Optical package comprising an adjustable lens component coupled to a multi-directional lens flexure

An optical package is provided comprising a lens system, the lens system comprising an adjustable lens component, a plurality of magnetic elements, and a multi-directional lens flexure. The adjustable lens component is mechanically coupled to a lens mounting portion of the multi-directional lens flexure. The magnetic elements comprise at least one fixed magnetic element and at least one motive magnetic element. The arrangement of the fixed and motive magnetic elements relative to each other forms a first fixed/motive element pair and a second fixed/motive element pair. The motive magnetic element of each fixed/motive element pair is mechanically coupled to a motive portion of the multi-directional lens flexure. The structure of the multi-directional lens flexure and the arrangement of the fixed/motive element pairs is such that non-orthogonal repulsive or attractive magnetic force vectors generated between magnetic elements of the respective fixed/motive element pairs generate movement of the adjustable lens component through orthogonal components x, y along X and Y axes of the X-Y optical reference frame.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates generally to lens systems incorporating one or more lens components that are adjustable in an optical reference frame. Such lens systems enjoy utility in a variety of optical packages including, but not limited to, semiconductor laser optical packages, laser projection systems, and other optical systems where it may be advantageous to provide for the adjustment of an optical component of the system. By way of illustration and not limitation, embodiments of the present disclosure relate generally to optical alignment in packages that include, inter alia, a semiconductor laser and a wavelength conversion device, such as second or third harmonic generation crystal or another type of wavelength conversion device. Embodiments contemplated herein will also find utility in more or less complex optical packages, including those where the adjustable lens component is the only optical component of the package.

2. Technical Background

Short wavelength light sources can be formed by combining a single-wavelength semiconductor laser, such as an infrared or near-infrared distributed feedback (DFB) laser, distributed Bragg reflector (DBR) laser, or Fabry-Perot laser, with a light wavelength conversion device, such as a second harmonic generation (SHG) crystal. The SHG crystal is used to generate higher harmonic waves of the fundamental laser signal. To do so, the lasing wavelength is preferably tuned to the spectral center of the wavelength converting SHG crystal and the output of the laser is preferably aligned with the waveguide portion at the input facet of the wavelength converting crystal.

Waveguide mode diameters of typical wavelength conversion devices, such as MgO-doped periodically poled lithium niobate (PPLN) crystals, can be in the range of a few microns. As a result, it can be very challenging to align the beam from the laser diode with the waveguide of the SHG crystal properly. Accordingly, a variety of adaptive alignment mechanisms have been developed to steer the beam spot of the long wavelength source into proper alignment with the input facet of the waveguide portion of the wavelength conversion device.

BRIEF SUMMARY OF THE INVENTION

According to the present disclosure, lens systems are configured for adaptive alignment and can be used in the aforementioned wavelength converted optical packages, or in any optical package where an adjustable lens component may find utility. In accordance with one embodiment disclosed herein, an optical package is provided comprising a lens system, the lens system comprising an adjustable lens component, a plurality of magnetic elements, and a multi-directional lens flexure. The adjustable lens component is mechanically coupled to a lens mounting portion of the multi-directional lens flexure. The magnetic elements comprise at least one fixed magnetic element and at least one motive magnetic element. The arrangement of the fixed and motive magnetic elements relative to each other forms a first fixed/motive element pair and a second fixed/motive element pair. The motive magnetic element of each fixed/motive element pair is mechanically coupled to a motive portion of the multi-directional lens flexure. The structure of the multi-directional lens flexure and the arrangement of the fixed/motive element pairs is are such that non-orthogonal repulsive or attractive magnetic force vectors generated between magnetic elements of the respective fixed/motive element pairs generate movement of the adjustable lens component through orthogonal components x, y along X and Y axes of the X-Y optical reference frame.

