Buyer's Guide … the one with the Encyclopedia!

ABCD matrix

  • Can both single-pass calculations and optical resonators be treated? Linear and ring resonators?
  • Can some ABCD software only calculate the properties of a given design, or can it optimize designs?
  • For optimizations, can I freely define any target function and enter any boundary conditions? (A powerful script language is vital for such things.)
  • Can the software import and export data from calculations and graphics?
  • Can it draw the optical setup, so that I could easily recognize errors in my inputs?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

Note that the software RP Resonator from RP Photonics would fulfill these demands.

acousto-optic modulators

  • Is the aperture sufficiently large for the laser beam?
  • Is the diffraction efficiency high enough?
  • How about the optical losses?
  • For Q-switched lasers: is the damage threshold of the modulator high enough? Is the switching sufficiently fast?
  • What modulator driver can I use? How about cables and connectors?
  • Are the outer dimensions small enough to integrate the modulator into my optical setup?

amplifiers

anti-reflection coatings

  • Does the coating have a sufficiently low residual reflectivity to avoid any problems with the application? Will that also be the case for some range of wavelengths, temperatures and angles of incidence?
  • In the case of difficult substrates (e.g., very small end faces, strongly curved faces): will the coating safely stick to the surface?
  • If the substrate will be subject to large temperature variation (e.g., a nonlinear crystal heated in a crystal oven): are the thermal expansion coefficients of substrate and coating sufficiently similar? (Problems can occur e.g. for crystals with anisotropic expansion.)
  • For use with pulsed lasers: is the optical damage threshold of the coating sufficiently high?

beam profilers

  • Is it a beam profiler based on a camera, or a device with a scanning aperture (moving slit or knife, for example)? Or is it possibly a wavefront sensor, which can also detect the optical phase profile?
  • In what range of optical powers can the profiler work? Will you have to manually mount a suitable optical attenuator? Will you possibly need to buy an additional attenuator? (Note that high-quality attenuators are required, which do not spoil the beam profile.)
  • In which wavelength range can it be used?
  • How large can the beam profile be, and what is the spatial resolution? (More pixels allow you to work in a wider range of beam sizes.)
  • Can the device work with laser pulses?
  • Is it a standalone device, having an own display (how large?), or is it used in connection with a PC or notebook, or possibly with a tablet?
  • Can it easily be mounted and aligned to the beam? Or will you have to align the beam itself? How much space does it require on the optical table?
  • Can it measure quantities like the beam radius in <$x$> and <$y$> direction, based on the <$1/e^2$> criterion and/or the second moment (D4σ method)? Can a constant background be subtracted?
  • Can it measure the whole beam caustic and get the beam divergence, beam parameter product and M2 factor from the data?
  • Can it measure the beam jitter (random movement of centroid or peak position)?

beam propagation software

  • Does the software take into account all relevant effects – e.g., diffraction, chromatic dispersion, nonlinearities, etc.?
  • Is the paraxial approximation used, or can the software deal with arbitrarily large divergence?
  • Can coupled counterpropagating waves be simulated?
  • Can one conveniently define the scenery through which the light propagates?
  • Can you display and store the computed output data in flexible ways?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

dielectric coatings

  • Does the coating have the desired reflectivities at the relevant wavelength – for some range of wavelengths, temperatures and angles of incidence?
  • In the case of difficult substrates (e.g., very small end faces, strongly curved faces): will the coating safely stick to the surface?
  • If the substrate will be subject to large temperature variation (e.g., a nonlinear crystal heated in a crystal oven): are the thermal expansion coefficients of substrate and coating sufficiently similar? (Problems can occur e.g. for crystals with anisotropic expansion.)
  • For used with pulsed lasers: is the optical damage threshold of the coating sufficiently high?

dielectric mirrors

  • Do they have the required reflectivities or transmittivities at all relevant wavelengths for the intended angle of incidence and polarization direction? (Caution: reflectivity spectra change with the angle of incidence and are polarization-dependent, except for normal incidence!)
  • Are they available with the required radius of curvature?
  • Is the optical quality high enough? Consider surface quality (e.g. scratch & dig) and wavefront distortions. Also consider the optical homogeneity of the substrate, which may affect transmitted beams.
  • May the reflection curves change with temperature or moisture?
  • For high-power applications: are there thermal effects due to parasitic absorption and bulging? How about the optical damage threshold?
  • For use ultrashort pulses: Is the chromatic dispersion appropriate?
  • For output couplers: are there parasitic reflections from the back side? Avoid them with an anti-reflection coating there and/or with a wedge shape of the substrate?
  • Are the substrate dimensions (diameter, thickness) appropriate?

