components due to a change in the relative positional relationship between these optical components.

[0060] 3 is a front view of the etalon filter 11. The etalon filter 11 has a body having end faces formed as parallel flat surfaces, and a reflective film formed on each end face to reflect light at a predetermined reflectance. The body is made of, for example, glass or silicon.

[0061] The heater 12A (12) is provided on an end face 11a, which is the surface of the etalon filter 11. In each drawing, only the end face on which the heater 12 is provided is given the reference numeral 11a.

[0062] The heater 12 has two end portions 12t and an extension portion 12a. The extension portion 12a extends between the two end portions 12t on the end surface 11a while curving with a predetermined width and thickness (height). In this embodiment, the extension portion 12a extends in an inverted U-shape that opens in the opposite direction to the Z direction, substantially along the periphery of the etalon filter 11. The heater 12 is an example of a heater wiring layer and may also be referred to as a resistance heating layer.

[0063] The heater 12 is formed directly on the end face 11a, which is the surface of the etalon filter 11, by, for example, vapor deposition or sputtering. With this configuration, the etalon filter 11 can be heated more efficiently and more quickly by the heater 12, and the temperature of the etalon filter 11, and therefore the wavelength of light, can be controlled with higher precision, compared to a configuration in which the heater is attached to the etalon filter 11 via a bonding material, or a configuration in which a separate member with a heater is attached to the etalon filter 11, i.e., a configuration in which the heater is attached to the etalon filter 11 via a separate member. Furthermore, the responsiveness of wavelength control can be improved.

[0064] The heater 12 is opaque and is therefore provided at a position outside the light passing area A on the end face 11a of the etalon filter 11. The light passing area A is, for example, an area where the intensity is 1 / e of the maximum intensity. ２ The heater 12 can be defined as a region where the temperature difference between the end face 11a and the end face 11a is equal to or greater than the temperature difference between the end face 11a and the end face 11a. This configuration can prevent the heater 12 from interfering with the propagation of light. Furthermore, the heater 12 extends so as to bend on the end face 11a and at least partially surround the passage region A. This configuration can heat a wider range of the end face 11a of the etalon filter 11, specifically a wider range around the passage region A, and can reduce the temperature difference (temperature unevenness) depending on the location compared to when the etalon filter 11 is heated locally, thereby enabling more precise control of the wavelength of light.

[0065] The specifications of the heater 12, such as its material, length, width, and thickness, are determined so as to obtain the required heating performance for the etalon filter 11 depending on the wavelength control range of the light. For example, when the optical module 100A is used as a wavelength-tunable laser, the specifications of the heater 12 are set so that the heater 12 can heat at least the pass region A of the etalon filter 11 to 150°C and can change the temperature of at least the pass region A of the etalon filter 11 within a range from room temperature to 150°C by changing the power supplied. The heater 12 may have a layered structure made of a material that generates heat when energized, i.e., Ti, Pt, Au, Ni, TaN, TiW, or indium tin oxide, or a material containing any of these. Specifically, the heater 12 may be formed as a film including a layered structure of, for example, Ti / Pt / Au, Ti / Pt, Ti / Pt / Ni, or Ti / Pt / TaN. Furthermore, the width of the heater 12 is, for example, 0.5 mm or more and 2.0 mm or less, and the thickness of the heater 12 is, for example, 0.05 mm or more and 0.3 mm or less.

[0066] The heater 12 may also be used for temperature detection. For example, if the heater 12 is made as a film including a Ti / Pt laminated structure, the resistance value of the heater 12 is likely to change in response to temperature changes. In this case, the temperature of the heater 12, and therefore the temperature of the etalon filter 11, can be detected by measuring the resistance value. The heater 12 used for temperature detection in this manner is an example of a temperature-sensing resistance wiring layer.

[0067] As described above, in this embodiment, the heater 12(d) is provided directly on the etalon filter 11. Therefore, the temperature of the etalon filter 11 can be individually adjusted with higher precision by the heater 12. Furthermore, in this embodiment, the heater 12 is provided at a position on the end face 11a (surface) of the etalon filter 11 that is outside the light passage area A. Therefore, it is possible to obtain the effect of more easily improving wavelength control precision and control responsiveness while suppressing light blocking by the heater 12.

[0068] Moreover, the heater 12 has a curved portion on the end surface 11 a and extends so as to at least partially surround the passage area A. This configuration makes it easier to increase the length of the heater 12, which makes it easier to ensure the desired heating performance of the heater 12.