According to one aspect of the present disclosure, the multi-directional lens flexure comprises a pair of upstanding portions and a bridge portion. The pair of upstanding portions are spaced from each other along the X-axis of the X-Y optical reference frame and comprise relatively stationary ends secured relative to the X-Y optical reference frame and relatively free ends connected to each other via the bridge portion. The lens mounting portion to which the adjustable lens component is mechanically coupled is located on the bridge portion of the multi-directional lens flexure and the motive portions to which the motive magnetic elements are mechanically coupled are located on the pair of spaced upstanding portions of the of the multi-directional lens flexure.

According to one aspect of the present disclosure, the multi-directional lens flexure comprises a pair of uni-axial flexures and a bridge portion. Each of the uni-axial flexures comprises a relatively stationary end secured relative to the X-Y optical reference frame and a relatively free end. The relatively free ends of the pair of uni-axial flexures are connected to each other via the bridge portion and the lens mounting portion is located on the bridge portion of the multi-directional lens flexure.

According to one aspect of the present disclosure, the multi-directional lens flexure comprises a uni-axial flexure comprising a relatively stationary end secured relative to the X-Y optical reference frame and a relatively free end. The plurality of magnetic elements comprise a common motive magnetic element and a pair of fixed magnetic elements. The common motive magnetic element is coupled to move with the relatively free end of the uni-axial flexure and the pair of fixed magnetic elements share the common motive magnetic element to form the first and second fixed/motive element pairs.

DETAILED DESCRIPTION

A lens system100according to one embodiment of the present disclosure is illustrated inFIG. 1. Generally, the lens system100comprises an adjustable lens component10, a plurality of magnetic elements24,25,26, and a multi-directional lens flexure30. The adjustable lens component10is mechanically coupled to a lens mounting portion32of the multi-directional lens flexure30.

In the illustrated embodiment, one of the magnetic elements25is a fixed magnetic element that is mechanically coupled to a fixed portion34of the multi-directional lens flexure30and the remaining magnetic elements24,26are motive magnetic elements that are mechanically coupled to a motive portion36of the multi-directional lens flexure30. The arrangement of the fixed and motive magnetic elements24,25,26relative to each other forms a first and second fixed/motive element pairs21,22. To facilitate adjustment, each of the first and second fixed/motive element pairs21,22will comprise a magnetic element that is capable of generating a controllable magnetic field, or a controllable response to a magnetic field. For example, an electromagnetic coil may be provided as the fixed or motive magnetic element of a fixed/motive element pair21,22.

The structure of the multi-directional lens flexure30and the arrangement of the fixed/motive clement pairs21,22are such that non-orthogonal repulsive or attractive magnetic force vectors VFgenerated between the magnetic elements of the respective fixed/motive element pairs21,22generate movement of the adjustable lens component10through orthogonal components x, y along X and Y axes of the X-Y optical reference frame defined by the lens system100. The multi-directional lens flexure30is configured as a spring element defining a resilient spring force that opposes movement of the adjustable lens component through the orthogonal components x, y.

More specifically, each motive magnetic element24,26is mechanically coupled to a different motive portion of the multi-directional lens flexure30, i.e., the pair of upstanding portions36illustrated inFIGS. 1-5. The pair of upstanding portions36are spaced from each other along the X-axis of the X-Y optical reference frame and comprise relatively stationary ends36A secured relative to the X-Y optical reference frame and relatively free ends36B connected to each other via a bridge portion38of the flexure30. The lens mounting portion32of the flexure30is located on the bridge portion38of the multi-directional lens flexure30. Referring toFIG. 2, because the multi-directional lens flexure30is formed from a relatively flexible material, attractive magnetic force vectors VFgenerated between the magnetic elements of the respective fixed/motive element pairs21,22attracts the upstanding portions36of the multi-directional lens flexure30towards each other along the X-axis of the X-Y optical reference frame. This motion elevates the lens mounting portion32of the multi-directional lens flexure30, and the adjustable lens10mounted thereto, along the Y-axis of the X-Y optical reference frame and can be controlled, for example, by using electromagnetic coils and suitable electronic control circuitry as the motive magnetic elements24,26.