double-clad fibers

  • What kind of laser-active dopant do you need – Er3+, Yb3+, Nd3+, Tm3+ or anything else?
  • Can it be a kind of silica fiber, or do you require some specialty glass, e.g. a fluoride fiber?
  • What doping concentration do you need? Alternatively, manufacturers often specify the absorption at some given wavelength(s) – for the core or for the pump cladding.
  • What is the fiber's quality? Is the power conversion efficiency reduced by quenching effects and the like?
  • What is the effective mode area or mode radius of the fiber core? (There are special large mode area fibers.)
  • (For single-mode fibers, the core diameter and numerical aperture are usually not relevant, if the mode area is known.)
  • (The propagation losses are usually not very relevant, except if an unusually long length of fiber is used.)
  • What is the diameter and numerical aperture of the pump cladding?
  • Is the pump cladding circular, elliptical or D-shaped?
  • How tight bending is possible, before the bend losses become too high?
  • How much optical average power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fluoride fibers, for example, have quite different mechanical properties than silica fibers.)
  • Are there fiber couplers available for combining pump and signal inputs, or for separate pump and signal at the end?

Also have a look at the check lists for rare-earth-doped fibers and for general fibers.

electro-optic modulators

  • Is the aperture sufficiently large for the laser beam?
  • Can the wanted modulation be achieved in terms of modulation index, bandwidth, etc.?
  • How about the optical losses?
  • For Q-switched lasers: is the damage threshold of the modulator high enough?
  • Is the switching sufficiently fast? Are there possibly disturbing ringing effects?
  • What modulator driver can I use? (What switching voltage is required?) How about cables and connectors?
  • Are the outer dimensions small enough to integrate the modulator into my optical setup?

femtosecond lasers

  • At what wavelength should it emit – with what precision or stability, and with what bandwidth?
  • What is the required average output power?
  • What is the output beam quality? (It will normally be close to diffraction-limited.)
  • What is the pulse duration, peak power and pulse repetition rate (variable or fixed)?
  • Is the pulse quality high enough concerning time–bandwidth product, temporal pedestals, pre- and after-pulses, and possible side lobes in the spectrum?
  • Will the pulse properties be stable in some range of temperatures and over a longer time?
  • Is the device sensitive to back-reflections? (Will you need a Faraday isolator to protect it? With what degree of isolation?)
  • Are the outer dimensions of the laser source setup and power supply or driver suitable for you?
  • Is the device sufficiently robust? (Does it require realignment after moderate mechanical shocks?)

Fabry–Perot interferometers

  • What free spectral range do you require?
  • What is the required finesse or transmission bandwidth?
  • What is the maximum transmittance?
  • Is the device monolithic, or does it have separate mirrors which need to be aligned?
  • How stable are the resonances? (Thermal drift?)
  • How is it mounted – with fine screws for alignment to the input beam?

fiber Bragg gratings

  • At what wavelength should it reflect light, and in what reflectivity and optical bandwidth?
  • Is it required to have side lobes in the reflection spectrum suppressed? (This is possible with apodized gratings.)
  • Is some of the light reflected into cladding modes?
  • In what kind of fiber is made – a single-mode fiber or a multimode fiber? With what effective mode area or mode radius?
  • Is the chromatic dispersion relevant? (Particularly some chirped fiber Bragg gratings are explicitly used for generating chromatic dispersion.)
  • For application with ultrashort pulses: can it tolerate the relevant peak power without causing nonlinear pulse distortions?

fiber collimators

  • For what kind of optical fiber should it work – single-mode fibers (with that effective mode area) or multimode fibers?
  • Do the fibers have angled or straight-cut ends?
  • What is the required collimated beam radius?
  • What is the operation wavelength or the range of wavelengths? (This is relevant for anti-reflection coatings. For broad wavelength ranges, one should have an achromatic lens in the collimator.)
  • Are integrated adjustment mechanics for the tilt and focusing required? (Otherwise, one may require additional opto-mechanics for moving the whole collimator.)
  • Are the insertion losses low enough?

