Full Transcript
https://www.youtube.com/watch?v=EREt0xxnlBU
[00:00] hello and welcome to your practices.
[00:04] hello and welcome to your practices webinar series and advanced packaging.
[00:06] webinar series and advanced packaging today I'm Ramsey Celine your practice.
[00:10] today I'm Ramsey Celine your practice lead at Tyndall National Institute where.
[00:12] lead at Tyndall National Institute where we focus on system integration and.
[00:14] we focus on system integration and advanced photonics packaging this.
[00:17] advanced photonics packaging this webinar continues our series where we.
[00:19] webinar continues our series where we step into the world of advanced.
[00:21] step into the world of advanced photonics packaging in the last episode.
[00:24] photonics packaging in the last episode we looked at fiber to chip coupling.
[00:26] we looked at fiber to chip coupling using grating couplers in today's.
[00:30] using grating couplers in today's episode we focus on a specific time of.
[00:32] episode we focus on a specific time of grating coupler appetize grating.
[00:35] grating coupler appetize grating couplers but Before we jump into that.
[00:38] couplers but Before we jump into that let's get familiar with a zoom platform.
[00:40] let's get familiar with a zoom platform which I'm sure many of you are already.
[00:42] which I'm sure many of you are already familiar with the key thing here is that.
[00:45] familiar with the key thing here is that there is a Q and a button if you have.
[00:49] there is a Q and a button if you have questions please use the Q&A section to.
[00:52] questions please use the Q&A section to post these questions we will collate the.
[00:55] post these questions we will collate the questions and answer them in a Q&A.
[00:58] questions and answer them in a Q&A session after the talk but to give you.
[01:02] session after the talk but to give you first a quick update there so now.
[01:05] first a quick update there so now Tindall National Institute and Ally onyx.
[01:08] Tindall National Institute and Ally onyx international are now making the triplex.
[01:12] international are now making the triplex silicon nitride technology available to.
[01:14] silicon nitride technology available to your practice customers this means that.
[01:18] your practice customers this means that you can now access lai onyx is silicon.
[01:21] you can now access lai onyx is silicon nitride technology from you can you can.
[01:25] nitride technology from you can you can get now with our wafer runs for.
[01:27] get now with our wafer runs for biosensing invisible applications.
[01:30] biosensing invisible applications telecoms and data comms you can even.
[01:32] telecoms and data comms you can even access their pink packaging and they now.
[01:37] access their pink packaging and they now also offer IC packaging as well for.
[01:39] also offer IC packaging as well for drivers that will tell you more about.
[01:42] drivers that will tell you more about this in a dedicated webinar in June but.
[01:47] this in a dedicated webinar in June but without further delay let me introduce.
[01:49] without further delay let me introduce you to my co-host dr. Francesco Flores.
[01:51] you to my co-host dr. Francesco Flores head of the training programs hello.
[01:53] head of the training programs hello Francesco Pazzi hi everybody.
[01:55] Francesco Pazzi hi everybody and with us as well today is Lucas Agana.
[01:59] and with us as well today is Lucas Agana who is helping develop our grating.
[02:01] who is helping develop our grating coupler technology here at Tyndall.
[02:02] coupler technology here at Tyndall.
[02:06] either look up everyone thank you for joining us over to you Francesco tell us what are you talk about today?
[02:11] fancy yeah so today we will use mainly on how we can boost the coupling efficiency of a grating coupler and we will see mainly two approaches the so called quality silicon overlay and as you already mentioned the apodization of the grating coupler and then I will show you why we should choose the odd-eyes grating coupler with respect to the standard one mainly due to coupling efficiency performance improvement and also this is really really important emission profiler I will explain briefly the scattering process so the difference is in the scattering process between the apple ice and the salmon grating coupler and then something that is really interesting from the application point of view because we will see how we can use all the information that we gathered.
[03:03] use all the information that we gathered so far to create something that can be used in real life.
[03:06] so why we'll introduce you to the grating couplers and then the concept of focusing rating couplers.
[03:09] so let's start the polysilicon overlay we saw that the coupling efficiency of a standard working capital is usually when you work with a summary.
[03:24] so also the thickness of the silicon wafer is 220 nanometer around fifty five sixty percent.
[03:31] the main reason why it's so low is because the scattering centers.
[03:34] so the ability of the silicon of the quantity of the material to properly scatter the light inside the waveguide is to weaken.
[03:43] in order to improve it we need to increase the effective refractive index.