Similarly, referring toFIG. 3, repulsive force vectors VFgenerated between the magnetic elements of the respective fixed/motive element pairs21,22repels the upstanding portions36of the multi-directional lens flexure30away from each other along the X-axis of the X-Y optical reference frame. This motion lowers the lens mounting portion32of the multi-directional lens flexure30, and the adjustable lens10mounted thereto, along the Y-axis of the X-Y optical reference frame.

The multi-directional lens flexure30can be formed from a relatively flexible material to define an overall spring-like construction that permits the various deformations described herein and is inclined to return to a resting zero-force configuration. Materials suitable for construction of the flexure include, but are not limited to flexible plastics, relatively thin metal shims, or flexible plastic/metal laminate structures, such as those found in flexible circuit interconnects. The concept of using a flexible plastic/metal laminate structure including electrical circuit interconnects is particularly advantageous in practicing the embodiments disclosed herein because such a configuration would simultaneously provide the mechanical flexure for adjusting the position of the adjustable lens10and the electrical interconnections for driving the respective fixed/motive element pairs21,22.

FIGS. 4 and 5, illustrate the manner in which attractive and repulsive magnetic force vectors VFcan be combined to generate motion along the X--axis of the X-Y optical reference frame. InFIGS. 4 and 5, two different combinations of repulsive and attractive magnetic force vectors VFgenerated between magnetic elements of the respective fixed/motive element pairs causes the upstanding portions36of the multi-directional lens flexure30to flex in a common direction along the X-axis of the X-Y optical reference frame, shifting a position of the lens mounting portion32of the multi-directional lens flexure30, and the adjustable lens mounted thereto, along the X-axis. Hybrid combinations of the repulsive and attractive force vectors VFillustrated inFIGS. 2-5can be used to shift the position of the adjustable lens10along the X and Y axes of the X-Y optical reference frame.

A lens system110incorporating a multi-directional lens flexure130according to another embodiment of the present disclosure is illustrated inFIG. 6and comprises a pair of uni-axial flexures132,134and a bridge portion136to which the adjustable lens component10is mechanically coupled. The lens system110also includes a relatively stationary lens component15. Each of the uni-axial flexures132,134comprises a relatively stationary end132A,134A, that is secured relative to the X-Y optical reference frame, and a relatively free end132B,134B. The free ends132B,134B are connected to each other via the bridge portion136. The multi-directional lens flexure130may be formed from a variety of resilient but flexible materials and is configured as a spring element defining a resilient spring force that opposes movement of the adjustable lens component through the orthogonal components x, y.

In the embodiment illustrated inFIG. 6, two of the magnetic elements124,125are fixed magnetic elements that are mechanically coupled to a fixed portion135of the multi-directional lens flexure130via a rigid base portion140. The remaining two magnetic elements126,127are motive magnetic elements that are mechanically coupled to the free ends132B,134B of the multi-directional lens flexure130. The arrangement of the fixed and motive magnetic elements124,125,126,127relative to each other forms first and second fixed/motive element pairs121,122. To facilitate adjustment, each of the first and second fixed/motive element pairs121,122will comprise a magnetic element that is capable of generating a controllable magnetic field, or a controllable response to a magnetic field.

Referring toFIG. 8, the structure of the multi-directional lens flexure130and the arrangement of the fixed/motive element pairs121,122ofFIG. 6are such that repulsive magnetic force vectors VFgenerated between magnetic elements of the respective fixed/motive element pairs121,122elevate the adjustable lens10along the Y-axis of the X-Y optical reference frame. Similarly, referring toFIG. 9, attractive magnetic force vectors VFgenerated between magnetic elements of the respective fixed/motive element pairs121,122lower the adjustable lens10along the Y-axis of the X-Y optical reference frame.FIGS. 10 and 11illustrate the manner in which different combinations of repulsive and attractive magnetic force vectors VFcan be used to shift the adjustable lens component along an arced adjustment path having components along the X and Y axes of the optical reference frame. As is the case with the embodiment illustrated with reference toFIGS. 1-5, hybrid combinations of the repulsive and attractive force vectors VFillustrated inFIGS. 8-11can be used to shift the position of the adjustable lens component10to a variety of positions in the X-Y optical reference frame.