[0069] Second and Third Embodiments FIG. 4 is a plan view showing an optical module 100B (100) according to a second embodiment with its top cover removed. FIG. 5 is a plan view showing an optical module 100C (100) according to a third embodiment with its top cover removed. As shown in FIG. 4 , in the optical module 100B, the laser element 4a includes an optical amplifier 4a1 and an optical filter 4a2. As shown in FIG. 5 , in the optical module 100C, the laser element 4a includes optical filters 4a2 and 4a3 and an SOA 4a4 (SOA: semiconductor optical amplifier) ​​along with the optical amplifier 4a1. The optical filters 4a2 and 4a3 are, for example, distributed bragg reflectors (DBRs), ring filters, phase adjustment filters, Mach-Zehnder filters, etc. Thus, even when the laser element 4a includes one or more optical function units other than the optical amplifier 4a1, the same effects as those of the first embodiment can be obtained. Furthermore, there is an advantage that the optical module 100 can be configured more compactly than when each optical function section is provided separately.

[0070] [Fourth Embodiment] FIG. 6 is a plan view showing an optical module 100D (100) according to a fourth embodiment with the top cover removed. As shown in FIG. 6, in the optical module 100D, the etalon filter 11 and the mirror 10a are integrated. The mirror 10a is, for example, a dielectric multilayer mirror. The heater 12 is provided on the end face 11a opposite the mirror 10a. This configuration also achieves the same effects as the first embodiment. Furthermore, this configuration allows the optical module 100 to be more compact since the etalon filter 11 and the mirror 10a are integrated, which has the advantage of making it easier to secure space for arranging other components, such as the photodiode 24.

[0071] Fifth Embodiment FIG. 7 is a plan view showing an optical module 100E (100) according to a fifth embodiment with the top cover removed. FIG. 8 is a side view of a portion of the optical module 100E. As shown in FIGS. 7 and 8 , in the optical module 100E, only the etalon filter 11 is attached to the heat shield 70. As shown in FIG. 8 , the heat shield 70 may have a beam structure. The beam structure can reduce the cross-sectional area of ​​the heat conduction path in the heat shield 70, thereby further improving heat shielding properties. This embodiment not only provides the same effects as the first embodiment, but also has the advantage of allowing the heat shield 70 to be smaller.

[0072] Sixth Embodiment FIG. 9 is a plan view showing an optical module 100F (100) according to a sixth embodiment with the top cover removed. As shown in FIG. 9, the optical module 100F includes one etalon filter 11 between the lens 51 and the optical isolator 6. A mirror 10b is provided at the end 4a12 of the optical amplifier 4a1, and a mirror 10a is provided at the end face 11a of the etalon filter 11 opposite the lens 51. This configuration also achieves the same effects as the first embodiment. While the heater 12 is provided at the end face 11a where the mirror 10a is provided, it may also be provided at the opposite end face where the mirror 10a is not provided.

[0073] Seventh Embodiment FIG. 10 is a plan view showing an optical module 100G (100) according to a seventh embodiment with the top cover removed. As shown in FIG. 10, the optical module 100G includes two etalon filters 11 arranged in series between a lens 51 and an optical isolator 6. A mirror 10b is provided at the end 4a12 of the optical amplifier 4a1, and a mirror 10a is provided on the end face 11a of the etalon filter 11 farthest from the lens 51, opposite the lens 51. A heater 12 is provided on the end face 11a of each etalon filter 11 farthest from the lens 51. This configuration also achieves the same effects as the first embodiment. Furthermore, this configuration has the advantage of enabling a wider controllable wavelength band due to the increased number of etalon filters 11. The heater 12 may also be provided on the end face of the etalon filter 11 closer to the lens 51.

[0074] Eighth and Ninth Embodiments Fig. 11 is a plan view showing an optical module 100H (100) according to the eighth embodiment with the top cover removed. Fig. 12 is a plan view showing an optical module 100I (100) according to the ninth embodiment with the top cover removed. As shown in Fig. 11, in the optical module 100H, a mirror 10a is provided in the optical isolator 6. As shown in Fig. 12, in the optical module 100I, a mirror 10a is provided in the beam splitter 23. With these configurations, the same effects as in the first embodiment can be obtained.