See also our high-quality tutorial on passive fiber optics!

fiber lasers

  • Are you sure that a fiber laser is better suited for your application than a bulk laser?
  • At what wavelength should it emit – with what precision or stability, and with what bandwidth?
  • What is the required output power?
  • What is the output beam quality?
  • Is the device sensitive to back-reflections? (Will you need a Faraday isolator to protect it? With what degree of isolation?)
  • For systems with pulsed output: what is the pulse duration, peak power and pulse repetition rate (variable or fixed)? Is the pulse quality high enough (concerning time–bandwidth product, temporal pedestals, pre- and after-pulses, side lobes in the spectrum, etc.)?
  • Are the outer dimensions of the laser head and power supply or driver suitable for you?
  • Is the device alignment-free? (Does it contain free space to fiber coupling units, for example, which might be misaligned e.g. as a result of mechanical shocks?)

fiber optics

From our high-quality tutorial on passive fiber optics, you can get a lot of useful background information.

fiber simulation software

  • Does it contain a mode solver?
  • Can one conveniently define all fiber parameters, and take parameter sets from some library containing commercially available fibers?
  • Is it also suitable for active fibers, i.e., for fiber amplifiers and lasers? Does it only have some simplified gain model, or can one define arbitrary level schemes and processes? Can interactions between different ions (e.g., energy transfers) be simulated?
  • Can arbitrarily many different waves (with different wavelengths) interact in the fiber?
  • Can all input waves have time-dependent optical powers?
  • Is it also suitable for waveguides without a radial symmetry, or for bulk lasers?
  • Can one conveniently define the fiber details such as arbitrary refractive index profiles or mode shapes, concentration profiles of laser-active ions or chromatic dispersion?
  • For fiber amplifier models: can amplified spontaneous emission and the noise figure be computed?
  • Can you display and store the computed output data in flexible ways?
  • Can it simulate the propagation of ultrashort pulses, also taking into account chromatic dispersion and various types of nonlinearities, also effects in non-fiber components?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

Note that the software RP Fiber Power from RP Photonics would fulfill these demands.

fibers

For single-mode fibers:

For multimode fibers:

  • What is the core diameter?
  • What is the numerical aperture? (This determines the maximum beam angle with respect to the fiber axis.)
  • What is the core shape – circular, elliptical, rectangular?
  • Is it a pure silica core and a depressed cladding, or a doped core and pure silica cladding? (This might be relevant e.g. concerning parasitic losses or nonlinearities.) There are also plastic optical fibers.
  • For telecom fibers: do you need a graded-index fiber with low intermodal dispersion?
  • What are the propagation losses (in dB/km)? (They are actually mode-dependent, so one cannot expect a simple specification to be precise.)

General aspects:

  • How tight bending is possible, before the bend losses become too high?
  • How much optical power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fluoride fibers, for example, have quite different mechanical properties than silica fibers.)

For active fibers, look at the check list for rare-earth-doped fibers.

See also our high-quality tutorials on passive fiber optics and fiber amplifiers!

large mode area fibers

  • What is the effective mode area or mode radius? (There are special large mode area fibers.)
  • Is the fiber truly single-mode, or does it support a few modes? (In the latter case, careful launching maybe important for the output beam quality, and certain instabilities can occur for operation with very high average output power.)
  • What are the propagation losses (in dB/km)?
  • Does it need to be polarization-maintaining?
  • How tight bending is possible, before the bend losses become too high?
  • How much optical power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?

For active fibers, also look at the check list for rare-earth-doped fibers.

laser crystals

  • Are you sure that you are using the best suited laser crystal material for your application? If not, you may want to consult an expert.
  • Also, before ordering crystals, one should be sure that one is using a proper laser design.
  • Check the required dimensions.
  • Check the doping concentration. Particularly for quasi-three-level gain media, this is quite important. Caution: manufacturers can not always guarantee a high accuracy of the doping concentration.
  • Will the crystal quality be sufficiently high? Possible aspects of relevance: homogeneous refractive index, no clustering of the dopant, impurities, parasitic absorption. (Some materials such as Cr4+:YAG are more critical than e.g. Nd:3+:YAG.)
  • Is the surface quality high enough? For example scratch/dig 10–5 and λ/20 for demanding applications?
  • For non-isotropic materials (e.g., Nd3+:YVO4): what is the proper crystal orientation? How can it be recognized if it is not obvious from the geometry?
  • Do you need anti-reflection coatings on the end faces?
  • For side-pumped lasers: are the sides properly processed (e.g. polished)?

