Frequently Asked Questions

What is the linewidth of your DFB lasers?
The typical linewidth of our DFB laser diodes is < 3 MHz (@20 ms). It is typically characterized by a self-heterodyne linewidth measurement.

What is the typical current tuning range of your DFB laser diodes?
The typical current tuning range is specified with +/- 0.4 nm. Larger tuning is very likely, but it is not warranted for each device. If you need a higher tuning range, please contact us: we are happy to advise you.

What is the typical tuning frequency of your DFB lasers?
Typically it is 5-10 kHz. Some 10’s of kHz are possible, but with higher tuning frequency, the total wavelength tuning will eventually drop down to zero. At 10 kHz tuning frequency this wavelength responsivity is about 40 % of the cw value.

What is the coherence length of your DFB lasers?
The coherence length is > 100 m.

What are the dimensions of the active area of the laser chip that emits light?
The dimension of the active area is approx. 4 µm x 1 µm. It is difficult to draw a line here for measurement, since the area around it (the cladding waveguide) might also contain some light.

If the datasheet lists a minimum optical power to e.g. 5 mW - do you have an estimate of typical power, or a specification for the maximum power?
In this case 5 mW is the minimum output power we guarantee for the ordered wavelength you require. Typically the power may be 5mW, but it is normally few mw higher, especially at higher currents. The maximum power is not specified. Higher power may be possible on request: please ask us.

What is the typical beam divergence of your DFB lasers?
As the divergence angle differs a little from batch to batch (strongly dependent as well on the size of the active zone), we do not specify this value. Typical values are in the order of 20°…40° (FWHM) in slow and 40°…60° in fast axis. But they may exceed these values, so if you are not sure what lens to use, ask us about collimation or let us recommend a lens!

What is the safety classification of your laser?
In general, you must neither with your eyes nor with optical instruments look directly into the laser beam! Please note, that the emitted laser light is invisible and may damage your eye. The classification depends on various factors, like wavelength, packaging (fiber coupling, collimation), operation point etc.
Basis for classification is the DIN EN 60 825-1 norm. Accordingly, our lasers range from class 1 to class 3, whereas most are classified class 3B. For detailed information you should refer to the respective datasheet. The laser class on the datasheet is only valid for use within the specified operational conditions. If you need further information, please contact us.

Can the LDs and ICLs be operated in cw as well as in pulsed mode?
Our lasers are specified for operation in continuous wave mode. If a laser can be operated in cw mode it also can be pulsed, but not vice versa. We do not have any specifications for pulsed mode. Please contact us in case you desire to pulse our devices.

Which absorption line should I choose for my application?
Have a look at our section "Applications by Gas“ to compare the specifications of matching wavelengths for various gases. You can also check the HITRAN database as linked in out tool section, have a look at the many scientific papers of our customers or ask us for detailed advice.

What is the lifetime of your lasers?
Our lasers have a guaranteed lifetime of > 8000 h. But our long experience shows expected lifetimes exceed 20,000 h.  

Can I operate the laser beyond max. operating parameters?
You should not try this without advice! The probability that the laser will break down is too high. The warranty expires as well. If you have any questions about the recommended operating parameters have a look at our data sheets or contact us for help. We have details of all devices in our database, so in case you need to make slight changes: we will know if it is safe or not.

What is the collimation lens made of?
We mostly use Lightpath lenses. In the range from 600 nm to 1800 nm they are made of D-ZK3 glass. Beyond 1800 nm they are made of a GeSbSe composed glass, called BD-2. Depending on the wavelength the lenses also get a special coating.

Is the lens collimation system designed to take into account the presence of a laser window?
Yes, our collimation system takes window aberrations into account. To optimize the collimated beam profile, our calculations are based on the beam divergence angles after the light has passed the window.

What is the performance loss of the laser beam after collimation?
After collimation, the laser beam will have a loss of approx. 20 - 40 %. Let us know what power you require!

Can I adjust the lens of a collimated TO5 / TO66 cube in x/y/z axis?
No, the lens is fixed after we collimated it. Inform us before purchase if you want to adjust the optics. We will adapt our setup and provide you with a tool to modify the z-Axis. Please keep in mind, that you lose any guarantee on the collimation in that case. Though you still have warranty on the laser, of course. Have a look at our TO66 collimation module. It offers the advantages of a collimated beam.

From which material are the windows made of?
The material of the window depends on the laser wavelength:
760 nm to 2700 nm: D263 glass
2700 nm to 5200 nm: undoped YAG crystal
> 5200 nm: ZnSe CaF₂-window

Do you have any information on the transmittance characteristics of D263 glass?
Our vendor indicates a luminous transmittance of > 92 %.

