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光デバイス講座

Notes on Handling Optical Devices

The visible wavelength range for human beings is 400 to 700 µm; our optical devices generate light in the infrared region, which is not seen by the eye even when looked at directly and has no impact on the eye itself. Power-supply spikes and surge current as well as static-electric charges can cause product aging or damage. This note explains the basic precautions for assuring the safety of optical devices as well as long-term stability.

Safety Precautions

Laser Safety

Since the light emitted from semiconductor lasers (LDs) is concentrated at a small light-emission point and has a high power density, there is a risk of causing harm to the human body even at low output power. Consequently, NEVER look directly into the light emitted during laser operation or allow reflected laser light to enter the eye. If the light must be observed, we recommend either using a fluorescent screen or an infrared camera, etc. Laser products are classified according to the danger level. The International Electrotechnical Commission (IEC) has established a standard called IEC 60825-1 for regulating basic safety, and this standard is called JIS C6802 in Japan. Be sure to refer to the summary of safety measures in this document when handling lasers. When handling lasers in the USA, an application must be made to the FDA. Since laser products are classified according to the output power and emission time period, some indication about preventive safety measures must be displayed. For details, refer to the latest safety regulations.

Example of IEC Explanatory Label, Explanation of FDA Explanatory Label

Handling Optical Fiber

The core of the optical fiber is made of glass with a fine diameter of less than a human hair and exposed/damaged optical fiber or the fiber tip can penetrate human skin easily. Additionally, fiber offcuts can cause injury. When handling the core of an optical fiber, always take adequate safety measures, such as wearing protective glasses and installing a protective cover to prevent flying glass fragments.

Notes on Storage

To maintain product quality, the storage environment must be managed to protect against high temperature and humidity, chemically active gases, static electricity, vibration, radiation, etc. For chip- carrier products shipped in trays, store in a dry-nitrogen gas environment after opening. Additionally, use antistatic storage containers and do not subject stored products to vibration and mechanical shock.

Preparations for Use

Spike and surge current can easily cause aging of and damage to optical devices. Always take adequate power and antistatic measures. Additionally, use an appropriate heatsink design.

Power Supply

  • To prevent forward or reverse surge current when powering-up, use a dedicated low-noise power supply with protective circuitry, such as a slow-start and slow-down design.
  • Poor contacts in the volume for setting the current, as well as short or open circuits can cause deterioration.
  • When using a built-in photodiode, take care to apply the rated reverse bias voltage.

Static Electricity

  • Even when an operator is grounded using a wristband, etc., take other antistatic precautions, such as wearing antistatic gloves and shoes.
  • As well as ensuring that test instruments, benchtop, floors, shelves, tools, jigs, soldering irons, etc., are all grounded, be sure to use antistatic containers and trays. An ionizer is also an effective antistatic measure.
Static Electricity

Heatsink

  • To prevent an increase in temperature resulting from the passage of current, always install a heatsink with an appropriate capacity on the LD. If the heatsink performance is inadequate, there is a risk of lower optical output and accelerated LD aging.
  • Use a heat sink with a surface roughness of 0.8 Ra and a flatness of at least 15 µm. Applying a thin layer of heat-conducting grease to the heatsink is effective, but an excessively thick layer may impede heat transfer.
  • When using a soldered chip-on-carrier product, use materials such as SiC or AlN with a similar heat expansion coefficient to the InP or GaAs LD chip substrate materials.

Precautions on Using Optical Devices

Fitting Heatsink

Refer to Fig. for the dimensions of the heatsink mounting. Using a torque wrench, loosely tighten the M2 bolts to the module with a torque of 0.05 N·m first, and then tighten to a torque of 0.1 N·m.

  • For a butterfly module, always attach the heatsink according to the procedures shown in Fig. (b). When securing the bolts at the positions (2) and (4) shown in Fig. (b), be careful not to touch the driver fiber cover.
  • Excessive pulling or bending of the pin may damage the module or cause deterioration of the airtight seal.
  • When soldering the chip carrier to the heatsink, be sure to not exceed a temperature of 300°C for more than 20 seconds (according to the detailed specifications for general-purpose chip carriers).
Fig. Heatsink Mounting and External View

Wiring

1. Check that the LD power-supply current is 0.

2. Note the following points when soldering the leads.

  • Do not exceed a soldering temperature of 260°C and a time of 10 seconds.
  • Only solder the tip of the pin.

3. Check that there is no contamination on the end face of the fiber to be connected and connect the fiber.

Driver

Connect a thermistor for temperature monitoring to the temperature controller and set the temperature control to ON. Only power-up the LD power supply after confirming that the temperature has stabilized.

General Precautions

This LD product uses arsenic (As) in its fabrication, so do not dispose of it by incineration or shredding. At disposal, use an appropriately qualified specialist and process it in accordance with the national laws on waste disposal of hazardous products.

Note the following.

Butterfly, Cylinder Modules

  • Touching the fiber cover and applying physical force, such as pulling, twisting, and bending the fiber risks breaking the fiber or causing damage.
  • Ensure that the fiber radius of curvature is at least 30 mm. Light leaking from the fiber may risk causing a fire.
  • Remove any contaminants, such as dust and dirt, on the end face of the fiber and connector tip using an air blower or special cleaning cloth. Contaminants remaining on the end face will increase connection loss.
  • Ensure that the power is off before connecting and disconnecting connectors. Connecting and disconnecting while the power is on risks damaging the LD.
  • Do not exceed the absolute maximum rating; Anritsu will not accept any responsibility for damage and failure caused by mishandling or operation beyond the rated specifications.

Chip on Carrier

  • To assure long and stable operation, use the product in a hermetically sealed package with inert-gas atmosphere.
  • To protect the chip, perform opening and other work in a dustproof environment, such as a clean room at a clean bench, where workers should wear masks.
  • Never touch the internal chip when handling and use clean washed tweezers for handling the carrier part.
  • Always confirm the chip front and back orientation and the polarity in accordance with the specifications and inspection results. Using a tester to confirm the polarity may damage the LD.
  • Cleaning the chip using ultrasonic waves may cause damage.
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