CN215905853U

CN215905853U - Optical-mechanical device

Info

Publication number: CN215905853U
Application number: CN202121243279.8U
Authority: CN
Inventors: L·马吉; M·A·肖
Original assignee: STMicroelectronics SRL
Current assignee: STMicroelectronics SRL
Priority date: 2020-06-05
Filing date: 2021-06-04
Publication date: 2022-02-25
Anticipated expiration: 2031-06-04
Also published as: CN113753844A

Abstract

Embodiments of the present disclosure relate to optical-mechanical devices. An embodiment apparatus includes an optically transparent substrate having a first surface and a second surface; a piezoelectric film disposed on the first surface, oscillating in response to a light beam propagating through the substrate; at least one reflective facet facing the substrate is arranged at the piezoelectric film; and an optical element receiving the light beam at an input end and directing the light beam to an output end coupled to the second surface. The optical element includes a light focusing path that focuses the light beam at a focal point of the piezoelectric film, and at least one light collimating path that collimates the light beam onto the at least one reflective facet. The optical element directs light reflected from the at least one reflective facet to the input end, the reflected light indicating a position of the optical element relative to the focal point. Advantageously with embodiments of the present disclosure, the use of a GRIN lens attached directly to a surface counteracts possible focus misalignment errors.

Description

Optical-mechanical device

Technical Field

This specification relates to opto-mechanical devices. One or more embodiments may be used for optical alignment.

Background

Micro-opto-electromechanical systems (MOEMS), also known as optical micro-electromechanical systems or optical MEMS, are systems that involve sensing or manipulating optical signals in a very small size range, for example, using integrated mechanical, optical and electrical systems, coupling a mechanical mode to an optical mode, or coupling an optical mode to a mechanical mode.

Systems of this type are discussed, for example, in Midolo, L., Schliesser, A. and Fiore, A. by "Nano-opto-electro-mechanical systems", Nature Nanotech 13,11-18(2018), doi:10.1038/s 41565-017-.

The opto-mechanical sensor can convert mechanical motion of the membrane (on the micrometer scale) into an optical signal or vice versa.

For example, an opto-mechanical sensor may include an oscillating nano-or micro-membrane and a light beam focused on the active area of the membrane, i.e., the area where opto-mechanical conversion may be maximized. For example, such an active area may be arranged in the center of the die or any other portion thereof.

Sensors of this type are for example in a.simonsen, s.saarinen, j.sanchez, J.

"Sensitive optical transmission of electric and magnetic signals to the optical domain", of Larsen, A.Schliesser, and E.Polzik, "Opti.Express27, 18561-18578 (2019).

In this type of film-based opto-mechanical sensor, the light beam used is focused to a target spot size, e.g. in the order of micrometers.

As a result, optical alignment between the focused beam (focal point) and the film (active) area is a relevant figure of merit.

Optical alignment using a focused beam can be challenging for various reasons, such as difficulty in accurately determining the correct location of the beam's minimum waist point, which can lead to poor performance and difficulty in optimizing alignment; and complicates the algorithm to search for the best alignment.

Conventional optical alignment arrangements using a focused beam of light may involve complex reading processes, including scanning along the X and Y axes for each position along the direction of light propagation (often referred to as the Z axis); analyzing all data to find the correct depth of focus; setting the system to a certain depth of focus; and performing a further scan to determine improved alignment.

The conventional solution as described above therefore presents the problem of the following drawbacks: the complexity of the alignment system and method; and the costs in terms of time and consumption associated with direct reading and feedback of optoelectronic devices/components.

SUMMERY OF THE UTILITY MODEL

It is an object of the present disclosure to provide a light apparatus to at least partially solve the above-mentioned problems in the prior art.

An aspect of the present disclosure provides an optical-mechanical device, including: an optically transparent substrate having a first surface and a second surface opposite the first surface; a piezoelectric film disposed at a first surface of the optically transparent substrate, the piezoelectric film configured to oscillate as a result of a light beam propagating through the optically transparent substrate and impinging on the piezoelectric film, wherein at least one reflective facet facing the optically transparent substrate is disposed at the piezoelectric film; and an optical element configured to receive the light beam at an input end and direct the light beam towards an output end coupled to the second surface of the optically transparent substrate; wherein the optical element comprises: a light focusing path configured to focus the light beam at a focal point located at the piezoelectric film; and at least one light collimating path configured to collimate the light beam onto the at least one reflective facet; wherein the optical element is configured to direct light reflected from the at least one reflective facet to the input end; and wherein the light reflected to the input end is indicative of the position of the optical element relative to the focal point.

According to one or more embodiments, wherein: the piezoelectric film includes at least one reflective facet having a central region and a peripheral region; a light focusing path in the optical element configured to focus the light beam at a central region of the at least one reflective facet; and at least one light collimating path in the optical element is configured to collimate the light beam at a peripheral region of the at least one reflective facet.

According to one or more embodiments, the opto-mechanical arrangement further comprises: a plurality of reflective facets; wherein the optical element comprises a plurality of light collimating paths configured to provide respective collimated light beams onto the plurality of reflective facets.

