CN117761843A - Optical module - Google Patents

Abstract

The present disclosure provides an optical module capable of suppressing a phase shift by making a temperature distribution nearly uniform. An optical module according to one embodiment includes: an optical element having a first side, a second side intersecting the first side, and a third side opposite the second side; a housing accommodating the optical element; a thermoelectric cooler mounted in the housing, the light-supplying element being mounted; a driving circuit disposed on the first side of the optical element; a first bonding pad arranged on the second side of the optical element; and a first wiring pattern provided in the frame of the case, connected to the first bonding pad of the optical element via a first bonding wire, and arranged with a plurality of peltier elements at intervals in the thermoelectric cooler. The spacing of the plurality of peltier elements located at the second side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

Description

Optical module

Technical Field

The present disclosure relates to optical modules.

Background

Patent document 1 describes an optical transmission module. The optical transmission module has an optical modulation element optically coupled to the optical semiconductor laser element. The optical transmission module is provided with a temperature adjustment device having: a substrate having a main surface and a rear surface; a first mounting portion provided on a main surface of the substrate with the first temperature control element interposed therebetween, for mounting the semiconductor laser element; and a second mounting section provided on the main surface of the substrate with the second temperature control element interposed therebetween, and mounting the light modulation element. The optical transmission module further includes: a package accommodating the semiconductor laser element, the optical modulation element, and the temperature adjusting device; and an intermediate block disposed between the first temperature control element and the second temperature control element and fixedly attached to the main surface of the substrate.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2021-174892

In an optical module including a mach-zehnder (MZI) modulator, the mach-zehnder modulator adjusts a phase using a refractive index change due to an electro-optical effect such as a quantum confinement stark effect (Quantum Confined Stark Effect) or a pockels effect. The mach-zehnder modulator has two waveguides extending parallel to each other. When the temperature distribution of the two waveguides is uneven, the optical path length between p and n may be changed, and the phase may be shifted. Therefore, it may be required to make the temperature distribution nearly uniform to suppress the phase shift.

Disclosure of Invention

The present disclosure aims to provide an optical module capable of suppressing a phase shift by making a temperature distribution nearly uniform.

The optical module of the present disclosure is provided with: an optical element having a first side, a second side intersecting the first side, and a third side opposite the second side; a housing accommodating the optical element; a thermoelectric cooler mounted in the housing, the light-supplying element being mounted; a driving circuit disposed on the first side of the optical element; a first bonding pad arranged on the second side of the optical element; and a first wiring pattern provided in the frame of the case, connected to the first bonding pad of the optical element via a first bonding wire, and arranged with a plurality of peltier elements at intervals in the thermoelectric cooler. The spacing of the plurality of peltier elements located at the second side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

Effects of the invention

According to the present disclosure, the temperature distribution can be made nearly uniform to suppress the phase shift.

Drawings

Fig. 1 is a partial cross-sectional view showing an internal structure of an optical module according to an embodiment.

Fig. 2 is a plan view showing an optical element of the optical module of fig. 1.

Fig. 3 is a top view schematically illustrating a thermoelectric cooler and a modulating element of the optical module of fig. 1.

Fig. 4 is a graph showing the temperature distribution in the width direction of the optical module of example 1 and the optical module of comparative example 1.

Fig. 5 is a graph different from fig. 4 showing the temperature distribution in the width direction of the optical module of example 1 and the optical module of comparative example 1.

Fig. 6 is a graph showing the phase shift between the optical module of example 1 and the optical module of comparative example 1.

Fig. 7 is a partial cross-sectional view showing the internal structure of the optical module according to the first modification.

Fig. 8 is a plan view schematically showing a thermoelectric cooler and a modulation element of an optical module according to a second modification.

Fig. 9 is a graph showing the temperature distribution in the width direction of the optical module of example 2 and the optical module of comparative example 2.

Fig. 10 is a graph different from fig. 9 showing the temperature distribution in the width direction of the optical module of example 2 and the optical module of comparative example 2.

Fig. 11 is a graph showing the phase shift between the optical module of example 2 and the optical module of comparative example 2.

Fig. 12 is a plan view schematically showing a thermoelectric cooler and a modulation element of an optical module according to a third modification.

Fig. 13 is a graph showing the temperature distribution in the width direction of the optical module of example 3 and the optical module of comparative example 2.

Fig. 14 is a graph different from fig. 13 showing the temperature distribution in the width direction of the optical module of example 3 and the optical module of comparative example 2.

Fig. 15 is a plan view schematically showing a thermoelectric cooler and a modulation element of an optical module according to a fourth modification.

Description of the reference numerals

1. 1A, 1B, 1C, 1D: an optical module;

2: a housing;

2b: a first sidewall;

2B: a housing;

2c: a second sidewall;

2d: a bottom wall;

2g: a frame;

2h: wiring patterns (first wiring patterns);

2j: a bonding pad;

2k: a frame;

2p: wiring patterns (second wiring patterns);

3: an input assembly;

3b: a lens holder;

4: an output assembly;

4b: a lens holder;

11: an optical base;

12: a light filter;

13: a composite filter block;

13b, 13c, 13d, 13f, 13g: a reflecting surface;

21. 21A1, 21A2, 21B, 21C, 21D: a temperature regulating device (thermoelectric cooler);

22: a carrier for the modulation element;

24: an input lens system;

25. 26: an output lens system;

27: a peltier element;

28: a thermistor;

30. 30B, 30C, 30D: a modulation element (optical element);

30b: a control terminal (first bond pad);

30c: electrode pads (third bonding pads);

30d: a control terminal (second bond pad);

31: a modulator chip;

31b: a side (third side);

31c: a side (second side);

31d: edges;

31f: a side (first side);

32: an input port;

33b: an output port;

33c: an output port;

34: a branching portion;

35b, 35c: a wave combining section;

36a, 36b, 36c, 36d, 36e, 36f, 36g, 36h: an optical waveguide;

37b: a first monitoring port;

37c: a second monitoring port;

38a, 38b, 38c, 38d, 38e, 38f, 38g, 38h: modulating the electrode;

38j, 38k, 38l, 38m: a master phase adjustment electrode;

