# 2. Total Internal Reflection

As it has been discussed in the first part that, the incident light coming from one medium to another as it strikes the boundary with certain angle, will be refracted in definite manner according to the $n_{1} \sin \theta_{1}=n_{2} \sin \theta_{2}$. Let’s just start this section by increasing incident angle of light in figure 2, first part. This is what will happen if the incident angle is increased:

Figure 1. Refraction phenomenon, with n1 is smaller than n2

As we know from the behavior described in the first part, we observed the light being refracted in increasing manner when the angle of incident light is increased as well. It is less likely that we can notice something intriguing in here.

How about if medium one has larger value than medium two ($n_{1}>n_{2}$)? We should have light will have lower velocity in medium 1 than in medium 2 ($v_{1} < v_{2}$) and thus angle of light with respect to the normal in medium 1 is smaller than in medium 2 ($\theta_{1}<\theta_{2}$). As we increase the angle of incident in medium 1, we will this result:

Figure 2. Refraction phenomenon evolves to total internal reflection, with n1 larger than n2

Total internal reflection is depicted in the right illustration of figure 2. In this phenomenon, the medium boundary acts as a reflector, instead of refractor under two conditions:

• Light propagates from medium with higher refractive index to the medium with lower refractive index ($n_{1}>n_{2}$).
• The angle of incident light has to satisfy minimum of certain angle, i.e. critical angle $\theta_{c}$.

Total internal reflection can be considered when the refracted light is in parallel direction with the interface (figure 2, middle illustration), i.e. $\theta_{2}=90^{\circ}$. Using Snell’s law equation described earlier in the first part and two conditions stated above, we can quantify the required incident angle so that it can trigger total internal reflection:

$n_{1} \sin \theta_{1}=n_{2} \sin \theta_{2}$

$n_{1} \sin \theta_{c}=n_{2} \sin 90^{\circ}$

$n_{1} \sin \theta_{c}=n_{2}$

$\sin \theta_c=\frac{n_2}{n_1}$

$\theta_c=\sin^{-1} \frac{n_2}{n_1}$

Total internal reflection is occured when the incident angle fulfills the critical angle whose value is determined by the medium 1 and 2, as it is expressed in the last formula of the above equations, called the critical angle equation:

$\theta_c=\sin^{-1} \frac{n_2}{n_1}$

This equation establishes the requirement for total internal reflection to take place: medium 2 must have refractive index smaller than medium 1. If it happened in opposite way, there will be no solution for this equation, meaning that total internal reflection does not take place.

# Let the density and its respective radius being known, then a critical beam angle shall be found!

It was happened when I read a paper from V. Consonni et al published in Physical Review B (or you can find it in here) about the shadowing effect part, in the page 4. V. Consonni et al gave a mathematical description (modelling) for the growth rate of self-induced GaN nanowires, and extracted several important parameters (for instance effective diffusion length on the sidewalls and substrate surface, desorption rate, driving forces for the diffusion of gallium adatoms to the nanowire top) based on the finding of equations from the fitting with the experimental results, which are as a function of growth time, gallium rate and growth temperature.

So, I found this “magic” at page 4, on the sub-part of “Theoretical modelling of the NW axial growth rate for the self-induced approach”, namely “shadowing effects”. Beforehand, I agreed with them regarding the geometrical considerations in the molecular beam epitaxy chamber determining the final form of nanowires which are heavily influenced by the incident angle of the gallium effusion cell and nitrogen plasma source with respect to the substrate (read here). It is important also to realize that the incident angle of these sources will be having an impact in the shadowing of the grown nanowires after they reach certain height.

To my surprise, V. Consonni et al provided three examples, just straight answer, of how shadowing effects took a role in affecting structural morphology of the nanowire (density, radius, spacing, height) and the respective angle of gallium beam. In all cases, they assumed nanowire to have regular square area. The first case is nanowire having density, radius, spacing of 100 ${\mu}m^{-2}$, 30 nm and 51 nm, respectively. They found out that with an angle of 21 degree, the gallium impinged on a nanowire with height of 133 nm. The second example is nanowire with density and radius of 100 ${\mu}m^{-2}$ and 30 nm, a critical gallium beam angle of 49 degree was found. What… The last example, nanowire with radius and gallium beam angle of 30 nm and 21 degree, the density was deduced to be 200 ${\mu}m^{-2}$. I just don’t understand that straight answer.. It is just BOOM! Just let the radius and density to be known, then gallium beam angle will be discovered by some calculations which I do not understand.

