Thorlabs - OCT Balanced Detectors

Balanced Detectors for OCT Selection Guide
Wavelength	Bandwidths Available	Fast Monitor Output Bandwidth
320 - 1000 nm	DC - 15 MHz DC - 75 MHz DC - 100 MHz DC - 200 MHz	DC - 1 MHz
800 - 1700 nm	DC - 15 MHz DC - 75 MHz DC - 100 MHz DC - 200 MHz	DC - 1 MHz
Optimized for 1060 nm (900 - 1400 nm Range)	DC - 400 MHz DC - 1 GHz	DC - 3 MHz
Optimized for 1300 nm (1200 - 1700 nm Range)	DC - 400 MHz DC - 1.6 GHz	DC - 3 MHz

Features

Bandwidths up to 1.6 GHz Available
Four Wavelength Options
- 320 - 1000 nm
- 800 - 1700 nm
- 900 - 1400 nm (Optimized for 1060 nm)
- 1200 - 1700 nm (Optimized for 1300 nm)
>25 dB Common Mode Rejection
All Versions Available with Fiber Inputs
Free Space Inputs on Some Detectors (See Below for Details)
<6.5 mV_RMS Output Voltage Noise
Switchable Power Supply Included

These balanced amplified photodetectors are designed specifically for OCT applications. They act as a balanced receiver by subtracting the two optical input signals from each other, resulting in the cancellation of common mode noise. This allows small changes in the signal path to be extracted from the interfering noise floor. A complete list of all of Thorlabs' balanced amplified photodetectors with fast monitor output can be found here.

The detectors consist of two balanced photodiodes and an ultra-low-noise, high-speed transimpedance amplifier. The two photodiodes are matched to achieve an excellent common mode rejection ratio (CMRR), leading to better noise reduction. Please see the Operation Tab for more details. All of these detectors feature three fast monitor ports for reduced noise. In addition to the RF-output from the transimpedance amplifier, the Monitor+ and Monitor- ports allow the response of each photodiode to be observed individually.

Bandwidths of DC - 200 MHz or Lower
Detectors with bandwidths of DC - 200 MHz or lower are available with either Si photodiodes for the 320 - 1000 nm range or InGaAs photodiodes for the 800 - 1700 nm range. Choose from four bandwidths: DC - 15 MHz, DC - 75 MHz, DC - 100 MHz, or DC - 200 MHz. The inputs on these detectors are not fiber-coupled to the photodiodes. Detectors with bandwidths of DC - 100 MHz or lower come with two removable FC input connectors, making them suitable for either free space or fiber-coupled applications. The DC - 200 MHz bandwidth detectors also have FC/PC connectors at the inputs, but they cannot be removed.

Bandwidths of DC - 400 MHz or Higher
Detectors with bandwidths of DC - 400 MHz or higher feature fiber-coupled InGaAs photodiodes connected to FC/APC optical inputs with exactly length-matched SMF-28e+ or HI1060 fiber to achieve excellent CMRR values across the full detector bandwidth. The fiber-coupled design suppresses line artifacts in the OCT image, which generally occur when detector coupling optics are used. The combination of fiber and photodiodes was chosen to optimize these detectors for either 1060 nm (900 - 1400 nm range) or 1300 nm (1200 - 1700 nm range).

Our highest bandwidth detectors are offered in an AC-coupled version only and are the latest design for OCT balanced amplified photodetectors. The PDB480C-AC and PDB481C-AC balanced detectors offer bandwidths from 30 kHz up to 1.6 GHz or 1.0 GHz, respectively, leading to considerable speed improvements. The ultra-low-distortion output stage supports up to a 2 V_p-p A/D card input range, which, combined with the fiber-coupled design, improves the image quality for OCT applications considerably.

Electrical Connections
Three SMA electrical connectors provide the balanced output signal plus a fast power monitor for each of the two input signals for all of the balanced detectors. These two monitors can be used as an independent power meter as well as for measuring low frequency modulated signals up to 1 MHz or 3 MHz, depending on the model chosen (see tables below for details).

Packaging/Power Supply
Housed in a shielded aluminum enclosure measuring 85 mm x 80 mm x 30 mm (3.35" x 3.15" x 1.18"), these detectors are post mountable using the included adapter plate, which can be attached to the bottom or side of the housing with the included 8-32 (M4) screws. The unit is powered with the provided ±12 V DC power supply. The input voltage of 110 V or 230 V can be manually selected by a switch.

Thorlabs also offers Fiber-Based Interferometers, which feature an integrated balanced detector.