[0075] Tenth Embodiment FIG. 13 is a plan view showing an optical module 100J (100) according to a tenth embodiment with the top cover removed. In addition to the same components as those of the first embodiment, the optical module 100J includes multiple lenses 50, a beam splitter 23, an SOA 4a4, and the like. The lens 50 and the beam splitter 23J are interposed between a mirror 10a provided on an end face of the etalon filter 11 and a mirror 10b provided at the end 4a12 of the optical amplifier 4a1. The heater 12 is provided on the end face 11a of the etalon filter 11 opposite the end face on which the mirror 10a is provided. This configuration also achieves the same effects as the first embodiment. The heater 12 may also be provided on the end face on which the mirror 10a is provided.

[0076] 11th to 13th Embodiments

[0077] Figures 14 to 16 are front views of an etalon filter 11 having heaters 12K to 12M (12) according to the 11th to 13th embodiments, respectively. Each heater 12 has an extension 12a extending between its ends 12t. The intermediate portion of the extension 12a is curved along the periphery of the passage area A. The heater 12K according to the 11th embodiment has one end 12t on each side of the extension 12a. The heater 12L according to the 12th embodiment has two end 12t on each side of the extension 12a. The heater 12M according to the 13th embodiment has three end 12t on each side of the extension 12a. These configurations also provide the same effects as the first embodiment.

[0077] [Fourteenth to Sixteenth Embodiments] Figures 17 to 19 are front views of etalon filters 11, 11N (11) having heaters 12N, 12O (12) according to the fourteenth to sixteenth embodiments, respectively. In these embodiments, the intermediate portion of the extension 12a is curved along the periphery of the passing region A for a longer section than in the eleventh to thirteenth embodiments, forming an Ω-like shape. As shown in Figure 18, the side surface 11b of the etalon filter 11N according to the fifteenth embodiment has a cylindrical surface shape that conforms to the extension 12a. Furthermore, while the extension 12a is curved in an arc shape in the fourteenth and fifteenth embodiments, the extension 12a in the sixteenth embodiment is curved in an elongated elliptical shape. These configurations also achieve the same effects as the first embodiment. Furthermore, these configurations allow the extension 12a and, therefore, the heater 12 to be longer.

[0078] 20 is a front view of an etalon filter 11 having a heater 12P (12) according to a seventeenth embodiment. In this embodiment, the extension 12a extends along the circumferential direction while reciprocating radially with respect to the optical axis Ax of light passing through the passage region A. This configuration also provides the same effects as the first embodiment. Furthermore, this configuration allows the extension 12a, and therefore the heater 12, to be made even longer.

[0079] 21 is a front view of an etalon filter 11 having a heater 12Q (12) according to an eighteenth embodiment. In this embodiment, the extension 12a extends so as to partially and multiple times surround the passage area A. This configuration also provides the same effects as the first embodiment. Furthermore, this configuration allows the extension 12a and, therefore, the heater 12 to be made even longer.

[0080] 22 is a perspective view of an etalon filter 11R (11) having a heater 12R (12) according to a 19th embodiment. In this embodiment, the heater 12R is provided not on the end face 11a of the etalon filter 11 but on the side face 11b, which serves as a surface through which light does not pass. The side face 11b is a curved surface having a cylindrical convex portion. The heater 12R extends from the side face 11b so as to partially and multiple times surround the passage region A. This configuration also achieves the same effects as the first embodiment. Furthermore, this configuration allows the extension 12a, and therefore the heater 12, to be even longer.

[0081] [Twentieth Embodiment] FIG. 23 is a front view of an etalon filter 11 having a heater 12S (12) according to the twentieth embodiment. In this embodiment, the heater 12S includes two wiring portions 12b spaced apart in the Y direction and an electric heating portion 12c spanning the two wiring portions 12b. The wiring portions 12b extend in the Z direction from the end 12t near the Y direction and the opposite end of the etalon filter 11 relative to the Y direction, respectively, with a predetermined width in the Y direction. The electric heating portion 12c has a substantially rectangular shape and is electrically connected to the two wiring portions 12b. The electric heating portion 12c is a film made of indium tin oxide (ITO) that generates heat when energized. The electric heating portion 12c has a transmittance of, for example, 85% or more and may also be referred to as a transparent conductive film. The electric heating portion 12c is an example of a heater wiring layer. On the other hand, the wiring portion 12b is made of, for example, a Cr / Ni laminated structure and is laminated on, for example, the electric heating portion 12c. The wiring portion 12b and the electric heating portion 12c are made by, for example, vapor deposition or sputtering. In this configuration, the passing region A is set within the substantially transparent electric heating portion 12c. That is, the laser light passes through the electric heating portion 12c. On the other hand, the two wiring portions 12b, 12b are opaque and do not overlap with the passing region A, and are arranged outside the passing region A. According to this embodiment, the passing region A can be provided in the electric heating portion 12c that is heated by current and the electric heating portion 12c can be made wider, allowing the passing region A to be heated more efficiently and quickly by the electric heating portion 12c. Furthermore, the electric heating portion 12c can reduce unevenness in the amount of heat generated by the etalon filter 11 depending on the location, thereby enabling more accurate temperature adjustment of the etalon filter 11 by the heater 12S, and ultimately wavelength control. The specifications of the wiring portion 12b and the heating portion 12c, such as the position and shape, are not limited to the example shown in FIG. 23, and can be modified in various ways.

