Superluminescent Diode (SLD) Light Sources for OCT Systems

Overview
Specs
Resolution SD-OCT
Package Diagram
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The SLD1325 Superluminescent Diode Mounted in a CLD1015 Compact Laser Diode Driver with TEC

Features

SLDs Optimized for Use in Spectral Domain OCT Systems
830, 880, 1050, or 1325 nm Center Wavelength
FC/APC-Terminated Fiber Pigtail Minimizes Optical Feedback
Integrated TEC and Thermistor for Temperature Control
Hermetically Sealed 14-Pin Butterfly Package

Superluminescent Diodes (SLDs) are the light source of choice in Spectral Domain Optical Coherence Tomography (SD-OCT) imaging. The broad spectrum and short coherence length of the emitted light improves the depth resolution in OCT images. Thorlabs offers SLDs designed for OCT applications with center wavelengths of 830, 880, 1050, or 1325 nm. Each device is built into a 14-pin butterfly package with an integrated thermoelectric cooler (TEC) and thermistor to ensure output stability. The output is coupled into an SM fiber terminated with a 2.0 mm narrow key FC/APC connector. Each SLD is shipped with an individualized product data sheet, which includes information on the spectrum and operating parameters of the device. Raw test data for each SLD is also available upon request; please contact Tech Support with inquiries. For more details about each SLD, please see the Specs tab.

Thorlabs is able to provide low-ripple SLDs with custom wavelengths or higher power diodes. Please note that the engineering design and wafer manufacturing costs involved make the purchase of low quantities very costly. For a quote on custom SLDs, please contact Tech Support.

The SLDs featured on this page have either a near-gaussian or flat-top optical spectrum. The calculation for the center wavelength differs with these two spectral shapes. Please see the Specs tab for center wavelength calculations.

Operation Guidelines
We strongly recommend adherence to the operating conditions marked on each package. While optimal performance is achieved by utilizing the recommended settings, we recognize users can adjust the spectral characteristics of the SLD by deviating from these recommended settings. For instance, operating at lower temperatures will cause a shift of the central wavelength to shorter wavelengths. It is imperative, however, that as the temperature is reduced, the injection current is also reduced so as not to exceed the recommended output power if one is noted on the data sheet that is included with the SLD.

These SLDs should be operated at a constant current and temperature, which is relatively simple with the proper SLD mount and drivers. To mount and drive these SLDs, Thorlabs recommends using a ITC4000 Series Laser Diode Driver with the LM14S2 Mount.

As with most active semiconductor devices, standard anti-static handling procedures must be adhered to in order to prevent an electrical discharge that could destroy the device.

Due to the nature of producing superluminescent diodes with ultra wide bandwidth, some of the SLDs sold below have spectral shapes that are near gaussian, while others have a shape with a flattened top. This difference in spectral shape demands two different methods of defining center wavelength in order to provide an accurate description of the diode.

Near-Guassian Center Wavelength Definition
The center wavelength for devices with a near-gaussian spectral shape is defined by an average weighted by the relative amplitude and may not correspond to peak power or the FWHM center wavelength due to the variability of the spectrum shape. For a given Optical Spectrum Analyzer (OSA) trace:

Weighted Average

where

CW is the Specified Center Wavelength
X_i is the Wavelength of a Trace Data Point
Y_i is the Amplitude of a Trace Data Point

Flat-Top Center Wavelength Definition
The center wavelength for devices with a flat-top spectral shape is defined by the midpoint between the two wavelengths located at 3 dB below the maximum intensity point on the spectrum. For a given OSA trace:

Weighted Average

where

CW is the Specified Center Wavelength
X_{R_3dB} is the Right Wavelength Edge of the 3 dB Bandwidth
X_{L_3dB} is the Left Wavelength Edge of the 3 dB Bandwidth

SLD Specifications

Note, these specifications are given as guidelines. The characterization sheet shipped with each SLD provides the min, max, and recommended operating parameters and specifications specific to that device. The ASE Power specification is the output from the fiber pigtail.