To elucidate this matter, I make simple self-explanation. I used plain figure, based on the first case, which I think the most reasonable example I want to approach due to the more data in it. The objective is simple, before shadowing plays role, I want to find the maximum gallium beam angle and density, while radius, spacing and height are known. The figure has same scale measurement as with nm:

Nanowires configuration based on the first example

Let’s consider that gallium beam angle comes to the nanowires in a single line (of course in reality, the nanowires are received bunch of gallium flux on them). The consideration of “just before” shadowing effect means that this effect does not occur, i.e. maximum height of nanowires are found to be around 133 nm. The figure below gives an illustrative idea of how the maximum gallium beam angle “just before” the shadowing effect.

Maximum gallium beam angle with respect to the nanowire before shadowing effect

If I made a larger angle, than shadowing effect would take place. This is the maximum angle before shadowing. We can calculate that angle by doing a little hack. We can consider those figure with this:

The alternative approach for angle calculation

I doubt the angle will be 21 degree. With $\tan \theta = \frac{111 nm}{133 nm}$, the maximum gallium beam angle is 39.84 degree.

The density of the nanowire itself is lower with my calculation. Since 1 ${\mu}m^{-2}$ is equal with $10^{-6}$ $nm^{-2}$. We have 1 nanowire every 111 nm, meaning that in 2000 x 500 $nm^{-2}$, we have only 81 nanowire for 1 ${\mu}m^{-2}$.

See! The protractor also shows around 39 degree

It might be that V. Consonni et al have lower maximum limit to ensure that shadowing effect really will not be occurred, while my illustration really push the maximum angle of gallium beam angle. Using my approximation, with gallium beam angle of 21 degree, the maximum height of nanowire can be around 192 nm.

Maximum height of nanowire with gallium incident angle of 21 degree

Ok, I will leave the shadowing part here.

# Numerical Aperture on The Fiber Optic (1)

Yesterday, I re-arranged my bookshelf containing my notes I had made during Master course in NTNU. I felt nostalgic with these notes and they brought me back to the time when I tried to write them as neat as possible so that they can be useful (readable) for me in the future. I thought that it must be better to document them digitally to prevent these notes to be permanently damaged when they are just in the form of paper.

In the following note, I will write the study on the numerical aperture of fiber optic. Fiber optic is a cable made of glass (or plastic) threads (fibers), used for transmitting data in guided mode (for example: internet connection) utilizing light waves. We can see how it looks like in figure 1. I find the concept of fiber optic is very interesting because it uses simple optical phenomenon in our daily life. Surprisingly, the basic knowledge for explaining the guided-light has been attained in junior high school. Unfortunately, what we learnt during that time was only simple phenomenon without realizing there is an advanced technology depending on it.

Figure 1. Fiber optic

I will divide this explanation into three sections: first we deal with the Snell’s law. This is quite basic of refraction phenomenon, but I think it is very important to grasp the fundamental part. Next, we will move to the total internal reflection, where we will make use of the trait of Snell’s law to control the light. Finally, the last part will deal with fiber optics, by utilizing total internal reflection property.

# 1. Snell’s law

The basic law governing guided transmitted light in fiber optic is Snell’s law. This law deals with light coming from point P one media (with refraction index 1, $n_{1}$) with certain angle relative to the normal axis ${\theta_1}$, to point Q another media (with refraction index 2, $n_{2}$) where the light will have change its angle relative to the normal axis ${\theta_2}$ (figure 2). Alteration of light direction (refraction) is begun at the interface between two different media. We can meet with this phenomenon daily by observing how the straw in the glass of water looks bent or the strange form of stair in the swimming pool.

Figure 2. Refraction of light. Taken from wikipedia

How does direction of light change? Roughly speaking because of the atomic structure composing the media. The mass of the atom will create certain density in that media leading to the specified interaction between light and the atom and it will determine speed of light penetrating in that media. We can say that refraction characteristics of material are varying from one to another. Therefore, in figure 2, propagation of light with speed of ${v_1}$ in media ${n_1}$ changes its speed to ${v_2}$ in media ${n_2}$. Since there is an alteration of speed meaning there is a slightly change in the direction of light, relative to the normal axis, and in this case is media with ${\theta_1}$ to ${\theta_2}$.

