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LOW LEVEL MEASURE & SOURCE A Greater Measure of Confidence www.keithley.com 1.888.KEITHLEY (U.S. only)

  • D ual-channel instrument for optical power measurements, beam measurements, and nanoscale materials and device research 100V source for bias requirements
  • Me asure photodetector current from 1fa to 20ma
  • 1 fa c urrent measurement resolution
  • M easure optical power directly when used with Model 2500INT I ntegrating s phere
  • 0 –10V analog output for high resolution optical power feedback
  • P rovides a high accuracy, high speed fiber alignment solution
  • sup ports assembly process, final testing, parts binning, and specification al lows faster alignment of the fiber with the laser diode’s optimum light emitting region C ombines fiber alignment and device characterization processes
  • us er-programmable photodetector calibration coefficients
  • 3 000-point buffer memory on each channel allows data transfer after test completion D igital I/o and Trigger li nk for binning and sweep test operations
  • I EEE-488 and rs- 232 interfaces The Model 2502 Dual-Channel Picoammeter provides two independent picoammeter-voltage source channels for a wide range of low level measurement applications including laser diode testing The Model 2502 is also designed to increase the throughput of Keithley’s LIV (light- current-voltage) test system for production test- ing of laser diode modules (LDMs) Developed in close cooperation with leading manufacturers of LDMs for fiberoptic telecommunication networks, this dual-channel instrument has features that make it easy to synchronize with other system elements for tight control over optical power measurements The Model 2502 features a high speed analog output that allows using the LIV test system at the fiber alignment stage of the LDM manufacturing process T hrough the use of buffer memory and a Trigger Link interface that’s unique to Keithley instruments, the Model 2502 can offer the fastest throughput available today for LIV testing of laser diode modules These instruments are ruggedly engineered to meet the reliability and repeatability demands of continuous operation in round-the-clock production environments l ow-le vel, High sp eed Measurements The Model 2502 combines Keithley’s expertise in low-level current measurements with high speed current measurement capabilities Each channel of this instrument consists of a voltage source paired with a high speed picoammeter . Each of the two channels has an independent picoammeter and volt - age source with measurements made simultaneously across both channels . Pa rt of a High sp eed lI V Test sy stem In a laser diode module DC/CW test stand, the Model 2502 provides the voltage bias to both the back facet monitor diode and a Model 2500INT I ntegrating Sphere or to a fiber-coupled photodetector . At the same time it applies the voltage biases, it measures the current outputs of the two photodetectors and converts these outputs to measurements of optical power The conversion is performed with the user-programmed calibration coefficient for the wavelength of the laser diode module . Fast, accurate measurements of optical power are critical for analyzing the coupling efficiency and optical power characteristics of the laser diode being tested When testing modules with multiple detectors, the Model 2502 packs more testing capabilities into less test rack space . fi ber al ignment The Model 2502’s built-in high speed analog output makes it suitable for precision fiber alignment tasks This instrument combines the ability to align the optical fiber quickly and accurately with a laser diode’s optimum light emitting region and the capability to make precision LIV measurements, all in the same test fixture The Model 2502’s wide dynamic range allows early beam skirt detection, reducing the time required for fiber alignment An LIV sweep can be performed during the alignment process to optimize fiber location for an entire operating range . High speed feedback minimizes delays in the alignment process, so it’s unneces- sary to sacrifice alignment speed to ensure accurate device characterization W ide Dynamic Measurement ra nge The Model 2502 offers low current measurement ranges from 2nA to 20mA in decade steps T his provides for all photodetector current measurement ranges for testing laser diodes and LEDs in applications such as LIV testing, LED total radiance measurements, measurements of cross-talk and insertion loss on optical switches,

2502 Dual-Channel Picoammeter

Measures low currents and high resistances quickly, accurately, and economically Measures low currents and high resistances quickly, accurately, and economically

