Abstract:
Embodiments include methods and devices for coupling light energy from laser emitters having a high spectral brightness and purity that may be used for a variety of purposes including the pumping of various laser gain materials.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. section 119(e) from U.S. Provisional Patent application Ser. No. 60/881,642 titled “Coupling Devices and Methods for Laser Emitters”, filed Jan. 22, 2007, by Hu, Y. et al. and U.S. Provisional Patent application Ser. No. 60/814,565 titled “Diode Laser System and Method of Manufacture”, filed Jun. 15, 2006, by Srinivasan, R. et al., both of which are also incorporated by reference herein in their entirety. 
     
     BACKGROUND 
       [0002]    Applications requiring light energy and specifically laser energy may benefit form the use of solid state light sources such as laser diodes which are commonly available, reliable to operate and relatively cost effective as a laser energy source. Such devices may include a single laser emitter or a plurality of laser emitters in a emitter bar that emit laser light simultaneously in a common direction. Typically the emitters of such solid state emitter bars are spaced from each other to allow sufficient cooling without the need for elaborate and expensive cooling systems. 
         [0003]    Laser diode bars are often used for communication technology devices, medical applications and other applications where it is desirable to couple the output of all the emitters of a single solid state emitter bar into a single optical fiber or other optical conduit. The spatial and spectral distribution of the emitter or emitters of a bar can make coupling the output of emitters challenging, particularly when coupling to a small diameter optical fiber. Also, the spectral distribution of a particular emitter or group of emitters may be too broad for particular applications. 
         [0004]    A micro-lens or micro-lens array may be used to reduce the divergence angle among the beam or beams emanating from an emitter bar. However, a solid state emitter bar which incorporates several, transversely separated emitters requires that an objective lens or lenses having a large numerical aperture be used if the beam is to be concentrated into a usefully small spot. Large numerical aperture objective lenses tend to be expensive. In addition, the alignment of multiple small micro-lenses or micro-lens arrays can be a difficult and time consuming process. Other devices such as volume index gratings (VIGs) may be used to narrow or otherwise control the spectral band of a laser emitter light energy output, however, such devices typically have fairly rigid acceptance criteria regarding the input angle and wavelength of light energy. 
         [0005]    As such, what has been needed are efficient methods and devices for coupling light energy from one or more laser emitters while maintaining a narrow spectral bandwidth, high degree of spectral brightness, purity and coupling efficiency. 
       SUMMARY 
       [0006]    Some embodiments of an optical apparatus include a laser emitter having a fast axis, a slow axis and an emission axis that is substantially perpendicular to the fast and slow axes aligned with an optical path of the apparatus. A fast axis collimator element is disposed adjacent the laser emitter, disposed in the optical path and configured to collimate light energy output of the laser emitter in a fast axis direction. A slow axis collimator element is disposed in the optical path and configured to collimate light energy output of the emitter in slow axis direction. A wavelength control element integrally formed with the slow axis collimator element is disposed in the optical path and configured to provide optical feedback to the laser emitter so as to control a spectral band of the light energy output of the laser emitter. 
         [0007]    Some embodiments of an optical apparatus include an emitter bar having a plurality of laser emitters each having a fast axis, a slow axis and an emission axis that is substantially perpendicular to the fast and slow axes. The laser emitters are disposed in a substantially linear configuration along a slow axis direction of the laser emitters. A fast axis collimator element is disposed adjacent the emitter bar, disposed in an optical path of the apparatus and configured to collimate light energy output of the emitters of the emitter bar in a fast axis direction. A slow axis collimator element is disposed in the optical path and configured to collimate light energy output of the emitters of the emitter bar in slow axis direction. A wavelength control element is formed integrally with the slow axis collimator and configured to provide optical feedback to the emitters of the emitter bar so as to narrow a spectral band of the light energy output of the emitters. 
         [0008]    Some embodiments of an integrated optical element for coupling laser emitter light energy include a wavelength control element and a slow axis collimator element integrally formed with the wavelength control element. For some embodiments, a fast axis collimator element is also integrally formed with the wavelength control element and the slow axis collimator element with the wavelength control element disposed between the slow axis collimator element and the fast axis collimator element. For some embodiments, the optical element is formed from a single piece of optical material with the slow axis collimator element formed into the material and a VIG written into the material adjacent the slow axis collimator element. 