To get rough qualitative measurement of the angle in each media, we can use this rule of thumb (based on figure 2: the incidence angle in medium 1 is larger than the refraction angle in medium 2 (${\theta_1} > {\theta_2}$) shows that light propagate faster in medium 1 than in medium 2 (${v_1} > {v_2}$). Since light propagate faster in medium 1 compared to medium 2, we can conclude that refraction index in medium 1 is smaller than medium 2 (${n_1} < {n_2}$). The denser the material is, the higher is the value of refractive index and the light will propagate slower depicted with the smaller angle of refraction (it will move closer to the normal axis).

For the case of refraction index in medium 1 is larger than medium 2 (${n_1} > {n_2}$), the result will show exactly in the reverse way: light will propagate slower in medium 1 than in medium 2 (${v_1} < {v_2}$) due to the fact that medium 1 is denser than medium 2 and this will lead to the incidence angle in medium 1 is smaller than the refraction angle in medium 2 (${\theta_1} < {\theta_2}$).

Based on the relationship we have established so far, this part will be closed with the formula between angle of incidence ${\theta_1}$ and refraction ${\theta_2}$, speed v and refraction index n for medium 1 and 2,

$\frac{\sin \theta_1}{\sin \theta_2}=\frac{v_1}{v_2}=\frac{n_2}{n_1}$

# Van der Waals (VdW) Bonding, GaAs on Si and Graphene as a Buffer Layer

Figure 1: a) Atomic geometry of GaAs/multi-layer graphene/Si interface showing only top-most graphene layer is strained by heteroepitaxial growth, b) schematic for structure with GaAs grown on top of single-layer graphene buffer layer/Si substrate. (Image source: http://www.semiconductor-today.com/news_items/2014/SEP/UCLA_100914.shtml and http://onlinelibrary.wiley.com/doi/10.1002/adfm.201400960/abstract)

Ok, In this post I will try to summarize this paper, one sentence at every question.

# Introduction

## Why is this important?

Photonics devices based on the integration of III-V materials (in this case is GaAs) on Si.

## What needs to be done?

Heteroepitaxial growth using MBE utilizing 2D material, owning to its VdW bonding which yields to accomodation to lattice mismatch between 3D-2D material.

## What has been done already?

MBE-grown GaAs NWs on graphene/Si substrate (A. M. Munshi et al, Nano Lett.2012124570), MOCVD-grown InAs/In(x)Ga(1-x)As NWs on graphene (Nano Lett. 2013131153) and GaAs/Si using layered GaSe ( J. Cryst. Growth 1995150685).

# Goal of the Research Project

Using graphene as a buffer layer in realizing VdW epitaxial growth of GaAs on Si

# Method

First, Y. Alaskar et al calculated surface energy of the graphene buffer layer with Ga and As prelayer; adsorption and migration energy of Al, Ga, In and As on graphene; The experimental is divided in fabrication (mechanical exfoliation of graphene and growing using MBE) and characterization (FESEM, AFM, Raman spectroscopy and XRD)

# Result

Theoretical result will not be presented in here, and instead, we focus on experimental result: (i) due to the low surface energy of graphene triggering high tension toward GaAs and (ii) low adsorption and mitigation energy of Ga and As on graphene at high temperature, island growth (3D) is formed instead of single crystal (2D) of GaAs

# Challenges and Bottlenecks

Developing understanding of VdW interaction between GaAs/graphene/Si

# Opportunities and Workarounds

Two-step growth is employed to investigate graphene using Ga- or As- prelayer.

Important: Growth morphology-surface energy, nucleation step-thin film properties, low surface energy of graphene, low adsorption energy of Ga and As, nucleation site, surface energy-adsorption energy, surface energy-growth temperature-wettability-nucleation process,

# Things we can and can’t

I am confused how to start this post.. But let’s start, shall we?

Do you know? One of my biggest regret in my life is not able to speak, read and write in Chinese. I can tell you, how many times I face situations where I felt embarrassed as the Chinese approached me, asked me about something in Chinese. My response will be always like this, “Err.. Can you switch to English?” or “I can’t speak in Chinese, I am sorry” These two sentences are always my “weapon” when I do not know what to reply them XD

The second point is not getting any musical ability. My siblings can play a bit of piano, but I? Hah! I am done with that. The only thing I can do is sing a song with my lousy voice XD

It is pitiful, isn’t it?