According to one or more embodiments, the plurality of reflective facets includes reflective facets disposed at the same distance from the center of the piezoelectric film.

According to one or more embodiments, wherein the plurality of reflective facets comprises: a square facet having a side length between about 250 microns and about 300 microns; and/or facets at about 300 microns from the center of the piezoelectric film.

According to one or more embodiments, the plurality of reflective facets comprises two facets arranged mirror-symmetrically about a center of the piezoelectric film.

According to one or more embodiments, wherein the optical element comprises: a substrate having a plurality of channels formed therein; and a plurality of optical fibers disposed in the channel; wherein the optical fiber provides an optical focusing path and at least one optical collimating path.

According to one or more embodiments, wherein: the optical focusing path in the optical element includes a light focusing gradient index GRIN lens having a focusing pitch; and at least one light collimating path in the optical element includes a light collimating GRIN lens having a collimating pitch, and the light focusing path and the light collimating path have a same total length and a same lens diameter.

According to one or more embodiments, at least one of the light focusing path and the at least one light collimating path in the optical element comprises an optical spacer portion.

According to one or more embodiments, wherein: the same total length is about 500 microns; and/or the same lens diameter is about 350 microns.

According to one or more embodiments, wherein: the device still includes: a housing having a support base with a through-hole therein, the support base of the housing being coupled to the second surface of the optically transparent substrate with a portion of the second surface of the optically transparent substrate aligned with the through-hole; and the output end of the optical element is coupled to the optically transparent substrate at the through hole in the support base of the housing.

An opto-mechanical device comprising: an optically transparent substrate comprising: a first surface; and a second surface opposite the first surface; a piezoelectric film disposed at a first surface of an optically transparent substrate; at least one reflective facet disposed at the piezoelectric film or disposed in the same plane on one side of the piezoelectric film, and facing the optically transparent substrate; and an optical element comprising: an input configured to receive a light beam; an output coupled to the second surface of the optically transparent substrate; a light focusing lens having a focal point for the light beam at the piezoelectric film; and a light collimating lens oriented to collimate the light beam onto the at least one reflective facet for reflection back toward the input end.

According to one or more embodiments, wherein: the piezoelectric film includes at least one reflective facet having a central region and a peripheral region; the light is focused at a central region of the at least one reflective facet with a focal point for the light beam; and a light collimating lens oriented to collimate the light beam at a peripheral region of the at least one reflective facet.

According to one or more embodiments, the opto-mechanical arrangement further comprises: a plurality of reflective facets; wherein the optical element comprises a plurality of light collimating lenses oriented to collimate the respective light beams onto the plurality of reflective facets.

According to one or more embodiments, wherein the optical element comprises: a substrate having a plurality of channels formed therein; and a plurality of optical fibers disposed in the channel; wherein the optical fiber provides a light focusing path for the light focusing lens and a light collimating path for the light collimating lens.

According to one or more embodiments, wherein: the light focusing lens is a light focusing gradient index GRIN lens having a focusing pitch; and the light collimating lens is a light collimating GRIN lens having a collimating pitch, and wherein the light focusing lens and the light collimating lens have the same lens diameter.

According to one or more embodiments, wherein: the device still includes: a housing having a support base with a through-hole therein, the support base of the housing being coupled to the second surface of the optically transparent substrate, a portion of the second surface of the optically transparent substrate being aligned with the through-hole; and the output end of the optical element is coupled to the optically transparent substrate at the through hole in the support base of the housing.

Advantageously with embodiments of the present disclosure, the use of a GRIN lens attached directly to a surface counteracts possible focus misalignment errors.

Drawings

One or more embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of an opto-mechanical transducer assembly;

FIG. 2, FIG. 2A, and FIG. 2B are diagrams of the underlying principles of one or more embodiments;

FIG. 3 is a diagram of an optical alignment method exemplified herein;

FIG. 4 is a perspective view of an alignment system according to the present disclosure;

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4;

FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 4;

FIG. 7 is a plan view of FIG. 4;

FIGS. 8, 8A, 9 and 9A are diagrams of the underlying optical principles of one or more embodiments;

fig. 10 and 11 are diagrams of a power distribution source;

FIG. 12 is a perspective view of an assembly as exemplified herein;

fig. 13 and 14 are perspective views of a housing according to the present disclosure;

FIG. 15, FIG. 16, and FIG. 17 are perspective views of an opto-mechanical assembly according to the present disclosure;

FIG. 18 is a perspective view of an optical element according to the present disclosure;

FIG. 19 is a perspective view of a device according to the present disclosure; and

fig. 20 is an enlarged view taken substantially along arrow XX of fig. 19.

Detailed Description

In the following description, one or more specific details are illustrated in order to provide a thorough understanding of examples of embodiments of the present description. Embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to not obscure certain aspects of the embodiments.

Within the framework of this description, a reference to an "embodiment" or "one embodiment" is intended to indicate that a particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment" or "in one embodiment" that may be present in one or more points of the present description do not necessarily refer to one or more of the same embodiment.

Furthermore, particular conformations, structures, or features may be combined in any suitable manner in one or more embodiments.

The headings/references used herein are for convenience only and therefore do not define the extent or scope of protection of the embodiments.

