FR2717911A1 - Integrated optical circuit. - Google Patents

Abstract

Integrated optical circuit comprising a detector (30) with a photosensitive area (32) substantially parallel to the front face of the end of an optical fiber (24) on the detector side. Both the detector (30) and the optical fiber (24) are held in a substrate (45).

Description

"Integrated optical circuit"

State of the art.

  The invention relates to an integrated optical circuit comprising a detector for receiving an optical signal, having a photosensitive zone and an optical fiber conducting the optical signal to the detector, this fiber being

  held in a substrate by its end on the side of the

  guardian, by means of at least one adjustment groove.

  Document P 42 40 950.0, not previously published

  clearly describes an integrated optical circuit with a chip or

  detector plate embedded in a polymer cover.

  A lower part of a polymer circuit has a waveguide and, parallel to its longitudinal axis,

  finds the detector chip when the poly-

  mother is reported on the bottom. The light in the waveguide is detected by evanescent coupling. For this it is necessary that the detector has a large length and a small width. This requires

  again great precision in adjusting the cover in

  lymer on the lower part. The efficiency of decoupling

  in the case of an evanescent coupling is relatively weak

corn.

Advantages of the invention.

  The present invention relates to an optical circuit

  that integrated corresponding to the type defined above, charac-

  terized in that the photosensitive zone of the detector is substantially parallel to the front face of the end of the optical fiber on the side of the detector and the detector is

held by the substrate.

  The integrated optical circuit according to the invention

  has the advantage of allowing high coupling efficiency

  vé. In addition, we have higher tolerances for adjusting

  the detector relative to the waveguide.

  It is particularly advantageous to provide a waveguide between the optical fibers and the detector,

  this guide being integrated in the substrate because in the subs-

  trat it can have any shape and even a curved shape, which gives more possibilities of design for the mounting of the detector. In particular, the waveguide makes it possible to conduct the optical signal in another optical circuit integrated between the guide fibers of

light and detector.

  The realization of the waveguide in the form of a groove filled with glue offers the advantage of being able to manufacture the waveguide, in the substrate, at the same time as the optical fibers are fixed. This removes a step

  of work in the manufacture of the integrated optical circuit.

  According to another advantageous characteristic,

  if in the path of the optical signal between the fibers op-

  ticks and the detector, at least one optical component is provided, this makes it possible to process the optical signal before the detector. According to another advantageous characteristic, the detector is integrated into the substrate, which gives a

  compact shape with integrated optical circuit and allows

  at the same time protect the detector against ex-

noxious legs.

  This also results in the advantage of being able to

  mount the detector in its desired position without requiring

  use additional means of adjustment and in particular

  link active means, if the detector can be adjusted

  into the substrate using a step adjustment device

  sif. The fixing of the detector in the substrate by glue constitutes a particularly simple realization and requiring few means to fix the detector

in the substrate.

  The displacement of the connection contacts of the

  detector outside the substrate ensures accessibility

  simple tee of these connection contacts, which advantageously reduces the electrical means to be used

  work for the integrated optical circuit.

  Completing the integrated optical circuit with a semiconductor circuit at the substrate provides

  the advantage of allowing further processing of

  electrical signals of the detector, directly at the integrated optical circuit; this also advantageously reduces the size of the integrated optical circuit. In addition, the combination of the integrated optical circuit and the semiconductor circuit improves the compatibility of the device for high frequencies because there are only very short

links between the two circuits.

  Subdividing the substrate into a cover and a bottom with matching adjustment elements offers the advantage of simplifying adjustment during mounting

of the integrated optical circuit.

  Drawings. Examples of embodiments are shown in the accompanying drawings and will be described in more detail

  detailed in the following description which refers to these

  drawings in which: - Figure 1 shows a molding die and the bottom part thus formed; - Figure 2 is a side view, cut away, of the integrated optical circuit; - Figure 3 shows, in section, a first embodiment of the integrated optical circuit; - Figure 4 is a sectional view of a second embodiment of the integrated optical circuit; - Figure 5 shows the lower part of the integrated optical circuit, with the optical fibers and the

detector, seen from above.

  Description of the exemplary embodiments.