Well, those two are top two items among others. I have numbers of remorse within my life. It is always coming later, those guilty feeling. Always.

My several items:

Recently, I met a friend who is very brilliant in Philosophy. He is not studying Philosophy after all, but he remembered lot of well-known Philosophers from several era as well as their well-known work. I could not do like what he does.

I am terrible speaker, especially when it comes to English :p

Getting bad grade for your course is something which bothers quite a lot. Why? That is because of the energy you have poured for the whole semester, which is averagely 4 months comes in vain. You need to start over next year.

As my highlight in my previous post, that friend will never be with you all the time. Some day, they will go. A new friend will come. In the future, they will go, and this cycles are endless… They are not the same to each other. They are special. Friends are… function of time.. I mean physically, as they are always within you, emotionally.

Now, I know what you are thinking…

You can’t stop the time. Seconds will keep ticking.

In this circumstances, does it mean that I am giving up? Simple answer: No.

There is still one thing we can do. Instead of focusing in what we can not do, I think it is better to have focus on “what is more important?”

Having this kind of way of thinking, maybe for most people, it is like a cliche where I just run away from what the thing I can’t do. Fine, it is their opinion. But from my case, I need something to push myself outside from my comfort zone.

What is important? It will take my way of thinking toward a new idea which I have not thought before. It challenges me in getting a possibilities of new stuff. Though it is not working sometime, but at least I have shifted my focus to the thing I feel it is important.

What is important? For me, I have my dreams, family and dearest friends. Whenever circumstances are not supporting me, I will only see those which are important to me.

It does take time, but am I going to give up? No

Nobody knows what will happen in the future, When sometimes we think that it will come in this way, suddenly it is altered to another. But who knows? It is your hope that makes you stand out. To what or whom do you put your hope on?

For my personal opinion, I am totally agree with the sons of Korah (Psalm 42:11)

By thinking what is important, we can see that this life -moment of time- must not be taken for granted. Talking about “not to be taken for granted”, my mind suddenly filled with my family and dearest friends. If you do realize that you are on the limit, especially when it comes to families and friends, you have to treasure them, think of what is important matter that you can do with them and hope in God that He will take care them for you. Never-ever make this kind of regret.

Sorry for my awful and unstructured English or argument, this post is kind of “rush” post from me.

Copenhagen, 17 August 2014*

*in celebration of 69th Indonesia independence day, hoping that I can take part for my nation resurrection in the coming future.

# Between Sukowono, Surabaya and Trondheim

Hello :)

This post is inspired by a friend of mine. She is living in Zambia now. It is the following sentence she wrote which triggered me to write this post,

Sky is the limit

For international student like me, living in the place which is far from home country has its own fun and challenging experience. I will not talk about the pleasure side. I think most international students out there have listed what the good things being independent and outside from your comfort zone. Even BBC has an article that either studying or working abroad makes us smarter. That article is reasonable that through difference experience, culture and people that we, as international students, have to face how to solve it through out every day life..

This is my personal reason why it is demanding: homesick. It is serious matter as I am desperately missing my nice life in my country, among my family and friends. But it is inevitable, isn’t it? This is life and I have to find out how to tackle this problem, so that I can develop and move forward.

I have been living in few places so far. I was educated from kindergarden and elementary school in Sukowono, while junior high school to senior high school in Jember (It is just 30 km away from Sukowono). Not a problem anyway, since I went back and forth house-school, everyday with public transportation. I used to nap time or just simply talk (more precisely: joking) with friends sitting beside me.

250 km was the distance between home to university where I pursued my bachelor degree. I need 5 hours to get there and by this reason, I decided to stay in Surabaya, the capital city of East Jave province. Now I couldn’t go home as frequent as I want, not only was it far but also several technical factors such as traffic jam, time efficiency and gasoline cost as my main considerations. At least, I could go home once in three months when I had minimum holidays of 7 days.