39a, 39b, 39c, 39d, 39e, 39f, 39g, 39h: an RF pad;

39j, 39k, 39l, 39m: a bias pad;

40a, 40b, 40c, 40d, 40e, 40f, 40g, 40h: a signal pad;

40j, 40k, 40l, 40m, 40n, 40o, 40p, 40q: a bias pad;

41: a heat sink;

42: a drive IC (drive circuit);

42b: an electrode pad;

51: a base for a wavelength variable light source;

52: a carrier for a wavelength variable light source;

53: a wavelength variable light source element;

54: a lens;

55: a wavelength control monitoring element;

56: a thermistor;

57: standard filters (metalon filters);

58: an isolator;

61: a base for a modulation element;

62: a carrier for the modulation element;

63: a composite filter block;

64: a polarization combining filter;

65: a light receiving element for monitoring the modulated output light intensity;

71: an optical path adjustment filter;

72: a reflecting mirror;

73: an optical path adjustment filter;

74: a polarization separation filter;

75: a lens;

75b: a first lens section;

75c: a second lens section;

75d: a third lens section;

76: a carrier for demodulation elements;

77: TIA (Trans Impedance Amplifier: transimpedance amplifier);

78: a demodulation element;

79: FPC (Flexible Printed Circuit: flexible printed circuit);

d1: a first direction;

d2: a second direction;

d3: a third direction;

IC42: a driver (driving circuit);

l1: inputting light;

l2: output light (first signal light);

l3: output light (second signal light);

l4: outputting light;

p1: a first heat capacity portion;

p2: a second heat capacity portion;

S, S1, S2, S3, S11, S12, S13, S21, S22, S23, T, T1, T2, T3: spacing;

w1: bonding wire (first bonding wire);

w2: bonding wire (third bonding wire);

w3: a bonding wire;

w4: bonding wire (second bonding wire).

Detailed Description

[ description of embodiments of the present disclosure ]

First, the description will be given by taking the contents of the embodiments of the optical module of the present disclosure. The optical module according to one embodiment (1) includes: an optical element having a first side, a second side intersecting the first side, and a third side opposite the second side; a housing accommodating the optical element; a thermoelectric cooler mounted in the housing, the light-supplying element being mounted; a driving circuit disposed on the first side of the optical element; a first bonding pad arranged on the second side of the optical element; and a first wiring pattern provided in the frame of the case, connected to the first bonding pad of the optical element via a first bonding wire, and arranged with a plurality of peltier elements at intervals in the thermoelectric cooler. The spacing of the plurality of peltier elements located at the second side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

In this optical module, an optical element is mounted on a thermoelectric cooler. The optical element and the thermoelectric cooler are housed in a case. The optical element has a second side and a third side opposite the second side. The first bonding pad is disposed on the second side of the optical element. The frame of the case has a first wiring pattern connected to a first bonding pad of the optical element via a first bonding wire. Since the first bonding pad and the first bonding wire are provided on the second side, heat flows out and in easily occur on the second side compared with the center of the optical element. In the optical module, a plurality of peltier elements are arranged at intervals in the thermoelectric cooler, and the intervals between the plurality of peltier elements located on the second side are narrower than the intervals between the plurality of peltier elements located in the center of the optical element. Therefore, the peltier element is more closely arranged on the second side than the center of the light element, and therefore the influence of the outflow and inflow of heat at the second side can be reduced. Therefore, the temperature distribution of the optical element can be made nearly uniform to suppress the phase shift.

(2) In the above (1), the optical element may be a multimode interferometer having a first optical waveguide through which the first signal light propagates and a second optical waveguide through which the second signal light different from the first signal light propagates. The first optical waveguide may be provided on a second side of the center of the multimode interferometer, and the second optical waveguide may be provided on a third side of the center of the multimode interferometer. In this case, the temperature of the first optical waveguide on the second side and the temperature of the second optical waveguide on the third side can be made nearly uniform.

(3) In the above (1) or (2), the optical module may include: a second bonding pad arranged on the third side of the optical element; and a second wiring pattern provided in the housing of the case and connected to the second bonding pad of the optical element via a second bonding wire. The interval between the plurality of peltier elements located on the third side may be narrower than the interval between the plurality of peltier elements located at the center of the light element. In this case, since the second bonding pad and the second bonding wire are provided on the third side, heat flows out and in easily occur on the third side compared with the center of the optical element. In the optical module, the intervals of the plurality of peltier elements located on the third side are narrower than the intervals of the plurality of peltier elements located at the center of the optical element. Therefore, the peltier element is more closely arranged on the third side than the center of the light element, and therefore the influence of the outflow and inflow of heat at the third side can be reduced. Therefore, the temperature distribution of the optical element can be made nearly uniform to suppress the phase shift.

(4) The optical module according to any one of the above (1) to (3) may further include: a third bonding pad arranged on the first side of the optical element; and a third wiring pattern provided in the driving circuit and connected to a third bonding pad of the optical element via a third bonding wire. The interval between the plurality of peltier elements located on the first side may be narrower than the interval between the plurality of peltier elements located at the center of the light element. In this case, since the third bonding pad and the third bonding wire are provided on the first side, heat flows out and in easily occur on the first side compared with the center of the optical element. In the optical module, the intervals of the plurality of peltier elements located on the first side are narrower than the intervals of the plurality of peltier elements located in the center of the optical element. Therefore, the peltier element is disposed closer to the first side than the center of the light element, and therefore the influence of the outflow and inflow of heat at the first side can be reduced. Therefore, the temperature distribution of the optical element can be made nearly uniform to suppress the phase shift.

(5) In the above (4), the driving circuit may be a heat generating element. The driving circuit is disposed on the first side of the optical element. In this optical module, as described above, the peltier element is closely arranged on the first side of the optical element on which the drive circuit is arranged. Therefore, the influence of the inflow and outflow of heat from the drive circuit can be reduced, and therefore the temperature distribution of the optical element can be made nearly uniform to suppress the phase shift.