[03:48] and the only way that we have to increase the effective and rotten index is if we want to work with a standard grading Cutler increase the amount of material that is capturing the light.
[03:57] how can we do that we can grow a little bit
[04:05] can we do that we can grow a little bit of polysilicon on top of the web guy in
[04:08] of polysilicon on top of the web guy in the region of the waveguide where later
[04:11] the region of the waveguide where later we are going to realize yah-tchi
[04:14] we are going to realize yah-tchi so we deposit a bit of polysilicon
[04:17] so we deposit a bit of polysilicon overlay and then reaction the result is
[04:20] overlay and then reaction the result is that we have a a weeper
[04:22] that we have a a weeper action because we have the some of the
[04:25] action because we have the some of the action of the world overlay plus a
[04:28] action of the world overlay plus a little bit of a finger off the web guide
[04:32] little bit of a finger off the web guide so we have a trenches that are thicker
[04:36] so we have a trenches that are thicker so we have more material there are
[04:38] so we have more material there are flattened index the effective refractive
[04:41] flattened index the effective refractive index is higher so the scattering
[04:43] index is higher so the scattering strength is higher another approach is a
[04:48] strength is higher another approach is a lighter in this case a light beam is
[04:51] lighter in this case a light beam is represented by a palsun so it's
[04:54] represented by a palsun so it's something that is finite in the time
[04:56] something that is finite in the time domain we can apply the same concept
[04:59] domain we can apply the same concept that we already applied for electronics
[05:01] that we already applied for electronics the main concept in this case is a
[05:04] the main concept in this case is a impedance matching so we can think the
[05:07] impedance matching so we can think the light has a pulse that is fixed in time.
[05:12] light has a pulse that is fixed in time and we want to adapt the impedance.
[05:15] and we want to adapt the impedance through the wall grating coupler what we can do is we can linearly change the.
[05:18] through the wall grating coupler what we can do is we can linearly change the picture along the longitudinal direction.
[05:22] can do is we can linearly change the picture along the longitudinal direction of the grating coupler stamp starting.
[05:26] of the grating coupler stamp starting from something that is small going to from something that is small going to something that is wider in this way we.
[05:28] from something that is small going to something that is wider in this way we are changing the effective index but we.
[05:35] are changing the effective index but we are changing it tuning it with respect to that specific response physical.
[05:39] are changing it tuning it with respect to that specific response physical response of the structure you can also.
[05:45] response of the structure you can also add a second step in your possession process by changing the height of the.
[05:49] add a second step in your possession process by changing the height of the trenches in this way you can better.
[05:51] process by changing the height of the trenches in this way you can better match effective index of the mode of the.
[05:53] trenches in this way you can better match effective index of the mode of the grating Carter and the effective index.
[05:56] match effective index of the mode of the grating Carter and the effective index of the fundamental mode of the waveguide.
[05:59] grating Carter and the effective index of the fundamental mode of the waveguide in this way you can reduce the light of.
[06:01] of the fundamental mode of the waveguide in this way you can reduce the light of this back reflective and the scattering.
[06:03] in this way you can reduce the light of this back reflective and the scattering processes as you can see from the.
[06:11] processes as you can see from the Hermann electromagnetic spectrum of the
[06:14] Hermann electromagnetic spectrum of the of the grating copper you can boost the
[06:18] of the grating copper you can boost the coupling efficiency up to 80% and even
[06:21] coupling efficiency up to 80% and even further reducing and minimizing the
[06:24] further reducing and minimizing the losses at the working wavelength yeah
[06:29] losses at the working wavelength yeah exactly but let's say it's not
[06:32] exactly but let's say it's not sufficient to focus our attention on the
[06:35] sufficient to focus our attention on the coupling
[06:36] coupling see we also need a good quality of the
[06:40] see we also need a good quality of the shape of the Bema in this case the main
[06:44] shape of the Bema in this case the main advantage of using an appetizer 18
[06:46] advantage of using an appetizer 18 coupler is that we can keep the same the
[06:50] coupler is that we can keep the same the ocean beam shape that we have inside the
[06:52] ocean beam shape that we have inside the waveguide as you can see here this is
[06:54] waveguide as you can see here this is the eigen mode of the nanowire the
[06:58] the eigen mode of the nanowire the webhead sorry and you can see that the
[07:01] webhead sorry and you can see that the shape of this mode is the ocean if we
[07:05] shape of this mode is the ocean if we use a standard rating copper we have
[07:07] use a standard rating copper we have this exponential load that is changing
[07:10] this exponential load that is changing completely the neutral coherence
[07:12] completely the neutral coherence information between the electric field.