My journey did not stop in here. I have made myself to pursue higher education outside of Indonesia. It was the experience together with sort of “questing and testing” myself in order to dig down what kind of unrevealed aspect of my innerself which I did not realize. So, of all applications I sent, university in Norway and Taiwan accepted me. Strangely, I decided to go to Norway which is really far from Indonesia. With the distance close to 16.000 km, crossing Asia and central Europe, I arrived in the place which was new for me, a foreign land with unknown culture, people and habit. Thanks to the God, what I feared by the time I determined myself taking a Master degree in Norway had been slowly faded. Through the cruel winter, poor sunlight, slippery road and many other things which are occured naturally in northern part of the world, I survived. I found the warmth heart of the people among the coldness; and the most important factor is friends. I enjoyed my days being with them; my life was colored by them, I was really grateful. As the time flied, one by one of my friends had to return back to their own country, and it brought me a great sadness. Finally, when I finished my education, it was my turn to leave Norway. The night before I left Norway, all of the memories I had for the past two years ran through in my head, similar like old projector with black and white color. So much trouble I had that night, remembering the unique and memorable life I made with my friends, through every cycle of emotion. The day after, I left Norway.. Sorrow lived in my heart but I could not cry. Such a nuisance XD

Time is cruel, I tell you my friend. It does not need to know what you have done or progress you have made. It will do as the time come. I am just knowing that our life is not the function of result, but it is a function of time. Therefore my advice is: treasure your time, be wise in using it! It will never come back..

The next journey of my life after completing Master Degree has been determined after I had been graduated from bachelor level: research. So the asnwer is clear enough: either becoming a researcher in industry or looking for PhD opportunity. In four months of engaging jobs and PhD searching, I have settled myself for company and university in the semiconductor field. Tens of applications were sent and just few answered me. Among them, only one positive feedback I received. It was a PhD position in NTNU, the university I am working now. It has been four months since I came back again to Trondheim and started my research. Though I returned to the same city where I have been living for two years, I experienced such different: a new perspective. Some aspects are not the same as I had when I was a master student. My old and best friends are not longer in here anymore, and such a reminiscence and memory I have for them, whenever I walk alone through the “wild” path I use to go from home to university and vice versa or when I have fellowship with some friends in the Church. I am vaguely remembering their face, but their presence are still living in this tiny heart.

I remembered correctly that when I had a final exam weeks during my junior and senior high school era, usually I did not sit in my room. As long as I could, I studied in the 2nd floor of my house where there was an open space, mainly used for drying the laundry stuff. So I sat and read there, under the bright of the sun, with the sky as my solely roof. For some time when I got bored, I used to see the sky, some shape of the clouds and birds. It did not only help returning my concentration, but also I felt that burden and tension in my mind were also blown away with the wind. This habit disappeared when I moved to Surabaya as it does not offer the townfolk great view of the sky; people are busy with their own things, without realizing an awesomeness of the sky is sitting above them, and I was one of them. The habit of staring the sky grew when I did my master in Trondheim but I much more enjoy it now.

Sky as it is seen from the bus stop close to my home

As the place where I live now is bit further up (about in the hill), I can see some part of outskirt of the town from the bus stop close where I live (around 10 m). Whenever I return from university, I always rest in this bus stop with no intention for taking bus of course, just re-take my lost breath for having 3.5 km walking or cycling up to the hill. Especially when it comes in cycling, I feel my heart beating so fast with heat generated in my both feet especially in thigh. As I arrive there, I feel satisfy with good time in work and exercising (walking or cycling) while enjoying sunset, clouds, vehicles in the far place, mountain, weather station on the peak of the mountain, Tyholt tower, roof of Nidaros Church, the fjords, apartments, roads, light road, people… It is paid off. In the same place, I often reflect, revise what I have been done for a day and plan for the tomorrow. While gazing the sky, my mind has wondering, looking to the future, where I will be after I finish my PhD degree and what kind of place in the next 10-15 years and things I have been designing so far. Sometimes, things are not going as I plan, but as soon as I set my mind to the dream I store in the “clouds” or sky, I feel eased up, putting my feet back to the ground with a conviction that “Everything will be OK and something will be get developed as long as there is a hard work, determination and commitment in solving present issues”. A new power has been obtained and I prepare my night for the new day. It takes 5-10 minutes for me to enjoy my solitude. A great thing also that, my desk in the university is just next to the window, so I can free my mind in between of busy working days.