(6) The optical module according to another embodiment includes: an optical element having a first side, a second side intersecting the first side, and a third side opposite the second side; a housing accommodating the optical element; a thermoelectric cooler disposed in the case and on which the light-supplying element is mounted; a first heat capacity part positioned around the optical element; and a second heat capacity part located around the optical element and located at a different place from the first heat capacity part. The heat capacity of the first heat capacity portion is larger than that of the second heat capacity portion. A plurality of peltier elements are arranged at intervals in the thermoelectric cooler. The spacing of the plurality of peltier elements on the first heat capacity side is narrower than the spacing of the plurality of peltier elements on the second heat capacity side.

In this optical module, an optical element is mounted on the thermoelectric cooler, and the optical element and the thermoelectric cooler are housed in a case. The optical element has a second side and a third side opposite the second side. The first heat capacity portion and the second heat capacity portion located at a different place from the first heat capacity portion are arranged around the optical element. The heat capacity of the first heat capacity portion is larger than that of the second heat capacity portion. Therefore, the first heat capacity portion is more likely to generate inflow and outflow of heat to and from the optical element than the second heat capacity portion. In this optical module, a plurality of peltier elements are arranged at intervals in the thermoelectric cooler, and the intervals between the plurality of peltier elements on the first heat capacity side are narrower than the intervals between the plurality of peltier elements on the second heat capacity side. Therefore, the peltier element is more closely arranged on the first heat capacity side than on the second heat capacity side, and therefore the influence of the outflow and inflow of heat at the first heat capacity side can be reduced. Therefore, the temperature distribution of the optical element can be made nearly uniform to suppress the phase shift.

[ details of embodiments of the present disclosure ]

Specific examples of the optical module according to the embodiments of the present disclosure are described below with reference to the drawings. The present invention is not limited to the following examples, but is defined by the claims, and is intended to include all modifications within the scope equivalent to the claims. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted. In addition, some drawings may be simplified or exaggerated for the sake of easy understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

Fig. 1 is a partial cross-sectional view showing an internal structure of an optical module 1 as an example. As shown in fig. 1, the optical module 1 includes a rectangular parallelepiped case 2, and an input module 3 and an output module 4 extending from the case 2. The input assembly 3 and the output assembly 4 are respectively cylindrical. The housing 2 has: a first side wall 2b extending along a first direction D1; a pair of second side walls 2c extending along a second direction D2 intersecting the first direction D1; and a bottom wall 2d on which the components of the optical module 1 are mounted. The first direction D1 is a longitudinal direction of the optical module 1, and the second direction D2 is a width direction of the optical module 1.

The first side wall 2b extends in both the first direction D1 and the third direction D3. The third direction D3 is a direction intersecting both the first direction D1 and the second direction D2, and corresponds to the height direction of the optical module 1. The pair of second side walls 2c are arranged side by side along the first direction D1, and each of the second side walls 2c extends in both the second direction D2 and the third direction D3. One end of the bottom wall 2D in the third direction D3 of the first side wall 2b and the second side wall 2c extends in both the first direction D1 and the second direction D2. The pair of first side walls 2b and the pair of second side walls 2c constitute a frame body 2g of the frame-shaped housing 2 as viewed from the third direction D3.

The input member 3 and the output member 4 protrude from one of the pair of second side walls 2c in the first direction D1. The input assembly 3 and the output assembly 4 are side by side along the second direction D2. The input module 3 is a portion for inputting the input light L1 from the outside of the optical module 1 to the inside of the optical module 1. The output module 4 is a portion for outputting the output light L4 from the inside of the optical module 1 to the outside of the optical module 1. Lenses are built in the input unit 3 and the output unit 4, respectively. The input assembly 3 has a lens holder 3b holding a lens of the input assembly 3, and the output assembly 4 has a lens holder 4b holding a lens of the output assembly 4.

The optical module 1 includes an optical base 11 mounted on the bottom wall 2d, and a filter 12 and a composite filter block 13 mounted on the optical base 11. The filter 12 transmits the input light L1 from the input assembly 3. The filter 12 inputs the input light L1 to the composite filter block 13. The composite filter block 13 is disposed on the opposite side of the input module 3 when viewed from the filter 12. The composite filter block 13 has a plurality of reflection surfaces 13b that reflect the input light L1.

The plurality of reflecting surfaces 13b includes a first reflecting surface 13c, a second reflecting surface 13d, a third reflecting surface 13f, and a fourth reflecting surface 13g. The first reflecting surface 13c and the second reflecting surface 13D are juxtaposed along the second direction D2. The position of the third reflecting surface 13f in the second direction D2 is offset with respect to the position of the first reflecting surface 13c in the second direction D2 and the position of the second reflecting surface 13D in the second direction D2. The position of the fourth reflecting surface 13g in the second direction D2 is offset with respect to the position of the first reflecting surface 13c in the second direction D2 and the position of the second reflecting surface 13D in the second direction D2. The third reflecting surface 13f and the fourth reflecting surface 13g are juxtaposed along the second direction D2.

The input light L1 incident on the composite filter block 13 from the filter 12 along the first direction D1 is reflected in the second direction D2 by the first reflection surface 13 c. The input light L1 reflected on the first reflecting surface 13c is reflected on the second reflecting surface 13D in the first direction D1 and is emitted to the opposite side to the input unit 3.

The output light L2 and the output light L3, which will be described later in detail, are input to the complex filter block 13 along the first direction D1 from the side opposite to the output assembly 4. The output light L2 is reflected in the second direction D2 at the third reflection surface 13 f. The output light L2 reflected on the third reflection surface 13f is reflected on the fourth reflection surface 13g in the first direction D1. The output light L3 is transmitted through the fourth reflecting surface 13g. The composite filter block 13 converts the output light L2 and the output light L3 into output light L4 and outputs the output light L4 to the output module 4. The output light L4 emitted to the output module 4 is output to the outside of the optical module 1.

The optical module 1 includes: a temperature control device (thermoelectric cooler) 21 mounted on the bottom wall 2d; a modulating element bracket 22 mounted on the temperature control device 21; and a modulator (optical element) 30 mounted on the modulator holder 22. The optical module 1 includes an input lens system 24, a first output lens system 25, and a second output lens system 26. The temperature regulating device 21 is a TEC (Thermo Electric Cooler: thermoelectric cooler).