For ease of explanation, the drawings are in simplified form and are not to scale.

In the drawings attached hereto, like parts or elements are denoted by like reference numerals, and corresponding description will not be repeated for each drawing for the sake of brevity.

The opto-mechanical transducer 10 as illustrated in fig. 1 may comprise:

a housing 12, for example a ceramic housing, comprising a material having, for example, a diameter of about 4mm (1mm 10 ═ 1mm ═ 10-^-3m 1 mm) of the central bore 120,and the central aperture 120 is configured as an aperture for receiving an optically transparent material (e.g., made of glass having a thickness of 0.2 mm), forming an optical window;

a plurality of electrically conductive leads 14, such as flat leads exposed at the surface of the housing 12;

one or more optically

transparent layers

16, 18, for example comprising a fused silica substrate 18 (about 0.5mm thick), optionally superimposed on top of a silicon die 16 having a hollow core 160 (aligned with the aperture 120) in which light can propagate in free space, the core 160 extending for example about 0.35mm thick;

a film layer 20, for example a piezoelectric film, located on the top plane of the quartz die 18 and comprising an at least partially reflective "bottom" surface 200 facing the top plane surface of the quartz die 18;

- (micro) spacers 22 configured to keep the film layer 20 separated from the top planar surface of the quartz die 18 to allow the film to vibrate or oscillate;

a conductive contact pad 24 coupled on the top surface of the film layer 20 and configured to control and/or detect a change in the opto-mechanical properties of the film 20 via electrical signals transmitted or received from the film layer 20;

conductive connections 26 coupling the conductive contact pads 24 on the membrane layer 20 to the conductive leads 14 in the support chassis 12; and

an optical element 30, e.g. a lens, configured to direct light emitted from a source at an input end (not visible in the figure) of the optical element 30 along an optical path aimed at the membrane 20, the optical element 30 being coupled to the package substrate 12 via an aperture 120 in the package base 12. For example, the optical element may have a diameter of about 2.5mm and a length of about the same dimension.

As illustrated in fig. 1, for example, the device 10 may be sealed via an outer cover 90 (e.g., a lid).

In one or more embodiments, the opto-mechanical device 10 may convert the optical signal to an electrical signal via mechanical vibration of the film layer 20 when light is focused on the film layer 20.

A GRIN lens as illustrated in fig. 2 is an example of an optical element 30 that may be advantageously used in the embodiments discussed herein.

By way of background, it can be recalled that an "optical object" 30A, as shown in FIG. 2A, is configured to focus a light beam with parallel rays from a light source S, "squeezing" it to a focal point FP at a depth of focus or distance F of the object 30, the "optical object" 30A being referred to as a focusing lens 30A. The corresponding position along the propagation axis Z, where the beam spot reaches its minimum radius, is referred to as the "focal point" FP (or beam waist).

In contrast, an optical object 30B, as shown in fig. 2B, which receives a diverging light beam from the light source S and generates a beam (in a conceptually ideal scene) without angular divergence residual or a beam with gaussian behavior (in a more realistic scene), is referred to as a collimating lens 30B. The collimating lens 30B may have a collimating length, i.e., the distance between the light source S and the lens 30B, such that the light beam from the light source is collimated.

The GRIN lens 30 as illustrated in fig. 2 may comprise a cylindrical or rod-shaped body extending linearly (i.e., longitudinally) between two

flat ends

306, 308 suitable for fiber coupling.

The optical behavior of the GRIN lens 30 may be based on the refractive index of the lens material, which varies spatially with the gradient profile in a manner known per se to those skilled in the art.

Fig. 2 shows a ray trace diagram within a GRIN rod 30 designed for use as a focusing lens. The linear rod 30 may have a length, also indicated as one "pitch" P, i.e., a length for obtaining a 1:1 image without inversion, which is related to the refractive index change of each GRIN lens.

As known to those skilled in the art, a GRIN lens may behave as a focusing lens or a collimating lens (or a diverging lens) depending on its pitch P.

For example, shortening the bar to the length of 1/2 or 1/4 portions of full pitch P, as illustrated by the arrows in FIG. 2, may change the optical characteristics of optical element 30.

In the device 10 illustrated in fig. 1, a GRIN lens may be used at 30 to focus the light beam (illustrated in fig. 2A) on the membrane bottom surface 200.

On the other hand, as previously mentioned, accurately aligning the focused light beam so that its waist is located at a position corresponding to the bottom surface 200 can be a challenging task.

As illustrated in fig. 3, one or more embodiments may use an optical element 30 based on a GRIN lens concept including a focusing lens portion 32 and a collimating lens portion 34 embedded in a single optical piece, such as a single (optical) fiber block.

For example, such an optical element 30 may be designed such that both the focusing lens portion 32 and the collimating lens portion 34 have respective (focal length) lengths F relative to each other, as formed together in a single block of optical fiber having a certain length.

As illustrated in fig. 3, such optical elements 30 may be used in conjunction with a reference reflective surface 40, for example included in the film layer 20 as a peripheral portion 400 around its bottom surface central portion 200, or as a pattern of non-connecting reflective surfaces, operating as fiducial marks. Such a reference reflective surface 40 coplanar with the bottom surface of the membrane 20 may help to perform improved optical alignment of the focal length F of the focusing lens portion 32.

