14-Pin Butterfly Packages: Selection for DFB, TOSA, and Tunable Lasers

When engineers pick a 14-pin butterfly over TO56/TO60 — pin field, fiber coupling, TEC integration, hermetic sealing, and how submount choice fits inside the shell.

14-pin side-mount butterfly hermetic package outline

Quick answer

The 14-pin butterfly is the standard flat hermetic housing for fiber-coupled DFB modules, TOSA/ROSA builds, and external-cavity tunable lasers. It beats TO headers when you need pigtail routing, monitor photodiode pins, and internal TEC — at the cost of flex-based assembly and a larger footprint.

Why the 14-pin butterfly exists

Telecom and photonics teams standardized the butterfly footprint decades ago because round TO cans could not cleanly route fiber pigtails, flex circuits, and TEC wiring for C/L-band modules. The 14-pin variant is the workhorse for DFB transmitters, external-cavity tunable lasers, and many TOSA/ROSA assemblies — enough pins for laser, monitor photodiode, thermistor, and TEC without custom feedthroughs every time.

Product page with catalog outlines and quote form:

FerraLink 14-pin butterfly

14-pin butterfly vs TO vs BOX

Factor	14-pin butterfly	TO56 / TO60	BOX cavity
Integration	Flex + fiber pigtail	PCB socket	Hybrid bench / custom
TEC	Common internal pocket	Optional	Flexible floor
Fiber	Built-in feed-through / side window	Cap window only	Custom lid optic
Typical λ	C/L-band telecom, 1550 nm lidar	Pump, industrial, sensing	Bar stack, multi-die
Submount role	Spreader tile on floor	Small slug in stem	Large floor tile

TO selection detail: to-header-selection-guide. Lidar hermetic context: hermetic-packaging-for-lidar.

Application: external-cavity tunable laser

Narrow-linewidth tunable sources need stable chip temperature, isolation optics, and a fiber exit that survives field life. The 14-pin butterfly packages TEC, thermistor, and monitor paths in a footprint burn-in fixtures already understand — which is why tunable laser programs often start from a standard shell rather than inventing a new box.

Thermal stack inside the shell

Junction temperature is set by the submount and attach under the die — not the butterfly lid alone. Telecom DFB builds frequently use AlN submounts for CTE match; higher-flux or pulsed programs may move to SiC spreading. Specify AuSn vs epoxy attach and cold-side flatness before locking pad geometry.

Material comparison: aln-vs-sic-submounts. Free drawing review: DFM review.

What to send for a butterfly RFQ

Operating wavelength band and window AR requirement
Pin assignment (laser, MPD, TEC+, TEC−, thermistor)
Fiber type (SM/PM), exit angle, and bend-radius keep-out
Die size, submount material preference, and attach process
Target leak rate and operating temperature range

Short quote form:

14-pin butterfly quote

or full package RFQ.

Gap

Your ERP socket, flex vendor, and fiber supplier — share the pin map and we align outline, window, and submount footprint before production quote.

The part that depends on your die

The rules above hold for most edge-emitter modules. What changes from program to program is geometry, duty cycle, and how hard you are pushing junction temperature — those inputs decide material, thickness, and whether catalog samples are enough.

Module outline, leak rate, and window transmission for your wavelength.
TEC vs uncooled budget for your channel plan.
Submount choice inside the full hermetic stack.

Go deeper — Package context

These guides answer adjacent questions teams ask while choosing a submount. Each ends the same way: what you can decide in general, then what needs your die and power.

More topics coming — thermal path, attach yield, qualification, and packaging context.

Frequently asked questions

What is a 14-pin butterfly package used for?expand_more

Fiber-coupled DFB and tunable laser modules, telecom TOSA/ROSA, and coherent datacom engines that need 14 DC connections, TEC routing, and a hermetic fiber exit.

Who supplies 14-pin butterfly housings?expand_more

FerraLink quotes industry-standard 14-pin butterfly and BOX-side-mount outlines with submount and DFM support — see /products/14-pin-butterfly for catalog starting points and RFQ.