  Figure 1 shows a matrix 18 serving as

  negative mold for the manufacture of a bottom part 10.

  The rectangular matrix 18 has an edge of its suface

  a roof-shaped boss 15 as well as a bos-

  rectangular sage 16 whose longitudinal axis is aligned with the ridge of the roof-shaped boss 15. The rectangular boss 16 is connected directly to the roof-shaped boss 15. At the other end of the rectangular boss

  16, there is a boss 17 in the form of a pyramid trunk also

  Lement directly connected to the rectangular boss 16. The bottom 10 also has a rectangular shape and has a roof-shaped cavity 11 corresponding to the boss 15 in

  roof shape; it also includes a cavity 12 rectan-

  gular corresponding to rectangular boss 16 as well

  that a pyramid trunk cavity 13 corresponding to the bos-

sage in trunk of pyramid 17.

  To manufacture the bottom 10, the ma-

  18 preferably nickel, which allows to use

  this matrix as negative to form several funds 10.

  To make the bottom 10, a liquid monomer is poured,

  for example MMA, on the matrix 18 is made polymer

  laugh. After clearing and removing the barbs, there is a finished bottom 10. The continuation of the operations concerning the bottom

  will be described in connection with FIG. 2.

  Figure 2 shows a side view, in exploded section, of the integrated optical circuit. The bottom 10 includes the

  cavity 11 in the shape of a roof, the cavity 12 of rectangular shape

  laire as well as the cavity 13 in the shape of a pyramid trunk.

  There is further provided a cover 12 having the same dimensions.

  Mensions that the bottom 10 and an adjustment groove 22 above

  roof-shaped lower part corresponding to the roof-shaped cavity 11 of the bottom 10; the cover 20 attached to the

  bottom 10 comes on this roof-shaped part. The cover

  key 20 further comprises a passage 21 arriving over the cavity in the trunk of a pyramid 13. During assembly,

  places the end of an optical fiber 24 in the two ca-

  vites in the shape of a roof 11, 22. In passage 21, a detector chip 30, rectangular, flat is provided, provided with a photosensitive zone 32 on its side facing the optical fiber

  24. On the same side, the detector chip 30 includes a connector.

  tact de chip 31. In the interval between the cover 20 and the bottom 10, there is an adhesive 23. On the upper side of the cover 20 there are also the integrated circuit 40 and

its switching contacts 41.

  The glue 23 is preferably a polymer

  hardening transparent with a high refractive index

  lower than that of the polymer of the cover 20 and of the bottom 10.

  When the cover 20 and the bottom 10 are joined together, the glue 23 is pushed back into the cavities 11, 22, 12, 13 and into the

  passage 21. At the same time, a metallic link is thus obtained

  canonically strong and durable between the cover 20, the bottom 10, the optical fiber 24 and the detector chip 30. In addition, the glue 23 in the rectangular cavity 12 forms a

  light guide 46 (see figure 3).

  Figure 3 shows the integrated optical circuit whose assembly is complete. The optical fiber 24 opens coaxially into the light guide 46 whose opposite end is located exactly in front of the photosensitive zone 32 of the detector chip 30. In addition, the integrated circuit 40 is fixed on the upper face of the cover 20 and the contacts 41 are connected by electrical connections 42 to the contacts 31 of the detector chip 30. The bottom 10 and

  the cover 20 thus forms a substrate 45.

  The detector chip 30 is thus held in the substrate 45 and the light transmitted by the optical fiber 24 arrives in the form of an optical signal through the waveguide 46 in the photosensitive zone 32; the electrical signals of this zone are transmitted by the contacts 31 of the chip to the integrated circuit 40. Ideally, for mounting, after having placed the glue 23 on the bottom 10, the detector chip 30 is introduced into the cavity 13 in

  shape of pyramid trunk; this form of pyra trunk

  mide performs an automatic passive adjustment of the de-

  guard 30. The viscosity of the adhesive 23 gives the detector chip 30 a slight stabilization of position. This stabilization is sufficient to allow the detector chip 30

  to cross the passage 21 when the cover is fitted

  circle 20. The discharge of the glue 23 also fills

  passage 21 with glue, which completes the stabilization

  sation of the position of the detector chip 30. The detector chip 30 is stabilized definitively after the setting of the glue 23. It is also planned to first connect the cover 20 and the base 10 to the optical fiber 24 and then

  place the detector chip 30 in passage 21. Usual-

  A polymer which hardens under the effect of ultraviolet light is used as the adhesive 23. Thus, it is only after introduction of the detector chip 30 that, by appropriate insolation, a connection is made mechanically.

stable of all components.