830 nm Superluminescent Diodes

Item #	SLD830S-A10W			SLD830S-A10			SLD830S-A20
Parameter^a	Min	Typical	Max	Min	Typical	Max	Min	Typical	Max
Center Wavelength^b	815 nm	830 nm	845 nm	820 nm	830 nm	840 nm	820 nm	830 nm	840 nm
Spectral Shape	Flat Top			Near Gaussian			Near Gaussian
Operating Current	-	-	240 mA	-	-	150 mA	-	-	240 mA
ASE Power^c,d	10 mW	-	-	10 mW	13 mW	-	20 mW	22 mW	-
Optical 3 dB Bandwidth^c,e	50 nm	60 nm	-	17 nm	20 nm	-	17 nm	20 nm	-
Optical 20 dB Bandwidth^c	-	-	-	-	50 nm	-	-	50 nm	-
RMS Gain Ripple^c,f(Click for Plot)	-	0.06 dB	0.3 dB	-	0.03 dB	0.15 dB	-	0.03 dB	0.15 dB
Forward Voltage^c	-	2.0 V	2.5 V	-	2.0 V	2.5 V	-	2.0 V	2.5 V
TEC Operation: Typ. / Max @ T_CASE = 25 °C / 70 °C
TEC Current	-	0.14 A	1.4 A	-	0.1 A	1.5 A	-	0.1 A	1.5 A
TEC Voltage	-	0.18 V	6.0 V	-	0.13 V	4.0 V	-	0.13 V	4.0 V
Thermistor Resistance	-	10 kΩ	-	-	10 kΩ	-	-	10 kΩ	-
Absolute Maximum Ratings^a
Absolute Max Current	240 mA			150 mA			240 mA
Operating Case Temperature	0 to 70 °C
Storage Temperature	-10 to 70°C
Pin Code	14 Pin, Type 1
Fiber Specifications
Fiber Type	780HP
Numerical Aperture	0.13
Core Diameter	4.4 µm
Mode Field Diameter (Nominal)	5.0 ± 0.5 µm @ 850 nm
Fiber Length	1.5 m
Connector	FC/APC, 2.0 mm Narrow Key

These Operating Specifications are a consistent set of values which will yield the specified performance. Please note that exceeding the Absolute Maximum Ratings in the table may cause device failure.
Center wavelength is defined based on the spectral shape of each device; see the definitions above.
At Operating Current
Corresponds to the output of the fiber pigtail.
For SLD830S-A10W: At the minimum ASE power, the minimum 3 dB bandwidth is guaranteed.
Measurement Resolution = 0.02 nm

880 nm Superluminescent Diodes

Item #	SLD880S-A7			SLD880S-A25
Parameter^a	Min	Typical	Max	Min	Typical	Max
Center Wavelength^b	860 nm	880 nm	900 nm	860 nm	880 nm	900 nm
Spectral Shape	Flat Top			Flat Top
Operating Current	-	-	225 mA	-	-	410 mA
ASE Power^c,d	6 mW	7 mW	-	23 mW	25 mW	-
Optical 3 dB Bandwidth^c	35 nm	40 nm	-	35 nm	40 nm	-
Optical 20 dB Bandwidth^c	-	80 nm	-	-	80 nm	-
RMS Gain Ripple^c,e(Click for Plot)	-	0.06 dB	0.3 dB	-	0.06 dB	0.3 dB
Forward Voltage^c	-	2.0 V	2.5 V	-	2.0 V	2.5 V
TEC Operation: Typ. / Max @ T_CASE = 25 °C / 70 °C
TEC Current	-	0.2 A	1.4 A	-	0.2 A	1.4 A
TEC Voltage	-	0.8 V	6.0 V	-	0.8 V	6.0 V
Thermistor Resistance	-	10 kΩ	-	-	10 kΩ	-
Absolute Maximum Ratings^a
Absolute Max Current	225 mA			410 mA
Operating Case Temperature	0 to 70 °C
Storage Temperature	-10 to 70°C
Pin Code	14 Pin, Type 1
Fiber Specifications
Fiber Type	780HP
Numerical Aperture	0.13
Core Diameter	4.4 µm
Mode Field Diameter (Nominal)	5.0 ± 0.5 µm @ 850 nm
Fiber Length	1.0 m
Connector	FC/APC, 2.0 mm Narrow Key

These Operating Specifications are a consistent set of values which will yield the specified performance. Please note that exceeding the Absolute Maximum Ratings in the table may cause device failure.
Center wavelength is defined based on the spectral shape of each device; see the definitions above.
Specification given at operating current. At the minimum ASE power, the minimum 3 dB bandwidth is guaranteed.
Corresponds to the output of the fiber pigtail.
Measurement Resolution = 0.02 nm