[0082] 21st Embodiment FIG. 24 is a front view of an etalon filter 11 having a heater 12T (12) according to a 21st embodiment. In this embodiment, the heater 12T is provided on the end face 11r of the etalon filter 11. The heater 12T has substantially the same shape as the heater 12K of the 11th embodiment. However, in this embodiment, a temperature measuring resistance wiring layer 13 is provided inside the heater 12T, in other words, between the passing region A and the heater 12T. The temperature measuring resistance wiring layer 13 has two end portions 13t and an extension portion 13a. The extension portion 13a extends between the two end portions 13t on the end face 11a while bending with a predetermined width and thickness (height). In this embodiment, the extension portion 13a extends in an inverted U-shape that opens in the opposite direction to the Z direction, substantially along the periphery of the passing region A. In this configuration, the heater 12T is longer than the temperature measuring resistance wiring layer 13. The temperature measuring resistance wiring layer 13 is made of, for example, a Ti / Pt laminated structure.

[0083] According to this embodiment, in addition to achieving the same effects as the first embodiment, the temperature of the etalon filter 11 can be estimated based on the resistance value of the temperature sensing resistance wiring layer 13, thereby further improving the accuracy of wavelength control. Furthermore, with this configuration, the temperature sensing resistance wiring layer 13 is located closer to the passage area A than the heater 12, so the accuracy of detecting the temperature in the passage area A and, therefore, the accuracy of wavelength control can be further improved. Furthermore, since the heater 12 can be made longer, the passage area A can be heated more efficiently and more quickly by the heater 12, which has the advantage of further improving the wavelength control responsiveness. The temperature sensing resistance wiring layer 13 is an example of a temperature detection unit.

[0084] 22nd Embodiment Fig. 25 is a front view of an etalon filter 11 having a heater 12U(12) according to a 22nd embodiment. The etalon filter 11 of this embodiment has a configuration in which the heater 12 and the temperature measuring resistance wiring layer 13 of the 21st embodiment are interchanged in location. That is, in this embodiment, the heater 12 is provided outside the temperature measuring resistance wiring layer 13, in other words, farther from the passing region A than the temperature measuring resistance wiring layer 13. This embodiment provides the same effects as the first embodiment. Furthermore, because the heater 12 is located closer to the passing region A than the temperature measuring resistance wiring layer 13, the passing region A can be heated more efficiently and quickly by the heater 12, which in turn provides the advantage of further improving wavelength control responsiveness.

[0085] 23rd Embodiment FIG. 26 is a front view of an etalon filter 11 having a heater 12V (12) according to the 23rd embodiment. The temperature-sensing resistance wiring layer 13 has substantially the same shape as the temperature-sensing resistance wiring layer 13 of the 21st embodiment (see FIG. 24 ). However, the shape of the heater 12V differs from the shape of the heater 12T of the 20th embodiment. Specifically, the extension portion 12a extends along the circumferential direction while reciprocating radially relative to the optical axis Ax of light passing through the passage region A. This embodiment achieves the same effects as the first embodiment. Furthermore, this configuration allows the heater 12 to be positioned outside the temperature-sensing resistance wiring layer 13 and to extend along the circumferential direction while reciprocating radially, thereby further increasing the length of the heater 12. This allows the passage region A to be heated more efficiently and quickly by the heater 12, thereby further improving wavelength control responsiveness.