For example, a light beam emitted by the light source S may be focused 32 and collimated 34 simultaneously as it passes through the optical element 30. As a result, collimated radiation emitted from the light source S may impinge on the reflective reference surface 40.

At least a portion of the impinging collimated rays will be reflected from the reflective reference surface 40. Such reflected rays R may move back along the optical element 30 and have the ability to be sensed, for example, via an optical circulator 31 disposed at the "distal" end of the element 30 (i.e., the end facing away from the reflective surface 40). For example, the circulator 31 may provide the reflected radiation R to a user circuit a, e.g. an actuator a, which is configured to perform feedback on the alignment of the optical element 30 with respect to the reference surface 40.

Alignment of the collimating lens 34 can be facilitated due to the larger spot size at the focal point FP.

The focusing lens 32 is incorporated in a common optical assembly 30 with the collimating lens 34, and thus may facilitate (in a substantially "passive" manner) simplifying alignment of the focusing lens 32.

Notably, the reflected light R provides a passive alignment feedback without an active opto-mechanical transducer per se, i.e., without power being supplied to the device 10.

As previously mentioned, this passive alignment process is relatively fast and easy.

For example, the optical element 30, once aligned with the assembly 10, may be directly attached (e.g., glued) to the assembly 10.

Alternatively, when the membrane 20 is assembled in the housing, it may be attached to the aperture 120 of the housing.

In the

optical alignment systems

30, 40 as illustrated in fig. 4-7, for example, the reference surface 40 may include a plurality of planar reflective surfaces (or facets) 400A, 400B arranged symmetrically with respect to the film layer 20, the plurality of planar reflective surfaces being at the same distance from the target focal point FP of the active surface 200 of the film 20; and the optical element 30 may comprise a plurality of

collimator lens portions

34A, 34B, the

parallel lens portions

34A, 34B being arranged symmetrically with respect to the focusing lens portion 32 (the optical axis thereof) of the optical element 30.

As discussed herein, the "target"

reference surface

40, 400 may be located on an exposed surface portion of the optically

transparent layer

16, 18 of the assembly 10, such as a surface portion aligned with the aperture 120 in the housing 12 of the device 10.

For simplicity, the arrangement of a pair of planar reflective surfaces (or facets) 400A, 400B and a corresponding pair of collimating

lens portions

34A, 34B is discussed below. Additionally, it should be understood that such number in the exemplary arrangement is not limited in any way, as virtually any number of planar reflective surfaces (or facets) 400A, 400B and

collimating lens portions

34A, 34B can be used in one or more embodiments.

As illustrated in fig. 5 (this is a cross-sectional view along line V-V of fig. 4): the focusing lens portion 32 of the optical element 30 may be incorporated into an optical fiber that includes a focusing GRIN lens portion 320 and an optical spacer portion 322; and the pair of collimating

lens portions

34A, 34B may comprise a first collimating lens portion 34A and a second collimating lens portion 24B, each comprising a collimating GRIN lens portion 340 and a further optical spacer portion 342.

For a particular wavelength of light, the focusing GRIN lens 320 may be obtained for a certain pitch P, e.g., P500 microns, and the collimating GRIN lens 340 may be obtained for a portion of the pitch, e.g., P' 1/2P.

Since the collimating lens 340 is shorter than the focusing lens 320, the collimating GRIN lens 340 may be coupled to an optical spacer or "buffer" such that the total length L given by the sum of the length of the

respective lens

340, 342 and the length of the respective spacer 342, 344₀The portions being the same for both the focus 32 and the

collimation

34A, 34B facilitate coupling of the optical element 30 to the light source S and the optically transparent layer 18.

The use of

GRIN lenses

320, 340 having different pitch lengths may provide advantageous ease of assembly of optical component 30 and may facilitate focus point FP to reach a target spot size at central surface 200 of membrane 20.

As illustrated in fig. 6 (which is a cross-sectional view along line VI-VI of fig. 4), the optical fibers embedded in the focusing portion 32 and the

collimating portions

34A, 34B, respectively, may be assembled in a housing comprising: a support layer 60 comprising a plurality of V-grooves 600, wherein the

optical fibers

32, 34A, 34B may be arranged to be each received in a respective V-groove (in a manner known to those skilled in the art); a cover layer 64 configured to be disposed over the

optical fibers

32, 34A, 34B to retain them in the respective V-grooves 600; and a filling layer 62, such as an epoxy layer, sandwiched between the support layer 60 and the cap layer 64, and filling the interstitial spaces between the V-grooves 600, the

fibers

32, 34A, 34B, and the cap layer 64.

FIG. 7 is the exemplary plan view of FIG. 4

showing reference regions

400A, 400B, e.g., two metal

square regions

400A, 400B having a side length C, and the center of the exemplary plan view being at the same distance H from the central region 200 of the film 20 target at focal point FP.

For example, the value of the distance H may have a value of about 500 microns.

Fig. 7 also shows the spot sizes BSf, BSc output from the focusing portion 32 and the collimating portion 34 of the optical element 30, as indicated by the dashed lines superimposed on the reference

reflective regions

400A, 400B, and 20, respectively.