The modulation element 30 is, for example, a multimode interferometer in which a mach-zehnder interferometer is formed on an indium phosphide (InP) substrate. The modulation element 30 may be an element in which an optical waveguide is formed on a Si substrate. As an example, the modulation element 30 includes indium phosphide (InP), silicon dioxide (SiO) ₂ ) Benzocyclobutene (BCB). The temperature adjustment device 21 and the modulation element 30 will be described in detail later. The input lens system 24 is mounted between the modulation element 30 and the composite filter block 13. The first output lens system 25 and the second output lens system 26 are mounted on both sides of the input lens system 24 in the second direction D2.

The optical module 1 includes: a heat sink 41 located on the opposite side of the composite filter block 13 as viewed from the modulation element 30; and a driver IC (Integrated Circuit: integrated circuit) (driver circuit) 42 mounted on the heat sink 41. Fig. 2 is a plan view showing the modulator 30. The modulation element 30 is, for example, a multimode interferometer having a plurality of optical waveguides. As shown in fig. 2, the modulation element 30 includes, for example, a modulator chip 31, an input port 32, a first output port 33b, a second output port 33c, a branching unit 34, a first combining unit 35b, a second combining unit 35c, optical waveguides 36a to 36h, a first monitor port 37b, and a second monitor port 37c.

As shown in fig. 1 and 2, the planar shape of the modulator chip 31 is, for example, a rectangular shape. The modulator chip 31 has sides 31b, 31c extending in the first direction D1 and sides 31D, 31f extending in the second direction D2. The input port 32 is an optical port through which the input light L1 output from the composite filter block 13 (second reflection surface 13 d) is input via the input lens system 24. The input port 32 is located at the edge 31d. For example, the input port 32 is located at the center in the second direction D2 of the side 31D. The driver IC42 is disposed on the side 31f (first side) of the modulator 30.

The first output port 33b is an optical port that outputs the output light (first signal light) L2 to the first output lens system 25, and the second output port 33c is an optical port that outputs the output light (second signal light) L3 to the second output lens system 26. The output light L2 output from the first output port 33b is transmitted through the first output lens system 25 and enters the composite filter block 13. The output light L3 output from the second output port 33c is transmitted through the second output lens system 26 and enters the composite filter block 13. The first output port 33b and the second output port 33c are provided on the side 31d of the modulator chip 31. The first output port 33b and the second output port 33c are arranged at symmetrical positions with respect to the input port 32.

The branching section 34 branches the input light L1 inputted from the input port 32 to the optical waveguides 36a to 36h. The first combining unit 35b combines the signal lights (a part of the plurality of signal lights) propagating through the optical waveguides 36e to 36h and supplies the resultant signal lights as output light L2 to the first output port 33b. The second combining unit 35c combines the signal lights (the remaining portions of the plurality of signal lights) propagating through the optical waveguides 36a to 36d and supplies the resultant signal lights as output light L3 to the second output port 33c.

The modulator 30 includes modulator electrodes 38a to 38h, mother phase adjustment electrodes 38j to 38m, and child phase adjustment electrodes (not shown). Modulation electrodes 38a to 38h are provided on the optical waveguides 36a to 36h, respectively. The modulation electrodes 38a to 38h supply the modulated voltage signals to the optical waveguides 36a to 36h to change the refractive index of the light passing through the optical waveguides 36a to 36h. Thereby, the phases of the light propagating through the optical waveguides 36a to 36h are modulated.

One end of each of the modulation electrodes 38a to 38h is electrically connected to an RF (Radio Frequency) pad 39a to 39h for signal input via a wiring pattern. The RF pads 39a to 39h for signal input are electrically connected to the driver IC42. The other ends of the modulation electrodes 38a to 38h are electrically connected to signal pads 40a to 40h for signal terminals, respectively, via wiring patterns. The mother phase adjustment electrodes 38j to 38m are electrically connected to bias pads 39j to 39m, respectively, via wiring patterns. The sub-phase adjustment electrodes are connected to the bias pads 40j to 40q for adjusting signal input via wiring patterns, respectively.

Fig. 3 is a plan view schematically showing the temperature adjustment device 21, the modulation element 30, and the drive IC42. As shown in fig. 3, the drive IC42 has an electrode pad 42b. The electrode pads 42b are arranged side by side along the second direction D2 at the end of the driving IC42 on the modulation element 30 side. The optical module 1 has a wiring pattern (first wiring pattern) 2h provided in a frame 2g of the housing 2. The end portions of the wiring patterns 2h in the second direction D2 of the case 2 are arranged side by side along the first direction D1. The modulation element 30 has electrode pads 30c at positions facing the drive ICs 42, the electrode pads 30c being aligned along the second direction D2. The optical module 1 has a bonding wire W2 electrically connecting the electrode pad 30c and the electrode pad 42b to each other.

For example, the modulation element 30 has a control terminal (first bonding pad) 30b. The control terminals 30b are arranged side by side along the first direction D1 on the side of the side 31c (second side). The wiring pattern 2h is connected to the control terminal 30b of the modulation element 30 via a bonding wire (first bonding wire) W1. The optical module 1 further includes a thermistor 28. The thermistor 28 is disposed between the modulation element 30 and the composite filter block 13, for example. The thermistor 28 is electrically connected to a pad 2j provided in the housing 2g via a bonding wire W3.

The temperature regulating device 21 has a plurality of peltier elements 27. The plurality of peltier elements 27 are arranged in a lattice shape side by side along the first direction D1 and side by side along the second direction D2. The peltier elements 27 are arranged at intervals S. For example, the spacing S of two peltier elements 27 side by side along the second direction D2 differs depending on the position of the peltier elements 27 in the second direction D2. The spacing S of the plurality of peltier elements 27 on the side 31c (on the control terminal 30b side of the modulator element 30 or on the wiring pattern 2h side of the case 2) is narrower than the spacing S of the plurality of peltier elements 27 on the side 31 b. That is, the peltier elements 27 are more closely arranged on the side 31c than on the side 31 b.

