Patent Publication Number: US-11656529-B2

Title: Light conversion systems, methods, and devices

Description:
FIELD 
     The present disclosure relates generally to sanitization systems and methods and, more particularly, to sanitization systems and method using frequency doubling to generate FAR-UVC for aircrafts. 
     BACKGROUND 
     The recent novel-coronavirus (SARS-COV-2) outbreak has negatively impacted the safety and health of many people. Pathogens can be transmitted via direct airborne transmission between users or via indirect contact transmission from different users occupying the same space at different times. For example, lingering pathogens may remain on contact surfaces of an aircraft cabin to be spread to passengers and/or crew members on a subsequent flight. The safety of passengers and crew members may be improved by performing disinfecting treatments to surfaces, such as seats, ceiling/wall panels, handles, and lavatory surfaces, etc., to mitigate the presence of pathogens on such surfaces. However, conventional disinfection procedures between flights may take time and may thus adversely affect the operating efficiency of the aircraft (increased interval time between flights), and the effectiveness and quality of such conventional treatments are often difficult to verify/track. 
     SUMMARY 
     A nonlinear converter is disclosed herein. The nonlinear converter may comprise: alternating layers of a dielectric material and a metal material, the nonlinear converter configured to receive a first wavelength and output a second wavelength; a first refractive index of the nonlinear converter for the first wavelength, the first wavelength being approximately double the second wavelength, the first refractive index corresponding to a metal fill ratio; and a second refractive index of the nonlinear converter for the second wavelength, the second wavelength being between 207 nm and 237 nm, the second refractive index being less than 0.5, the second refractive index corresponding to the metal fill ratio. 
     In various embodiments, at least a portion of the first wavelength is halved in response to traveling through the nonlinear converter. Approximately equal may be between 0% and 10% or between 0% and 5%. The dielectric material may be aluminum nitride, and the metal material may be aluminum. The second refractive index may be between 0 and 0.3. The nonlinear converter may be configured to receive a first light with the first wavelength and output the first light and a second light with the second wavelength. 
     A sanitization apparatus is disclosed herein. The sanitization apparatus may comprise: a light source configured to emit a light having a first wavelength between 414 and 474 nm; and a nonlinear converter disposed proximate to the light source, the nonlinear converter comprising alternating layers of a dielectric material and metal material, the nonlinear converter configured to provide a phase mismatch between an input wavelength and a second harmonic generation wavelength between 0% and 10% within the nonlinear converter. 
     In various embodiments, the second harmonic generation wavelength is between 207 and 237 nm. A first refractive index of the nonlinear converter for the second harmonic generation wavelength may be less than 0.5, the first refractive index corresponding to metal fill ratio of the alternating layers. In various embodiments, a second refractive index of the nonlinear converter for the input wavelength is approximately double the first wavelength. The second refractive index may correspond to the metal fill ratio. The nonlinear converter may be configured to generate a third wavelength and fourth wavelength within traveling through the alternating layers of the dielectric material and the metal material, the third wavelength and the fourth wavelength being approximately equal. Approximately equal may be between 0% and 5%. 
     A method of sanitizing a surface is disclosed herein. The method may comprise: generating a light having a first wavelength between 414 and 474 nm; and converting the light into a first portion of the light having the first wavelength and a second portion of the light having a second wavelength, the second wavelength being half the first wavelength, converting the light being through a phase-mismatch free medium, the phase-mismatch free medium including a phase mismatch between 0% and 10%. 
     In various embodiments, converting the light further comprising generating, via a nonlinear converter, a third wavelength corresponding to the first wavelength and a fourth wavelength corresponding to the second wavelength, the third wavelength and the fourth wavelength being approximately equal. The method may further comprise directing the second portion of the light towards the surface. Directing the second portion of the light toward the surface may be through a prism. The method may further comprise the first portion of the light in a first direction that is collimated with a second direction of the second portion of the light. The method may further comprise scanning a predetermined area of the surface with the second portion of the light. 
     The forgoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims. 
         FIG.  1    illustrates a view of a cabin of an aircraft, in accordance with various embodiments; 
         FIG.  2    illustrates a schematic view of a sanitization system, in accordance with various embodiments; 
         FIG.  3 A  illustrates a schematic view of a sanitization apparatus, in accordance with various embodiments; 