         [0009]    Some embodiments of a method of coupling light energy into an optical conduit include emitting light energy from at least one laser emitter, collimating the emitted light energy in a fast axis direction with a fast axis collimator element, collimating the emitted light energy in a slow axis direction with a slow axis collimator element and controlling the wavelength of the emitted light energy with optical feedback generated by a wavelength control element integrally formed with the slow axis collimator element. The method also includes directing the light energy into an optical conduit, which may include focusing the light energy into an optical fiber for some embodiments. 
         [0010]    These features of embodiments will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a laser emitter bar having a single laser emitter. 
           [0012]      FIG. 2  is a side view of an optical apparatus for coupling the output of a laser emitter bar into an optical fiber. 
           [0013]      FIG. 3  is a top view of the optical apparatus of  FIG. 2 . 
           [0014]      FIG. 4  is a side view of an optical apparatus for coupling the output of a laser emitter bar into an optical fiber. 
           [0015]      FIG. 5  is a top view of the optical apparatus of  FIG. 4 . 
           [0016]      FIG. 6  is a perspective view of a laser emitter bar having 5 laser emitters disposed in a substantially linear configuration along a slow axis direction. 
           [0017]      FIG. 7  is a side view of an optical apparatus for coupling the output of a laser emitter bar into an optical fiber. 
           [0018]      FIG. 8  is a top view of the optical apparatus of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a laser emitter bar  10  having a single laser emitter  12  disposed on an output surface  14 . A fast axis direction of light energy emitted from the laser emitter  12  is indicated by arrow  16  which is perpendicular to a slow axis direction of light energy emitted from the laser emitter  12 , indicated by arrow  18 . The laser emitter  12  is positioned or otherwise configured so as to emit light energy in an output beam that propagates along an emission axis  20  which may be perpendicular to both the slow axis direction  18  and fast axis direction  16 . The emission axis  20  of the laser emitter  12  may also be substantially perpendicular to the output surface  14  of the laser emitter bar  10 . 
         [0020]    Generally, the emitting aperture of some laser diode embodiments of the laser emitter  12  may be rectangular in shape with the long dimension along the slow axis direction  18  of the laser emitter  12  having a size of typically tens or hundreds of microns, while the short dimension along the fast axis direction  16  is typically one to several microns in size. Radiation such as light energy emerging from a laser emitter  12  diverges with the divergence angle being greater along the short or fast axis emitter direction  16 . Divergence angles are lower in the direction of the long or slow axis emitter direction. Some embodiments of the laser emitter  12  may have a physical width in the slow axis direction  18  of about 50 microns to about 300 microns, a height in the fast axis direction  16  of about 1 micron to about 3 microns, and a cavity length along the emission axis direction of about 0.5 mm to about 5 mm. Such laser emitter embodiments  12  may have a divergence of light energy output of about 2 degrees to about 12 degrees in the slow axis direction  18  and a divergence of light energy output of about 30 degrees to about 75 degrees in the fast axis direction  16 . Some laser emitter embodiments  12  may include laser diodes such as edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs) and the like. Materials for some embodiments of the laser emitter of the laser emitter bar  10  may include semiconductor materials such as GaAs, InP or any other suitable laser gain medium. 
         [0021]    Some embodiments of the laser emitter  12  may emit light energy having a wavelength of about 700 nm to about 1500 nm, more specifically, about 800 nm to about 1000 nm. In addition, some embodiments of laser emitter  12  may emit light having a centroid or peak wavelength of about 300 nm to about 2000 nm, more specifically, of about 600 nm to about 1000 nm, including wavelengths across the near infrared spectrum. Some embodiments of useful laser emitters  12  may emit light at a peak wavelength of about 350 nm to about 550 nm, 600 nm to about 1350 nm or about 1450 nm to about 2000 nm. Such laser emitters  12  may be operated in either a pulsed mode or continuous wave mode. Frequently, the output spectral band of individual laser emitters  12  which are not wavelength controlled (for example wavelength controlled by providing wavelength-dependent feedback from a VIG or the like) may be about 0.5 nm to about 2.0 nm or more. Due to the variation in peak emission wavelength in addition to the spectral band for each individual laser emitter  12 , the overall bandwidth of a laser emitter bar embodiment that includes multiple laser emitters, discussed in more detail below, may be about 2 nm to about 5 nm, for some embodiments. 