1050 nm Superluminescent Diodes

Item #	SLD1050S-A60^a
Parameter^a	Min	Typical	Max
Center Wavelength^b	1025 nm	1050 nm	1075 nm
Spectral Shape	Flat Top
Operating Current	-	-	1010 mA
ASE Power^c,d	55 mW	60 mW	-
Optical 3 dB Bandwidth^c	60 nm	70 nm	-
Optical 20 dB Bandwidth^c	-	100 nm	-
RMS Gain Ripple^c,e	-	0.03 dB (Click for Plot)	0.2 dB
Forward Voltage^c	-	2.0 V	2.5 V
TEC Operation: Typ. / Max @ T_CASE = 25 °C / 65 °C
TEC Current	-	0.7 A	2.5 A
TEC Voltage	-	0.9 V	3.2 V
Thermistor Resistance	-	10 kΩ	-
Absolute Maximum Ratings^a
Absolute Max Current	1010 mA
Operating Case Temperature	0 to 70 °C
Storage Temperature	-10 to 70°C
Pin Code	14 Pin, Type 1
Fiber Specifications
Fiber Type	HI1060
Numerical Aperture	0.14
Core Diameter	6.2 µm
Mode Field Diameter (Nominal)	6.2 ± 0.3 µm @ 1060 nm
Fiber Length	1.5 m
Connector	FC/APC, 2.0 mm Narrow Key

These Operating Specifications are a consistent set of values which will yield the specified performance. Please note that exceeding the Absolute Maximum Ratings in the table may cause device failure.
Center wavelength is defined based on the spectral shape of each device; see the definitions above.
At Operating Current. At the minimum ASE power, the minimum 3 dB bandwidth is guaranteed.
Corresponds to the output of the fiber pigtail.
Measurement Resolution = 0.02 nm

1325 nm Superluminescent Diode

Item #	SLD1325
Parameter^a	Min	Typical	Max
Operating Current	-	-	780 mA
Center Wavelength^b	-	1325 nm	-
Spectral Shape	Flat Top
ASE Power^c	10 mW	-	-
Optical 3 dB Bandwidth	100 nm	-	-
RMS Gain Ripple	-	-	-
Forward Voltage	-	-	4 V
Fiber Type	SMF-28e
Operating Temperature Range	0 to 40 °C
TEC Operation
TEC Current	-	-	4 A
TEC Voltage	-	-	4 V
Thermistor Resistance^d	-	-	10 kΩ
Integrated Isolator
Isolation	30 dB	-	-

These Operating Specifications are a consistent set of values which will yield the specified performance. Please note that exceeding the Absolute Maximum Ratings in the table may cause device failure.
Center wavelength is defined based on the spectral shape of each device; see the definitions above.
Corresponds to the output of the fiber pigtail at the operating current.
Steinhart - Hart Coefficients: C₁ = 1.1291x10^-3,
C₂ = 2.3413x10^-4, and C₃ = 0.8767x10^-7

Theoretical Limit of Axial Resolution for a 1325 nm SD OCT system

Theoretical axial resolution for a Spectral Domain OCT System utilizing a 1325 nm light source with 100 nm bandwidth in air, assuming an ideal source with Gaussian spectral distribution.

The theoretical axial (depth) resolution of a Spectral Domain OCT imaging system is

Here, Δz, is the axial resolution (FWHM of the autocorrelation function) while Δλ is the FWHM of the power spectrum of the SLD light source. The index of refraction (n) of air is ~1, so for a central wavelength (λ) of 1325 nm and a spectral bandwidth of 100 nm, the theoretical axial resolution would be approximately 7.7 µm (see plot). This equation assumes an ideal source with Gaussian spectral distribution. To reduce side-lobe artifacts that may arise from utilizing non-Gaussian sources, we recommend applying a spectral filter to the detected interferogram. Depending on the filter applied, the actual resolution may be reduced.

Butterfly Package, Type 1

Pin	Description	Pin	Description
1	+ TEC	14	- TEC
2	Thermistor	13	Case Ground
3	NC	12	NC
4	NC	11	SLD Cathode
5	Thermistor	10	SLD Anode
6	NC	9	NC
7	NC	8	NC

Posted Comments:

robert (posted 2017-08-22 09:01:35.56)

Dear, I have one question regarding SLD unit in OCT instruments for example Topcon OCT-2000. Has a SLD unit lifitime and how we can count this lifetime ? Is this is depending only from how many OCT images has been done or also how many years are old SLD unit. IS life time is also depending of working hours of SLD for example we have switch on OCT 8 hours every day and we done maybe 20 OCT images. Thanks a lot for your help. Regards, Robert Rimc

tfrisch (posted 2017-09-13 11:22:29.0)

Hello, thank you for contacting Thorlabs. Lifetime can be estimated, but it will vary for different operating conditions. I will reach out to you directly to discuss your application.

jjurado (posted 2011-07-12 10:31:00.0)

Response from Javier at Thorlabs to last poster: Thank you very much for your feedback. You are correct in asserting that the theoretical resolution is based on the assumption of a Gaussian profile. There are analytical filtering techniques which can be performed to reshape the spectrum of the SLD1325 to provide a Gaussian shape. The actual resolution will sacrifice a bit, but in practice it is nominal. We will add information to the resolution tab shortly to clarify this. Please do not hesitate to contact us at techsupport@thorlabs.com if you have any further questions or comments.

user (posted 2011-07-11 10:41:04.0)

The theoretical resolution is based on a gaussian shape. The equation is not valid for this light source, but you suggest it would.