         FIG.  3 B  illustrates a schematic view of a nonlinear converter, in accordance with various embodiments; 
         FIG.  4    illustrates a plot of refractive index vs. fill ratio for a nonlinear converter, in accordance with various embodiments; 
         FIG.  5    illustrates a plot of power vs. nonlinear converter thickness, in accordance with various embodiments; 
         FIG.  6    is a process performed by a control system for a sanitization system, in accordance with various embodiments; 
         FIG.  7    is a perspective view of a portion of a sanitization system  100 , in accordance with various embodiments; and 
         FIG.  8    is a perspective view of a lavatory in an aircraft, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined. 
     In various embodiments, Far-UV (222 nm wavelength light) has promise to work in occupied spaces but may utilize significant power to disinfect an entirety of a cabin. Additionally, Far-UV (222 nm wavelength light) may have limitations as to total dosage a human may receive. In various embodiments, integrating Far-UV (222 nm wavelength light) via excimer lamps would be relatively expensive and utilize heavy high power intensity light sources, such as excimer lamps. Excimer lamps utilize a high voltage supply and have a large gas discharge. In various embodiments, the systems and methods disclosed herein are configured to generate a first light with a first wavelength (i.e., input wavelength or pump wavelength), convert a portion of the first light to a second light with a second wavelength (i.e., output wavelength or second harmonic generation (SHG) wavelength), the second wavelength (i.e., output wavelength or second harmonic generation (SHG) wavelength) being half the first wavelength (i.e., input wavelength or pump wavelength), and/or maintain a portion of the first light as an indicator. In various embodiments, the first wavelength (i.e., input wavelength or pump wavelength) is between 414 nm and 474 nm, or between 429 nm and 459 nm, or approximately 444 nm. 
     In various embodiments, the sanitization system disclosed herein, utilize an improved light converter. The improved light converter disclosed herein may replace conventional phase-matching techniques, while maintaining a frequency doubling/wavelength halving effect to facilitate conversion of blue light (between 414 and 474 nm) to at least a portion of Far-UV light (222 nm light). 
     With reference to  FIG.  1   , a cabin  51  of an aircraft  50  is shown, according to various embodiments. The aircraft  50  may be any aircraft such as an airplane, a helicopter, or any other aircraft. The aircraft  50  may include various lighting systems  10  that emit visible light to the cabin  51 . Pathogens, such as viruses and bacteria, may remain on surfaces of the cabin  51 , and these remaining pathogens may result in indirect contact transmission to other people (e.g., subsequent passengers). For example, the cabin  51  may include overhead bins  52 , passenger seats  54  for supporting passengers  55 , handles  56 , lavatory surfaces, and other structures/surfaces upon which active pathogens may temporarily reside. As will be discussed further below, in order to reduce the transmission/transfer of pathogens between passengers, one or more of the lighting systems  10  may blend disinfecting electromagnetic radiation output into the visible light in order to facilitate disinfection of the cabin  51  (e.g., during flights and/or between flights). The lighting systems  10  may be broken down into different addressable lighting regions that could be used on an aircraft. For example, the regions on an aircraft may include sidewall lighting, cross-bin lighting, over wing exit lighting, ceiling lighting, direct lighting, flex lights, reading lights, dome lights, lavatory lights, mirror lights, cockpit lights, cargo lights, etc. The regional breakdown of the lighting system allows lighting control over broad areas of the aircraft. In various embodiments, lighting system  10  may be disposed in/incorporated by a passenger service unit (PSU) for a row of seats. As such, a lighting system  10  could be provided for each row of an aircraft, as well as for each section of different sections of a given row of an aircraft. 
     Referring now to  FIG.  2    a schematic view of a sanitization system  100  for an aircraft cabin, is illustrated, in accordance with various embodiments. In various embodiments, the sanitization system  100  comprises a main control system  101  and a plurality of PSUs (e.g., first PSU  110 , second PSU  120 , third PSU  130 , etc.). Although illustrated as including three PSUs, the number of PSUs of a sanitization system  100  is not limited in this regard. For example, a PSU may be disposed in each row of seats disposed in a respective column of an aircraft cabin. For example, a cabin with 50 rows and 3 columns may have 150 PSUs (e.g., each row in each column having a PSU). In various embodiments, the PSUs are not limited to rows in the aircraft cabin and may be placed throughout the aircraft cabin as well. For example, PSUs, in accordance with the present disclosure, may be disposed in the lavatory, aisles, cockpit, or any other area of an aircraft cabin where it may be desirable to have sanitization. 