For example, as illustrated in fig. 7: the focused beam spot size BSf may reach a waist size below 20 μm, ideally 10 μm (1 μm-10-⁶m ═ 1 μm); and the collimated beam spot size BSc may be about 300 μm at the

respective reference regions

400A, 400B.

During the optical alignment operation, an alignment error δ c of the collimated light beam BSc relative to the reference

reflective regions

400A, 400B may be detected due to the signal R reflecting back from the reflective surfaces of the reference

reflective regions

400A, 400B. Such an alignment error δ c may indicate a corresponding alignment error δ f of the focused beam with respect to the target focus FP.

In one or more embodiments, optical element 30 may be considered aligned with respect to reference surface 40 when collimated beam spot size BSc fits (completely) in reference

reflective regions

400A, 400B, i.e., when alignment error δ c is negligible up to zero. As a result, it can also be considered that focal point FP is aligned with respect to the target position, corresponding to a negligible (ideally, up to zero) focus alignment error δ f when collimated beam spot size BSc fits perfectly in reference

reflective regions

400A, 400B, i.e., collimation alignment error δ c is negligible (ideally, up to zero).

Fig. 8 is an enlarged view of the focusing portion 32 of the optical element 30, showing a ray trace in which the light beam propagates and is output at the optical interface 330 (e.g., an optical window having a certain thickness T).

As illustrated in fig. 8, the focusing section 32 may have a total length L given by the sum of the length Pf of the focusing GRIN lens 320 and the length Bf of the focusing buffer 322₀(e.g., L)₀Pf + Bf), the length Pf of the focusing GRIN lens 320 is, for example, equal to the full pitch and is about 500 microns, and the focus buffer 322 is, for example, made of fused silica.

For example, the GRIN lens 320 may have a substantially cylindrical shape with a constant diameter E (e.g., between 350 microns and 500 microns).

FIG. 8A is a plot of RMS focused beam spot size BSf (in microns) as a function of distance (in millimeters) from an ideal focal point FP that is taken as the origin of the abscissa.

As illustrated in FIG. 9, the total length L of the collimating portion 34₀May be given by the sum of the length Pc of the collimating GRIN lens 340, e.g., about half the lens pitch, and the length Bc of the collimating buffer 342, e.g., made of fused silica, e.g., L₀＝Pc+Bc。

In one or more embodiments, such total length L₀Same for the focusing part 32 and the collimating part 34, e.g. L₀＝Pc+Bc＝Pf+Bf。

For example, the GRIN focusing lens 320 may have a corresponding length Pf of about 5.35mm, the collimating GRIN lens 324 may have a second length Pc of about 3.07mm, and about 2.28mm with the optical buffer 342 having a third length Bc, such that the total length Pc + Bc of the collimating GRIN lens and the collimating optical buffer 342 is equal to the length of the focusing GRIN lens Pf.

Figure 9A is a plot of RMS collimated beam spot size BSc (in microns) as a function of distance (in millimeters) from a reference surface 40 taken as the origin of the abscissa.

Fig. 10 is a graph of the amount of optical power LP reaching one of the reference surfaces 40, 400A, 400B as a function of the calculated alignment error δ C for various values of the length C of the reference surface. In the example considered, the total power of the light emitted into the optical element 30 is considered to be equal to 1 watt for the sake of simplicity of performing the power loss calculation.

Fig. 11 is a graph of the difference Δ LP between the power value at zero deviation (e.g., δ C0) and the power value with the maximum misalignment (e.g., δ C0.1 microns), plotted as a function of the corresponding reflective surface length C.

As illustrated in fig. 10 and 11, the accuracy of detecting misalignment can be improved for values of the length C of the

reflective surfaces

400A, 400B between 250 and 300 microns, with 250 microns being the nominal optimum.

Fig. 12-20 illustrate possible stages of assembling the sensor 10 along the lines discussed previously.

As illustrated in fig. 12, such a sensor assembly 10 may include:

an optical chip layer 18, for example, an optically transparent fused silica layer;

an active film 20, for example a nanomembrane of piezoelectric material;

a pair of conductive bond pads 24 coupled to the film, wherein the active region of the film 20 is located between the bond pads 24, the bond pads 24 being configured for providing an electrical connection between the wire and the film 20; and

a pair of

reference surfaces

400A, 400B, symmetrically arranged on the sides of the membrane 20 so that their position with respect to the membrane 20 is well-defined, which may comprise metal or other reflective coatings provided in the chip by photolithography in a manner known per se.

In one or more embodiments, the optical element 30 can be directly aligned with respect to the assembly 100 and coupled thereto (e.g., glued).

Alternatively, as illustrated in fig. 13, 14, the assembly 10 may be included in a package 12 having a glass window 120, and the optical element 30 may be coupled to such a package window. For example, the chip assembly of fig. 12 may be mounted within the packages of fig. 13 and 14.

Fig. 13 and 14 are examples of a (e.g., ceramic) chip support package 12, the chip support package 12 including an array of conductive leads 14 and a via 120 carrying a glass window on the bottom surface of the support 12. Fig. 14 is a perspective view of the package of fig. 13 turned over, showing the back side 12a of the planar support 12 with the glass window 120.