         [0022]      FIGS. 2 and 3  illustrate an optical apparatus  24  that may be used for coupling light energy from a laser emitter  12  into an optical conduit with the use of an integrated optical element. The optical apparatus  24  includes the laser emitter bar  10  with a laser emitter  12  having a fast axis indicated by arrow  26 , a slow axis indicated by arrow  27  and an emission axis that is substantially perpendicular to the fast and slow axes and substantially aligned with an optical path of the apparatus  24 . A fast axis collimator element  28  is disposed adjacent the laser emitter  12 , disposed in the optical path of the apparatus  24  and configured to collimate light energy output of the laser emitter  12  in a fast axis direction  26 . An integrated optical element  30  includes a slow axis collimator element  32  disposed in the optical path of the apparatus  24  and configured to collimate light energy output of the emitter  12  in slow axis direction  27 . The integrated optical element  30  also includes a wavelength control element  34  disposed adjacent the slow axis collimator element  32 . The wavelength control element  34  is disposed in the optical path of the apparatus  24  between the fast axis collimator element  28  and the slow axis collimator element  32  and is configured to provide optical feedback to the laser emitter  12  so as to control a spectral band of the light energy output of the laser emitter  12 . Focusing optics  36  are aligned with an output axis of the integrated optical element  30  and are configured to focus light energy into an input surface  38  of an optical fiber  40  having an input axis aligned with an output axis of the focusing optics  36 . 
         [0023]    The fast axis collimator element  28  may be a cylindrical lens or a portion thereof having a focal length that is configured to substantially collimate light energy from the laser emitter  12  in a fast axis direction  26 . The collimation of light energy in the fast axis direction  26  for some embodiments may be sufficient such that at least about 70 percent of the emitted light energy from the laser emitter  12  incident on the wavelength control element  34  is within an acceptance angle of the wavelength control element  34 . For such a configuration, the wavelength control element  34  may reflect about 5 percent to about 35 percent of the incident light energy back towards the laser emitter  12  in the form of optical feedback. Some embodiments of the cylindrical lens of the fast axis collimator element  28  may have a width in the fast axis direction  26  of about 0.5 mm to about 1 mm, a thickness of about 0.3 mm to about 2 mm and a focal length of about 0.15 mm to about 1 mm. Suitable materials for the fast axis collimator element  28  may include quartz, silica glass as well as other optical materials. 
         [0024]    The integrated optical element embodiment  30  shown is formed from a single piece of optical material, however, similar embodiments may be made from separate elements which are thereafter bonded or otherwise secured together to form a unitary structure. The integrated optical element  30  as a whole or portions thereof may be made from a variety of suitable optical materials such as quartz, silica glass and the like. However, for embodiments of the integrated optical element  30  that are made from a single optical material, it may be useful for the optical material to be a photo-sensitive material so that a wavelength control element  34  in the form of a VIG or the like may be written or otherwise created directly into the optical material adjacent the slow axis collimator element  32 . Such optical materials may include photo-refractive crystal materials such as LiNbO 3  and BGO. The optical material may also include glasses, polymers and dichromated gelatins. 
         [0025]    The slow axis collimator element  32  is a cylindrical lens formed into the optical material of the integrated optical element  30  that substantially collimates the light energy output of the laser emitter  12  in the slow axis direction  27  and has a convex outer surface  42 . Some embodiments of the cylindrical lens of the slow axis collimator element  32  of the integrated optical element  30  may have a width in the slow axis direction  27  of about 1 mm to about 12 mm, a thickness of about 1 mm to about 5 mm and a focal length of about 2 mm to about 10 mm. 