     In various embodiments, the main control system  101  includes a controller  102  and a memory  104  (e.g., a database or any appropriate data structure; hereafter “memory  104 ” also may be referred to as “database  104 ”). The controller  102  may include one or more logic devices such as one or more of a central processing unit (CPU), an accelerated processing unit (APU), a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or the like (e.g., controller  102  may utilize one or more processors of any appropriate type/configuration, may utilize any appropriate processing architecture, or both). In various embodiments, the controller  102  may further include any non-transitory memory known in the art. The memory  104  may store instructions usable by the logic device to perform operations. Any appropriate computer-readable type/configuration may be utilized as the memory  104 , any appropriate data storage architecture may be utilized by the memory  104 , or both. 
     The database  104  may be integral to the control system  101  or may be located remote from the control system  101 . The controller  102  may communicate with the database  104  via any wired or wireless protocol. In that regard, the controller  102  may access data stored in the database  104 . In various embodiments, the controller  102  may be integrated into computer systems onboard an aircraft. Furthermore, any number of conventional techniques for electronics configuration, signal processing and/or control, data processing and the like may be employed. Also, the processes, functions, and instructions may include software routines in conjunction with processors, etc. 
     System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by the processor, cause the controller  102  to perform various operations. The term “non-transitory” is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se. Stated another way, the meaning of the term “non-transitory computer-readable medium” and “non-transitory computer-readable storage medium” should be construed to exclude only those types of transitory computer-readable media which were found in In Re Nuijten to fall outside the scope of patentable subject matter under 35 U.S.C. § 101. 
     The instructions stored on the memory  104  of the controller  102  may be configured to perform various operations, such as performing cleaning schedules between flights, cleaning a specific row in response to a trigger (i.e., a sneeze or the like), etc. 
     In various embodiments, the main control system  101  from  FIG.  2    further comprises a power source  108  and a display device  106 . The power source  108  may comprise any power source known in the art, such as a battery, a solar source, an alternating current (AC) source, a rechargeable source, or the like. In various embodiments, the display device  106  may be configured to provide inputs into the control system  101  and alternate between various modes (e.g., alternating from an in-flight mode to a post-flight mode or the like). In various embodiments, the sanitization system  100  may alternate modes automatically in response to detecting a change in mode is desired, as described further herein. 
     In various embodiments, the main control system  101  is in operable communication with each PSU in the plurality of PSUs (e.g., PSUs  110 ,  120 ,  130 ). In various embodiments, each PSU comprises a local controller (e.g., controllers  111 ,  121 ,  131 ). Each local controller (e.g., controllers  111 ,  121 ,  131 ) may be in accordance with main controller  102 ). For example, each local controller (e.g., controllers  111 ,  121 ,  131 ) may include one or more logic devices such as one or more of a central processing unit (CPU), an accelerated processing unit (APU), a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or the like (e.g., controllers  111 ,  121 ,  131  may utilize one or more processors of any appropriate type/configuration, may utilize any appropriate processing architecture, or both). In various embodiments, the controllers  111 ,  121 ,  131  may each further include any non-transitory memory known in the art. The memory may store instructions usable by the logic device to perform operations. Any appropriate computer-readable type/configuration may be utilized as the memory, any appropriate data storage architecture may be utilized by the memory, or both. 
     In various embodiments, each PSU (e.g., PSUs  110 ,  120 ,  130 ) may comprise light(s) (e.g., light(s)  112 ,  122 ,  132 ), a sanitization apparatus (e.g., sanitization apparatus  113 ,  123 ,  133 ), and/or sensor(s) (e.g., sensors  114 ,  124 ,  134 ). As described further herein, the controller  102  may command the various local controllers (e.g., controllers  111 ,  121 ,  131 ) to instruct the devices therein. 
     In various embodiments, the power source  108  is sized and configured to power all of the lights (e.g., light(s)  112 ,  122 ,  132 , etc.) of all of the PSUs (e.g., PSUs  110 ,  120 ,  130 , etc.) of a sanitization system  100 . Since the sanitization apparatuses ( 113 ,  123 ,  133 ) utilize a light source having a wavelength between 414 nm and 474 nm, significantly less power may be utilized during a sanitization process as disclosed further herein. In this regard, the power source  108  may be kept similar to a typical power source  108  for an aircraft cabin control system, in accordance with various embodiments. 
     In various embodiments there may be a single sensor or a plurality of sensors for each PSU. For example, sensor(s) (e.g., sensor(s)  114 ,  124 ,  134 ) may each include a microphone array, an occupancy sensor, a manual trigger, or a combination thereof. In this regard, the sanitization system  100  may be configured to detect occupancy and/or configured to detect an event where cleaning may be desired, such as a detecting a sneeze, a cough, or the like. 