As illustrated in fig. 15, the assembly 10 may be placed and attached (e.g., glued) over the glass window 120 with a portion of the optical chip layer 18 exposed or aligned therewith. As illustrated in fig. 15 and 17, for electrical connection between the opto-mechanical assembly 10 and the exterior of the package, wire bonding may be performed to electrically couple bond pads 24, the bond pads 24 being coupled to the film 22 and the array of leads 14 in the support 12.

In one or more embodiments as illustrated in fig. 16, a protective cover 90 may be attached to the package support 12, sealing the volume therein, thereby protecting the chip assembly 100 from the external environment.

Fig. 17 shows the back side 12a of the support 12, with the film 20 and the reference surfaces 400A, 400B visible from the optically transparent glass window 120.

Fig. 18 is a perspective view of an optical component 30, which optical component 30 may include a set of three

optical fibers

32, 34A, 34B, inserted within the same fiber block 30 or coupled therebetween via a mechanical mount (not visible in the figures).

Aligning the optical element 30 to the film 20 may include coupling the free output end of the optical element 30 to the window 120 on the side of the window 120 exposed on the back side of the package 12 as illustrated in fig. 19.

Fig. 20 shows an enlarged view of a portion indicated by an arrow XX of fig. 19.

In the arrangement as illustrated herein, the process of aligning δ c, δ f relative to the optical element 30 of the film 20 may include, prior to fixedly coupling the optical element 30 to the window 120:

-emitting S a pair of collimated light beams BSc towards the reflective reference surfaces 400A, 400B, while emitting a focused light beam BSf towards the membrane 20;

-receiving 31 the optical signal R reflected back from the

reflective surface

40, 400A, 400B, 200; and

changing the position of the optical element 30 relative to the glass window 120 (and the membrane 20) depending on the reflected signal R, e.g. via an actuator a.

As a result, it is possible to align the

collimator lenses

34A, 34B with the δ c, δ f reference surfaces 400A, 400B.

Because the position of the reference

reflective surfaces

400A, 400B is known relative to the active area of the membrane 20, and because the

optical fibers

32, 34A, 34B are aligned with each other as a result of being integrated 30, the focusing portion 32 is aligned with the active area of the membrane 20 by design.

The apparatus (e.g., 10) may include:

an optically transparent substrate (e.g. 18) having a first surface and a second surface opposite the first surface;

-a piezoelectric film (e.g. 20) arranged at a first surface of the optically transparent substrate, the piezoelectric film being configured to oscillate due to light propagating through the optically transparent substrate and impinging on the piezoelectric film, wherein at least one reflective facet (e.g. 40, 400A, 400B) facing the optically transparent substrate is provided at the piezoelectric film; and

an optical element (e.g., 30) configured to receive the light beam at an input end and to direct the light beam to an output end coupleable to the second surface of the optically transparent substrate;

-wherein the optical element comprises: a light focusing path (e.g., 32) configured to focus (e.g., 320) the light beam at a focal point (e.g., FP) located at the piezoelectric film; and at least one light collimating path (e.g., 34A, 34B) configured to impinge a collimated (e.g., 340) light beam onto the at least one reflective facet;

-wherein the optical element is configured to direct light (e.g., R, 31) reflected from the at least one reflective facet to the input end; and

wherein the light reflected to the input indicates (e.g., δ c, δ f) the position of the optical element relative to the focal point.

In an apparatus as exemplified herein:

the piezoelectric film may include at least one reflective facet (e.g., 40) having a central region (e.g., 200) and a peripheral region (e.g., 400), an

The light focusing path in the optical element is configured to focus the light beam at a central region (e.g., 200, FP) of the at least one reflective facet, an

At least one light collimating path in the optical element is configured to collimate the light beam (e.g. 340) at a peripheral region of the at least one reflective facet.

The apparatus illustrated herein may include a plurality of reflective facets (400A, 400B), in which apparatus the optical element may include a plurality of light collimating paths (e.g., 34A, 34B) configured to provide respective collimated light beams (e.g., 340) onto the plurality of reflective facets.

In a device as exemplified herein, the plurality of reflective facets may comprise reflective facets arranged at the same distance (e.g., H) from the center (e.g., FP) of the piezoelectric film.

In a device as exemplified herein, the plurality of reflective facets comprises two facets arranged mirror-symmetrically about a center of the piezoelectric film.

In an apparatus as exemplified herein, the plurality of reflective facets may comprise:

a square facet having a side length (e.g., C) between about 250 microns and about 300 microns, and/or

Facets at about 300 microns (e.g., H) from the center of the piezoelectric film.

In an apparatus as exemplified herein, an optical element can comprise:

a substrate (e.g., 60) having a plurality of channels (e.g., 600) formed therein,

-a plurality of optical fibers (e.g. 32, 34A, 34B) arranged in a channel (e.g. 600), an

An optical fiber (e.g. 32, 34A, 34B) provides a light focusing path (e.g. 32) and at least one light collimating path (e.g. 34, 34A, 34B).

