Booster Optical Amplifiers (BOAs), 785 nm

  • Polarization-Dependent Booster Optical Amplifiers (BOAs)
  • SM-Fiber-Pigtailed Butterfly Package
  • 775 nm ASE Center Wavelength

FC/APC Connectors

Close-up of Butterfly Package


BOA with SM Fiber and
FC/APC Connectors

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  • Amplifying Polarized Laser Signals Around 785 nm
  • Amplifying Widely Tunable Lasers Around 785 nm
The center wavelength of a BOA can be readily tailored for specific applications. It is quite common to adjust the BOA wavelength spectrum to match the specific laser source. Please contact us if you have custom wavelength requirements for pilot-projects or OEM applications.
Internal Diagram
Click to Enlarge
When current is applied across the ridge waveguide, excited state electrons are stimulated by input light, leading to photon replication and signal gain.


  • Polarization Dependent: Amplifies One Polarization State
  • 1.5 m Long, SM Fiber Pigtails with FC/APC Connectors
  • Small Signal Gain: 17 dB (Typical)
  • Saturation Output Power: 16.5 dBm (Typical)
  • 3 dB Bandwidth: 28 nm (Typical)
  • Each End Face of the Semiconductor is AR Coated (R < 0.1%) to Prevent Lasing

Booster Optical Amplifiers (BOAs) are single-pass, traveling-wave amplifiers that perform well with both monochromatic and multi-wavelength signals. Since BOAs only amplify one state of polarization, they are best suited for applications where the input polarization of the light is known. This BOA consists of a highly efficient GaAs Quantum Well (QW) layer structure, which is designed for amplifying polarized optical signals around 785 nm and is also an ideal gain medium for implementing wide-bandwidth tunable lasers.

As seen in the schematic to the right, the input and output of the amplifier are coupled to the active layer of the ridge waveguide on the optical amplifier chip. The device is contained in a standard 14-pin butterfly package, with either single mode or polarization-maintaining fiber pigtails that are terminated with FC/APC connectors. The BOA785S uses single-mode, non-polarization-maintaining 780HP fiber. An integrated thermoelectric cooler (TEC) and thermistor allow this BOA to be temperature controlled, thus stabilizing the gain and the spectrum.

For additional details concerning the construction and operating parameters of our BOAs, please see the Optical Amplifiers tab.

Recommended Driver
The CLD1015 butterfly LD/TEC controller is recommended to control these amplifiers. This LD/TEC controller and mount combination offers full control via a touch screen. When operating these optical amplifiers with the CLD1015, the orientation for type 1 pin configurations should be used.

ASE Center Wavelength
The center wavelength (CWL) of the amplified spontaneous emission (ASE) spectrum in broadband semiconductor devices, such as optical amplifiers, may show variation between lots. Please refer to the blue icons (info) below for the CWL tolerances of each particular model. For applications in which a specific ASE center wavelength is a critical concern, please contact Tech Support for information on the CWL of currently available lots.

Item #a Info Center
Operating Current
3 dB
Saturation Output
Power (@ -3 dB)c,d
Small Signal Gain
(@ Pin = -20 dBm)c,d
Noise Figurec,d Fiber Type
BOA785S info 775 nm 325 mA 28 nm 16.5 dBm 17 dB 9.5 dB 780HP
  • All specifications are typical unless otherwise noted.
  • This is the center wavelength of the amplified spontaneous emission (ASE), and is not necessarily the operating wavelength. An operating wavelength of 785 nm was selected for testing to yield the specified saturation output power.
  • Measured at 785 nm
  • Measured at the Operating Current
Comparison of a SOA to a standard Fabry-Perot Laser Diode

Booster optical amplifiers (BOAs) and semiconductor optical amplifiers (SOAs) are single-pass, traveling-wave amplifiers that perform well with both monochromatic and multi-wavelength signals. Since BOAs only amplify one state of polarization, they are best suited for applications where the input polarization of the light is known. For applications where the input polarization is unknown or fluctuates, a Semiconductor Optical Amplifier (SOA) is required. However, the gain, noise, bandwidth, and saturation power specifications of a BOA are superior to that of a SOA because of the design features that make the SOA polarization insensitive.

