DFB Lasers

STG Series DFB Lasers & Modules

We offer a broad range of DFB lasers in the C-band and L-band on 50 or 100 GHz channel spacing as well as at 1310 nm, 1064 nm, and other custom wavelengths. Power level options include 40–100 mW out of the fiber for high power 14-pin lasers and 10-18mW options for high bandwidth 7-pin configurations. Distributed feedback lasers (DFB lasers) simultaneously provide smooth, tunable control of wavelength and the extremely narrow spectral width required for precise fiber optic communication and spectroscopy applications. Integrated modules provide further narrowing of the spectral line in a compact OEM package that features a simple tuning interface.

We have developed a number of DFB laser designs to enhance performance for specific customer applications, and new DFB laser designs to increase efficiency, isolation, and accuracy continue to be developed:

• Integrated thermoelectric coolers (TECs) can reduce the overall current consumption or widen the range of allowable environmental temperatures.

• Precision thermistors provide more accurate feedback and control of the temperature at the most critical location, the semiconductor chip.

• Internal isolators protect the laser from noise perturbations and catastrophic damage from light returning from other components.

1. STG Series DFB Lasers

1.1 High Power DFB Lasers, STG-AA1418

40mW in 14-pin butterfly package

The STG-AA1416 is a CW InGaAs/InP multi-quantum well (MQW) laser diode. The module is ideal in applications where low relative intensity noise (RIN) and stable polarization maintaining properties are needed. The module contains a high efficiency cooler, high performance isolator, thermistor, and monitor detector and is designed and built using our high reliability platform for defense applications.

Key Characteristics:

• C-band (1537-1565 nm) wavelengths

• 40mW ex-fiber output power

Features:

• ITU grid wavelengths, 50 or 100GHz spacing

• Low RIN

• High isolation

• High efficiency TEC

• Polarization-maintaining or single-mode fiber

• Laser welded, hermetically sealed

• Built in thermistor and monitor photodiode

• Tested to Telcordia GR-468 Core/MIL-STD-883

Applications:

• Long haul WDM transmission

• RF links

• Seeding

• Pulsing

• Sensing

• CATV

Specification:

Remark:

1. Iₒₚ and Tₒₚ are defined on device specific test sheet supplied with each unit.

Data Tables

Typical output power and back facet monitor current vs input current

Typical TEC performance Tc=25°C

Typical RIN (Relative Intensity Noise) By design, not tested per part

Absolute Maximum Ratings

* Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and operation of the device at or beyond these conditions is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.

1.2. High Bandwidth DFB Lasers, STG-AA0701

7 PIN K Packaging

The STF-AA0701 distributed feedback laser (DFB) is an InGaAsP/InP multi-quantum well laser diode. This module is ideal for applications where high bandwidth, mode stability, low relative intensity noise (RIN), and stable output power are needed. The STG-AA0701 series contains a thermoelectric cooler, thermistor, back facet monitor detector, and bias tee. The module is designed and built using our high-reliability platform for defence components.

Key Characteristics:

• C-band (1537-1565 nm) and 1310nm wavelengths

• 10 or 18mW ex-fiber output power options

Features:

• 10 or 18mW output power

• High bandwidth

• Built in isolator

• Ultrafast pulsing capability

• Laser welded, hermetically sealed

• Built in TEC, thermistor, and monitor detector

• Rugged to shock and vibration

Application:

• Analog RF links

• High speed pulsing

Specification:

Remark:

1. Reference model number STG-AA0702 for units without internal isolator. SMSR not specified for this model.

2. Optional 900μm loose-tube PVDF buffer recommended for laboratory use.

3. Other connector options available, contact sales for more information

Data Tables

Typical output power and back facet monitor current vs input current (1550 nm)

Typical output power and back facet monitor current vs input current (1310 nm)

Typical TEC performance Tchip=25°C

Absolute Maximum Ratings

*Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and operation of the device at or beyond these conditions is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.

1.3 High Power DFB Lasers, STG-AA1401

Single frequency lasers in 14-pin butterfly package

Our high power distributed feedback laser (DFB) is an InGaAs/InP multi-quantum well (MQW) laser diode. The module is ideal in applications where low relative intensity noise (RIN) and stable polarization-maintaining properties are needed. The module contains a thermo-electric cooler, thermistor, and monitor detector and is designed and built using our high reliability platform for defence applications.