         [0026]    The wavelength control element  34  shown is a VIG which is written into the optical material of the integrated optical element  30  adjacent the slow axis collimator element  32 . Creation of periodic perturbations in a zone of the optical material of the integrated optical element  30  adjacent the slow axis collimator element  32  may be used to generate the wavelength control element  34  in the optical material of the integrated optical element  30 . The wavelength control element  34  may be used to narrow a spectral band of the light energy of the laser emitter  12 . Such VIG embodiments may also be known as volume Bragg gratings (VBGs), volume holographic gratings (VHGs) or any other suitable device. The wavelength control element  34  may be generated to have a variety of useful configurations including a chirped configuration, a graded configuration or the like. Chirped or graded VIG configurations may be used to provide predetermined patterns or spectral profiles for the optical feedback reflected from the wavelength control element  34  back into the laser emitter  12 . The VIG or wavelength control element  34  shown may have a width along the slow axis direction  27  of about 1 mm to about 12 mm and a thickness of about 0.3 mm to about 3 mm. 
         [0027]    In use, light energy may be coupled into an optical conduit, such as fiber optic  40 , by emitting light energy from the laser emitter  12  and collimating the emitted light energy in a fast axis direction  26  with the fast axis collimator element  28 . The fast axis collimated light energy then propagates from the fast axis collimator element  28  to the wavelength control element  34  of the integrated optical element  30 . Light energy having a suitable angle of incidence with respect to the wavelength control element  34  for acceptance into the wavelength control element  34  may then enter the wavelength control element  34 . For some embodiments, at least about 70 percent of the emitted light energy incident on the wavelength control element  34  is collimated in a fast axis direction  26  sufficiently to be within an acceptance angle of the wavelength control element  34 . 
         [0028]    Some embodiments of the wavelength control element  34  may then control or otherwise modify the wavelength or spectral band of the light energy by providing optical feedback to the laser emitter  12 . As discussed above, for some embodiments, the light energy of the optical feedback from the wavelength control element  34  may include a narrowed spectral band with respect to the light energy incident on the wavelength control element  34  from the laser emitter  12 . Such a configuration may provide at least about 5 percent reflection of the light energy incident on the wavelength control element  34  back towards the laser emitter  12  in the form of optical feedback with the reflected optical feedback having been controlled or narrowed in the spectral band. The light energy which has not been reflected passes through the wavelength control element  34  and is then collimated in the slow axis direction  27  with the slow axis collimator element  32 . The light energy may then be focused by the focusing optics  36  and directed into the fiber optic  40 . 
         [0029]      FIGS. 4 and 5  illustrate an embodiment of an optical apparatus  46  that may be used for coupling light energy from the laser emitter  12  of the laser emitter bar  10  into the optical fiber  40 . The optical apparatus  46  includes an integrated optical element  48  having a wavelength control element  50 , a slow axis collimator element  52  and a fast axis collimator element  54 . The wavelength control element  50  is disposed between the fast axis collimator element  54  and slow axis collimator element  52  with all three elements  50 ,  52  and  54  being integrally formed together into the single unitary integrated optical element  48 . The fast axis collimator element  54 , slow axis collimator element  52  and wavelength control element  50  of the integrated optical element  48  may have the same or similar features, dimensions and materials as the fast axis collimator element  28 , slow axis collimator element  32  and wavelength control element  34 , respectively, of the optical apparatus  24  discussed above. However, the fast axis collimator element  54  and slow axis collimator element  52  of the embodiment shown in  FIGS. 4 and 5  may also have sufficient power to serve as focusing optics as well as collimating optical elements for some embodiments. 
         [0030]    The integrated optical element  48  shown having all three elements  50 ,  52  and  54  is formed from a single piece of optical material, however, similar embodiments may be made from separate elements which are thereafter bonded or otherwise secured together to form a unitary structure. The integrated optical element  48  as a whole or portions thereof may be made from a variety of suitable optical materials such as quartz, silica glass and the like. However, for embodiments of the integrated optical element  48  that are made from a single optical material, it may be useful for the optical material to be a photo-sensitive material, such as those discussed above, so that a wavelength control element  50  in the form of a VIG or the like may be written or otherwise created directly into the optical material between the slow axis collimator element  52  and the fast axis collimator element  54 . 
