optical buffers are recognized as essential components in wavelength routers , in which the packets of data can be stored for resolving packet contention problems and also delay the outgoing packets.1,2 in practice , the optical router patents have been proposed and recorded,35 which can be useful for various applications .
recently , the promising techniques of microscopic volume trapping and transportation within the add / drop multiplexer have been reported in both theory6 and experiment,7 respectively , in which the transporter is known as an optical tweezer . here , the optical tweezer generation technique has become a powerful tool for the manipulation of micrometer - sized particles . to date
moreover , the use of dynamic tweezers is now also understood in practical works.810 schulz et al11 have shown that the transfer of trapped atoms between two optical potentials can be performed . in principle , optical tweezers use forces exerted by intensity gradients in the strongly focused beams of light to trap and move the microscopic volumes of matters , in which the other combination of force is induced by the interaction between photons , which is caused by photon scattering effects . in application , the field intensity can be adjusted and tuned , in which the desired gradient field and scattering force can form the suitable trapping force . hence , the appropriate force can be configured for the transmitter / receiver , which can perform the long distance microscopic transportation . in this paper , dynamic optical tweezers / vortices
are generated using a dark soliton , bright soliton , and gaussian pulse propagating within an add / drop optical multiplexer incorporating two nanoring resonators ( panda ring resonator ) .
the dynamic behaviors of solitons and gaussian pulses are well described by tasakorn et al.12 by using the proposed system , the transceiver can be integrated and performed by using a single device . here , the use of the transceiver to form the transportation of microscopic volumes of matter , especially13 for molecule transportation in liquid core waveguide,14,15 drug delivery , and dna transportation , in which the buffer is needed before reaching the required destination .
in operation , the trapping forces are exerted by the intensity gradients in the strongly focused beams of light to trap and move the microscopic volumes of matters , in which the optical forces are customarily defined by the relationship:16 
 ( 1)f = qnmpc here q is a dimensionless efficiency , nm is the refractive index of the suspending medium , c is the speed of light , and p is the incident laser power , measured at the specimen .
q represents the fraction of power utilized to exert force . for plane wave incidences on a perfectly absorbing particle
because biological specimens are usually contained in aqueous media , the dependence of f on nm can rarely be exploited to achieve higher trapping forces .
increasing the laser power is possible , but only over a limited range due to the possibility of optical damage .
it depends upon the numerical aperture ( na ) , laser wavelength , light polarization state , laser mode structure , relative index of refraction , and the geometry of the particle .
furthermore , in the rayleigh regime , trapping forces decompose naturally into two components . since , in this limit , the electromagnetic field is uniform across the dielectric , particles can be treated as induced point dipoles .
the scattering force is given by:16 
 ( 2)fscatt = nmsc , 
 ( 3)=83(kr)4r2(m21m2 + 2)2 here is the scattering cross section of a rayleigh sphere with radius r. s is the time averaged poynting vector , n is the index of refraction of the particle , m = n / nm is the relative index , and k = 2nm/ is the wave number of the light .
the scattering force is proportional to the energy flux and points along the direction of the propagation of the incident light .
the gradient field ( fgrad ) is the lorentz force acting on the dipole induced by the light field .
it is given by:16 
 ( 4)fgrad=2e2,where 
 ( 5)=nm2r3(m21m2 + 2)is the polarizability of the particle .
the gradient force is proportional and parallel to the gradient in energy density ( for m > 1 ) .
the stable trapping requires that the gradient force is in the  direction , which is against the direction of incident light ( dark soliton valley ) .
it is greater than the scattering force . by increasing the na , when the focal spot size is decreased , the gradient strength is increased,16,17 which happens within a tiny system , for instance , a nanoscale device such as the nanoring resonator . in our proposal ,
the trapping force is formed by using a dark soliton , in which the valley of the dark soliton is generated and controlled within the panda ring resonator by the control port signals . in this paper
, we used the same theory of optical trapping and ring resonator , in which the simulation results and applications are differed from the previous work.18 from figure 1 , the output field ( et1 ) at the through port is given by:19 
 ( 6)et1=aei1bei2el2jknl2  [cet1(el2jknl2)2+dei2(el2jknl2)31f(e2ljknl2)2]where 
 a 
 ( 11)(12),b 
 ( 11)(12)1(12)e0l , c 
 1(11)(12)2e0e0l , d 
 ( 11)(12)1(11)2(12)e0e0l2 , andf 
 ( 11)(12)(11)(12)e0e0l . 

( 11)(12)1(12)e0l , 
 1(11)(12)2e0e0l , 
 ( 11)(12)1(11)2(12)e0e0l2 , and 
 ( 11)(12)(11)(12)e0e0l . here ,
et and ed represent the optical fields of the through port and drop ports , respectively .