STG-AA1401 series including STG-AA1402, STG-AA1406, STG-AA1408, and STG-AA1415.

Key Characteristics:

• C-band and L-band wavelengths 1537-1565 and 1565-1617 nm

• 40-100mW ex-fiber output power options

Features:

• ITU grid wavelengths, 50 or 100 GHz spacing

• Low RIN

• PM or SM fiber

• High isolation option

• Laser welded, hermetically sealed

• Built in thermistor and monitor photodiode

• Optional Bias-T

• Tested to Telcordia GR-468 Core/MIL-Std 883

Application:

• Long haul WDM transmission

• RF links

• Seeding

• Pulsing

• Sensing

• CATV

Specification:

Remark:

1. Reference model number STG-AA1401 for units without internal isolator. SMSR not specified for this model.

2. Iₒₚ and Tₒ ₚp to achieve rated power and frequency at factory test defined on device specific test sheet supplied with each unit.

3. Optional additional 900μm loose-tube PVDF buffer recommended for laboratory use.

4. Other connector options available, contact sales for more information.

Data table (80mW laser shown)

Absolute Maximum Ratings

Remark:

* Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and operation of the device at or beyond these conditions is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.

2. STG Series DFB Laser Modules

2.1 DFB laser Module, STG-EM650

The STG-EM650 integrates a high-power fiber-coupled DFB laser with both an ultra-low noise laser current source and temperature controller. It represents a precision OEM solution for fiber-coupled high power DFB lasers operating with excellent frequency stability, narrow linewidth, low noise, and stable polarization. The module contains a high-power DFB laser, optical isolator, single-mode fiber pigtail, thermo-electric cooler, thermistor, and monitor detector integrated with a laser current source, temperature controller, and monitor detector readout amplifier. The entire module operates from a single +5 V supply. The unit provides a bi-directional power adjust input that may be used for SBS prevention, for constant power operation in conjunction with the monitor detector readout signal and an external control loop, or for finely adjusting the laser oscillation frequency via chirp. The unit also incorporates a bi-directional temperature adjust input for coarse tuning of the laser oscillation frequency. The module is designed and built using our high reliability platform for defence components and incorporates an advanced ultra-low noise laser current source. It drives the internal TEC with a class AB linear H-bridge and incorporates multiple layers of EMI protection. It is our highest performance integrated laser solution and offers performance comparable to laboratory equipment in a much small package.

Key Features:

• Integrated current source

• Integrated temperature controller

• Integrated monitor detector amplifier

• High optical output power

• ITU wavelengths – Full C band coverage

• Low RIN

• Narrow linewidth

• PM/SM fiber with or without furcation tubing

Key Benefits:

• Simple interface

• Small form factor

• Operates from single +5V supply

Application:

• Long haul WDM transmission

• RF Links

• CATV

• Seeding

• Sensing

• Low-noise high-power source

Specification:

Absolute Maximum Ratings

Stresses beyond those listed may cause permanent damage to the device. These are stress ratings only and operation of the device at these or conditions beyond these is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.

Mechanical drawing

Electrical Connection

Typical Operating Characteristics (80mW Module)

Typical Operating Characteristics (Continued)

Remark:

1.Power stability of this magnitude is strongly influenced by any movement of the fiber. To duplicate this stability measurement the fiber must be secured and motionless.

2. For 228.849 THz (1310 nm) lasers the laser frequency tolerance is ±1.750 THz (±10 nm).

3. Frequency stability measured by heterodyne of two free running STG-EM650 units over 100s.

4. The peak of the RIN curve corresponds to the relaxation oscillation frequency of the laser which varies in proportion to the drive current above threshold by frelax α ((Ild/Ithreshold) - 1)1/2. Customers employing this device in RIN sensitive applications should therefore be aware that reducing power using the PA input will reduce performance.

NOTES

WARNINGS: several of the parameters listed in the specifications above are denoted with a warning. These warnings are covered by the following notes, which should be understood before operating the device.

Mounting

The STG-EM650 is conductively cooled through its base and needs to be mounted using a thermal interface material to a customer supplied heatsink. We recommend Panasonic PGS series pyrolitic graphite sheets, available in the US from Digi‐Key Corporation. Care should be taken to keep the base temperature of the module between -10 and 60°C at all times during operation.