[07:15] information between the electric field components of our beam in the case of an.
[07:20] components of our beam in the case of an appetizer grating cutlery instead the.
[07:22] appetizer grating cutlery instead the shaker on so the envelope of the emitted.
[07:24] shaker on so the envelope of the emitted beam is Gaussian so we are maintaining.
[07:29] beam is Gaussian so we are maintaining keeping the same neutral phase.
[07:33] keeping the same neutral phase difference between the several photons.
[07:37] difference between the several photons that are inside our Tulsa and if we put.
[07:43] that are inside our Tulsa and if we put everything together.
[07:45] everything together what we have is let's consider a.
[07:48] what we have is let's consider a standard grating coupler with the.
[07:51] standard grating coupler with the overlay so the pitch is constant what we.
[07:54] overlay so the pitch is constant what we have is that since we are increasing the.
[07:56] have is that since we are increasing the effective refractive index in the region.
[07:59] effective refractive index in the region where we are going to realize the.
[08:00] where we are going to realize the grating coupler we can boost the.
[08:02] grating coupler we can boost the coupling efficiency at 1550 for example.
[08:05] coupling efficiency at 1550 for example we can have something that is around 72%.
[08:08] we can have something that is around 72% for sure better than the 55 56 percent.
[08:11] for sure better than the 55 56 percent that we so during the last webinar but.
[08:13] that we so during the last webinar but if we also up the concept of matching.
[08:17] if we also up the concept of matching UVs.
[08:18] UVs so we also apply a linearly changing variation of the picture so we are measuring the impedance we can boost in addition the coupling efficiency and we can reach for example something like 85 86 percent in this case we are going below the 1b so we have now a system that is really comparable with the edge shattering yes as you can see in this two movies the appetizer 18 coupler reduces the back reflection and the scattering process in celebrating cultural region boosting the amount of light I discovered inside the waveguide and the these two are 3d fdtd movies and as you can see here you can really see how the light travels and interact with the entire structures exactly.
[09:17] the entire structures exactly now the next step is can we prove that.
[09:20] now the next step is can we prove that these new structures improve structure.
[09:24] these new structures improve structure are suitable to realize a real logic.
[09:27] are suitable to realize a real logic circuit the answer is yes so what we have to do is introduce another step.
[09:30] circuit the answer is yes so what we have to do is introduce another step.
[09:32] have to do is introduce another step that is that we have to switch from one generating cutler's to 2d Bretting.
[09:34] that is that we have to switch from one generating cutler's to 2d Bretting.
[09:36] generating cutler's to 2d Bretting cutters a 2d grating Kaplan's is a single device that is able to couple the.
[09:39] cutters a 2d grating Kaplan's is a single device that is able to couple the.
[09:42] single device that is able to couple the light towards two different directions.
[09:44] light towards two different directions so in this case for example this is a 2d system this is our grating coupler and.
[09:47] so in this case for example this is a 2d system this is our grating coupler and.
[09:50] system this is our grating coupler and is able to scatter the light coming from the top towards two orthogonal direction.
[09:54] is able to scatter the light coming from the top towards two orthogonal direction.
[09:57] the top towards two orthogonal direction the X and the y so in this case we have a two different coupling efficiency one for the X direction.
[10:00] the X and the y so in this case we have a two different coupling efficiency one.
[10:02] a two different coupling efficiency one for the X direction the C axis and 1 for the Y direction.
[10:05] for the X direction the C axis and 1 for the Y direction.
[10:08] the C axis and 1 for the Y direction then see why why it's so important because if we consider that we are using.
[10:11] then see why why it's so important because if we consider that we are using.
[10:15] because if we consider that we are using now life that is not polarized so we are.