[0086] 27 and 28 are front views showing modified examples of the etalon filter 11, and Figures 29 to 32 are rear views showing modified examples of the etalon filter 11. Note that the etalon filters 11 shown in Figures 27 to 32 are each provided with a heater 12N (see Figure 17) having the same configuration as that of the fourteenth embodiment, but are not limited to this, and a heater 12 having another configuration may be provided.

[0087] In the examples of FIGS. 27 to 32 , the etalon filter 11 is provided with a temperature sensor such as a thermistor 14. Furthermore, each etalon filter 11 is provided with wiring 15 (15W to 15Z) for energizing the thermistor 14. The wiring 15 includes, for example, an electrode portion 15t, an extension 15a, a pad portion 15b, and a wire portion 15c. In the example of FIG. 27 , the thermistor 14 and the wiring 15 form a circuit extending from the electrode portion 15t on the left side of the figure via the extension 15a, a pad portion (not shown) to which the thermistor 14 is electrically connected, the thermistor 14, the wire portion 15c, the pad portion 15b, and the extension 15a, in this order, to the electrode portion 15t on the right side of the figure. With this configuration, the temperature at the location where the thermistor 14 is provided and thus the temperature in the passage region A can be estimated from a detected value, such as the potential difference between two electrode portions 15t or a resistance value based on the potential difference. In this case, feedback control based on the detected value may be performed for the temperature control of the etalon filter 11 using the heater 12. Similar circuits are configured in the examples of Figures 28 to 32, and similar detection and control can be performed. The thermistor 14 as a temperature sensor is an example of a temperature detection unit.

[0088] In the examples of Figures 27 and 28, the thermistor 14 and wiring 15 are provided on the end face 11a on which the heater 12 is provided. On the other hand, in the examples of Figures 29 to 32, the thermistor 14 and wiring 15 are provided on the end face 11c opposite the end face 11a on which the heater 12 is provided. The end faces 11a and 11c are examples of the front surface. Note that when the end face 11a is referred to as the front surface, the end face 11c may also be referred to as the back surface. The thermistor 14 and wiring 15 may also be provided on the side face 11b of the etalon filter 11. In this case, the side face 11b is an example of the front surface.

[0089] As shown in FIGS. 27-32, the thermistor 14 and wiring 15 can be arranged in a variety of layouts.

[0090] 27 and 29, although the surfaces (end surfaces 11a, 11c) on which the thermistor 14 and wiring 15 are provided are different, the arrangement of the thermistor 14 and wiring 15 on each surface is substantially the same. In these examples, the circuit including the thermistor 14 and wiring 15 is arranged to surround the outside of the passing region A and the heater 12 in a plan view seen in a direction perpendicular to the end surfaces 11a, 11c.

[0091] 28 and 30, although the surfaces (end surfaces 11a, 11c) on which the thermistor 14 and wiring 15 are provided are different, the arrangement of the thermistor 14 and wiring 15 on each surface is substantially the same. In these examples, the circuit including the thermistor 14 and wiring 15 is provided in a position outside the passing region A and the heater 12 without surrounding the heater 12 in a plan view seen in a direction perpendicular to the end surfaces 11a, 11c.

[0092] 27 to 30, the circuit including the thermistor 14 and wiring 15 is arranged so as not to overlap the heater 12 in a plan view when viewed in a direction perpendicular to the end faces 11a and 11c. In contrast, in the examples of Figures 31 and 32, the circuit is arranged so as to partially overlap the heater 12 in the plan view. According to the examples of Figures 31 and 32, the thermistor 14 can detect the temperature at a position closer to the passage region A than in the examples of Figures 27 to 30. The examples of Figures 31 and 32 have the advantages of making it possible to configure the etalon filter 11 more compactly and improving control accuracy by being able to detect the temperature in the passage region A with higher accuracy.

[0093] The modifications shown in FIGS. 27 to 32 can also provide the same effects as those of the above-described embodiments.

[0094] While the above describes exemplary embodiments and modifications of the present invention, these are merely examples and are not intended to limit the scope of the invention. The above embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be appropriately modified and implemented.

[0095] The present invention can be used in optical devices and tunable lasers.