  Figure 4 shows another embodiment of the

  integrated optical circuit. In this figure the same references

  References denote the same elements as those above. The assembly shown differs from that of FIG. 2 by the elimination of the rectangular cavity 12. In this case,

  the photosensitive zone 32 of the detector chip 30 is covered

  plied directly to the optical fiber 24. This allows a particularly simple realization, compact and with a particularly effective coupling, between the chip

  detector 30 and the optical fiber 24.

  Figure 5 shows, in top view, another embodiment of the integrated circuit. For simplicity, the cover 20 and the glue 23 have not been shown. The optical fiber 24 is, in this case, also placed in the roof-shaped cavity 11 of the bottom 10. In the course of the rectangular cavity 12, the surface

  top of bottom 10 is provided with a corresponding structure

  to a Bragg 47 optical resonator.

  Bragg 47 is used to filter, leaving only the compound

  luminous health of the optical signal which corresponds to the

  resonance quence of this Bragg 47 resonator.

  allows selective frequency detection of op-

  ticks. In addition, the bottom 10 has two pyramid bosses.

  daux 14 with pyramidal cavities of equivalent shape in the cover 20. This facilitates the adjustment of the cover on the bottom 10 during assembly. he is also

  provided another integrated optical circuit between the optic fiber

  as 24 and the detector chip 30 in the path of the waveguide 46. As another integrated optical circuit, it is possible, for example, to use optical gate circuits or

filter circuits.

R E V E N D I CATIONS

  1) Integrated optical circuit comprising a

  guard for receiving an optical signal, having an area

  photosensitive and an optical fiber conducting the op-

  tick on the detector, this fiber being held in a substrate by its end on the detector side, by means of at least one adjustment groove, circuit

  characterized in that the photosensitive area (32) of the detector

  tor (30) is substantially parallel to the front face of the end of the optical fiber (24) on the detector side

  and the detector (30) is held by the substrate (45).

  ) Integrated optical circuit according to the claim

  tion 1, characterized in that a waveguide is provided between the front face of the end of the optical fiber (24) on the detector side and the photosensitive zone (32)

  (46) integrated into the substrate (45) and whose axis is longitudinal

  nal is aligned with the longitudinal axis of the optical fiber (24).

  ) Integrated optical circuit according to the claim

  tion 2, characterized in that the waveguide (46) is a

  groove (12) filled with a transparent adhesive (23) hardened

sand.

  ) Integrated optical circuit according to one of the

  vendications 1 to 3, characterized in that, in the line between the front face of the end of the optical fiber (24) on the side of the detector and the photosensitive zone (32), on the path of the optical signal there is at least one optical component (47), preferably a selective filter of

  wavelength or other integrated optical circuit.

  50) Integrated optical circuit according to one of the

  vendications 1 to 4, characterized in that the detector (30)

is embedded in the substrate (45).

  ) Integrated optical circuit according to one of the

  vendications 1 to 5, characterized in that the detector (30) is adjustable in position using a device

  passive adjustment (13) provided in the substrate.

  7) Integrated optical circuit according to one of the re-

  vendications 1 to 6, characterized in that the detector (30) is fixed to the substrate (45) with glue (23).

  8) Integrated optical circuit according to one of the re-

  vendications 1 to 7, characterized in that the detector (30) comprises connection contacts (31) located at

the exterior of the substrate (45).

  9) Integrated optical circuit according to the claim

  tion 8, characterized by an electronic circuit (40) provided

  on the substrate (45), preferably a semi-circuit

  conductor provided with switching contacts (41) connected to the

connection contacts (31).

  10) Integrated optical circuit according to one of

  claims 1 to 9, characterized in that the substrate

  (45) has a cover (20) and a bottom (10) having

  one of the corresponding adjustment elements (14) facilitating

  an exact union of the cover (20) and the bottom (10).