         [0031]    The fast axis collimator element  54  may be a cylindrical lens or a portion thereof having an outer convex surface  56  and a focal length that is configured to substantially collimate and focus light energy from the laser emitter  12  in a fast axis direction  58 . The collimation and focusing of light energy in the fast axis direction  58  for some embodiments may be sufficient such that at least about 70 percent of the emitted light energy from the laser emitter  12  incident on the wavelength control element  50  is within an acceptance angle of the wavelength control element  50 . Some embodiments of the cylindrical lens of the fast axis collimator element  54  may have a width along the fast axis direction  58  of about 1 mm to about 5 mm, a thickness of about 1 mm to about 5 mm and a focal length of about 0.5 mm to about 10 mm. Suitable materials for the fast axis collimator element  54  may include quartz, silica glass and the like. 
         [0032]    The slow axis collimator element  52  is a cylindrical lens formed into the optical material of the integrated optical element  48  that substantially collimates and focuses the light energy output of the laser emitter  12  in the slow axis direction  60  and has a convex outer surface  62 . Some embodiments of the cylindrical lens of the slow axis collimator element  52  of the integrated optical element  48  may have a width along the slow axis direction  60  of about 1 mm to about 12 mm, a thickness of about 1 mm to about 5 mm and a focal length of about 2 mm to about 10 mm. 
         [0033]    The wavelength control element  50  in the form of a VIG may be written or otherwise formed into the material between the slow axis collimator element  52  and fast axis collimator element  54 . As discussed above, the creation of periodic perturbations in a zone of the optical material of the integrated optical element  48  adjacent the slow axis collimator element  52  may be used to generate the wavelength control element  50  in the optical material of the integrated optical element  48 . The wavelength control element  50  may be used to narrow a spectral band of the light energy of the laser emitter  12  and may also have a chirped configuration, a graded configuration or the like. The VIG or wavelength control element  50  shown may have a width along the slow axis direction  60  of about 1 mm to about 12 mm and a thickness of about 0.5 mm to about 6 mm. 
         [0034]    In use, light energy may be coupled into an optical conduit, such as fiber optic  40 , by emitting light energy from the laser emitter  12 . The emitted light energy then enters the fast axis collimator element  54  of the integrated optical element  48  where the emitted light energy is collimated and focused in the fast axis direction  58 . The fast axis collimated and focused light energy then propagates from the fast axis collimator element  54  to the wavelength control element  50  of the integrated optical element  48 . 
         [0035]    Light energy having a suitable angle of incidence with respect to the wavelength control element  50  may then enter the wavelength control element  50  or otherwise be transformed by the wavelength control element  50 . For some embodiments, at least about 70 percent of the emitted light energy incident on the wavelength control element  50  is collimated and focused in a fast axis direction  58  sufficiently to be within an acceptance angle of the wavelength control element  50 . Some embodiments of the wavelength control element  50  may then control or otherwise modify the wavelength or spectral band of a portion of the light energy and provide optical feedback to the laser emitter  12  in the form of reflected light energy. For some embodiments, at least about 5 percent of the light energy incident on the wavelength control element  50  is reflected back towards the laser emitter  12  to provide optical feedback to the laser emitter  12 . 
         [0036]    As discussed above, for some embodiments, the light energy of the optical feedback from the wavelength control element  50  may include a narrowed spectral band with respect to the light energy incident on the wavelength control element from the laser emitter  12 . Light energy that has not been reflected by the wavelength control element  50  may then pass through the wavelength control element  50  and be collimated and focused in the slow axis direction  60  with the slow axis collimator element  52 . The focused light energy may then be directed into the fiber optic  40  or any other suitable optical conduit or receptacle. 
