1、集成光學(xué),主講人：劉柳 ,Integrated Photonics,1,特征模的展開,任意電場(chǎng)分布的光波入射如何轉(zhuǎn)變成波導(dǎo)的模式（導(dǎo)模+輻射模）？ 處理方法：將任意電場(chǎng)分布展開，分解成不同模式的電磁場(chǎng)分布。 數(shù)學(xué)上用正交函數(shù)展開，如傅立葉級(jí)數(shù)等，稱之為特征模展開； 各導(dǎo)波模以相應(yīng)階數(shù)模的傳播常數(shù)傳播； 隨著光的傳播，不同模之間的相位差將發(fā)生變化，導(dǎo)致導(dǎo)波模疊加以后的電磁場(chǎng)分布也隨著傳播過程而變化，光束像蛇一樣反復(fù)蠕動(dòng)前進(jìn)。,3,耦合效率,標(biāo)準(zhǔn)光纖和波導(dǎo)在端面耦合時(shí)模式失配損耗是插入損耗的主要因素 利用光纖和波導(dǎo)模場(chǎng)的重疊積分可以得到兩者耦合時(shí)的損耗 改變波導(dǎo)的幾何尺寸，從而改變波導(dǎo)的模場(chǎng)分布，

2、可以使波導(dǎo)的模場(chǎng)和光纖的模場(chǎng)達(dá)到較好的耦合,特征模展開的系數(shù),功率耦合效率,無損傳輸,理想耦合,偶對(duì)稱模,奇對(duì)稱模,超模理論,超模理論（Super mode）,當(dāng)在輸入端z = 0處，由波導(dǎo)#1輸入光波，在這一點(diǎn)會(huì)激勵(lì)起電場(chǎng)振幅相等，相位相同的偶對(duì)稱模和奇對(duì)稱模。隨著這兩種模在耦合區(qū)域的傳播，兩個(gè)模之間產(chǎn)生相位差(e - o)z。其相位差為時(shí)的傳輸距離為： L = / (e - o),實(shí)踐課一Python and CAMFR,主講人：劉柳 ,7,CAMFR,CAMFR (CAvity Modelling FRamework) is a fast, flexible, friendly full

3、-vectorial Maxwell solver. Its main focus is on applications in the field of nanophotonics, like wavelength-scale microstructures (like photonic crystal devices) lasers (like vertical-cavity surface-emitting lasers) light-emitting diodes (like resonant-cavity LEDs) It is based on a combination of ei

4、genmode expansion and advanced boundary conditions like perfectly matched layers (PML).,8,CAMFR,CAMFR can be used to calculate the scattering matrix of a structure the field inside a structure, for any given excitation band diagrams of an infinite periodic structure threshold material gain and reson

5、ance wavelength of laser modes the response to a current source in an arbitrary cavity structures terminated by a semi-infinite repetition of another structure This functionality is currently available for two types of geometries: 2D Cartesian structures 3D cylindrical symmetric structures,9,CAMFR,1

6、0,2D Cartesian structures,3D cylindrical symmetric structures,Basic structures (Slab):,CAMFR,11,Simulate final structures (Stack):,Stack consists of several slabs connected in sequence,Slab 1,Slab 2,Slab N,Each interface was treated with a serial of mode transmission and reflection coefficients,Each

7、 slab has n modes In the slab each mode propagates with its propagation constant with out coupling,Each interface has n*n*2*2 coefficients,T,R,Brief History of Python,Invented in the Netherlands, early 90s by Guido van Rossum Open sourced from the beginning, man-aged by Python Software Foundation Co

8、nsidered a scripting language, but is much more Scalable, object oriented and functional from the beginning Used by Google from the beginning,Pythons Benevolent Dictator For Life,“Python is an experiment in how much freedom program-mers need. Too much freedom and nobody can read anothers code; too l

9、ittle and expressive-ness is endangered.” - Guido van Rossum,Pythons place in the Market,TIOBE has been collecting data on programming language “popularity” for many years Counts results for a query like programming” on popular search engines,10/10 TIOBE Programming Community Index,/

10、,Installing,Python is pre-installed on most Unix systems, including Linux and MAC OS X The pre-installed version may not be the most recent Two “l(fā)atest versions” 2.7 released 7/10 & 3.2 released 10/10 Python 3 is a non-backward compatible. We use python 2.7 Download from /download/ P

11、ython comes with a large library of standard modules,Useful packages: Pyreadline shell enhancement, required by some packages NumPy for numerical algebra, trigonometry, etc. SciPy useful for numerical integration, ODE solutions, interpolations, etc.: based on NumPy Matplotlib matlab type of plotting

12、 Books: Learning Python, Mark Lutz & David Ascher, OReilly Press, 1999 Programming Python, Mark Lutz, OReilly Press, 2006 Core Python Programming (2nd Edition), Wesley J. Chun, Prentice Hall, 2006 Websites: - online version of built-in Python function documentation http:/lauren

13、/python/pqrc - Python Quick Reference Card http:/rgruet.free.fr - long version of Python Quick Reference Card - extensive Python forum,Some Useful Packages and Resources,Thank You !,To be continued ,18,課后習(xí)題（作為最終評(píng)分的一部分）,任選一題,19,1、考慮一個(gè)簡(jiǎn)單的三層對(duì)稱平板波導(dǎo)，包層材料為空氣（1.0），芯層材料為硅（3.476）或二氧化硅（1.445）。計(jì)算當(dāng)分別取這兩種材料時(shí)，波導(dǎo)TE基模的模場(chǎng)寬度（定義為E場(chǎng)的半高度全寬）隨波導(dǎo)厚度變化的趨勢(shì)曲線。試分析每條曲線為什么會(huì)這樣變化，分析這兩種材料對(duì)應(yīng)的曲線為什么會(huì)有不同。厚度取值范圍為20nm-