laser diodes

  • What is the required emission wavelength? How precise does it have to be? (There are wavelength-stabilized laser diodes, exhibiting a much reduced temperature dependence of the wavelength, which is otherwise often of the order of 0.3 nm/K.)
  • Do you have to tune the emission wavelength, e.g. via the drive current?
  • Do you require a particularly narrow emission bandwidth, or is a standard bandwidth of a couple of nanometers acceptable?
  • Keep in mind that the output characteristics may be spoiled if the diode gets a substantial optical feedback in your setup.
  • How much output power do you need?
  • For quasi-continuous-wave operation: can the required power be provided for a long enough time? What is the allowed duty cycle?
  • For gain-switched diodes: are the obtained pulses sufficiently short and intense? Are there any after-pulses?
  • Is a high power efficiency (wall-plug efficiency) important?
  • What is the required beam quality in <$x$> and <$y$> direction?
  • Do you need an attached beam shaper for conditioning (e.g., collimating) the output beam?
  • In noise-sensitive applications: what is the relative intensity noise?

laser mirrors

  • Do they have the required reflectivities or transmittivities at all relevant wavelengths for the intended angle of incidence and polarization direction? (Caution: reflectivity spectra change with the angle of incidence and are polarization-dependent, except for normal incidence!)
  • Are they available with the required radius of curvature?
  • Is the optical quality high enough? Consider surface quality (e.g. scratch & dig) and wavefront distortions. Also consider the optical homogeneity of the substrate, which may affect transmitted beams.
  • May the reflection curves change with temperature or moisture?
  • For high-power applications: are there thermal effects due to parasitic absorption and bulging? How about the optical damage threshold?
  • For use ultrashort pulses: Is the chromatic dispersion appropriate?
  • For output couplers: are there parasitic reflections from the back side? Avoid them with an anti-reflection coating there and/or with a wedge shape of the substrate?
  • Are the substrate dimensions (diameter, thickness) appropriate?

laser simulation software

  • Does it contain detailed physical models of laser-active ions, including e.g. quasi-three-level gain media, or only simple models for standard cases like Nd:YAG?
  • Is it suitable for bulk lasers, fiber lasers or both? Can it be used for resonator design?
  • Can it handle arbitrarily time-dependent input powers of pump and signal waves?
  • Can one simulate the shaping or amplification of ultrashort pulses, so that it can be used e.g. for developing mode-locked lasers?
  • Can one import or export all sorts of data, e.g. via files?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

lasers

Before buying any laser, it is important to determine what specifications need to be met for the laser to be suitable for the intended application. Read the article on laser specifications to learn about many essential aspects.

lenses

  • Are they available with the required focal length?
  • Have you checked whether the lens should be biconvex, plano-convex, plano-concave, biconcave, or a meniscus or doublet lens?
  • Is the numerical aperture sufficiently large?
  • Is the optical quality high enough? Consider surface quality (e.g. scratch & dig) and wavefront distortions.
  • Can you use simple spherical surfaces, or do you need aspheric optics, possibly with freeform surfaces?
  • Do you need achromatic lenses for operation in wide wavelength ranges?
  • Do you need anti-reflection coatings? Broadband or high-performance narrowband?
  • For high-power applications: are there thermal effects due to parasitic absorption? How about the optical damage threshold?
  • How to mount the lenses? Is the holder suitable for application with high-power beams (even if they are misaligned)?

multimode fibers

  • What is the core diameter?
  • What is the numerical aperture? (This determines the maximum beam angle with respect to the fiber axis.)
  • What is the core shape – circular, elliptical, rectangular?
  • Is it a pure silica core and a depressed cladding, or a doped core and pure silica cladding? (This might be relevant e.g. concerning parasitic losses or nonlinearities.) There are also plastic optical fibers.
  • For telecom fibers: do you need a graded-index fiber with low intermodal dispersion?
  • What are the propagation losses (in dB/km)? (They are actually mode-dependent, so one cannot expect a simple specification to be precise.)
  • How tight bending is possible, before the bend losses become too high?
  • How much optical power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fibers with unusual dimensions, however, can be problematic.)