Tyler (posted 2009-02-13 08:11:21.0)

A response from Tyler at Thorlabs to xzhao: Thank you for pointing out the units mistake. It has been fixed.

xzhao (posted 2009-02-13 00:30:17.0)

Dear Webmaster, The Spec for SLD1325 should be Bandwidth* >100 nm but not Bandwidth* >100 mW Thanks, Xuefeng Zhao Thorlabs Japan

830 nm Superluminescent Diodes for OCT

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830 nm Superluminescent Diodes with 20 nm or 60 nm Typical 3 dB Bandwidth
Extremely Low Typical Gain Ripple
10 mW or 20 mW Minimum Fiber-Coupled Output Power

These superluminescent diodes are designed to be used in OCT Systems that require an illumination source with extremely low typical gain ripple of 0.03 dB or 0.06 dB (RMS) and a relatively flat spectrum over a 20 nm or 60 nm wide 3 dB bandwidth. They are available with a minimum fiber-coupled output power of 10 mW or 20 mW.

The specifications in the table below are typical. Each SLD is shipped with an individualized data sheet that includes dominant wavelength, output power, operating current, and other information specific to that device.

Item #	SLD830S-A10W			SLD830S-A10			SLD830S-A20
Parameter^a	Min	Typical	Max	Min	Typical	Max	Min	Typical	Max
Operating Current	-	-	240	-	-	150 mA	-	-	240 mA
Center Wavelength^b	815 nm	830 nm	845 nm	820 nm	830 nm	840 nm	820 nm	830 nm	840 nm
Spectral Shape	Flat Top			Near Gaussian			Near Gaussian
ASE Power^c,d	10 mW	-	-	10 mW	13 mW	-	20 mW	22 mW	-
Optical 3 dB Bandwidth^c,e	50 nm	60 nm	-	17 nm	20 nm	-	17 nm	20 nm	-
Optical 20 dB Bandwidth^c	-	-	-	-	50 nm	-	-	50 nm	-
RMS Gain Ripple^c,f(Click for Plot)	-	0.06 dB	0.3 dB	-	0.03 dB	0.15 dB	-	0.03 dB	0.15 dB
Output Spectrum (Click for Plot)
LIV Plot (Click for Plot)
Fiber Type	780HP

Full specifications are available by clicking on the Specs tab above.
The center wavelength definition for these devices depends on spectral shape. See the Specs tab above.
At Operating Current
Corresponds to the output of the fiber pigtail.
For SLD830S-A10W: At the minimum ASE power, the minimum 3 dB bandwidth is guaranteed.
Close zoom of output spectrum to show gain ripple; Measurement Resolution = 0.02 nm

Click to Enlarge

Click to Enlarge

Images of (a) the lens, (b) the anterior, and (c) the retina of the eye obtained using a Ganymede II SD-OCT System modified to integrate an SLD830S-A10 as a light source. The images each have an in-tissue depth of 6.2 mm and were taken using a 36 kHz A-scan rate.

880 nm Superluminescent Diodes for OCT

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880 nm Superluminescent Diodes with 40 nm Typical 3 dB Bandwidth
7 mW or 25 mW Typical Fiber-Coupled Output Power
FC/APC-Terminated Fiber Pigtail Minimizes Optical Feedback

These superluminescent diodes are designed to be used in OCT Systems. They have a low typical gain ripple of 0.06 dB (RMS) and a relatively flat spectrum over a 40 nm wide 3 dB bandwidth. They are available with a typical fiber-coupled output power of 7 mW or 25 mW.