The spacing S of the plurality of peltier elements 27 located on the side of the edge 31c is narrower than the spacing S of the plurality of peltier elements 27 located in the center of the modulating element 30. The center of the optical element (modulation element 30) indicates the center of the optical element (modulation element 30) when viewed from the third direction D3. For example, the space S1 between the peltier element 27 located on the most side 31c side and the peltier element 27 located on the second side 31c side is narrower than the space S2 between the peltier element 27 located on the second side 31c side and the peltier element 27 located on the third side 31c side. The space S2 is narrower than the space S3 between the peltier element 27 located on the third side 31c and the peltier element 27 located on the fourth side 31 c. As an example, the spacing S1 is 0.15mm, the spacing S2 is 0.2mm, and the spacing S3 is 0.25mm. The spacing S of the plurality of peltier elements 27 located in the center of the modulating element 30 may also be the same as the spacing S3.

Next, the operational effects obtained by the optical module 1 of the present embodiment will be described. The optical module 1 includes a modulation element 30 mounted on the temperature control device 21. The modulator element 30 and the temperature control device 21 are housed in the case 2. The modulation element 30 has a side 31c and a side 31b opposite the side 31 c. A control terminal 30b is arranged as a first bonding pad on the side 31c of the modulation element 30. The frame 2g of the case 2 has a wiring pattern 2h connected to the control terminal 30b of the modulator 30 via a bonding wire W1. Since the control terminal 30b and the bonding wire W1 are provided on the side 31c, heat flows out and in easily occur on the side 31c as compared with the side 31b. In the optical module 1, a plurality of peltier elements 27 are arranged at intervals S in the temperature adjustment device 21, and the intervals S of the plurality of peltier elements 27 on the side of the side 31c are narrower than the intervals S of the plurality of peltier elements 27 on the side of the side 31b. Therefore, the peltier element 27 is more closely arranged on the side 31c than on the side 31b, and therefore the influence of the outflow and inflow of heat at the side 31c can be reduced. Therefore, the temperature distribution of the modulation element 30 can be made nearly uniform to suppress the phase shift.

That is, since the control terminal 30b and the bonding wire W1 are provided on the side 31c, heat flows out and in easily occurs on the side 31c compared with the center of the modulator 30. In the optical module 1, the spacing S of the plurality of peltier elements 27 located on the side of the side 31c is narrower than the spacing S of the plurality of peltier elements 27 located at the center of the modulation element 30. Therefore, the peltier element 27 is disposed closer to the side 31c than the center of the modulator element 30. Therefore, the influence of the outflow and inflow of heat at the side 31c can be reduced, and the temperature distribution of the modulation element 30 can be made nearly uniform to suppress the phase shift.

As described above, the modulation element 30 may be a multimode interferometer having the first optical waveguides 36e to 36h through which the output light L2 as the first signal light propagates and the second optical waveguides 36a to 36d through which the output light L3 as the second signal light, which is different from the output light L2, propagates. The first optical waveguides 36e to 36h may be provided on the side of the central side 31b of the multimode interferometer, and the second optical waveguides 36a to 36d may be provided on the side of the central side 31c of the multimode interferometer. In this case, the temperatures of the first optical waveguides 36e to 36h located on the side 31b and the temperatures of the second optical waveguides 36a to 36d located on the side 31c can be made nearly uniform.

Fig. 4 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 1 and the temperature distribution of the modulation element in the optical module of comparative example 1 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is 75 ℃). The optical module of embodiment 1 is the same as the optical module 1 described above. The optical module of comparative example 1 is different from the optical module 1 in that the intervals of two peltier elements arranged side by side in the width direction (second direction D2) are the same as each other (a plurality of peltier elements are uniformly arranged). The horizontal axis of fig. 4 represents displacement in the width direction (X direction), and the vertical axis of fig. 4 represents a temperature difference on a line Z (see fig. 3) extending in the X direction when the center of an end portion (side 31 b) of the modulation element on the opposite side to the control terminal is 0. As shown in fig. 4, in the optical module of comparative example 1, the temperature increases as the optical module is closer to the control terminal side. On the other hand, in the optical module of example 1, even when the optical module is close to the control terminal, the temperature rise is suppressed to 0.05 ℃.

Fig. 5 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 1 and the temperature distribution of the modulation element in the optical module of comparative example 1 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is-5 ℃). As shown in fig. 5, in the optical module of comparative example 1, the temperature is lower as the optical module is closer to the control terminal side. On the other hand, in the optical module of example 1, even when the temperature is close to the control terminal side, the temperature drop is suppressed to 0.05 ℃.

Fig. 6 is a graph showing the analysis results of the phase shift of the first optical waveguide and the second optical waveguide of the optical module of example 1 and the optical module of comparative example 1. As shown in fig. 6, in the optical module of comparative example 1, a phase shift of 0.45 pi/°c was generated in the first optical waveguide, and a phase shift of 2.88 pi/°c was generated in the second optical waveguide. In contrast, in the optical module of example 1, a phase shift of 0.37 pi/. Degree.c was generated in the first optical waveguide, and a phase shift of 0.89 pi/. Degree.c was generated in the second optical waveguide. Thus, it can be seen that: in example 1 in which the arrangement of the peltier elements is tighter as the control terminal is closer, the phase shift can be suppressed as compared with comparative example 1 in which the arrangement of the peltier elements is uniform. In particular, in the optical module of embodiment 1, the phase shift in the width direction can be significantly suppressed.

Next, various modifications of the optical module of the present disclosure will be described. A part of the optical module of each modification described later has the same configuration as that of the optical module 1 described above. Therefore, in the following description, the same reference numerals are given to the descriptions repeated as those of the configuration of the optical module 1, and are omitted as appropriate.

Fig. 7 is a perspective view showing the internal structure of the optical module 1A according to the first modification. Since the configuration of a part of the optical module 1A is the same as that of the above-described optical module 1, the same reference numerals as those used for the description of the optical module 1 will be given below, and will be omitted as appropriate. The optical module 1A includes optical components different from those of the optical module 1. The light module 1A has two temperature adjustment devices 21, the two temperature adjustment devices 21 being side by side along the first direction D1. The two temperature adjustment devices 21 are a first temperature adjustment device 21A1 and a second temperature adjustment device 21A2.