BOAs and SOAs are similar in design to Fabry-Perot Laser Diodes, the difference being that Fabry-Perot laser diodes have reflective coatings on both end faces of the semiconductor chip. The optical feedback from the reflective end faces establishes a cavity in which lasing can occur. SOAs and BOAs have an anti-reflection (AR) coating on both end faces of the semiconductor chip. The AR coatings limit the optical feedback into the chip so that lasing does not occur.

As is typical for all amplifiers, BOAs/SOAs operate in two regimes: a linear, flat, constant gain regime and a non-linear, saturated output regime. When used to amplify a modulated signal, the linear regime is typically used to eliminate pattern-dependent distortion, multi-channel cross-talk, and transient response issues common to EDFAs. The non-linear regime is used to take advantage of the highly non-linear attributes of the semiconductor gain medium (cross-gain modulation, cross phase modulation) to perform wavelength conversion, optical 3R regeneration, header recognition, and other high-speed optical signal processing functions.

For a continuous wave input signal, the amount of power that can be produced by the amplifier is determined by the saturation output power (Psat) parameter. Psat is defined as the output power at which the small-signal gain has been compressed by 3 dB. The maximum amount of CW power that can be extracted is approximately 3 dB higher than the saturation power.

SOA Linear vs Non-linear Regimes

Posted Comments:
Martin Henriksen  (posted 2023-03-16 12:52:23.12)
Hi Thorlabs Is it possible to get the BOA785S in a polarization maintaining version? Kind regards Martin NKT Photonics
jdelia  (posted 2023-03-16 01:12:46.0)
Thank you for contacting Thorlabs. I have reached out to you directly to discuss the feasibility of this custom request. For future custom requests, you can reach out to us at
Dong IL Lee  (posted 2022-12-19 20:34:17.323)
*Revised; Hi, does this BOA785S can be operated with the LD/TEC controller of ITC4001 or ITC502 along with the LM14S2?
Dong IL Lee  (posted 2022-12-19 20:24:27.69)
Hi, does this BOA785S can be operated with the LD/TEC controller of ITC4001 or ITC502?
ksosnowski  (posted 2022-12-21 11:13:49.0)
Thanks for reaching out to Thorlabs. BOA785S can be operated with both of these controllers, ITC502 however would limit the drive current to 200mA. ITC4001 can supply 1A, which is sufficient for BOA785S which has a maximum operating current of 325mA.
Sylvain DE LESELEUC  (posted 2022-02-18 18:26:44.97)
Hi, Would it possible to have the BOA785 with PM fiber? Cheers, Sylvain
ksosnowski  (posted 2022-02-18 01:55:15.0)
Thanks for contacting us Sylvain, we may be able to offer this BOA with PM fiber as a special item. I am reaching out to discuss your application further.
Dong IL Lee  (posted 2022-01-23 21:36:16.693)
Dear Thorlabs company, I have a few questions and have listed them below, 1. Does the BOA support bi-directional amplifying? I am trying to use it bi-directionally(ex. Left -> Right, Right -> Left at the same time). Is it possible to use it like that? If yes, would the amplified power follow the description in the spec sheet? (ex. the saturation output power of 16.5 dBm) 2. Does the polarization controller must be required to use BOA? Thanks for the consideration Dong IL Lee
YLohia  (posted 2022-01-24 03:25:20.0)
Thank you for contacting Thorlabs. Unfortunately, this BOA is not bi-directional. The input and output side of BOA chip design is different to ensure reliable higher power operation on the output side (using a tapered waveguide design). We don’t characterize the performance in the other direction. In general, you will see lower saturation power, lower gain, and higher noise figure when you use the BOA in the other direction. A polarization paddle controller is recommended for this particular BOA since the input fiber is SM (which has an affect on the input polarization state) and the BOA is a polarization-sensitive device. Not using a polarization controller on the input would yield an unstable output and a time-varying gain.

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+1 Qty Docs Part Number - Universal Price Available
BOA785S Support Documentation
BOA785S785 nm Booster Optical Amplifier, 16.5 dBm, Butterfly Package, SM, FC/APC