         [0037]      FIG. 6  illustrates a laser emitter bar  70  having 5 laser emitters  12  which individually may have the same or similar characteristics to the characteristics of the emitter  12  of laser emitter bar  10  discussed above. A fast axis direction of light energy emitted from the emitters  12  is indicated by arrow  72  and is perpendicular to a slow axis direction of light energy emitted from the emitters which is indicated by arrow  74 . The emitters  12  are positioned or otherwise configured so as to emit light energy in output beams that propagate along an emission axis  76  which may be perpendicular to both the slow axis direction  74  and fast axis direction  72 . The emission axes  76  of the emitters  12  may be substantially perpendicular to an output surface  78  of the laser emitter bar  70  and parallel to each other. The emitters  12  are disposed on the output surface  78  of the emitter bar  70  in a substantially linear arrangement along the slow axis direction  74  of light energy emitted from the emitters  12 . 
         [0038]    Laser emitter bar embodiments  70  having multiple laser emitters  12  may have any suitable number of laser emitters, such as about 2 laser emitters  12  to about 100 laser emitters  12 , more specifically, about 10 laser emitters  12  to about 66 laser emitters  12 . Some laser emitter bar embodiments  70  may include an even number of laser emitters  12  such as about 8, 10, 20, 38 or 48 emitters  12 . For some embodiments, each laser emitter bar  70  having about 6 emitters may have an output power of about 5 W to about 50 W, more specifically, about 10 W to about 20 W. Due to the variation in peak emission wavelength in addition to the spectral band for each individual laser emitter  12 , the overall bandwidth of a laser emitter bar embodiment  70  that includes multiple laser emitters  12  may be about 2 nm to about 5 nm. 
         [0039]      FIGS. 7 and 8  illustrate an optical apparatus  80  having an integrated optical element  82  that may be used for coupling light energy to an optical conduit  40 . The optical apparatus  80  includes the emitter bar  70  having a plurality of laser emitters  12  each having a fast axis  72 , a slow axis  74  and an emission axis  76  that is substantially perpendicular to the fast and slow axes. The laser emitters  12  are disposed in a substantially linear configuration along the slow axis direction of the laser emitters  12  indicated by arrow  86 . A fast axis collimator element  88  is disposed adjacent the emitter bar  70 , disposed in an optical path of the apparatus  80  and configured to collimate light energy output of the emitters  12  of the emitter bar  70  in a fast axis direction indicated by arrow  90 . The integrated optical element  82  includes a slow axis collimator element  92  and a wavelength control element  94  formed together from a single piece of optical material. The slow axis collimator element  92  is disposed in the optical path and configured to collimate light energy output of the emitters  12  of the emitter bar  70  in the slow axis direction  86 . The wavelength control element  94  is configured to provide optical feedback to the emitters  12  of the emitter bar  70  so as to narrow a spectral band of the light energy output of the emitters  12 . Focusing optics  96  are aligned with an output axis of the slow axis collimator element  92  in order to focus the light energy into the optical fiber  40  having an input axis aligned with an output axis of the focusing optics  96 . For the embodiment shown, the slow axis collimator element  92  includes an array of slow axis collimator lenses  98  and the fast axis collimator element  88  is a singlet cylindrical lens. However, for some embodiments, the fast axis collimator element  88  may also include an array of fast axis collimator lenses (not shown). 
         [0040]    The fast axis collimator element  88  may be a cylindrical lens or a portion thereof having a focal length that is configured to substantially collimate light energy from the laser emitters  12  in the fast axis direction  90 . The collimation of light energy in the fast axis direction  90  for some embodiments may be sufficient such that at least about 70 percent of the emitted light energy from the laser emitters  12  incident on the wavelength control element  94  is within an acceptance angle of the wavelength control element  94 . For such a configuration, the wavelength control element  94  may reflect about 5 percent of the incident light energy back towards the laser emitters  12  in the form of optical feedback. Some embodiments of the cylindrical lens of the fast axis collimator element  88  may have a width along the fast axis direction  90  of about 0.5 mm to about 1 mm, a thickness of about 0.3 mm to about 2 mm and a focal length of about 0.15 mm to about 1 mm. Suitable materials for the fast axis collimator element  88  may include quartz, silica glass as well as other suitable optical materials. 