The optical module 1A includes a wavelength variable light source base 51 mounted on the first temperature adjustment device 21A1, a wavelength variable light source bracket 52 mounted on the wavelength variable light source base 51, and a wavelength variable light source element 53 mounted on the wavelength variable light source bracket 52. The optical module 1A includes a plurality of lenses 54 mounted on the wavelength variable light source base 51, a plurality of wavelength control monitoring elements 55, a thermistor 56, a standard filter 57, and an isolator 58. The light L11 output from the wavelength variable light source element 53 is input to the plurality of lenses 54, and the light L11 transmitted through the plurality of lenses 54 is input to the isolator 58.

The optical module 1A includes a modulator base 61 mounted on the second temperature control device 21A2 and a modulator bracket 62 mounted on the modulator base 61, and the modulator 30 is mounted on the modulator bracket 62. The optical module 1A includes a composite filter block 63 mounted on the modulator base 61, a polarization combining filter 64, and a modulated output light intensity monitoring light receiving element 65. The light L11 transmitted through the isolator 58 is input to the composite filter block 63 and the polarization combining filter 64. In the polarization combining filter 64, the output light L2 and the output light L3 are combined and input to the composite filter block 63. The combined output light L2 and a part of the output light L3 are transmitted through the composite filter block 63 and output from the sleeved output module 4 to the outside of the optical module 1. The remaining portions of the combined output light L2 and output light L3 are reflected by the composite filter block 63 and monitored by the modulated output light intensity monitoring light receiving element 65.

The optical module 1A includes a first optical path adjustment filter 71, a reflecting mirror 72, a second optical path adjustment filter 73, a polarization separation filter 74, a lens 75 including a first lens portion 75b, a second lens portion 75c, and a third lens portion 75d, and a demodulation element bracket 76. The first optical path adjustment filter 71, the reflecting mirror 72, the second optical path adjustment filter 73, the polarization separation filter 74, the lens 75, and the demodulation element bracket 76 are mounted on the bottom wall 2d of the housing 2.

The optical module 1A has: TIA (Trans Impedance Amplifier: transimpedance amplifier) 77 mounted on heat sink 41; demodulation element 78 mounted on demodulation element bracket 76; and an FPC (Flexible Printed Circuit: flexible printed circuit) 79 protruding from the housing 2 to the opposite side from the input assembly 3 and the output assembly 4. The input light L1 inputted from the input unit 3 into the optical module 1 passes through the first optical path adjustment filter 71 and enters the polarization separation filter 74.

A part of the input light L1 reaching the polarization separation filter 74 is transmitted through the polarization separation filter 74 and is input to the first lens portion 75b of the lens 75. The remaining part of the input light L1 reaching the polarization separation filter 74 is reflected twice in the polarization separation filter 74 and is input to the third lens portion 75d of the lens 75. The light L11 is input from the composite filter block 63 to the second optical path adjustment filter 73 and the mirror 72 in the second direction D2. The light L11 is reflected by the mirror 72 in the first direction D1 and is input to the second lens portion 75c of the lens 75. The optical module 1A of the first modification is described above. The same operational effects as those of the optical module 1 described above can be obtained also in the optical module 1A.

Fig. 8 is a plan view schematically showing the temperature control device 21B, the modulation element 30B, the driver IC42, and the housing 2k of the housing 2B of the optical module 1B according to the second modification. As shown in fig. 8, the optical module 1B further includes a wiring pattern 2p (second wiring pattern) provided in the housing 2k of the case 2B. The wiring pattern 2p is arranged along the first direction D1 on the opposite side of the wiring pattern 2h as viewed from the modulator 30B. The modulation element 30B also has a control terminal (second bonding pad) 30d. The control terminals 30D are arranged side by side along the first direction D1 on the side 31b (third side). The wiring pattern 2p is connected to the control terminal 30d of the modulation element 30B via a bonding wire (second bonding wire) W4.

The temperature regulating device 21B has a plurality of peltier elements 27. The spacing S of the plurality of peltier elements 27 on the side 31B (the control terminal 30d side of the modulator element 30B or the wiring pattern 2p side of the case 2B) is narrower than the spacing S of the plurality of peltier elements 27 on the center of the modulator element 30B. That is, the peltier elements 27 are arranged closer to the side 31B than the center of the modulator element 30B.

For example, the space S11 between the peltier element 27 located on the most side 31b side and the peltier element 27 located on the second side 31b side is narrower than the space S12 between the peltier element 27 located on the second side 31b side and the peltier element 27 located on the third side 31b side. The space S12 is narrower than the space S13 between the peltier element 27 located on the third side 31b and the peltier element 27 located on the fourth side 31 b. As an example, the spacing S11 is 0.15mm, the spacing S12 is 0.2mm, and the spacing S13 is 0.25mm.

The optical module 1B according to the second modification example includes: a control terminal 30d arranged on the side 31B of the modulation element 30B; and a wiring pattern 2p provided in a housing 2k of the case 2B and connected to a control terminal 30d of the modulator 30B via a bonding wire W4. The spacing S of the plurality of peltier elements 27 located on the side 31B is narrower than the spacing of the plurality of peltier elements 27 located at the center of the modulating element 30B. Since the control terminal 30d and the bonding wire W4 are provided on the side 31B, heat flows out and in easily occurs on the side 31B compared with the center of the modulator 30B. In the optical module 1B, the spacing S of the plurality of peltier elements 27 located on the side 31B is narrower than the spacing S of the plurality of peltier elements 27 located at the center of the modulation element 30B. Therefore, the peltier element 27 is more closely arranged on the side 31B than the center of the modulation element 30B, and therefore the influence of the outflow and inflow of heat at the side 31B can be reduced. Therefore, the temperature distribution of the modulation element 30B can be made nearly uniform to suppress the phase shift.