Sky as it is seen from my desk at university

Through sky-gazing, I realize something: we are living under the same sky. No matter where we are, there is a common connection between us. One of the most miserable event in my life is separation or parting. Realizing the moment when that will be the last time I enjoy moment with my friend, and think that the “good bye” is meant to be “So long!”, the last and final word to be spoken. An occasion with rare statement of a friend when we about to part with each other, “we will not see each other again” broke deep inside my heart, leaving a scratch on it. Unexpectedly, all the reminiscence appeared and anxiety of leaving friend for indecisive time and thousands km of distances. Throughout my life, I met some great friends from whom I learnt a lot: some fellows are still in Trondheim while number of them are away and I also receive a new friends \^_^/; I am grateful that my experience living as an international student has brought me to have chance encountering them. It is them, whom I treasure. My feeling at the moment? I am badly missing them! Nevertheless, whenever I look fixedly at the sky as well as through constant prayer, they are within my reach emotionally. Something is on the sky, a magical space linking us together.

Between Sukowono, Surabaya and Trondheim: these places are bonded together, though the mighty distances separating them. My recollection are treasured within these cities. Despite I live separatedly from my friends and family, but one thing I remember:

it is the sky that becomes the only limit between me and them. And one day, take it in mind that I will meet them, under the same sky :)

It is a great to meet a new friend(s) who you can get familiar with. It is awesome when you talk to them as you will not feel time passing. It is substantial by the time you listen to them since you feel relaxed just by opening your heart to accept them as they are. If you do find them, treasure them, as they will not be able with you all the time.

“Is there any adventure more exciting than meeting new people and finding out what lives within them?” -Sonja Henie, Norwegian skater-

I remember a great song created and sung by GooseHouse, called “Sky”. Here is the pieces of the lyric:

We’ll walk our own ways
Then looking back,
“I’m alone” you may say
Hey, don’t you forget
We always share the sky
Always…

Andreas

# Preview for my second month

Ok, I am really behind my schedule to post this. Here are the things took place from 17 April through 17 May 2014:

1st week

• My first Easter week in Trondheim as a PhD student. Living a second chance of life in the same city has given me a bit of different perspective on how going through it. To appreciate the 7-day off (Easter-spring break), I went for two-day away from Trondheim, to Surnadal, staying in a house with more than 100 years old of history, witnessing many important events in the local area.

That view!

• My off-days were accompanied with lunch invitation by friend of mine. What a nice day! I spent almost 6 hours in my friend’s place, doing nothing :p
• During the Easter day, on Sunday, I helped a friend to run a Sunday school. But it was a suicide attempt as I do not have “enough” Norsk speaking ability. As you can see, I just did some body language to communicate and… a desire to learn Norsk has been growth. The day after, last day of vacation was spent in helping a family who moved out to new place.

2nd week

• One of my flatmate celebrated a birthday. It was nice to share the joy together. The day after, I visited another Indonesian family who returned back to Indonesia for good, dedicating their life for the country. I am looking forward to hear news from them soon!
• Ah, one day was the time I needed to have graphene electronic bandgap visualized and the result was still not like what I want! Well, let’s move to another part of interest.
• Finally, our small apartment has our own microwave, but though it is an old microwave (and insanely heavy!), its performance is still on the top!
• Finally, the sun had come out from its hideout. After Church meeting, I spent 2 hours with my friend, sitting around and enjoying the sun. Lol, something I will not do in Indonesia :p

3rd week

• My very 1st draft of research proposal has been done. It was terrible :))
• Invitation on 1st May. It was also goodbye dinner for a friend, leaving Norway on 4 May. He is going to marry soon in this summer! Almost 3 hours we spent together. The day after, I had invitation for another dinner. Two days in a row!
• Voluntary work? I did by helping a little in cleaning one room in the Church :))

4th week

• Wow, my 2nd draft was finished. Still terrible, but at least better. The day after, it was a full-day seminar about PhD introduction, outside of NTNU.
• Next days in a row: 3rd group meeting, and I was passively participating the discussion. Commemorating a PhD defense of Indonesian friend. Easter celebration in Indonesian Bible Study. On Sunday, the Church’s main pastor moved to another city and a farewell party was held. I heard they had a big feast.. Ooh, where was I? Oversleeping in my room :p
• 2nd day of PhD introductory seminar, and it was held in NTNU. The day after was another fascinating seminar: working with Norwegians.
• In this week, the group had a big event where one of the PhD student was going to defend his work and after that, he was officially received a Doctoral degree. Congratulation!
• And in the end, 17 May, a constitusional day of Norway was celebrated. So much fun!

200 years of Norwegian constitusional celebration (It is my friend who took this nice photo. I will borrow for a bit :D)

Well, I am looking forward for the third month :)