AlN or SiC submount inside a butterfly?expand_more

InP/GaAs DFB dies often start on AlN for CTE match; higher-power or uncooled variants may use SiC spreading tiles. Match metallization to your AuSn or epoxy attach before fixing footprint.

Product catalog

Browse hermetic package outlines

FerraLink supplies TO headers, butterfly modules, cavity housings, and optical windows — quoted per outline with engineering support.

Request package quote Hermetic packages catalog TO headers & laser bases Butterfly & cavity packages Optical windows & caps

Next step

Validate your stack in the Submount Advisor

Free

Work email unlocks free thermal validation on your die size — part number, failure screening, and spec PDF in ~30 seconds.

Thermal profileJunction temperature & 3D steady-state field for your die geometry
Failure screeningIndicative AuSn fatigue, die stress, and warpage before you lock the BOM
Any footprintEnter dimensions — part number & stack layout generated in real time
Spec sheet PDFQuote-ready export included with your advisor session

Open advisor — free Order samples

Your dimensions → thermal field → part number & spec PDF

What most teams do next on a submount program

At some point the work stops being “which material in general” and becomes a drawing, a first lot, and attach data on your line. Where you are in that sequence usually picks the path — not a package brochure.

1
You already have a drawing you trust
Stack is frozen — maybe a repeat build, maybe a straight swap on geometry you have run before. You send the drawing (or catalog part number), we build to print, and you qualify on the bench or go straight to a pilot quantity.
Fits: AlN or SiC submounts, pre-deposited AuSn, standard copper DPC.
Usually fits when: Best when you are comfortable owning the stack and only need parts.
$50–$500 · 2–4 weeks
Order samples or request a build quote →
We’ll confirm drawing fit, pricing, and lead time before you commit.
Next step: Upload your drawing (DXF, Gerber, or STEP) or paste a catalog part number on the RFQ form — we reply within about two business days with quote and lead time.
Browse catalog evaluation samples →
2
You are changing material or stack details — want a drawing and feasibility check first
Common when moving from an AlN reference to SiC (or the other way): same rough intent, different conductivity, pad rules, and thickness. You may have an old drawing that does not translate literally. Here teams usually want a conversion layout, thermal/stress screening against your power and cycling targets, and a clear pass/fail before they cut metal or commit to a large sample order.
Usually fits when: Typical first project with us when the stack is new to your team or to SiC/AlN in this footprint.
from $2,500 · 2–3 weeks
Most first-time engagements land here. After you have a released drawing and data from us, repeat builds are usually drawing-in — no second study unless the die or duty cycle moves.
If you’ve run Submount Advisor, attach the export or paste the summary so we start from the same scenario.
Request Focused Analysis scope & quote →
Fixed-scope SOW and price before engineering starts.
Next step: Send your existing drawing or target die size + peak power on the intake form — we return a written scope and fixed price for the study.
3
The die or program is still moving — you need a development plan
Emitter geometry, power level, or reliability targets are not fixed yet. You need a DOE plan (what to build each run and why), analysis between runs, and drawings that stay inside our process window — scoped as a multi-run program on top of sample and NRE costs.
Usually fits when: When iteration and test planning are the bottleneck, not a single drawing release.
$10,000+ (scoped) · 6–10+ weeks
Discuss a DOE + first-build plan →
Scoped program plan and budget before any build slots are reserved.
Next step: Share a short brief (die, power, what you’re trying to learn) — we’ll schedule a 15–30 min call or reply by email with a proposed DOE outline and ballpark.

Still narrowing AlN vs SiC before any drawing work? Stack Scoping ($750–$1,250) is a lighter memo — material pick and geometry bands only, without full feasibility sign-off.

Not sure which bucket you are in? Send what you have — past drawing, Advisor export, or a short note on die and power — and we will point you to the smallest step that actually moves the program. Contact engineering