Fig. 9 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 2 and the temperature distribution of the modulation element in the optical module of comparative example 2 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is 75 ℃). The optical module of embodiment 2 is the same as the optical module 1B described above. The optical module of comparative example 2 is different from the optical module 1B in that the intervals of two peltier elements 27 arranged side by side in the width direction (second direction D2) are the same as each other (a plurality of peltier elements are uniformly arranged). The horizontal axis of fig. 9 represents displacement in the width direction, and the vertical axis of fig. 9 represents a temperature difference on a line Z (see fig. 8) extending in the X direction when the center of the side 31b of the modulation element is 0. As shown in fig. 9, in the optical module of example 2, compared with comparative example 2, the temperature change was suppressed to 0.05 ℃ or lower in the X direction, and it was found that the temperature distribution was nearly uniform.

Fig. 10 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 2 and the temperature distribution of the modulation element in the optical module of comparative example 2 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is-5 ℃). As shown in fig. 10, in the optical module of example 2, compared with comparative example 2, the temperature change was suppressed to 0.05 ℃ or lower in the X direction, and it was found that the temperature distribution was nearly uniform.

Fig. 11 is a graph showing the analysis results of the phase shift of the first optical waveguide and the second optical waveguide of the optical module of example 2 and the optical module of comparative example 2. As shown in fig. 11, in the optical module of comparative example 2, a phase shift of 0.73 pi/°c was generated in the first optical waveguide, and a phase shift of 3.06 pi/°c was generated in the second optical waveguide. In contrast, in the optical module of example 2, a phase shift of 0.47 pi/. Degree.c was generated in the first optical waveguide, and a phase shift of 0.5 pi/. Degree.c was generated in the second optical waveguide. Thus, it can be seen that: in example 2 in which the arrangement of the peltier elements is tighter as the control terminal 30d is closer, the phase shift can be suppressed as compared with comparative example 2 in which the arrangement of the peltier elements is uniform. In particular, in the optical module of embodiment 2, the phase shift in the width direction can be significantly suppressed.

Fig. 12 is a plan view schematically showing the temperature control device 21C, the modulation element 30C, the driver IC42, and the housing 2k of the housing 2B of the optical module 1C according to the third modification. The driving IC42 is a heat generating body. As shown in fig. 12, in the optical module 1C, the temperature adjusting device 21C has a plurality of peltier elements 27. The spacing T of two peltier elements 27 side by side along the first direction D1 differs depending on the position of the peltier elements 27 in the first direction D1. The intervals T of the plurality of peltier elements 27 located on the side 31f as the first side (the electrode pad 30C side of the modulating element 30C or the driving IC42 side as the driving circuit) are narrower than the intervals T of the plurality of peltier elements 27 located at the center of the modulating element 30C. That is, the peltier elements 27 are arranged closer to the side 31f than the center of the modulator element 30C.

For example, the interval T1 between the peltier element 27 located on the most side 31f side and the peltier element 27 located on the second side 31f side is narrower than the interval T2 between the peltier element 27 located on the second side 31f side and the peltier element 27 located on the third side 31f side. The interval T2 is narrower than the interval T3 between the peltier element 27 located on the third side 31f and the peltier element 27 located on the fourth side 31 f. As an example, the interval T1 is 0.15mm, the interval T2 is 0.2mm, and the interval T3 is 0.25mm.

The optical module 1C includes: a bonding wire W2 disposed on the side 31f of the modulator 30C; and an electrode pad 42b provided in the drive IC42 and connected to the electrode pad 30C (third bonding pad) of the modulation element 30C via a bonding wire W2 (third bonding wire). The intervals T of the plurality of peltier elements 27 located on the side 31f are narrower than the intervals T of the plurality of peltier elements 27 located at the center of the modulating element 30C. Since the electrode pad 30C and the bonding wire W2 are provided on the side 31f, heat flows out and in easily occur on the side 31f compared with the center of the modulation element 30C. In the optical module 1C, the interval T of the plurality of peltier elements 27 located on the side 31f is narrower than the interval T of the plurality of peltier elements 27 located at the center of the modulation element 30C. Therefore, the peltier element 27 is more closely arranged on the side 31f than the center of the modulation element 30C, and therefore the influence of the outflow and inflow of heat at the side 31f can be reduced. Therefore, the temperature distribution of the modulation element 30C can be made nearly uniform to suppress the phase shift.

In the optical module 1C, the driver IC42 as a driver circuit is a heat generating element, and the driver IC42 is disposed on the side 31f of the modulator element 30C. In the optical module 1C, as described above, the peltier element 27 is closely arranged on the side 31f of the modulation element 30C on which the drive IC42 is arranged. Therefore, the influence of the outflow and inflow of heat from the driving IC42 as a heating element can be reduced, and therefore the temperature distribution of the modulation element 30C can be made nearly uniform to suppress the phase shift.

Fig. 13 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 3 and the temperature distribution of the modulation element in the optical module of comparative example 2 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is 75 ℃). The optical module of embodiment 3 is the same as the optical module 1C described above. The horizontal axis of fig. 13 represents displacement in the width direction, and the vertical axis of fig. 13 represents a temperature difference on a line Z (see fig. 12) extending in the X direction when the center of the side 31b of the modulation element is 0. As shown in fig. 13, in the optical module of example 3, even when the optical module is separated from the side 31b, the temperature change is suppressed to 0.05 ℃.

Fig. 14 is a graph showing the analysis results of the temperature distribution of the modulation element in the optical module of example 3 and the temperature distribution of the modulation element in the optical module of comparative example 2 (the difference between the temperature distribution of the modulation element when the temperature of the optical module is 35 ℃ and the temperature distribution of the modulation element when the temperature of the optical module is-5 ℃). As shown in fig. 14, in the optical module of example 3, compared with comparative example 2, the temperature change was suppressed to 0.05 ℃ or lower in the X direction, and it was found that the temperature distribution was nearly uniform.

Fig. 15 is a plan view schematically showing the temperature control device 21D, the modulation element 30D, the drive IC42, and the housing 2k of the housing 2B of the optical module 1D according to the fourth modification. The number of bonding wires W4 of the optical module 1D is different from that of the optical module 1B described above. The optical module 1D includes: a first heat capacity portion P1 located around the modulation element 30D; and a second heat capacity portion P2 located around the modulation element 30D and located at a different place from the first heat capacity portion P1.