Noise suppression

The STG-EM650 is a no‐compromises low‐noise integrated laser solution; the temperature controller output is class AB linear, there are no DC/DC converters in the module, the lowest noise components and architectures available are used along with heavy filtering and EMI shielding. Nevertheless, power supply ripple and noise should be minimized and the cable shield should be connected to the STG-EM650 connector shield and tied to the appropriate signal at the power supply end of the cable.

Power Adjust (PA)

The STG-EM650 is designed to run in constant current mode with the drive current set for the as‐ordered output power to achieve the highest possible performance. However, some applications require fine tuning of the laser bias current. The PA input provides this functionality, but its use carries an amount of risk. If bias adjustment is not required this input should be left open. Use of this input carries the potential to overdrive the laser and/or circuitry with the ability to destroy or drastically reduce the device lifetime. No internal protections on this input are provided, but the user is encouraged to clamp or otherwise limit the voltage and current that may be applied to this input.

The default operating power corresponds to an input of 2.05V. For maximum reliability it is recommended that power only be reduced, although if required it can be driven as high as 2.2V (corresponding to a 10% boost in output power). The safest method of using this input is to pull the voltage down using an external resistor or potentiometer to ground. Applying a resistance to ground will create a voltage divide circuit between the external resistance and an internal resistance of 1K to the 2.05V reference. Damage due to overdrive will not be covered under warranty. Use of this input will likely decrease the performance of the STG-EM650 by bypassing its internal ultra‐low noise voltage reference. The PA input must never be shorted directly to Vcc, which would cause circuit malfunction or rapidly destroy the DFB laser.

Temperature Adjust (TA)

The STG-EM650 is designed to operate the laser chip at a constant temperature holding the output frequency within 5 GHz of the ordered frequency. However, some applications require coarse tuning of the output frequency via temperature. In these cases, the laser may be tuned using the TA input. Temperature deviations of more than a few degrees (50 GHz in laser frequency) from the as‐ordered setpoint may result in decreased stability and increases the likelihood of the laser experiencing a longitudinal mode‐hop. The achievable tuning range will depend on the specific laser chip, the ambient temperature, and the thermal resistance to the ambient.Use of this input carries the inherent potential of overdriving the TEC. The TA input is clamped to Vcc through integrated protection diodes. If Vta is established before Vcc these clamp diodes will conduct. The input current should always be limited to ≤3.5mA to prevent destruction of the clamp diodes.

The safest method of driving this input is with a tri-state output whose output is current limited when active, maintained at high‐impedance until Vcc is established, and whose output returns to high‐impedance before Vcc is removed. The device warranty will not be honored for lasers with overdriven TECs. Use of this input also carries the likelihood of decreased frequency stability as it bypasses the internal ultra‐low noise voltage reference.The TA input must never be shorted directly to Vcc or ground which would cause circuit malfunction or rapidly destroy the DFB laser.

Grounding

Care must be taken with grounding, cabling, and connections due to the amount of current the module consumes. Make sure that the voltage on pins PA/TA reference ground as close to the STG-EM650 as possible if either input is connected.

DO NOT connect the cable shield to ground at both ends of the cable to avoid producing a ground loop. #

DO NOT connect the STG-EM650 housing to ground to avoid producing a ground loop.

Startup Considerations

The STG-EM650 consumes a considerable amount of current in the startup phase and when operating at temperature extremes. A voltage source plus cabling able to deliver the maximum specified current at no less than the minimum voltage is therefore needed. Current limiting below the specified maximum during the startup phase will result in an internally measured drive voltage lower than specified. This condition can result in permanent, non‐warrantable damage to the device. If the user fails to sequence the supplies as described in the Power and Temperature adjust sections of this document and Applications Note, the device will immediately suffer non‐warrantable damage or destruction.

Applications Information

Be sure to check this website for the latest applications information for this device. Application note covers general usage of the STG-EM650 along with information particular to tuning via temperature or chirp. If you plan to tune this device, it is highly recommended that you read this app note.

For Application Note, please contact us for more information.