[10:18] now life that is not polarized so we are like that is circular polarized in a like that is circular polarized in a circularly polarized beam we have both t enpm at the same time so one direction is only for T the other direction is only for TM and we can think to realize a circuit that is able to connect and then sum the two components this means that we can sum for example the coupling efficiency traveling along the x direction we the is face plus the cutting efficiency of the light travelling along the Y direction with his own face the Sun is just up let's say see now that is modulating depending on the angle of the avenging payment so in this case we do not have a simple pulse anymore we have something inside that can store information this is the basic concept of the logical circuit so what
[11:18] concept of the logical circuit so what we have is something that has logic
[11:21] we have is something that has logic inside now it's interesting that also to
[11:25] inside now it's interesting that also to using the black formula see that
[11:28] using the black formula see that changing for example the polarization
[11:31] changing for example the polarization angle we can also change a little bit
[11:34] angle we can also change a little bit the wavelength the peak of the
[11:36] the wavelength the peak of the wavelength
[11:37] wavelength this is really important because we are
[11:40] this is really important because we are able to achieve finally our structure or
[11:43] able to achieve finally our structure or that unit on purpose remember that piece
[11:46] that unit on purpose remember that piece becomes on the track that in the blog
[11:49] becomes on the track that in the blog below you have everything together the
[11:52] below you have everything together the picture the effective refractive index
[11:54] picture the effective refractive index and the angle of incidence that in this
[11:56] and the angle of incidence that in this case is the polarization angle the only
[12:00] case is the polarization angle the only last step that we can make to realize a
[12:04] last step that we can make to realize a grating Cutler that is even better is to
[12:07] grating Cutler that is even better is to optimize the shape in this case we can
[12:11] optimize the shape in this case we can realize the so-called focusing grating
[12:13] realize the so-called focusing grating colors so instead of using flat trenches
[12:16] colors so instead of using flat trenches we can use you see trenches that are on
[12:20] we can use you see trenches that are on porpoises Bank in this case the trenches.
[12:24] porpoises Bank in this case the trenches are also acting as focusing lenses so.
[12:28] are also acting as focusing lenses so the light disc at reddit words the web.
[12:31] the light disc at reddit words the web guy is also focus inside the entrance of.
[12:35] guy is also focus inside the entrance of the Waverider this is really important.
[12:38] the Waverider this is really important because we are avoiding Laxus from the.
[12:41] because we are avoiding Laxus from the left and right side of the grating Capra.
[12:43] left and right side of the grating Capra and using the apodization we are.
[12:47] and using the apodization we are avoiding the best Catalina if we put.
[12:50] avoiding the best Catalina if we put everything together we can have a.
[12:52] everything together we can have a focusing appetite spreading Coppola.
[12:54] focusing appetite spreading Coppola 1-dimensional as seen here in C or if we.
[12:58] 1-dimensional as seen here in C or if we want something that is more refined we.
[13:00] want something that is more refined we can also realize that appetizer focusing.
[13:03] can also realize that appetizer focusing to the grating couplers and we can have.
[13:06] to the grating couplers and we can have the concept of mixing the signals so put.
[13:09] the concept of mixing the signals so put the information inside our modulated.
[13:13] the information inside our modulated Bheema.
[13:19] okay let's say this was not really easy.
[13:24] okay let's say this was not really easy and I see that it's maybe not straightforward so if you have any questions feel free to ask us also let's say tough question we are here to answer your tough question and if you go through the maybe webinar again later feel free to email us and ask as many questions as you want yeah thank you very much Francesco
[13:50] Thank You Luca that was very interesting I have a few questions myself already and before we jump into the Q&A session let me just tell you a bit about what's coming up next you know this is a series and we'll be doing them every couple of weeks and today's episode we spoke about Epidaurus grating couplers in the next episode it's a special issue Luca what will you be talking about in the next episode
[14:18] I'm gonna talk about how we design the grating capper and I'm gonna talk about our design routine that is based on the particles were algorithm so
[14:26] based on the particles were algorithm so basically how to apply these particles.
[14:28] basically how to apply these particles were algorithm to the optimization of.
[14:30] were algorithm to the optimization of the grating toddler and how to boost the.
[14:32] the grating toddler and how to boost the coupling efficiency right so people will.
[14:34] coupling efficiency right so people will be able to learn how to do ourselves.
[14:36] be able to learn how to do ourselves that's pretty cool in the next episode.
[14:39] that's pretty cool in the next episode we'll be in three weeks so on the 9th of.
[14:41] we'll be in three weeks so on the 9th of June like I say it's a special issue.
[14:44] June like I say it's a special issue here a look I'll be showing us about.
[14:46] here a look I'll be showing us about this optimization procedure if you've.
[14:48] this optimization procedure if you've missed an episode or you wanna can.
[14:51] missed an episode or you wanna can rewatch any of the previous webinars you.
[14:54] rewatch any of the previous webinars you can watch them all on our euro practice.
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