In an apparatus as exemplified herein:

the optical focusing path in the optical element may comprise a light focusing gradient index, GRIN, a lens (e.g. 320) with a focusing pitch (e.g. Pf), and

at least one light collimating path in the optical element comprises a light collimating GRIN lens (e.g. 34A, 34B) with a collimating pitch (e.g. Pc), and the light focusing path and the light collimating path may have the same total length (e.g. L)₀) And the same lens diameter (e.g., E).

In an apparatus as exemplified herein, at least one of the light focusing path and the at least one light collimating path in the optical element can include an optical spacer portion (e.g., 322, 342).

In an apparatus as exemplified herein, the same overall length may be about 500 microns, and/or the same lens diameter may be about 350 microns.

In an apparatus as exemplified herein, an apparatus can include a housing (e.g., 12, 90) having a support base (e.g., 12) with a through-hole (e.g., 120) therein, the support base of the housing being coupled to a second surface of an optically transparent substrate, a portion of the second surface of the optically transparent substrate being aligned with the through-hole; and the output end of the optical element is coupled to the optically transparent layer at the through hole in the support base of the housing.

A method as exemplified herein may comprise:

-emitting (e.g., S) a light beam aimed at least one reflective facet (e.g., 40, 400A, 400B) into an input end of an optical element (e.g., 30) of an opto-mechanical device (e.g., 10) as exemplified herein; and

-sensing (e.g. 31) light (e.g. R) reflected towards an input end of an optical element (e.g. 30); and

-aligning (e.g. a) the optical element with respect to a focal point at the piezoelectric film of the device, depending on the sensed reflected light.

It is an object of one or more embodiments to help overcome the disadvantages in the foregoing discussion.

According to one or more embodiments, such an object is achieved by means of an electro-optical device having the features set forth in the claims below.

One or more embodiments may relate to a corresponding optical alignment method.

The claims are an integral part of the technical teaching provided herein with reference to the examples.

One or more embodiments may include an optical element. The optical lens may be a gradient index, briefly GRIN, example of a lens.

One or more embodiments may provide one or more of the following advantages: the use of GRIN lenses attached directly to the surface counteracts possible focus misalignment errors; direct reading of chip performance may be superfluous; optical alignment can be performed using standard equipment and procedures; and performing optical alignment using the reflected power of the collimated beam may make performance of the reading chip superfluous, thereby simplifying the alignment process.

One or more embodiments may involve combining a GRIN lens with an optical buffer such that the overall length of the focusing and collimating system is the same.

One or more embodiments may involve reading the reflected power of the collimated beam, which facilitates "skipping" direct reading of the chip.

In one or more embodiments, the focusing system and the collimation system may advantageously be placed in the same fiber block, so that the stability in the relative position arrangement is a function of the precision in the assembly of the single fiber block (about 1 micron).

In one or more embodiments, reflective geometries may be formed on the chip, which may help, for example, provide optical fiducial marks.

One aspect of the disclosure provides a method of operating an opto-mechanical device, the opto-mechanical device comprising: an optically transparent substrate having a first surface and a second surface opposite the first surface, a piezoelectric film disposed at the first surface, at least one reflective facet disposed at the piezoelectric film facing the substrate, and an optical element having an input end and an output end, and the output end coupled to the second surface of the optically transparent substrate, the method comprising: receiving, through an input end of the optical element, a light beam directed at the at least one reflective facet; directing, by the optical element, the light beam toward an output end of the optical element; oscillating, by the piezoelectric film, in response to a light beam propagating through the optically transparent substrate and impinging on the piezoelectric film; directing, by the optical element, light reflected from the at least one reflective facet to an input end of the optical element; sensing light reflected at an input end of the optical element; and aligning the optical element with respect to a focal point at the piezoelectric film according to the sensed reflected light.

According to one or more embodiments, wherein the directing of the light beam towards the output end comprises: the light focusing path through the optical element focuses the light beam at a focal point located at the piezoelectric film. According to one or more embodiments, wherein the directing of the light beam towards the output end further comprises: at least one light collimating path through the optical element collimates the light beam onto the at least one reflective facet.

According to one or more embodiments, wherein the piezoelectric film comprises at least one reflective facet having a central region and a peripheral region, and the method further comprises: focusing the light beam at a central region of the at least one reflective facet through the light focusing path; and collimating the light beam at a peripheral region of the at least one reflective facet through the at least one light collimating path.

According to one or more embodiments, wherein the optical element comprises a plurality of optical fibers arranged in a plurality of channels, and the method further comprises: through the optical fiber, a light focusing path and at least one light collimating path are provided.

According to one or more embodiments, wherein the apparatus comprises a plurality of reflective facets, and the method further comprises: a plurality of light collimating paths through the optical element collimate respective light beams onto the plurality of reflective facets.

In addition, it should be understood that the various individual embodiment choices illustrated in the drawings of this description are not necessarily intended to be employed in the same combination as illustrated in the drawings. One or more embodiments may therefore employ these (otherwise non-mandatory) options individually and/or in different combinations with respect to the combinations illustrated in the figures.

Without prejudice to the underlying principles, the details and the embodiments may vary, even significantly, with respect to what has been described by way of example only, without departing from the scope of protection. The scope of protection is defined by the appended claims.