2.2 CWDM Integrated RF Transmitter, STG-EM655

High Bandwidth Directly Modulated DFB laser Module

The STG-EM655 high bandwidth integrated module is a member of our line of high performance single-frequency modules based on precision DFB laser technology. STG-EM655 RF Transmitter integrates a highbandwidth fiber-coupled DFB laser with both an ultra-low noise laser current source and temperature controller. The module also contains an optical isolator and back facet monitor detector readout amplifier. The entire module operates from a single +5 V supply and offers a bi-directional bias adjust input that may be used to control the laser output power or finely adjust the laser oscillation frequency via chirp. The unit also incorporates a bi-directional temperature adjust input for coarse tuning of the laser oscillation frequency. The module is designed and built using our highreliabilityplatform for defense components and incorporates an advanced ultra-low noise laser current source.The STG-EM655 drives the internal TEC with a class AB linear H-bridge and incorporates multiple layers of EMI protection. The device accepts a standard female DB9 connector for the application of power and low-frequency tuning signals while the RF input accepts a standard male 2.92 mm “K” connector. The output optical fiber is available with or without PVDF furcation tubing terminated with a variety of standard opticalconnectors.

Models Available:

• 1310 nm with 18mW output power

• C-band wavelength with 10mW output power

Features:

• Integrated current source

• Integrated temperature controller

• Integrated monitor detector amplifier

• SM or PM fiber with or without furcation tubing

• Simple interface

• Small form factor

• Operates from single +5V supply

Application:

• RF links

• CATV

• Seeding

• Sensing

Specification:

Remark:

1.Power stability of this magnitude is strongly influenced by any movement of the fiber. To duplicate this stability measurement the fiber must be secured and motionless.

2.Units are available without isolator (product series STG-EM656). Devices without optical isolators are subject to mode-hops and are susceptible to back reflections. The wavelength stability devices with no optical isolator cannot be guaranteed.

3. The peak of the RIN curve corresponds to the relaxation oscillation frequency of the laser which varies in proportion to the drive current above threshold by f relax α ((I ld /I threshold ) - 1)1/2. Customers employing this device in RIN sensitive applications should therefore be aware that reducing the bias level using the power adjust input will reduce performance. Reducing the bias level reduces the device modulation bandwidth by the same relationship.

4. Optional 900 μm loose-tube PVDF buffer recommended for laboratory use.

5. Other connector options available, contact sales for more information.

Max Ratings

Remark:

* Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only and operation of the device at or beyond these conditions is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.

Drawing and performance Graphs

Drawings and performance graphs,continued

Pinout

Application Notes

Mounting

The STG-EM655 is conductively cooled through its base and needs to be mounted using a thermal interface material to a customer supplied heatsink. We recommend Panasonic PGS series pyrolitic graphite sheets, available in the US from Digi-Key Corporation.

Do not use graphite sheets with adhesive backing.

Care should be taken to keep the base temperature of the module between -10 - 60°C at all times during operation.

Noise Suppression

The STG-EM655 is a no-compromises low noise integrated laser solution; the temperature controller output is class AB linear, there are no DC/DC converters in the module, the lowest noise components and architectures available are used along with heavy filtering and EMI shielding. Nevertheless, power supply ripple and noise should be minimized and the cable shield should be connected to the STG-EM655 connector shield and tied to the appropriate signal at the power supply end of the cable.

Bias Level Adjust (PA)

The STG-EM655 is designed to run in constant current mode with the drive current set for the as-ordered output power to achieve the highest possible performance. However, some applications require fine tuning of the laser bias current. The PA input provides this functionality, but its use carries an amount of risk. If bias adjustment is not required this input should be left open. Use of this input carries the potential to overdrive the laser and/or circuitry with the ability to destroy or drastically reduce the device lifetime. No internal protections on this input are provided, but the user is encouraged to clamp or otherwise limit the voltage and current that may be applied to this input.

The default operating power corresponds to an input of 2.05 V. For maximum reliability it is recommended that power only be reduced, although if required it can be driven as high as 2.2 V (corresponding to a 10% boost in output power). The safest method of using this input is to pull the voltage down using an external resistor or potentiometer to ground.

Applying a resistance to ground will create a voltage divide circuit between the external resistance and an internal resistance of 1 K to the 2.05 V reference. Damage due to overdrive will not be covered under warranty. Use of this input will likely decrease the performance of the STG-EM655 by bypassing its internal ultra-low noise voltage reference.

Warning: The PA input must never be shorted directly to V CC which would cause circuit malfunction or rapidly destroy the laser.