LOW LEVEL MEASURE & SOURCE www.keithley.com 1.888.KEITHLEY (U.S. only) A Greater Measure of Confidence a nd many o thers . The Model 2502 meets industry testing requirements for the transmitter as well as pump laser modules . The extensive current measurement range pro - vides excellent sensitivity and resolution for beam current and radiation monitoring measurements H igh ac curacy Dark Current Measurements The Model 2502’s 2nA current measurement range is ideal for measuring dark currents and other low currents with 1fA resolution Once the level of dark current has been determined, the instrument’s REL function automatically subtracts the dark current as an offset so the measured values are more accurate for optical power measurements V oltage bi as Capability The Model 2502 provides a choice of voltage bias ranges: ±10V or ±100V This choice gives the system integrator the ability to match the bias range more closely to the type of photodetector being tested, typically ±10V for large area photodetectors and ±100V for avalanche-type photodetectors This ability to match the bias to the photodetector ensures improved measurement linearity and accuracy . Also, the 100V range provides a source voltage for an SEM target bias supply High Testing Throughput The Model 2502 is capable of taking 900 readings/second per channel at 4½-digit r esolution . This speed is comparable with the measurement speed of the Model 2400 SourceMeter SMU instrument, which is often used in conjunction with the Model 2502 to perform opto e lectronic device test and characterization . Both instruments support Trigger Link (a proprietary “hardware handshaking” t riggering system that’s unique to Keithley products) and buffer memory . When programmed to execute a sweep, Trigger Link ensures measurement integrity by keeping the source and measure- ment functions working in lock step while the buffer memories record the measurements Together, source memory, buffer memory, and Trigger Link eliminate GPIB traffic during a test sweep, improv - ing test throughput d ramatically . ra tio and Delta Measurements The Model 2502 can provide ratio or delta measurements between the two completely isolated channels, such as the ratio of the back facet monitor detector to the fiber-coupled photodetector at varying levels of input current T hese functions can be accessed via the front panel or the GPIB interface . For test setups with multiple detectors, this capability allows for targeted control capabilities for the laser diode module P rogrammable li mits and fi lters As with most Keithley instruments, the Model 2502’s current and voltage limits can be programmed to ensure device protection during critical points such as start of test, etc These instruments also provide Average and Median filters, which can be applied to the data stored in the buffer memory . ad aptable to Evolving DuT r equirements Unlike optical power meters with integrated detectors, the Model 2502 allows the user to choose from a wide range of measurement capabilities simply by selecting an appropriate photodetector and programming the calibration c oefficient of this detector at the wavelength of choice . Interface op tions To speed and simplify system integration and control, the Model 2502 includes the Trigger Link feature and digital I/O lines, as well as standard IEEE-488 and RS-232 interfaces The Trigger Link feature combines six The Model 2502 is designed for tight integration with other Keithley instruments that are often used in lI V test systems for laser diode m odules. These other instruments include the Model 2400 so urceMeter® and Model 2510 TEC so urceMeter sMu instruments. or dering Information

2502 Dual-Channel

a ccessories s upplied us er’s Manual aPPlI C aT I oNs

  • sc anning electron microscope (sE M) beam measurements
  • P roduction testing of:
  • lase r diode modules
  • C hip on submount laser diodes
  • l EDs
  • P assive optical components
  • lase r diode bars
  • fi ber alignment Thermistor Peltier 2510 2400/ 2420 2502 Fiber 2500INT Integrating Sphere Computer GPIB Trigger Link

7007-1 S hielded IEEE-488 Cable, 1m (3 .3 f t) 7007-2 S hielded IEEE-488 Cable, 2m (6 .6 f 7009-5 S hielded RS-232 Cable 7078-TRX-3 L ow Noise Triax Cable, 0 .9 m (3 ft) 8501-1 T rigger Link Cable, 1m (3 .3 f KPCI-488LPA I EEE-488 Interface/Controller for the PCI Bus KUSB-488B I EEE-488 USB-to-GPIB Interface Adapter sEr VICEs aVaIl ablE 2502-3Y-EW 1 -year factory warranty extended to 3 years from date of shipment C/2502-3Y-DATA 3 ( Z540-1 compliant) calibrations within 3 years of purchase* *Not available in all countries Measures low currents and high resistances quickly, accurately, and economically Measures low currents and high resistances quickly, accurately, and economically

LOW LEVEL MEASURE & SOURCE A Greater Measure of Confidence www.keithley.com 1.888.KEITHLEY (U.S. only) independent software selectable trigger lines on a single connector for simple, direct control over all instruments in a system . This feature is e specially useful for reducing total test time if the test involves a sweep . The Model 2502 can sweep through a series of measurements based on triggers received from other instruments . The digital I/O lines simplify external handler control and binning operations . T he Model 2502 Dual-Channel Picoammeter can measure and display either photo- d iode current or optical power for two photodiodes with appropriate user- s upplied optical power gain/wavelength c alibration factors . T he Model 2502 includes an analog output jack on the rear panel for each channel . Measurement sp ecifications Temperature acc uracy1, 2 C oefficient D c Input M aximum 3°C ±5°C °–18°C & 28°–50°C I mpedance3 ra nge r e solution (% rdg. + offset) (%rdg. + offset)/°C Maximum) 2 .0 00000 n A f A 1 .0 0% + p A 0 .0 1 + f A kW 0 .0 0000 n A f A 0 .4 0% + p A 0 .0 1 + f A kW 00 .0 000 n A f A 0 .3 0% + p A 0 .0 2 + p A W 2 .0 00000 µ A p A 0 .2 0% + p A 0 .0 2 + p A W 0 .0 0000 µ A p A 0 .1 0% + n A 0 .0 1 + n A 2 .0 W 00 .0 000 µ A p A 0 .1 0% + n A 0 .0 1 + n A 2 .0 W 2 .0 00000 m A n A 0 .1 0% + µ A 0 .0 2 + n A 0 .2 W 0 .0 0000 m A n A 0 .1 0% + µ A 0 .0 2 + n A 0 .2 W MAXIMUM INPUT: ±20 .0mA . TY PIC a l sPEED aN D NoIsE rEJECTI oN4 re adings/s D igits G PIb (sC PI) G PIb (488.1) N PlC N Mr r 4½ 7 00 9 00 0 .0 1 — 5½ 4 60 4 75 0 .1 — 0 dB PHoToD I oD E V olTaGE bIa s sPECIfI CaT IoNs2 acc uracy M aximum l o ad T emperature ra nge r e solution 3°C ±5°C C urrent r e gulation 5 Coefficient 0 t o ±10 V 400 µV (0 .1 5% of setting 0 mA < 0 .3 0%, 50 ppm/°C + 5 m 0 t o 20 mA 0 t o ±100 V 4 mV (0 .3 % of setting 0 mA < 0 .3 0%, 00 ppm/°C + 5 0 mV) 0 t o 20 mA GENEral Typical Noise fl oor Measurement spe cification 6 Typical Noise fl oor rMs sT DEV), 100 sa mples ran ge 0.01 NPlC 0 .1 NPlC 1.