Also have a look at the check list for general fibers.

nanosecond lasers

As nanosecond lasers are in most (although not all) cases Q-switched lasers, we use the same check list as for these:

nonlinear crystal materials

  • Are you sure that you are using the best suited nonlinear crystal material and dimensions for your application? If not, you may want to consult an expert.
  • Check the required crystal dimensions.
  • Will the crystal quality be sufficiently high? Possible aspects of relevance: homogeneous refractive index, parasitic absorption.
  • Is the surface quality high enough? For example scratch/dig 10–5 and λ/20 for demanding applications?
  • What is the proper crystal orientation? How can it be recognized if it is not obvious from the geometry?
  • Do you need anti-reflection coatings on the end faces?

picosecond lasers

  • At what wavelength should it emit – with what precision or stability, and with what bandwidth?
  • What is the required average output power?
  • What is the output beam quality? (It will normally be close to diffraction-limited.)
  • What is the pulse duration, peak power and pulse repetition rate (variable or fixed)?
  • Is the pulse quality high enough concerning time–bandwidth product, temporal pedestals, pre- and after-pulses, and possible side lobes in the spectrum?
  • Will the pulse properties be stable in some range of temperatures and over a longer time?
  • Is the device sensitive to back-reflections? (Will you need a Faraday isolator to protect it? With what degree of isolation?)
  • Are the outer dimensions of the laser source setup and power supply or driver suitable for you?
  • Is the device sufficiently robust? (Does it require realignment after moderate mechanical shocks?)

polarization-maintaining fibers

  • What is the cut-off wavelength? (Below that wavelength, the fiber will be multimode.)
  • What is the effective mode area or mode radius? (There are special large mode area fibers.)
  • (The core diameter and numerical aperture are usually not relevant, if the mode area is known.)
  • What are the propagation losses (in dB/km)?
  • How tight bending is possible, before the bend losses become too high?
  • How much optical power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fluoride fibers, for example, have quite different mechanical properties than silica fibers.)

For active fibers, look at the check list for rare-earth-doped fibers.

pulse propagation modeling

  • Is the software suitable for pulse propagation in the relevant media – for example, bulk materials, optical fibers or other waveguides?
  • Can one send the pulses through arbitrary sequences of media, ideally controlled with a script?
  • Can all relevant physical effects be taken into account – e.g. chromatic dispersion, nonlinearities including Raman scattering, etc.?
  • Does it allow one to enter the relevant details of materials and waveguides in a convenient way?
  • Can you define input pulses in simple parametrized forms (e.g., as Gaussian pulses with given energy, duration, center wavelength) and as tabulated data in the time and frequency domain?
  • Can you display and store the computed output data in flexible ways?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

Note that the software RP Fiber Power from RP Photonics would fulfill these demands.

Q-switched lasers

rare-earth-doped fibers

  • What kind of laser-active dopant do you need – Er3+, Yb3+, Nd3+, Tm3+ or anything else?
  • Can it be a kind of silica fiber, or do you require some specialty glass, e.g. a fluoride fiber?
  • What doping concentration do you need? Alternatively, manufacturers often specify the absorption at some given wavelength(s).
  • What is the fiber's quality? Is the power conversion efficiency reduced by quenching effects and the like?
  • What is the effective mode area or mode radius? (There are special large mode area fibers.)
  • (For single-mode fibers, the core diameter and numerical aperture are usually not relevant, if the mode area is known.)
  • (The propagation losses are usually not very relevant, except if an unusually long length of fiber is used.)
  • For double-clad fibers: what is the diameter and numerical aperture of the pump cladding? Is the pump cladding circular, elliptical or D-shaped?
  • How tight bending is possible, before the bend losses become too high?
  • How much optical average power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fluoride fibers, for example, have quite different mechanical properties than silica fibers.)
  • Are there fiber couplers available for combining pump and signal inputs, or for separate pump and signal at the end?

Also have a look at the check list for general fibers and for double-clad fibers.

resonator design

If resonator designs are done by a consultant:

  • Does he or she have a detailed understanding of the relevant physics, including the typically resulting trade-offs, and also practical experience with many laser resonators of different types?
  • Does he or she have powerful software (see below)?
  • Can the alignment sensitivity be taken into account in optimizations?
  • Is the design of unstable resonators possible?
  • If nonlinear frequency conversion is also involved: can the parameters for optimum conversion be computed and taken into account in the design?