Item #	PDB410A	PDB410C	PDB420A	PDB420C	PDB440A	PDB440C	PDB460A	PDB460C
Detector Type	Si/PIN	InGaAs/PIN	Si/PIN	InGaAs/PIN	Si/PIN	InGaAs/PIN	Si/PIN	InGaAs/PIN
Wavelength Range	320 - 1000 nm	800 - 1700 nm	320 - 1000 nm	800 - 1700 nm	320 - 1000 nm	800 - 1700 nm	320 - 1000 nm	800 - 1700 nm
Typical Max Responsivity	0.53 A/W	1.0 A/W	0.53 A/W	1.0 A/W	0.53 A/W	1.0 A/W	0.53 A/W	1.0 A/W
Active Detector Diameter	0.8 mm	0.3 mm	0.8 mm	0.3 mm	0.8 mm	0.3 mm	0.8 mm	0.15 mm
Bandwidth (3 dB)	DC - 100 MHz		DC - 75 MHz		DC - 15 MHz		DC - 200 MHz
Common Mode Rejection Ratio	>25 dB (Typical >35 dB)		>35 dB		>35 dB		>25 dB (Typical >35 dB)
Transimpedance Gain^a	50 x 10³ V/A		250 x 10³ V/A		51 x 10³ V/A		30 x 10³ V/A
Conversion Gain RF-Output	26.5 x 10³ V/W	50 x 10³ V/W	133 x 10³ V/W	250 x 10³ V/W	27 x 10³ V/W	51 x 10³ V/W	16 x 10³ V/W	30 x 10³ V/W
Conversion Gain Monitor Outputs	10 V/mW @ 820 nm	10 V/mW @ 1550 nm	10 V/mW @ 820 nm	10 V/mW @ 1300 nm	10 V/mW @ 820 nm	10 V/mW @ 1550 nm	10 V/mW @ 820 nm	10 V/mW @ 1550 nm
CW Saturation Power RF-Output	135 µW @ 820 nm	72 µW @ 1550 nm	27 µW @ 820 nm	15 µW @ 1550 nm	130 µW @ 820 nm	70 µW @ 1550 nm	225 µW @ 820 nm	120 µW @ 1550 nm
Minimum NEP (DC - 10 MHz)	7 pW/Hz^1/2	3.8 pW/Hz^1/2	6.5 pW/Hz^1/2	3.5 pW/Hz^1/2	6.4 pW/Hz^1/2	3.3 pW/Hz^1/2	13.2 pW/Hz^1/2	6.0 pW/Hz^1/2
Fiber Optical Inputs	FC/PC or FC/APC (Removable)							FC/PC or FC/APC (Not Removable)
Photodiode Damage Threshold	20 mW
Electrical Outputs	SMA (Qty. 3)
RF-Output Impedance	50 W
RF-Output Coupling	DC, AC-Coupling upon Request
Dimensions	85 mm x 80 mm x 30 mm (3.35" x 3.15" x 1.18")
Power Supply	±12 V @ 200 mA

Transimpedance Gain is reduced by a factor of two for 50 Ohm loads.

Item #	PDB470C^a	PDB471C^a	PDB480C-AC^a	PDB481C-AC^a
Detector
Detector Type	InGaAs/PIN
Optical Inputs	FC/APC
Internal Coupling Fiber	SMF-28e+	HI1060	SMF-28e+	HI1060
Coupling Loss	<0.5 dB (<0.3 dB Typ.)	<1.0 dB (<0.4 dB Typ.)	<0.5 dB (<0.3 dB Typ.)	<1.0 dB (<0.4 dB Typ.)
Operating Wavelength	Optimized for 1300 nm (1200 - 1700 nm Range)	Optimized for 1060 nm (900 - 1400 nm Range)	Optimized for 1300 nm (1200 - 1700 nm Range)	Optimized for 1060 nm (900 - 1400 nm Range)
Typical Max Responsivity	0.9 A/W @ 1300 nm	0.72 A/W @ 1060 nm	0.9 A/W @ 1300 nm	0.72 A/W @ 1060 nm
Active Detector Diameter	0.075 mm	0.080 mm	0.075 mm	0.080 mm
Optical Back Reflection	<-40 dB
Photodiode Damage Threshold	10 mW	5 mW	10 mW	5 mW
RF OUTPUT
RF OUTPUT Bandwidth (3 dB)	DC - 400 MHz		30 kHz - 1.6 GHz	30 kHz - 1.0 GHz
Common Mode Rejection Ratio	>25 dB (>30 dB Typ.)
RF OUTPUT Transimedance Gain^b	10 x 10³ V/A		16 x 10³ V/A^c
RF OUTPUT Conversion Gain^b	9 x 10³ V/W @ 1330 nm	7.2 x 10³ V/W @ 1060 nm	14.4 x 10³ V/W @ 1300 nm^c	11.5 x 10³ V/W @ 1060 nm^c
RF OUTPUT Power at 1 dB Compression^c	-		+16.5 dBm Min +18 dBm Max
RF OUTPUT CW Saturation Power	420 µW @ 1300 nm	530 µW @ 1060 nm	-
RF OUTPUT Coupling	DC (AC Coupling Available upon Request)		AC Coupling Only
RF OUTPUT Impedance	50 Ohms
Minimum NEP	8 pW/Hz^1/2 (DC to 100 MHz)		9.3 pW/Hz^1/2 (30 kHz to 100 MHz)	9.0 pW/Hz^1/2 (30 kHz to 100 MHz)
Overal Output Voltage Noise	<2 mV_RMS		<9 mV_RMS	<6.5 mV_RMS
MONITOR Outputs
MONITOR Output Impedance	200 Ohms
MONITOR Output Bandwidth (3 dB)	DC - 3 MHz
MONITOR Output Conversion Gain, High Z Load^b	9 V/mW @ 1300 nm	7.2 V/mW @ 1060 nm	9 V/mW @ 1300 nm	7.2 V/mW @ 1060 nm
MONITOR Output Voltage Swing, High Z Load	10 V Max
Overall Output Voltage Noise	<0.65 mV_RMS
DC Offset	< ±2 mV
General
Electrical Outputs	SMA
DC Power Supply	±12 V @ 200 mA
Operating Temperature Range^d	0 °C to 40 °C
Storage Temperature Range	-40 °C to 70 °C
Dimensions (W x H x D)	85 mm x 80 mm x 30 mm (3.35" x 3.15" x 1.18")
Weight	0.35