The lens system120ofFIG. 7is similar in many respects to the embodiment illustrated inFIG. 6of the present disclosure, with the exception that the multi-directional lens flexure takes the form of a single uni-axial flexure232comprising a relatively stationary end232A secured relative to the X-Y optical reference frame and a relatively free end232B to which the adjustable lens component10is mounted. In addition, the set of magnetic elements comprise a common motive magnetic element224and a pair of fixed magnetic elements225,226arranged such that the fixed magnetic elements225,226share the common motive magnetic element224to form the first and second fixed/motive element pairs221,222. The common motive magnetic element224is coupled to move with the relatively free end232B of the uni-axial flexure232. As is the case with the embodiment ofFIG. 6, repulsive and attractive magnetic force vectors VFgenerated between the magnetic elements of the respective fixed/motive element pairs221,222elevate and lower the adjustable lens component10along the Y-axis of the X-Y optical reference frame. Different combinations of repulsive and attractive magnetic force vectors VFcan be used to shift the adjustable lens component10to a variety of positions in the X-Y optical reference frame. The flexure232may be formed from a variety of resilient but flexible materials and is configured as a flexible rod that defines a resilient spring force that opposes movement of the adjustable lens component through the orthogonal components x, y.

Although the lens systems disclosed herein can be utilized in a variety of optical packages, the optical package illustrated schematically inFIG. 12illustrates the utility of providing for optical adjustment in the context of a frequency-doubled optical package comprising a semiconductor laser5, a wavelength conversion device20, and a lens system that is configured to optically couple an output beam of the semiconductor laser5into a waveguide portion of a wavelength conversion device20. In the illustrated embodiment, the lens system comprises an adjustable lens component10and a stationary lens component15. The adjustable lens component10is adjustable in one or more degrees of freedom relative to an X-Y optical reference frame. The movement of the adjustable lens component10adjusts the position of the output beam on the input facet of the wavelength conversion device20to optimize the output of the wavelength conversion device20. Optical packages of this nature can also include a beam splitter40, an optical intensity monitor50, and a programmable controller60to provide a feedback mechanism for controlling the adjustable optical component10as a function of output intensity. Lens systems according to the present disclosure can find utility in more or less complex optical packages, including those where the adjustable lens component is the only optical component of the package.

For the purposes of describing and defining the present invention, it is noted that a “magnetic element” is any structure that comprises a material upon which an attractive or repulsive force can be generated due to the presence of a magnetic field, including but not limited to a permanent magnet, a structure, like an electromagnetic coil, that comprises a permanent magnet, a metal that responds to a magnetic field, a structure that comprises a metal that responds to a magnetic field, or combinations thereof

For the purposes of describing and defining the present invention, it is noted that reference herein to a variable being a “function” of a parameter or another variable is not intended to denote that the variable is exclusively a function of the listed parameter or variable. Rather, reference herein to a variable that is a “function” of a listed parameter is intended to be open ended such that the variable may be a function of a single parameter or a plurality of parameters.

Having described the invention in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. For example, although the embodiments illustrated inFIGS. 6 and 7utilize a stationary lens component15in combination with the adjustable lens10, the stationary lens component15need not be provided in every embodiment contemplated by the present disclosure. In addition, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention.

It is noted that one or more of the following claims utilize the term “wherein” to transition from the preamble of the claim to the body of the claim. For the purposes of defining the present invention, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”