         [0041]    The integrated optical element embodiment  82  shown is formed from a single piece of optical material, however, similar embodiments may be made from separate elements which are thereafter bonded or otherwise secured together to form a unitary structure. The integrated optical element  82  as a whole or portions thereof may be made from a variety of suitable optical materials such as quartz, silica glass and the like. Integrated optical element embodiments  82  that are made from a single optical material may be made from a photo-sensitive material, such as those discussed above, so that the wavelength control element  94  in the form of a VIG or the like may be written or otherwise created directly into the optical material adjacent the slow axis collimator element  92 . 
         [0042]    The slow axis collimator element  92  is an array of cylindrical lenses  98  formed into the optical material of the integrated optical element  82 . Each cylindrical lens  98  substantially collimates the light energy output of a respective laser emitter  12  in the slow axis direction  86 . Each cylindrical lens  98  of the array has a convex outer surface  100  and may have a width along the slow axis direction  86  of about 5 mm to about 12 mm, a thickness of about 1 mm to about 5 mm and a focal length of about 2 mm to about 10 mm. 
         [0043]    The wavelength control element  94  shown is a VIG which is written into the optical material of the integrated optical element  82  adjacent the cylindrical lens array of the slow axis collimator element  92 . The VIG may be created as discussed above with periodic perturbations generated in a zone of the optical material of the integrated optical element  82  adjacent the slow axis collimator element  92  and may include a chirped configuration, a graded configuration or the like. The VIG or wavelength control element  94  shown may have a width along the slow axis direction  86  of about 5 mm to about 12 mm and a thickness of about 0.3 mm to about 3 mm. 
         [0044]    In use, light energy may be coupled into an optical conduit, such as fiber optic  40 , by emitting light energy from the laser emitters  12  of the laser emitter bar  70  and collimating the emitted light energy in the fast axis direction  90  with the fast axis collimator element  88 . The fast axis collimated light energy then propagates from the fast axis collimator element  88  to the wavelength control element  94  of the integrated optical element  82 . Light energy having a suitable angle of incidence with respect to the wavelength control element  94  for acceptance into the wavelength control element  94  may then enter the wavelength control element  94 . For some embodiments, at least about 70 percent of the emitted light energy incident on the wavelength control element  94  is collimated in a fast axis direction sufficiently to be within an acceptance angle of the wavelength control element  94 . 
         [0045]    Some embodiments of the wavelength control element  94  may then control or otherwise modify the wavelength or spectral band of the light energy by providing optical feedback to the laser emitters  12 . As discussed above, for some embodiments, the light energy of the optical feedback from the wavelength control element  94  may include a narrowed spectral band with respect to the spectral band of the light energy incident on the wavelength control element  94  from the laser emitters  12 . Such a configuration may provide at least about 5 percent reflection of the light energy incident on the wavelength control element  94  back towards the laser emitters  12  in the form of optical feedback with the reflected optical feedback having been controlled or narrowed in the spectral band. The light energy of each laser emitter  12  which has not been reflected by the wavelength control element  94  then passes through the wavelength control element  94 . This light energy is then collimated in the slow axis direction  86  by a respective cylindrical lens  98  of the cylindrical lens array of the slow axis collimator element  92 . The light energy may then be focused by the focusing optics  96  and directed into the fiber optic  40  or any other suitable optical conduit or receptacle. 
         [0046]    Although the embodiment of the optical apparatus of  FIGS. 7 and 8  show a single laser emitter bar  70  having a plurality of laser emitters  12 , other embodiments of a similar optical apparatus  80  may include multiple laser emitter bars  70  having single or multiple emitters  12 . For example, two or more laser emitter bars  70  may be disposed in a stacked configuration with emitters  12  thereof substantially aligned in a fast axis direction  90 . Additional optical elements, including fast axis collimator elements  88  and corresponding integrated optical elements  82 , corresponding to and optically aligned with each laser emitter bar  70  may then be used in order to facilitate coupling of light energy emitted from such a stacked array of laser emitter bars  70  into a single optical conduit or multiple respective optical conduits. 
         [0047]    With regard to the above detailed description, like reference numerals used therein refer to like elements that may have the same or similar dimensions, materials and configurations. While particular forms of embodiments have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the embodiments of the invention. Accordingly, it is not intended that the invention be limited by the forgoing detailed description.