UM 2p5 parameters 1and2

User Manual Index > 2.5 Parameters

2.5.1 Miscellaneous keywords

– end no arguments: the end statement ends a parameter file: lines following the line of the end statement are ignored. If a parameter file ends before an end statement is encountered, execution stops and a warning message is written to the error file. (Synonyms: END)

– verbose = .true. [LOGICAL] Default value is .false.. If set to .true., a lot more information will be written to the default output file. This proves useful when a mode is difficult to find. (Synonyms: VERBOSE, Verbose)

– ! starts a comment. Comments end at the end of the line. You may add comments after keywords and arguments on the same line. Any characters between an exclamation mark and an end of line character are ignored.

2.5.2 Fibre structure compiler keywords

Definition keywords

– central cylinder = radius [REAL] epsilon [COMPLEX]: This keyword takes two arguments. It adds a central cylinder with radius radius and permittivity epsilon to the structure. (Synonyms: add central cylinder)

– central cylinder radius = radius [REAL]: Adds a cylinder with radius radius centered on the origin to the structure. If the permittivity or refractive index of this cylinder is not defined by central cylinder epsilon or central cylinder index, the central cylinder’s refractive index will be the same as the refractive index of all other cylinders.

– central cylinder epsilon = epsilon [COMPLEX]: Sets the central cylinder’s permittivity to epsilon. If the radius of the central cylinder is not defined elsewhere, no central cylinder will be added to the structure. (Synonyms: central cylinder permittivity)

– central cylinder index = n [COMPLEX]: Sets the central cylinder’s refractive index to n. If the radius of the central cylinder is not defined elsewhere, no central cylinder will be added to the structure. (Synonyms: central cylinder refractive index)

– pitch = l [REAL]: Sets the pitch (center to center distance) between cylinders to l. (Synonyms: PITCH, Lambda)

– Nr = N_r [INTEGER]: Number of rings. Sets the distance from the origin to the center of the last hole on the x-axis to N_r ×pitch. See Fig. 1. (Synonyms: nr, number of rings, NUMBER OF RINGS)

– MNr = M N_r [INTEGER]: Number of missing rings. Sets the distance from the origin to the center of the first hole on the x-axis to M N_r ×pitch. See Fig. 1. (Synonyms: mnr, missing rings, MISSING RINGS, number of core rings)

– cladding radius = R_Cl [REAL]: Defines the cladding radius (see Fig.1). (Synonyms: cladding_radius, CLADDING_RADIUS, Cladding radius, Cladding_radius, Cladding Radius)

– jacket radius = R_J [REAL]: Defines the jacket radius (see Fig.1). (Synonyms: jacket_radius, JACKET_RADIUS, Jacket radius, Jacket_radius, Jacket Radius)

– No Cladding (no arguments): This keywords informs the internal structure compiler that the structure does not have a cladding. The cladding refractive index will be set to the refractive index of the matrix, and the cladding radius will be set to an arbitrary value between the furthest point of all cylinders and the jacket radius. Note that when the matrix and the cladding have same index, FIBRE automatically replaces the reflection matrix of the matrix/cladding interface by the null-matrix and the transmission matrix between the matrix and the cladding by the identity matrix. The No Cladding keyword supersedes definitions of cladding index and radius: if the No Cladding keyword has been used anywhere before a build fibre statement, the structure will have no cladding, regardless of whether the cladding’s refractive index and radius have been defined elsewhere. (Synonyms: no_cladding, No_cladding, NO CLADDING, no cladding, NO_CLADDING)

– cylinder radius = R [REAL] Sets the radius of all cylinders to R. Note that the radius of the central cylinder can be defined separately before or after this keyword using central cylinder radius or central cylinder. (Synonyms: cylinder_radius, CYLINDER_RADIUS, Cylinder radius, Cylinder_radius, Cylinder Radius)

– diameter on pitch ratio = q [REAL] Sets the radius of all cylinders to 0.5 × q×pitch. Note that the radius of the central cylinder can be defined separately before or after this keyword using central cylinder radius or central cylinder. (Synonyms:d/Lambda, d/pitch, diameter/pitch, diameter on pitch, diameter_on_pitch)

– No Jacket (no arguments): This keywords informs the internal structure compiler that the structure does not have a jacket. This keyword is only valid in combination with the No Cladding keyword, which must be stated before the occurrence of No Jacket. The jacket refractive index will be set to the refractive index of the cladding (and hence of the matrix), and the cladding and jacket radii will be set to arbitrary values so that the interfaces are beyond the cylinder furthest from the origin. Note that when the cladding and the jacket have same refractive index, fibre automatically replaces the reflection matrix of the cladding/jacket interface by the null-matrix and the transmission matrix of that interface by the identity matrix. The No Jacket keyword supersedes definitions of jacket index and radius: if the No Jacket keyword has been used anywhere before a build fibre statement, the structure will have no jacket, regardless of whether the cladding’s refractive index and radius have been defined elsewhere. Using No Jacket before No Cladding will cause an error message in the error file and FIBRE will stop. (Synonyms: no_jacket, No_jacket, NO JACKET, no jacket, NO_JACKET)

– jacket index = n_J [COMPLEX]: Sets the jacket’s refractive index to n_J . (Synonyms:nj, nJ, n_J, n_j)

– cladding index = n_Cl [COMPLEX]: Sets the cladding’s refractive index to n_Cl. (Synonyms: nc, nC, n_C, n_c)

– cylinder index = n_i [COMPLEX]: Sets the refractive index of all cylinders to n_i. Note that the refractive index of the central cylinder can be defined separately before or after this keyword using central cylinder index, central cylinder epsilon or central cylinder. (Synonyms: ni, nI, n_I, n_i)

– matrix index = n_M [COMPLEX]: Sets the refractive index of the matrix to n_M. (Synonyms: nm, nM, n_M, n_m)

Note that for keywords defining a refractive index or a permittivity, you may also use the character strings ’silica’ (or any other text string including a capital or lowercase ’s’) to use the Sellmeier expansion of silica to define the refractive index.

Action keywords

– save structure = structure file name [CHARACTER STRING]: Writes the current structure to structure file name. The part of structure file name before the last dot will be used as the radix on which all output file names are build, unless a later use of the file name radix redefines this radix. If no structure is loaded in memory (be it through build fibre, load pos file or load bcf file) a warning is written to the error file and the statement is ignored. (Synonyms: write structure, write structure file, save fibre, save fiber)

– Build Fibre (no arguments): This keyword runs the internal structure compiler. All current structure parameters are compiled into a structure (definition, position, radius, refractive index of all cylinders of the structure, of the cladding and the jacket). Before running any simulation, a structure must be defined, either through the internal structure compiler or through loading a position file (with load position file or load bcf file) (Synonyms: Build Fiber, Build Structure, build fibre, build fiber,build structure, make fibre, Make Fibre, make fiber, Make Fiber, BUILD FIBER,BUILD FIBRE, BUILD STRUCTURE, compile fibre, compile fiber )

– load structure file = structure file name [CHARACTER STRING]: Defines a structure by loading the structure file structure file name . See section 2.6 for the syntax of structure files. (Synonyms: structure file, structure, STRUCTURE FILE, structure_file, STRUCTURE_FILE, load fibre, load structure)

Other keywords affecting the fibre structure:

– load bcf file = bessel coefficient file name [CHARACTER STRING] See section 2.5.5 (Synonyms: load mode)