[0096] DESCRIPTION OF SYMBOLS 1...Housing 1a...Output port 1b...Side wall 1c...Bottom wall 2...Lens 3...Optical fiber 4...Chip-on submount 4a...Laser element 4a1...Optical amplifier 4a11...End (first end) 4a12...End (second end) 4a2, 4a3...Optical filter 4a4...SOA 4b...Submount 4c...Thermistor 6...Optical isolator 10a...Mirror (first mirror) 10b...Mirror (second mirror) 11, 11N, 11R...Etalon filter 11a...End face (front surface) 11b...Side surface (front surface) 11c...End face (front surface, rear surface) 12, 12A, 12K to 12R, 12T to 12V...Heater 12a...Extension 12b...Wiring portion 12c...Electric heating portion (heater wiring layer) 12t...End 13...Temperature measuring resistance wiring layer DESCRIPTION OF SYMBOLS 13a...extension 13t...end 14...thermistor (temperature detection unit) 15 (15W to 15Z)...wiring (circuit) 15a...extension 15b...pad portion 15t...electrode portion 23, 23J...beam splitter 24...photodiode 50, 51, 52...lens 60...carrier 60a...first substrate 60b...second substrate 60c...thermoelectric element 60P...peltier module (first temperature adjustment unit, second temperature adjustment unit) 70...heat shielding member 90...bonding material 100, 100A to 100J...optical module (tunable laser, optical device) A...passage area Ax...optical axis X...direction Y...direction Z...direction

Claims

1. An optical device comprising: a base; a plurality of optical components fixed to the base; an etalon filter as the optical component; and a heater wiring layer disposed on the surface of the etalon filter at a position outside the light passing area, the heater wiring layer generating heat when current is applied.

2. The optical device according to claim 1, wherein the heater wiring layer is provided on an end face through which the light passes as the surface.

3. The optical device according to claim 1, wherein the heater wiring layer is provided on a side surface of the surface through which the light does not pass.

4. The optical device according to claim 1, wherein the heater wiring layer extends so as to at least partially surround the passing region.

5. The optical device according to claim 1, wherein the etalon filter has a body and reflective films provided on the input and output ends of the body, and the body is made of glass or silicon.

6. The optical device according to claim 1, wherein the heater wiring layer has a layered structure made of any one of Ti, Pt, Au, Ni, Ta2N, TiW, and indium tin oxide, or a material containing any one of these.

7. The optical device according to claim 1, wherein the heater wiring layer is used for temperature detection.

8. The optical device according to claim 7, wherein the heater wiring layer used for temperature detection includes a Ti / Pt laminated structure.

9. An optical device according to claim 1, wherein the heater wiring layer is capable of changing the temperature of the light passing area of the etalon filter within a range of from room temperature to 150°C by changing the power supplied thereto.

10. The optical device according to claim 1, wherein the optical component comprises a plurality of etalon filters each having the heater wiring layer.

11. The optical device of claim 1, further comprising a temperature detector disposed on said surface.

12. The optical device according to claim 11, wherein the temperature detection section is a temperature sensing resistance wiring layer whose resistance value changes in response to a change in temperature.

13. The optical device according to claim 12, wherein the temperature sensing resistance wiring layer is positioned closer to the passing region than the heater wiring layer.

14. The optical device according to claim 12 or 13, wherein the heater wiring layer is longer than the temperature sensing resistance wiring layer.

15. The optical device according to claim 12, wherein the temperature sensing resistance wiring layer is positioned farther from the passing region than the heater wiring layer.

16. The optical device according to claim 1 or 13, wherein the heater wiring layer extends along the circumferential direction while reciprocating in the radial direction relative to the optical axis of the light passing through the passage area.

17. The optical device according to claim 1 or 13, wherein the heater wiring layer extends so as to surround at least partially and in multiple layers around the passing region.

18. A tunable laser comprising: an optical amplifier that generates and amplifies light and outputs it from a first end and a second end opposite the first end; a first mirror that reflects the light output from the first end; a second mirror that reflects the light output from the second end; an etalon filter that is provided between the optical amplifier and the first mirror or the second mirror, has predetermined wavelength characteristics, and passes the light output from the optical amplifier; and a heater wiring layer that is provided on the surface of the etalon filter at a position outside the light passing area and generates heat when current is applied.

19. The tunable laser according to claim 18, further comprising a lens provided between said optical amplifier section and said etalon filter, through which light traveling between said optical amplifier section and said etalon filter passes.

20. A tunable laser according to claim 18 or 19, comprising: a temperature control mechanism for adjusting the temperature of the optical amplification section; and a heat insulating member interposed between the temperature control mechanism and the etalon filter to suppress heat conduction between the temperature control mechanism and the etalon filter.

Images