All technical data are valid at 23 ± 5 °C and 45 ± 15% relative humidity (non-condensing).
Values for transimpedance and conversion gain are lossless gain values [i.e. losses introduced by the FC/APC connectors (typically 0.15 to 0.35 dB) are not considered].
For a 50 Ohm Load.
Non-Condensing.

Operation of the Balanced Detectors with Bandwidths up to 400 MHz

These Balanced Amplified Photodetectors consist of two well-matched photodiodes and an ultra-low noise, high-speed transimpedance amplifier (TIA) that generates an output voltage (RF OUTPUT) proportional to the difference between the photocurrents in the two photodiodes (i.e., the two optical input signals). Additionally, the unit has two fast monitor outputs (MONITOR+ and MONITOR-) to observe the optical input power levels on each photodiode separately. These outputs can be used to measure an RF modulation on the signal up to 1 MHz for versions with a bandwidth of 300 MHz or lower and up to 3 MHz for versions with a bandwidth of DC to 400 MHz.

Balanced receiver

Operation of the PDB480C-AC and PDB481C-AC Balanced Detectors

Similar to the balanced detectors described above, the PDB480C-AC and PDB481C-AC Balanced Amplified Photodetectors consist of two well-matched, fiber-coupled photodiodes connected to the inputs with length-matched fibers and an ultra-low noise, ultra-low distortion high-speed transimpedance amplifier (TIA). Similar to the detectors described above, this TIA generates an output voltage (RF OUTPUT) proportional to the difference between the photocurrent in the two photodiodes (i.e,. the two optical input signals). Additionally, the unit offers two fast monitor outputs (MONITOR+ and MONITOR-) that allow the user to measure the individual optical input power levels as well as low frequency modulated signals up to 3 MHz.

Balanced receiver

RF Output

SMA Female

For the PDB410, PDB420, PDB440, and PDB460 photodetectors, the maximum RF OUTPUT voltage is ±3.6 V for Hi-Z & ±1.8 V into 50 Ω loads.

The RF OUTPUT CW saturation power is 420 µW @ 1300 nm and 530 µW at 1060 nm for the PDB470C and PDB471C, respectively.

For the PDB480 photodetectors, the RF OUTPUT Power at 1 dB compression into 50 Ω loads is +16.5 dBm (Min), +18 dBm (Typical)

Monitor (+/-)

SMA Female

Maximum Voltage is +10 V for Hi-Z & +1.5 V into 50 Ω loads.

Please Give Us Your Feedback

Email		Feedback On
(Optional)
Contact Me:
Your email address will NOT be displayed.

Please type the following key into the field to submit this form:

Click Here if you can not read the security code.
This code is to prevent automated spamming of our site
Thank you for your understanding.

Would this product be useful to you? Little Use 1 2 3 4Very Useful

Enter Comments Below:

Characters remaining 8000

Posted Comments:
No Comments Posted

Click on any phrase below to search our site using our new Search Engine:

1060nm 1 GHz 1.0 GHz 1.6 GHz 1.6GHz 1060 nm 1300 nm 1300nm 1GHz 400 MHz 400MHz AC AC-coupled amplified amplified balanced detector amplified photodetector amplified photodetectors balanced balanced detector balanced photodetector balanced receiver bandwidth cmrr common coupled detector detectors excellent excellent cmrr fast fastmonitor fast-monitor fiber fibercoupled fiber-coupled fixed gain ingaas detector fixed gain si detector gain high high bandwidth high gain infrared infrared detector InGaAs ingaas balanced detector ingaas detector ingas ingas balanced detector ingas detector input ir detector laser laser photodiode mode monitor noise noise reduction OCT optical detector output pdb photodetectors photodiode ratio reciever reduction rejection si balanced detector si detector switchable gain ultra-low

View All »Matching Part Numbers

OCT Balanced Detectors

Features

Operation of the Balanced Detectors with Bandwidths up to 400 MHz

Operation of the PDB480C-AC and PDB481C-AC Balanced Detectors

RF Output

SMA Female

Monitor (+/-)

SMA Female