What does "CAP" refer to in the quote?
"CAP" refers to the cap that will be placed onto the TO5, TO66 or TO5.6 housing. The cap is available with or without window. We are using caps with interior AR coating for the TO5 and TO66 headers. Visit our packaging section. In the rubric accessories you will find a description of the available caps.

What are the advantages and disadvantages of a cap with window / cap without window?
If you choose the cap without window, you will have a mechanical protection of the laser and avoid optical noise from the window. However, the laser will not be protected from all outer influences. Since the noise introduced by the window is marginal, we strongly recommend using an AR-coated window. If you choose the cap with window, the laser will be mechanically protected and, very important, hermetically sealed. The laser chip will be protected from any outer influences, such as moisture, oxygen or dust. Please refer to our packaging section for detailed technical drawings and dimensions of the mountings.

Is it possible to order the laser without the window?
Yes, you can order the laser with a cap without window. But you will have to be extremely careful to protect the laser chip from impacts like dust, water vapour or oxygen. That is why we recommend using a window. We offer AR coated windows for our TO5 and TO66 housings to avoid fringes. In this way, you benefit from the advantages of a hermetically sealed package while having least impact on the laser beam. For the TO5.6 housings there is no AR coating available, the window is just for protection.

How good is the AR coating on the laser window?
The AR coating on the window is always optimized for a certain wavelength range. The covered range is from approx. 760 nm to 2700 nm by a kind of glass named D263. The reflectivity is < 0.5 %. Optical fringes are marginal.

Do all lasers need to have a temperature control system and a heatsink?
Yes, a temperature control system is essential for the thermal management of the laser. Our DFB lasers guarantee stable wavelength emission at a specified operating temperature. We recommend actively controlling the laser temperature by installing a temperature control system in your setup. Design a proper heatsink!! Ask us for assistance in case you are unsure. Please have a look at our TO5, TO66 or SM butterfly and PM butterfly mounts. These packages are equipped with a TEC and NTC. You might also wish to check our TO5 and TO66 heatsinks. They facilitate the heat removal and provide connectors for laser diode driver and temperature controller as well as M6 threads for optical posts. You can use them with any standard cage system. To compare the various packages visit our packaging section.

For which wavelengths are SM and PM fiber coupled butterfly packages available?
For SM fiber coupled lasers we use fibers with an integrated lens on the fiber tip. These types of fibers are available for all wavelengths as described in our packaging section. For PM fibers we need to install isolators and two AR-coated lenses. These will be different for every wavelength – which is the root cause why only a few wavelengths are offered PM-coupled. Please ask us if you need another wavelength coupled.

Do your housings already have an isolator?
Isolators are required only if you have moderate or strong optical feedback into the chip. We equip our PM fiber coupled butterfly housing with isolators. PM butterfly packages with integrated optical isolators are available at the wavelengths mentioned above. For further wavelengths please contact us.

I already have a laser diode set which includes diode mounts, temperature controller, current controller and detector. Do I need any of the additional laser packaging options in the quotation?
If the mount matches our packaging, you are able to use the existing mounts and drivers.

Which driver can I use?
For LDs and ICLs we use e.g. the TTC001 and KLD101 system from Thorlabs. You may purchase them directly from Thorlabs or from us: we will do the pre-installation for you. Alternatively RedWaveLabs is manufacturing OEM-electronics and claim to have experience with our devices: we recommend to contact them directly.

What could be the source of noise (driver, fringes, …) in my system?
Noise may occur from the DFB laser itself (baseline noise), but most of the times it comes from the driver and the TDAL-setup. A good description of sources of noise and the design of your system can be found here [104, 105].

Do you have drawings of the cage system?
For technical drawings of the cage systems, kindly contact the respective manufacturers. Our datasheet for the TO5 and TO66 heatsinks shows the specifications and dimensions of the cube as well as of the electric connectors and M6 threads.

What should I do if problems with a laser occur and I want to send a laser back?
If you experience any problems with one of our lasers please contact our sales team. They will give you advice whether and how you can send the laser back to us.

Do you have a distributor in my country?
Due to the fact that our products are used all over the world, we work together with several qualified sales partners for better service. Distributors are listed on the company section.  

I have a special idea, but I cannot find this product on the market, what should I do?
Contact the technology leader for a customized product!

Your devices are too expensive!
No, they are not: You have to look at the cost of ownership, of course! Imagine you have devices in the field and they got returned from your customer because the laser quality failed. Or you have to face changing specifications from one batch to the next. Or a telecom-sponsored vendor loses interest in a side-product. Or… there are so many reasons why you should contact us and not only look at the cheapest offer on the market. A quick call or email with nanoplus before your purchase elsewhere will help you to make a good decision – even if against us. Sometimes we would even recommend purchasing at our competitors: yes, some of them also have good products …do not tell our CEO we said that. :o)