     In various embodiments, each sanitization apparatus (e.g., sanitization apparatus  113 ,  123 ,  133 ) may be connected via digital communications, discrete communications, or wireless communications to a respective local controller (e.g., controllers  111 ,  121 ,  131 ). In various embodiments, a respective local controller may be configured to monitor a health of a respective sanitizer, as well as a life of a respective sanitization apparatus. For example, controller  111  may be configured to receive light source life data from the sanitization apparatus  113 , each PSU (e.g., PSUs  110 ,  120 ,  130 ) may be configured to track a total dosage of FAR-UV supplied to a given area. For example, the controller  111  of PSU  110  may receive a duration that sanitization apparatus  113  has been in operation and limit operation when a threshold dosage is being approached. 
     Referring now to  FIG.  3 A , a schematic view of the sanitization apparatus  113  from  FIG.  2   , in accordance with various embodiments. In various embodiments, the sanitization apparatus  113  comprises a light source  202 . In various embodiments, the light source  202  may comprise a light emitting diode (LED), a Nd:YAG/LBO laser, a lnGaN laser diode, an lnGaN laser pump source or the like. In various embodiments, any light source capable of generating a light with a first wavelength (i.e., input wavelength or pump wavelength) between 414 nm and 474 nm is within the scope of this disclosure. In various embodiments, the light source may weigh significantly less than a light source capable of generating a UVC wavelength (e.g., between 200 nm and 280 nm). In various embodiments, the light source  202  is in operable communication with a controller (e.g., a local controller  111  from  FIG.  1    and/or a main controller  102 ). In this regard, in response to receiving a signal from a controller, the light source  202  may be activated and generate a wavelength between 414 nm and 474 nm, or between 429 and 459 nm, or approximately 444 nm. 
     In various embodiments, the sanitization apparatus  113  further comprises a nonlinear converter  204 . The nonlinear converter  204  is configured to double a frequency of a portion of an incoming light, in accordance with various embodiments. In various embodiments, the nonlinear converter  204  is configured for second harmonic generation (SHG). Phase matching may be used in nonlinear crystals for efficient nonlinear interaction between electromagnetic waves with different wavelengths. Several strategies are utilized for nonlinear phase matching in bulk crystal (e.g., birefringent phase matching, angle phase matching, and/or quasi-phase matching). 
     In various embodiments, materials with a refractive index near zero may tend to provide a phase-mismatch-free environment for nonlinear optical processes and may be disruptive for nonlinear conversion, as described further herein. In various embodiments, index near zero material may be supported with cavities or single-back reflectors to increase an optical path. 
     With brief reference now to  FIG.  3 B , a nonlinear converter  204  in accordance with various embodiments, is illustrated. The nonlinear converter  204  may comprise alternating layers of a dielectric material  302  and a metallic material  304 . The nonlinear converter  204  is configured with a refractive index near zero. A “near zero” refractive index as described herein refers to a refractive index between 0 and 1, or between 0 and 0.75, or between 0 and 0.5, or between 0 and 0.3. In various embodiments, both the real portion and the imaginary portion of index are near zero. In this regard, the real part of the refractive index being near zero facilitates a phase mismatch-free medium as described previously herein. The imaginary part of the refractive index being near zero may minimize optical losses. 
     Although illustrated as comprising alternating layers of the dielectric material  302  and the metallic material  304 , the present disclosure is not limited in this regard. For example, one skilled in the art may recognize various orientations or configurations to produce a near zero refractive index material that provides nonlinear conversion properties as outlined herein. In this regard, any nonlinear converter configured to receive a first wavelength of light (i.e., an input wavelength or a pump wavelength) and output a second wavelength of light (i.e., an output wavelength or SHG wavelength) with a near zero refractive index for the first wavelength of light and the second wavelength of light is within the scope of this disclosure. 
     In various embodiments, the dielectric material  302  comprises a thickness to and the metallic material  304  comprises a thickness t m . The thicknesses td, t m  are measure in an axial direction of the nonlinear converter (i.e., perpendicular to a first axial surface  301  defining an inlet for an incoming light), in accordance with various embodiments. 
     In various embodiments, the dielectric material  302  includes a refractive index, nd and the metal material includes a refractive index, n m . The refractive index, n d  is a function of the fill ratio. Fill ratio is a function of the thickness, t m , of the metal material  304  and the thickness, t d , of the dielectric material. In particular, fill ratio (f m ) is defined by the following equation: 
     