Item #	SLD880S-A7			SLD880S-A25
Parameter^a	Min	Typical	Max	Min	Typical	Max
Operating Current	-	-	225 mA	-	-	410 mA
Center Wavelength^b	860 nm	880 nm	900 nm	860 nm	880 nm	900 nm
Spectral Shape	Flat Top			Flat Top
ASE Power^c,d	6 mW	7 mW	-	23 mW	25 mW	-
Optical 3 dB Bandwidth^c	35 nm	40 nm	-	35 nm	40 nm	-
Optical 20 dB Bandwidth^c	-	80 nm	-	-	80 nm	-
RMS Gain Ripple^c,e(Click for Plot)	-	0.06 dB	0.3 dB	-	0.06 dB	0.3 dB
Output Spectrum (Click for Plot)
LIV Plot (Click for Plot)
Fiber Type	780HP

Full specifications are available by clicking on the Specs tab above.
The center wavelength definition for these devices depends on spectral shape. See the Specs tab above.
Specification given at the operating current. At the minimum ASE power, we guarantee the minimum 3 dB bandwidth.
Corresponds to the output of the fiber pigtail.
Close zoom of output spectrum to show gain ripple; Measurement Resolution = 0.02 nm

1050 nm Superluminescent Diode for OCT

Zoom

Item #	SLD1050S-A60
Parameter^a	Min	Typ	Max
Operating Current	-	-	1010 mA
Center Wavelength^b	1025 nm	1050 nm	1075 nm
Spectral Shape	Flat Top
ASE Power^c,d	55 mW	60 mW	-
Optical 3 dB Bandwidth^c	60 nm	70 nm	-
Optical 20 dB Bandwidth^c	-	100 nm	-
RMS Gain Ripple^c,e(Click for Plot)	-	0.03 dB	0.2 dB
Output Spectrum (Click for Plot)
LIV Plot (Click for Plot)
Fiber Type	HI1060

Full specifications are available by clicking on the Specs tab above.
The center wavelength definition for these devices depends on spectral shape. See the Specs tab above.
Specification given at operating current. At the minimum ASE power, we guarantee the minimum 3 dB bandwidth.
Corresponds to the output of the fiber pigtail.
Close zoom of output spectrum to show gain ripple. Measurement Resolution = 0.02 nm

1050 nm Superluminescent Diode with 70 nm Typical 3 dB Bandwidth
60 mW Typical Fiber-Coupled Output Power
FC/APC-Terminated Fiber Pigtail Minimizes Optical Feedback

This superluminescent diode is designed to be used in OCT Systems. It has a low typical gain ripple of 0.03 dB (RMS) and a relatively flat spectrum over a 70 nm wide 3 dB bandwidth. This SLD is available with a typical fiber-coupled output power of 60 mW.

The specifications in the table to the right are typical. The SLD is shipped with an individualized data sheet that includes dominant wavelength, output power, operating current, and other information specific to that device.

1325 nm Superluminescent Diode for OCT

Zoom

Item #	SLD1325
Parameter^a	Min	Typ	Max
Operating Current	-	-	780 mA
Center Wavelength^b	-	1325 nm	-
Spectral Shape	Flat Top
ASE Power^c,d	10 mW	-	-
3 dB Optical Bandwidth^c	100 nm	-	-
Output Spectrum (Click for Plot)
LIV Plot (Click for Plot)
Fiber Type	SMF-28e
Integrated Optical Isolator
Isolation	30 dB	-	-

Full specifications are available by clicking on the Specs tab above.
The center wavelength definition for these devices depends on spectral shape. See the Specs tab above.
At Operating Current
Corresponds to the output of the fiber pigtail.

1325 nm Center Wavelength with >100 nm Bandwidth
Integrated Optical Isolator for Enhanced Output Stability
FC/APC-Terminated Fiber Pigtail Minimizes Optical Feedback

The SLD1325, with a typical center wavelength of 1325 nm, is designed to have an extremely broad bandwidth of >100 nm (FWHM), making it ideal for high-axial-resolution SD-OCT applications (see the Resolution SD-OCT tab above for more information). This SLD is packaged with an integrated TEC and thermistor for temperature control, as well as an optical isolator for enhanced optical stability.

The SLD should be operated in a constant current constant temperature mode, which is relatively simple with the proper SLD mount and drivers. To mount and drive the SLD1325, Thorlabs recommends using the CLD1015 Compact Laser Diode Driver.

Note that the specifications in the table to the right are given as guidelines. The characterization sheet shipped with each SLD provides the min, max and recommended operating parameters and specifications specific to that device. All devices will exceed the bandwidth and power specifications listed below.

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Superluminescent Diode (SLD) Light Sources for OCT Systems

Features

SLD Specifications

830 nm Superluminescent Diodes

880 nm Superluminescent Diodes

1050 nm Superluminescent Diodes

1325 nm Superluminescent Diode

Butterfly Package, Type 1

830 nm Superluminescent Diodes for OCT

880 nm Superluminescent Diodes for OCT

1050 nm Superluminescent Diode for OCT

1325 nm Superluminescent Diode for OCT