The first heat capacity portion P1 is located on the side of the side 31c as viewed from the modulating element 30D. The first heat capacity portion P1 includes a control terminal 30b, a bonding wire W1, and a wiring pattern 2h arranged on the side 31c of the modulator 30D. The second heat capacity portion P2 is located on the side of the side 31b as viewed from the modulating element 30D. The second heat capacity portion P2 includes a control terminal 30D, a bonding wire W4, and a wiring pattern 2P arranged on the side 31b of the modulator 30D. The number of bonding wires W1 is greater than the number of bonding wires W4. Therefore, the heat capacity of the first heat capacity portion P1 is greater than that of the second heat capacity portion P2. That is, the heat inflow from the first heat capacity portion P1 to the modulator element 30D is larger than the heat inflow from the second heat capacity portion P2 to the modulator element 30D.

In the temperature regulating device 21D, the interval S of two peltier elements 27 juxtaposed along the second direction D2 differs according to the position of the peltier elements 27 in the second direction D2. The spacing S of the peltier elements 27 on the first heat capacity portion P1 side (side 31c side) is narrower than the spacing S of the peltier elements 27 on the second heat capacity portion P2 side (side 31b side). That is, the peltier element 27 is disposed closer to the first heat capacity portion P1 than to the second heat capacity portion P2.

For example, the space S1 between the peltier element 27 located on the most side 31c side and the peltier element 27 located on the second side 31c side is narrower than the space S21 between the peltier element 27 located on the most side 31b side and the peltier element 27 located on the second side 31b side. For example, the space S2 between the peltier element 27 located on the second side 31c and the peltier element 27 located on the third side 31c is narrower than the space S22 between the peltier element 27 located on the second side 31b and the peltier element 27 located on the third side 31 b. For example, the interval S3 between the peltier element 27 located on the third side 31c and the peltier element 27 located on the fourth side 31c is the same as the interval S23 between the peltier element 27 located on the third side 31b and the peltier element 27 located on the fourth side 31 b. As an example, the spacing S1 is 0.15mm, the spacing S21 is 0.18mm, the spacing S2 is 0.2mm, the spacing S22 is 0.23mm, and the spacing S3 and the spacing S23 are 0.25mm.

In the optical module 1D, the modulation element 30D is mounted on the temperature adjustment device 21D, and the modulation element 30D and the temperature adjustment device 21D are housed in the case 2B. The modulation element 30D has a side 31b and a side 31c opposite to the side 31 b. Around the modulator element 30D, a first heat capacity portion P1 and a second heat capacity portion P2 located at a different place from the first heat capacity portion P1 are arranged. The heat capacity of the first heat capacity portion P1 is greater than the heat capacity of the second heat capacity portion P2. Therefore, the first heat capacity portion P1 is more likely to generate heat flowing out and in the modulation element 30D than the second heat capacity portion P2. In the optical module 1D, a plurality of peltier elements 27 are arranged at intervals in the temperature adjustment device 21D, and the intervals S of the plurality of peltier elements 27 on the first heat capacity portion P1 side are narrower than the intervals S of the plurality of peltier elements 27 on the second heat capacity portion P2 side. Therefore, the peltier element 27 is disposed closer to the first heat capacity portion P1 than to the second heat capacity portion P2, and therefore the influence of the outflow and inflow of heat at the first heat capacity portion P1 side can be reduced. Therefore, the temperature distribution of the modulation element 30D can be made nearly uniform to suppress the phase shift.

The embodiments and various modifications of the optical module of the present disclosure are described above. However, the present invention is not limited to the above-described embodiment or modification examples. That is, those skilled in the art will readily recognize that the present invention can be variously modified and altered without departing from the spirit and scope of the invention as set forth in the claims. For example, the shape, size, number, material, and arrangement of the components of the optical module are not limited to those described above, and may be changed as appropriate.

Claims (6)

1. An optical module is provided with:

an optical element having a first side, a second side intersecting the first side, and a third side opposite the second side;

a housing accommodating the optical element;

a thermoelectric cooler mounted in the case for mounting the optical element;

a driving circuit disposed on the first side of the optical element;

a first bonding pad disposed on the second side of the optical element; and

a first wiring pattern provided in a frame of the case and connected to the first bonding pad of the optical element via a first bonding wire,

a plurality of peltier elements are arranged at intervals in the thermoelectric cooler,

the spacing of the plurality of peltier elements located at the second side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

2. The optical module of claim 1, wherein,

the optical element is a multimode interferometer having a first optical waveguide for propagation of a first signal light and a second optical waveguide for propagation of a second signal light different from the first signal light,

the first optical waveguide is disposed closer to the second side than a center of the multimode interferometer,

The second optical waveguide is disposed closer to the third side than a center of the multimode interferometer.

3. The optical module according to claim 1 or 2, comprising:

a second bonding pad disposed on the third side of the optical element; and

a second wiring pattern provided in a frame of the case and connected to the second bonding pad of the optical element via a second bonding wire,

the spacing of the plurality of peltier elements located on the third side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

4. The optical module according to claim 1 or 2, comprising:

a third bonding pad disposed on the first side of the optical element; and

a third wiring pattern provided in the driving circuit and connected to the third bonding pad of the optical element via a third bonding wire,

the spacing of the plurality of peltier elements located at the first side is narrower than the spacing of the plurality of peltier elements located at the center of the light element.

5. The optical module of claim 4, wherein,

the driving circuit is a heating body.

6. An optical module is provided with:

An optical element having a first side, a second side intersecting the first side, and a third side opposite the second side;

a housing accommodating the optical element;

a thermoelectric cooler disposed inside the case for mounting the optical element;

a first heat capacity portion located around the optical element; and

a second heat capacity part positioned around the optical element and at a different place from the first heat capacity part,

the heat capacity of the first heat capacity part is larger than that of the second heat capacity part,

a plurality of peltier elements are arranged at intervals in the thermoelectric cooler,

the spacing of the plurality of peltier elements on the first heat capacity side is narrower than the spacing of the plurality of peltier elements on the second heat capacity side.