       
         
           
             
               
                 
                   
                     f 
                     m 
                   
                   = 
                   
                     
                       t 
                       m 
                     
                     
                       
                         t 
                         m 
                       
                       + 
                       
                         t 
                         d 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     Additionally, a refractive index is a function of metal fill ratio for various wavelengths of light. For example, with reference now to  FIG.  4   , a plot of refractive index as a function of fill ratio for a metal material (e.g., aluminum) and a dielectric material (e.g., aluminum, nitride) for a first wavelength (i.e., input wavelength or pump wavelength) (444 nm) and a second wavelength (i.e., output wavelength or second harmonic generation (SHG) wavelength) (222 nm) are illustrated. In various embodiments, based on the plot from  FIG.  4   , a metal fill ratio for the nonlinear converter  204  may be determined as described further herein. 
     In various embodiments, the metal fill ratio for the nonlinear converter  204  may be determined based on matching a frequency of a first wavelength (e.g., a fundamental wavelength) of an input light with a second wavelength (i.e., output wavelength or second harmonic generation (SHG) wavelength) output from the nonlinear converter (e.g., a second harmonic generation wavelength). For example, a wavelength through the nonlinear converter  204  is defined by the following equation: 
     
       
         
           
             
               
                 
                   λ 
                   = 
                   
                     
                       λ 
                       0 
                     
                     n 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     In various embodiments, a fill ratio from the plot in  FIG.  4    may be determined based on minimizing the refractive index for the first wavelength (i.e., input wavelength or pump wavelength) and the second wavelength (i.e., output wavelength or second harmonic generation (SHG) wavelength), based on having a refractive index below 1, where the refractive index of a the first wavelength (e.g., a fundamental wavelength of the input light or pump light) is approximately double a refractive index of a second wavelength (i.e., output wavelength or SHG wavelength). “Approximately double” as referred to herein, is between 1.8 and 2.2 times, or between 1.9 and 2.1 times, or between 1.95 and 2.05 times, in accordance with various embodiments. For example, for a metal material  304  comprising aluminum and a dielectric material  302  comprising aluminum nitride a fill ratio of 0.55 may have a refractive index for a first wavelength (i.e., input wavelength or pump wavelength) of 444 nm of approximately 0.487 and a refractive index of a second wavelength (i.e., output wavelength or SHG wavelength) of 222 nm of approximately 0.236. 
     Thus, a wavelength through the nonlinear converter  204  for a first wavelength (i.e., input wavelength or pump wavelength) of 444 nm having a refractive index of 0.487 would be approximately 911 nm. Similarly, a wavelength through the nonlinear converter  204  for a second wavelength (i.e., output wavelength or SHG wavelength) of 222 nm corresponding to the second harmonic generation would be approximately 941.5. Thus, a mismatch between the first wavelength (i.e., input wavelength or pump wavelength) and the second wavelength (i.e., output wavelength or SHG wavelength) through the nonlinear converter would be defined by the following equation: 
     
       
         
           
             
               
                 
                   Mismatch 
                   = 
                   
                     
                       
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                           λ 
                           SHG 
                         