 = kneff is the propagation constant , neff is the effective refractive index of the waveguide , and the circumference of the ring is l = 2r , where r is the radius of the ring . 1 and 2 are the coupling coefficients of the add / drop filters , kn = 2/ is the wave propagation number for in a vacuum , and the waveguide ( ring resonator ) loss is  = 0.5 dbmm .
the fractional coupler intensity loss is  = 0.1 . in the case of the add / drop device
, the nonlinear refractive index does not affect the system , therefore , it is neglected .
the electric fields e0 and e0l are the field circulated within the nanoring at the right and left side of add / drop optical filter .
the power output ( pt1 ) at through port is written as : 
 ( 7)pt1=|et1|2 . the output field (
et2)at drop port is expressed as:19 
 ( 8)et2=(12)(12)ei2  [(11)(12)12e0ei1el2jknl2+xe0e0lle2i(el2jknl2)21ye0e0l(e2ljknl2)2],where 
 x 
 ( 12)(11)(11)2(12),y = 
 ( 11)(12)(11)(12 ) 
 ( 12)(11)(11)2(12 ) , 
 ( 11)(12)(11)(12 ) the power output ( pt2 ) at drop port is : 
 ( 9)pt2=|et2|2 . in operation , the optical tweezers can be trapped , transported , and stored within the panda ring resonator and wavelength router , which can be used to form the microscopic volume ( molecule ) transportation and drug delivery via the waveguide,18 in which the manipulation of trapped microscopic volumes within the optical tweezers has been reported .
molecular buffers are devices that can be used to store or delay atoms / molecules for a period of time ( see figure 2 ) , where light intensity and velocity can also be controlled , which was described by rosenberry et al20 and lignie and woerdman,21 available for medical application .
molecular buffers are a new device , which are operated in the same way as gas buffers.22 the polarizability of the particle is calculated by using equation ( 5 ) , in this case , we assume that the sphere particle is polystyrene ( n = 1.5894 ) and the liquid medium is water ( n = 1.33 ) , and the optical power which is required to trap particles of a certain size / polarizibility is 9.1w , which is the slope as shown in figure 3a . in simulation , the bright soliton with center wavelength at 1.50 m , peak power 2w , pulse 35fs is input into the system via the input port , and the coupling coefficients are given as 0 = 0.5 , 1 = 0.35 , 2 = 0.1 , and 3 = 0.35 , respectively .
the ring radii are radd = 10 and 30 m , rr = 50 and 100 nm , and rl = 50 and 100 nm , respectively . to date , the evidence of a practical device with a radius of 30 nm has been reported by piyatamrong et al.19 aeff are 0.50 , 0.25 , and 0.25 m . in this case
, the dynamic tweezers ( gradient fields ) can be in the form of bright solitons , gaussian pulses , and dark solitons , which can be used to trap the required microscopic volume .
there are four different center wavelengths of tweezers generated ; the dynamical movements are seen in figure 4 , where ( a ) |e1| , ( b ) |e2| , ( c ) |e3| , ( d ) |e4| , ( e ) through port , and ( f ) drop port signals , where in this case all microscopic volumes are received by the drop port . in practice ,
the fabrication parameters which can be easily controlled are the ring resonator radii instead of the coupling constants .
the important aspect of the result is that the tunable tweezers can be obtained by tuning ( controlling ) the add ( control ) port input signal , in which the required amount of microscopic volume ( atom / photon / molecule ) can be obtained and seen at the drop / through ports , otherwise they propagate within a panda ring before collapsing / decaying into the waveguide .
more results of the optical tweezers generated within the panda ring are shown in figure 5 , where in this case , the bright soliton is used as the control port signal to obtain the tunable results .
the output optical tweezers of the through and drop ports with different coupling constants are as shown in figure 5a , while the different wavelength results are as shown in figure 5b , which can be performed by the selected targets . in application
, the trapped microscopic volumes ( molecules ) can move into the wavelength router via the through port , while the retrieved microscopic volumes are received via the drop port ( connecting target ) .
the advantage of the proposed system is that the transmitter and receiver can be fabricated on - chip and alternatively operated by a single device .
the magnitude of the optical trapping force is the pico newton , which depends upon the relative refractive index of particle , which was given by kumar et al.23 the particle radius was given by hu et al,24 fischer and srensen,25 and nieminen et al,26 which is located in the cavity .
we have proposed a new system that can be used to trap ( delay ) and transport molecules into an optical waveguide by using optical tweezers , which can be used for drug storage and as a delivery system . by utilizing the reasonable dark soliton input power ,
the dynamic tweezers can be controlled and stored ( delayed ) within the system before reaching the final destination .
tweezer amplification is also available by using the nanoring resonators , in which the signals can be modulated via the control port as shown in figures 4b and 5a . in conclusion
, we have shown that the use of a transceiver for long distance microscopic volume by using the proposed system , in which the drug delivery or molecular communication can be performed via the wavelength router to the required ( connecting ) targets . however , the problems of large microscopic volume and neutral matter may cause a problem , in which the pursuit of new guide pipes and media,27 for instance , nano tubes and specific gases , will be the issue of investigation .
 a novel design of molecular buffer for molecule storage and delivery using a panda ring resonator is proposed . 
 the optical vortices can be generated and controlled to form the trapping tools in the same way as the optical tweezers . in theory , the trapping force is formed by the combination between the gradient field and scattering photons , which is reviewed . by using the intense optical vortices generated within the panda ring resonator , the required molecules can be trapped and moved ( transported ) dynamically within the wavelength router or network , ie , a molecular buffer . 
 this can be performed within the wavelength router before reaching the required destination . 
 the advantage of the proposed system is that a transmitter and receiver can be formed within the same system , which is available for molecule storage and transportation . 
Introduction
Theory
Molecular buffer
Conclusion