Temperature Adjust (TA)

The STG-EM655 is designed to operate the laser chip at a constant temperature of 25° C holding the output frequency within a window of 5 GHz. However, some applications require coarse tuning of the output frequency via temperature. In these cases, the laser may be tuned using the TA input. Temperature deviations of more than a few degrees (50 GHz in laser frequency) may result in decreased stability and increases the likelihood of the laser experiencing a longitudinal mode-hop. Use of this input carries the inherent potential of overdriving the TEC. The TA input is clamped to V CC through integrated protection diodes.

If V ta is established before V CC these clamp diodes will conduct. The input current should always be limited to ≤3.5 mA to prevent destruction of the clamp diodes. The safest method of driving this input is with a tristate output whose output is current limited when active, maintained at high impedance until V CC is established, and whose output returns to high-impedance before V CC is removed. The device warranty will not be honored for lasers with overdriven TECs. Use of this input also carries the likelihood of decreased frequency stability as it bypasses the internal ultra-low noise voltage reference.

Warning: The TA input must never be shorted directly to V CC or ground which would cause circuit malfunction or rapidly destroy the laser.

Grounding, DC to RF

Care must be taken with grounding, cabling, and connections due to the amount of current the module consumes. Make sure that the voltage on pins PA/TA reference ground as close to the STG-EM655 as possible if either input is connected.

DO NOT connect the cable shield to ground atboth ends of the cable to avoid producing a ground loop.

DO NOT connect the STG-EM655 housing to ground to avoid producing a ground loop.

The shield of the RF input 2.92 mm connector is connected to the laser anode and the centerconductor to the laser cathode via the RF matching resistor. Care should be taken that the connection of an RF source does not result in a DC leakage path. The ground of the RF source must be isolated from the ground of the DC power supply, as 1.3 V typical bias voltage difference will exist between the RF ground and DC ground due to the laser diode bias voltage. In addition, shorting of the RF connector places an electrical short in parallel with the laser which will prevent the laser from operating.

Startup Considerations

The STG-EM655 consumes a considerable amount of current in the startup phase and when operating at temperature extremes. A voltage source plus cabling able to deliver the maximum specified current at no less than the minimum voltage is therefore needed. Current limiting below the specified maximum during the startup phase will result in an internally measured drive voltage lower than specified. This condition can result in permanent, non-warrantable damage to the device.

Warning: If the user fails to sequence the supplies as described in the Power and Temperature Adjust sections of this document and Applications Note, the device will immediately suffer non-warrantable damage or destruction.

Power Supply

This device requires between 4.6 V and 5.5 V as measured from the V CC to ground terminals. These voltages must be maintained for currents ranging from 0-3A necessitating the use of short wires and/or large AWG wire.

Warning: Failure to supply sufficient voltage at the device terminals may result in excess current draw and permanent, non-warrantable damage. If the device draws 3A for more than 10 seconds, turn off power and check for excessive wiring resistance or a baseplate temperature outside the operational range.

Additional Information

Be sure to check this website for the latest application information for this device.

Application note covers general usage of the STG-EM655 along with information particular to tuning via temperature or chirp. If you plan to tune this device, we highly recommended that you read this application note.

For Application Note, please contact us for more information.

2.3 CWDM Integrated RF Transmitter, STG-EM657

High Bandwidth Directly Modulated DFB Laser Module

The STG-EM657 high bandwidth integrated module is a member of our line of high performances single-frequency modules based on precision DFB laser technology. The STG-EM657 RF Transmitter integrates high bandwidth fiber-coupled DFB laser with both an ultra-low noise laser current source and temperature controller. The module also contains an optical isolator and back facet monitor detector readout amplifier. The entire module operates from a single +5 V supply and offers a bi-directional bias adjust input that may be used to control the laser output power or finely adjust the laser oscillation frequency via chirp. The unit also incorporates a bi-directional temperature adjust input for coarse tuning of the laser oscillation frequency. The module is designed and built using our high reliability platform for defence components and incorporates an advanced ultra-low noise laser current source. The STG-EM657 drives the internal TEC with a class AB linear H-bridge and incorporates multiple layers of EMI protection. The device accepts a standard female DB9 connector for the application of power and low-frequency tuning signals while the RF input accepts a standard male 2.92 mm “K” connector. The output optical fiber is available with or without PVDF furcation tubing terminated with a variety of standard optical connectors.