Concerning resonator design software:

  • Does it allow one to parametrize designs, i.e., compute details like arm lengths from a set of given parameters, rather than having to enter all details?
  • Does it allow for sophisticated optimizations, e.g. with arbitrary merit functions to take care of detailed requirements including boundary conditions, and can it use the Monte-Carlo method or similar?
  • Can it compute the alignment sensitivity of a resonator and take that into account in optimizations?
  • Can it draw the resonator setup, so that one can easily notice errors in the inputs?
  • Would it be possible to generate arbitrary plots in order to visualize all relevant properties?
  • Does it offer a script language with which one can control various aspects, e.g. mathematically process input and output data?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

Note that the software RP Resonator from RP Photonics would fulfill these demands.

semiconductor lasers

  • What is the required emission wavelength? How precise does it have to be? (There are wavelength-stabilized laser diodes, exhibiting a much reduced temperature dependence of the wavelength, which is otherwise often of the order of 0.3 nm/K.)
  • Do you have to tune the emission wavelength, e.g. via the drive current?
  • Do you require a particularly narrow emission bandwidth, or is a standard bandwidth of a couple of nanometers acceptable?
  • Keep in mind that the output characteristics may be spoiled if the diode gets a substantial optical feedback in your setup.
  • How much output power do you need?
  • For quasi-continuous-wave operation: can the required power be provided for a long enough time? What is the allowed duty cycle?
  • For gain-switched diodes: are the obtained pulses sufficiently short and intense? Are there any after-pulses?
  • Is a high power efficiency (wall-plug efficiency) important?
  • What is the required beam quality in <$x$> and <$y$> direction?
  • Do you need an attached beam shaper for conditioning (e.g., collimating) the output beam?
  • In noise-sensitive applications: what is the relative intensity noise?

single-mode fibers

  • What is the cut-off wavelength? (Below that wavelength, the fiber will be multimode.)
  • What is the effective mode area or mode radius? (There are special large mode area fibers.)
  • (The core diameter and numerical aperture are usually not relevant, if the mode area is known.)
  • Does it need to be polarization-maintaining?
  • What are the propagation losses (in dB/km)?
  • How tight bending is possible, before the bend losses become too high?
  • How much optical power can the fiber tolerate? (Additional properties at the launch end may still occur if too much power gets to the coating.)
  • What is the outer fiber diameter with and without protective coating?
  • What is the coating material? Is it a standard material which can be removed with a usual fiber stripper?
  • Can the fiber be cleaved with a standard fiber cleaver? (Fluoride fibers, for example, have quite different mechanical properties than silica fibers.)

For active fibers, look at the check list for rare-earth-doped fibers.

thin-film design software

  • Can one conveniently define arbitrary sequences of layers?
  • Can one parametrize such layer sequences – e.g., in order to easily implement systematic variations of layer thickness or refractive index?
  • Can new materials with arbitrary chromatic dispersion be defined, e.g. using a Sellmeier formula?
  • Can active media (i.e., with laser gain) be treated?
  • Can it compute all properties of interest – for example, amplitudes and phases of transmitted and reflected light, chromatic dispersion for transmitted and reflected light, field distributions in the structure, etc.?
  • Would it be possible to generate arbitrary plots in order to visualize all relevant properties?
  • Does it offer a script language with which one can control various aspects, e.g. mathematically process input and output data?
  • Can it optimize a structure such that an arbitrarily defined figure-of-merit function is minimized?
  • Can it import data from a spectrometer, e.g. in order to display measured and computed reflectivity curves together?
  • Can it produce output files for controlling a coating machine?
  • Does it come with proper documentation and a comprehensive online help system?
  • Is competent technical support available?

Note that the software RP Coating from RP Photonics would fulfill these demands.

waveplates

  • What retardance do you need – λ/2, λ/4 or anything else, for what wavelength(s)?
  • Will a simple multi-order waveplate be sufficient, or do you need a (true or effective) zero-order waveplate, which can be operated in a much wider wavelength range? (There are also achromatic waveplates for particularly wide wavelength regions.)
  • Should it have anti-reflection coatings – for what wavelengths?
  • Is the surface quality high enough?
  • For use with pulsed lasers: is the optical damage threshold sufficiently high?
  • Might operation in a wide temperature range be a problem?

YAG lasers

(The check list for Q-switched lasers contains additional details in the context of pulse generation.)

END