Claims

1. An opto-mechanical device, comprising:

an optically transparent substrate having a first surface and a second surface opposite the first surface;

a piezoelectric film disposed at the first surface of the optically transparent substrate, the piezoelectric film configured to oscillate as a result of a light beam propagating through the optically transparent substrate and impinging on the piezoelectric film, wherein at least one reflective facet facing the optically transparent substrate is disposed at the piezoelectric film; and

an optical element configured to receive the light beam at an input end and direct the light beam toward an output end coupled to the second surface of the optically transparent substrate;

wherein the optical element comprises:

a light focusing path configured to focus the light beam at a focal point located at the piezoelectric film; and

at least one light collimating path configured to collimate the light beam onto the at least one reflective facet;

wherein the optical element is configured to direct light reflected from the at least one reflective facet to the input end; and

wherein the light reflected to the input end is indicative of a position of the optical element relative to the focal point.

2. The opto-mechanical device according to claim 1, wherein:

the piezoelectric film comprises the at least one reflective facet having a central region and a peripheral region;

the light focusing path in the optical element is configured to focus the light beam at the central region of the at least one reflective facet; and

the at least one light collimating path in the optical element is configured to collimate the light beam at the peripheral region of the at least one reflective facet.

3. The opto-mechanical device of claim 1, further comprising:

a plurality of said reflective facets;

wherein the optical element includes a plurality of light collimating paths configured to provide respective collimated light beams onto the plurality of the reflective facets.

4. The opto-mechanical device of claim 3, wherein the plurality of reflective facets comprises reflective facets arranged at the same distance from a center of the piezoelectric film.

5. The opto-mechanical device of claim 4, wherein the plurality of reflective facets comprises:

a square facet having a side length between about 250 microns and about 300 microns; and/or

A facet about 300 microns from the center of the piezoelectric film.

6. The opto-mechanical device of claim 3, wherein the plurality of reflective facets comprises two facets arranged mirror-symmetrically about a center of the piezoelectric film.

7. The opto-mechanical device of claim 1 wherein the optical element comprises:

a substrate having a plurality of channels formed therein; and

a plurality of optical fibers disposed in the channel;

wherein the optical fiber provides the light focusing path and the at least one light collimating path.

8. The opto-mechanical device according to claim 1, wherein:

the light focusing path in the optical element comprises a light focusing gradient index GRIN lens having a focusing pitch; and

the at least one light collimating path in the optical element includes a light collimating GRIN lens having a collimating pitch, and the light focusing path and the light collimating path have a same total length and a same lens diameter.

9. The opto-mechanical arrangement of claim 8, wherein at least one of the light focusing path and the at least one light collimating path in the optical element comprises an optical spacer portion.

10. The opto-mechanical device according to claim 8, wherein:

the same total length is about 500 microns; and/or

The same lens diameter is about 350 microns.

11. The opto-mechanical device according to claim 1, wherein:

the device further comprises: a housing having a support base with a through-hole therein, the support base of the housing being coupled to the second surface of the optically transparent substrate with a portion of the second surface of the optically transparent substrate aligned with the through-hole; and

the output end of the optical element is coupled to the optically transparent substrate at the through hole in the support base of the housing.

12. An opto-mechanical device, comprising:

an optically transparent substrate comprising:

a first surface; and

a second surface opposite the first surface;

a piezoelectric film disposed at the first surface of the optically transparent substrate;

at least one reflective facet disposed at the piezoelectric film or disposed in the same plane on one side of the piezoelectric film, and facing the optically transparent substrate; and

an optical element comprising:

an input configured to receive a light beam;

an output coupled to the second surface of the optically transparent substrate;

a light focusing lens having a focal point for the light beam at the piezoelectric film; and

a light collimating lens oriented to collimate the light beam onto the at least one reflective facet for reflection back to the input end.

13. The opto-mechanical device according to claim 12, wherein:

the light is focused with the focal point for the light beam at the central region of the at least one reflective facet; and

the light collimating lens is oriented to collimate the light beam at the peripheral region of the at least one reflective facet.

14. The opto-mechanical device of claim 12, further comprising:

a plurality of said reflective facets;

wherein the optical element includes a plurality of light collimating lenses oriented to collimate respective light beams onto the plurality of the reflective facets.

15. The opto-mechanical device of claim 12 wherein the optical element comprises:

a substrate having a plurality of channels formed therein; and

a plurality of optical fibers disposed in the channel;

wherein the optical fiber provides an optical focusing path for the optical focusing lens and the optical collimating path for the optical collimating lens.

16. The opto-mechanical device according to claim 12, wherein:

the light focusing lens is a light focusing gradient index GRIN lens having a focusing pitch; and

the light collimating lens is a light collimating GRIN lens having a collimating pitch, and wherein the light focusing lens and the light collimating lens have the same lens diameter.

17. The opto-mechanical device according to claim 12, wherein:

the device further comprises: a housing having a support base with a through-hole therein, the support base of the housing being coupled to the second surface of the optically transparent substrate, a portion of the second surface of the optically transparent substrate being aligned with the through-hole; and