Models Available:

• 1310 nm and C-band wavelength options with 18mW and 10mW output power respectively

Features:

• Integrated current source

• Integrated temperature controller

• Integrated monitor detector amplifier

• SM or PM fiber with or without furcation tubing

• Simple interface

• Small form factor

• Operates from single +5 V supply

Application:

• RF links

• CATV

• Seeding

• Sensing

Specification:

Remark:

1.Power stability of this magnitude is strongly influenced by any movement of the fiber. To duplicate this stability measurement the fiber must be secured and motionless.

2.Units are available without isolator. Devices without optical isolators are subject to mode-hops and are susceptible to back reflections. The wavelength stability devices with no optical isolator cannot be guaranteed.

3.The peak of the RIN curve corresponds to the relaxation oscillation frequency of the laser which varies in proportion to the drive current above threshold by f relax α ((I ld /I threshold ) - 1) 1/2. Customers employing this device in RIN sensitive applications should therefore be aware that reducing the bias level using the power adjust input will reduce performance. Reducing the bias level reduces the device modulation bandwidth by the same relationship.

4. Optional 900 μm loose-tube PVDF buffer recommended for laboratory use.

5. Other connector options available, contact sales for more information.

Max Ratings

Drawing and performance Graphs

Drawings and performance graphs,continued

Pinout

Application Notes

Mounting

The STG-EM657 is conductively cooled through its base and needs to be mounted using a thermal interface material to a customer supplied heatsink. Do not use graphite sheets with adhesive backing as the adhesive is an insulator. Care should be taken to keep the base temperature of the module between -10 - 60°C at all times during operation.

Bias Level Adjust (PA)

The STG-EM657 is designed to run in constant current mode with the drive current set for the as-ordered output power to achieve the highest possible performance. However, some applications require fine tuning of the laser bias current. The PA input provides this functionality, but its use carries an amount of risk. If bias adjustment is not required this input should be left open. Use of this input carries the potential to overdrive the laser with the ability to destroy or drastically reduce the device lifetime. No internal protections on this input are provided, but the user is encouraged to clamp or otherwise limit the voltage and current that may be applied to this input.

The default operating power corresponds to an input of 2.05 V. For maximum reliability it is recommended that power only be reduced, although if required it can be driven as high as 2.2 V (corresponding to a 10% boost in output power). The safest method of using this input is to pull the voltage down using an external resistor or potentiometer to ground. Applying a resistance to ground will create a voltage divide circuit between the external resistance and an internal resistance of 9.74 K to the 2.05 V reference.

Damage due to overdrive will not be covered under warranty. Use of this input will likely decrease the performance of the STG-EM657 by bypassing its internal ultra-low noise voltage reference.

Warning: The PA input must never be shorted directly to V CC which would cause circuit malfunction or rapidly destroy the laser.

Temperature Adjust (TA)

The STG-EM657 is designed to operate the laser chip at a constant temperature of 25°C holding the output frequency within a window of 5 GHz. However, some applications require coarse tuning of the output frequency via temperature. In these cases, the laser may be tuned using the TA input. Temperature deviations of more than a few degrees (50 GHz in laser frequency) may result in decreased stability and increases the likelihood of the laser experiencing a longitudinal mode-hop.

Use of this input carries the inherent potential of overdriving the TEC. The TA input is clamped to V CC through integrated protection diodes. If V ta is established before V CC these clamp diodes will conduct. The input current should always be limited to ≤3.5 mA to prevent destruction of the clamp diodes. The safest method of driving this input is with a tristate output whose output is current limited when active, maintained at high impedance until V CC is established, and whose output returns to high-impedance before V CC is removed.

The device warranty will not be honored for lasers with overdriven TECs. Use of this input also carries the likelihood of decreased frequency stability as it bypasses the internal ultra-low noise voltage.

Warning: The TA input must never be shorted directly to V CC or ground which would cause circuit malfunction or rapidly destroy the laser.

Grounding, DC to RF

Care must be taken with grounding, cabling, and connections due to the amount of current the module consumes. Make sure that the voltage on pins PA/TA reference ground as close to the STG-EM657 as possible if either input is connected.

DO NOT connect the cable shield to ground at both ends of the cable to avoid producing a ground loop.