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                           λ 
                           f 
                         
                       
                       
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                       λ 
                       f 
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     where λ SHG  is the second harmonic generation wavelength through the nonlinear converter  204 , and λ ƒ  is the fundamental frequency through the nonlinear converter  204 . Thus, in the example above, the mismatch would be approximately 3.3%. 
     In various embodiments, after having a fill ratio resulting in a low mismatch between wavelengths (e.g., between 0% and 20% mismatch, or between 0% and 10% mismatch, or between 0% and 5% mismatch), a thickness of the metal material  304  and the dielectric material  302  may be determined. Power output may be a function of number of periods through a material. For example, with reference to  FIG.  5   , power output of a metal material  304  comprising aluminum and a dielectric material  302  comprising aluminum nitride is illustrated for a first wavelength (i.e., input wavelength or pump wavelength) of light at approximately 444 nm and a second wavelength (i.e., output wavelength or SHG wavelength) of light at approximately 222 nm. In this regard, a power output of the second wavelength (i.e., output wavelength or SHG wavelength) (e.g., 222 nm) may be maximized, a power output of the first wavelength (i.e., input wavelength or pump wavelength) (e.g., 444 nm) may be maximized, or power output of both the first wavelength (i.e., input wavelength or pump wavelength) and the second wavelength (i.e., output wavelength or SHG wavelength) may be determined with the goal of maximizing both power outputs, in accordance with various embodiments. 
     In various embodiments, determining a compositing for a nonlinear converter  204  as described herein may comprise balancing the following factors: (1) maximizing power output of the second wavelength (i.e., output wavelength or SHG wavelength) (e.g., approximately 222 nm wavelength light); (2) minimizing a refractive index of the second wavelength (i.e., output wavelength or SHG wavelength); and (3) minimizing a mismatch between the first wavelength (i.e., input wavelength or pump wavelength) through the nonlinear converter and the second wavelength (i.e., output wavelength or SHG wavelength) through the nonlinear converter. 
     Although described herein with respect to aluminum as the metal material  304  and aluminum nitride as the dielectric material, the present disclosure is not limited in this regard. For example, any metal material and dielectric material determined in accordance with the above is within the scope of this disclosure. 
     In various embodiments, the nonlinear converter  204  comprises a Far-UV refractive index between 0 and 1, or between 0 and 0.5 or between 0 and 0.3. In various embodiments, a nonlinear converter  204  is configured to generate a first wavelength corresponding to an input wavelength and a second wavelength (i.e., output wavelength or SHG wavelength) corresponding to a second harmonic generation wavelength. In various embodiments the first wavelength (i.e., input wavelength or pump wavelength) and the second wavelength (i.e., output wavelength or SHG wavelength) generated within the nonlinear converter  204  are approximately equal. “Approximately equal” as defined herein refers to a mismatch of between 0% and 20% or 0% and 10% or 0% and 5%, or 0% and 3%. A metal fill ratio of the metal material  304  to the dielectric material  302  may correspond to a first refractive index of a wavelength between 414 nm and 474 nm. The metal fill ratio of the metal material  304  to the dielectric material  302  also corresponds to a second refractive index of a wavelength between 207 nm and 237 nm. In various embodiments, the first refractive index is approximately double the second refractive index. 
     Referring back to  FIG.  3 A , in various embodiments, the output from the nonlinear converter  204  is received by a prism  206  configured to direct the light received from the nonlinear crystal. For example, the first portion of the light with the first wavelength (i.e., input wavelength or pump wavelength) may directed through first output  207  of the prism  206  and the second portion of the light with the second wavelength (i.e., output wavelength or SHG wavelength) may be directed through a second output  208 . In various embodiments, the first output and the second output may be collimated (i.e., parallel or the like). In this regard, the first wavelength (i.e., input wavelength or pump wavelength) may indicate to a person that the area is being sanitized as the first wavelength (i.e., input wavelength or pump wavelength) would have greater visibility relative to the second wavelength (i.e., output wavelength or SHG wavelength), in accordance with various embodiments. Although illustrated as being separated, the first wavelength (i.e., input wavelength or pump wavelength) and the second wavelength (i.e., output wavelength