The shield of the RF input 2.92 mm connector is connected to the laser anode and the center conductor to the laser cathode via the RF matching resistor. RF source should be AC coupled to the RF input. The RF and DC ground are at laser anode potential. An internal switching regulator is used to provide a negative reference to bias the laser.

The presence of this switching regulator allows for more convenient operation in systems where the RF and DC supply must have the same ground, but increases the noise level of the STG-EM657 relative to the STG-EM655 or STG-EM650. The switching regulator noise causes a broadening of the laser line width to approximately 4MHz, and switching harmonics are visible in the low frequency RIN of the laser. This noise is no longer significant at frequencies greater than 200 MHz, and thus should not impact most high speed communication applications.

Startup Considerations

The STG-EM657 consumes a considerable amount of current in the startup phase and when operating at temperature extremes. A voltage source plus cabling able to deliver the maximum specified current at no less than the minimum voltage is therefore needed. Current limiting below the specified maximum during the startup phase will result in an internally measured drive voltage lower than specified. This condition can result in permanent, non-warrantable damage to the device.

Warning: If the user fails to sequence the supplies as described in the Power and Temperature Adjust sections of this document and Applications Note, the device will immediately suffer non-warrantable damage or destruction.

Power Supply

This device requires between 4.6 V and 5.5 V as measured from the V CC to GND terminals. These voltages must be maintained for currents ranging from 0-3.5 A necessitating the use of short wires and/or large AWG wire.

Warning: Failure to supply sufficient voltage at the device terminals may result in excess current draw and permanent, non-warrantable damage. If the device draws 3.5 A for more than 10 seconds, turn off power and check for excessive wiring resistance or a baseplate temperature outside the operational range.

Additional Information

Be sure to check the website for the latest application information for this device. Application note covers general usage of the STG-EM657 along with information particular to tuning via temperature or chirp. If you plan to tune this device, we highly recommended that you read this application note.

For Application Note, please contact us for more information.

STC Series DFB/ DBR/ VCSEL Laser

We offer DFB/ DBR/ VCSEL laser, which is special designed for gas detection such as CH4, H2S, NH3, H2O, CO, CO2, C2H4, HF, C2H2, etc. Features with narrow linewidth up to 2MHz, ultra compact dimension, high power and wavelength stability, they are widely used in fiber gas detection, seed light source, fiber optical sensing field, etc.

Features:

• Stable wavelength and output power;

• Narrow linewidth;

• No jump mode output in operating current range

Applications:

• Optical fiber gas detection system;

• Optical sensing;

• Fiber communications

Laser Wavelength for Gas Detection

Lasers for Fiber Communication:

STC Series Wavelength Tunable Laser

We offer wavelength tunable laser, the output wavelengths can be changed continuously within a certain range. Tunable lasers come with good beam quality, high stability and long life time, they are widely used in spectroscopy, photochemistry, medicine, biology, integrated optics, laser processing, etc.

Features:

• Good beam quality;

• Compact design;

• High stability;

• Long life time;

• Easy operation

Applications:

• Spectroscopy;

• Medicine; Photochemistry;

• Biology;

• Integrated optics

Tunable Diode Laser

Tunable Ti:Sapphire Laser

Tunable Infrared Laser

STDL Series DFB Diodes

(1) 16xx nm DFB

The STDL-DFB 6 XXXX series is an InGaAsP based distributed feedback laser series in available in a TO 56 package, with an aspherical lens 1653 nm wavelength for gas sensing is available in BTF chip form. These devices have been optimized for & photonics telecommunication, test measurements as well as sensing applications.

Applications

• OTDR

• Photonic Sensing (gas)

• Biomedical Sensing

• Telecommunication

Features & Performance

• Uncooled 16xx n m DFB laser

• Operating temperature from -5C to 70C

• 1653nm selection for Gas Sensing

• Optical output min. 3mW (TO)

Customised wavelengths available.

(2) 1310nm DFB (20mW)

The STDL-DFB31020D is an InGaAsP based distributed feedback laser chips. These devices have been optimized for telecommunication test & measurements as well as Datacom applications.

Applications

• OTDR

• FTTx

• PSM-4

• CWDM

Features & Performance

• Uncooled operation from 5 to 70°C

• Output power (CW) of 20mW at 25°C, Iop 47mA (typical)

• Typical SMSR >=35dB

• Designed for CW transmission

Custom wavelengths available.

*L is longer, for higher power devices.