or SHG wavelength) may be coaxial in accordance with various embodiments. In this regard, the first wavelength (i.e., input wavelength or pump wavelength) may indicate more clearly a location being sanitized, in accordance with various embodiments. Additionally, in various embodiments, the residual light of the first wavelength (i.e., input wavelength or pump wavelength) through first output  207  may be mixed with an additional light source (e.g., light(s)  112  from  FIG.  2   ) to create white light, such as for use as a reading light or the like. Although described with respect to sanitization apparatus  113 , any sanitization apparatus disclosed herein (e.g., sanitization apparatuses  123 ,  133 ) may be in accordance with sanitization apparatus  113  from  FIG.  3   , in accordance with various embodiments. 
     Referring now to  FIG.  6   , a method of sanitization a portion of an aircraft is illustrated, in accordance with various embodiments. The method may comprise receiving, via a controller, a scanning command (step  402 ). The scanning command may include a predefined area. In various embodiments, since the output from the prism of  206  of the sanitization apparatus  113  is a beam, it can be directed in a manner similar to a barcode scanner or the like. In contrast, excimer lamps, and other far-UV light sources cannot generate a beam of light that can be directed. Thus, the systems and methods disclosed herein may facilitate scanning areas and avoiding people when sanitizing a particular area. In this regard, sensor(s)  114 ,  124 ,  134  from  FIG.  2    may include infrared sensors, LiDAR sensors, or the like. The sensors may be configured to detect and identify people, and the controller (e.g., main controller  102  or local controllers  111 ,  121 ,  131 ) may be configured to command the sanitization apparatus to direct the output beam(s) away from people, in accordance with various embodiments. 
     The method  400  may further comprise scanning a predetermined area in response to receiving the scanning command (step  404 ). In various embodiments, the predetermined area may be an area that commonly comes into contact with passengers, such as tray tables, arm rests, or the like. In various embodiments, scanning the predetermined area may be an active scanning where portions of the area are avoided in response to detecting a person as described previously herein. 
     Referring now to  FIG.  7   , a perspective view of a portion of the sanitization system  100  from  FIG.  2    is illustrated, in accordance with various embodiments. The sanitization system  100  includes the light(s)  112  and the sanitization apparatus  113 . In various embodiments, each light(s)  112  may correspond to a seat in a respective row. For example, a first light  611  may be configured to align towards a first seat  621  in a row  601  of in the aircraft cabin  651 . In this regard, each light in the light(s)  112  in a PSU  110  may be configured to emit light towards a seat in a row of the respective PSU  110 . 
     In various embodiments, the sanitization apparatus  113  in a PSU  110  includes the light source  202 , the nonlinear converter  204 , and the prism  206  from  FIG.  2   . Although illustrated as including a plurality of the sanitization apparatus  113 , any number of sanitization apparatuses  113  for a respective PSU  110  is within the scope of this disclosure. In various embodiments, the local controller  111  (or main controller  102 ) from  FIG.  2    may adjust a beam direction of a respective sanitization apparatus  113  during a sanitization process (e.g., method  400 ). In various embodiments, the sanitization system  100  may be configured to direct the light away from a passenger&#39;s head (e.g., towards the tray tables, or the like). 
     Referring now to  FIG.  8   , a perspective view of a sanitization system  700  is illustrated, in accordance with various embodiments. In various embodiments, the sanitization system  700  may be disposed in a lavatory  702  of an aircraft cabin (e.g., aircraft cabin  51  from  FIG.  1   ). In this regard, the sanitization system  700  may be configured in a manner similar to sanitization system  100 . For example, the sanitization system may include sensor(s) configured to detect whether the bathroom is occupied (e.g., sensor(s)  114  from  FIG.  2   ), a sanitization apparatus  710  (e.g., sanitization apparatus  113 ), and a controller (e.g., controller  111  from  FIG.  1   ). In various embodiments, the sanitization system  700  may be in communication with main controller  102  from the sanitization system  100  from  FIG.  2   . In this regard, the lavatory  702  may be configured to be sanitized during in-flight cycle, post-flight cycle, or the like. In various embodiments, the lavatory  702  may be configured to be sanitized after use (e.g., in response to detecting a user entering and detecting a user leaving). 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment,” “an embodiment,” “various embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. 
     Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.