0 NPlC 10

2 .000000 nA 2 pA 1 pA 40 fA 15 fA 20 .00000 nA 2 pA 1 pA 40 fA 15 fA 200 .0000 nA 200 pA 100 pA 2 pA 500 fA 2 .000000 µA 200 pA 100 pA 2 pA 500 fA 20 .00000 µA 20 nA 10 nA 200 pA 50 pA 200 .0000 µA 20 nA 10 nA 200 pA 50 pA 2 .000000 mA 2 µA 1 µA 25 nA 5 nA 20 .00000 mA 2 µA 1 µA 25 nA 5 nA SOURCE CAPACITANCE: Stable to 10 .0 nF typical . I NPUT BI AS CU RRENT 7: 50fA m ax . @ 23°C . I NPUT VOLTAGE BURDEN 8: 4 .0m V max . VO LTAGE SOU RCE SL EW RA TE: 0ms/V typical . CO MMON MODE VOLTAGE: 200VDC . CO MMON MODE ISOLATION: Typically 10 9W in parallel with 150nF . O VERRANGE: 105% of measurement range . M EMORy BUFFER: 6000 readings (two 3000 point buffers) . Includes selected measured value(s) and time stamp . PROGRAMMABILIT y: I EEE-488 (SCPI-1995 .0 ), RS-232, five user- d efinable power-up states plus factory default and *RST . D IGITAL INTERFACE: Enable: Active low input . H andler Interface: Start of test, end of test, 3 category bits . +5V @ 300mA supply Di gital I/O: 1 trigger input, 4 TTL/Relay Drive outputs (33V @ 500mA, diode clamped) . P OWER SUPPLy: 1 00V/120V/220V/240V ±10% L INE FREQUENC y: 50, 60Hz . P OWER DISSIPATION: 60VA . E MC: Complies with European Union Directive 89/336/EEC . V IBRATION: MIL-T-28800F Random Class 3 . S AFET y : Complies with European Directive 73/23/EEC . W ARM-UP: 1 hour to rated accuracy . D IMENSIONS: 89mm high × 213mm wide × 370mm deep (3½ in × 8 3⁄8 in × 149⁄16 in) . Bench configuration (with handle and feet): 104mm high × 238mm wide × 370mm deep (4 1⁄8 in × 93⁄8 in × 149⁄16 in) . W EIGHT: 23 .1 kg (10 .5 lbs) . EN VIRONMENT: Operating : 0°–50°C, 70% R .H . up to 35°C non-condensing . Derate 3% R .H ./ °C, 35°–50°C . St orage: –25° to 65°C, non-condensing NoT E s 1 . S peed = Normal (1 .0 N PLC), Filter On . 2 . 1 y ear . 3 . M easured as ∆ Vin/∆Iin at full scale (and zero) input currents . 4 . D ual channel, internal trigger, measure only, display off, Autorange off, Auto Zero off, source delay = 0, filters off, limits off, CALC5 and CALC6 off, 60Hz . 5 . M easured as ∆ Vin/∆Iin at full scale (20mA) and zero load currents . 6 . N oise floor measured as rms (1 standard deviation), 100 samples, Filter off, open (capped) input . 7 . S pecification by design . 8 . M easured (at input triax) as ∆ Vin at full scale (20mA) vs . zero input currents . 9 . T he analog output voltage for each channel is referenced to that channel’s floating ground . aNa lo G o uT PuT sPECIfI CaT I oNs OUTPUT V OLTAGE R ANGE9: Output is inverting: – 10V out for positive full scale input . 10V out for negative full scale input . OU PUT I MPEDANCE: 1kW typical ran ge acc uracy 23°C ±5°C ±(%output + offset) T emperature Coefficient 0°–18°C & 28°–50°C ±(%output + offset)/°C rise Time Typical (10% to 90%) 2 .000000 nA 6 .0 % + 90 mV 0 .3 0% + 7 m V 6 .1 ms 20 .00000 nA 3 .0 % + 9 m V 0 .1 1% + 700 µ V 6 .1 ms 200 .0000 nA 6 .0 % + 90 mV 0 .3 0% + 4 m V 395 µs 2 .000000 µA 3 .0 % + 9 m V 0 .1 1% + 400 µ V 395 µs 20 .00000 µA 6 .0 % + 90 mV 0 .3 0% + 4 m V 135 µs 200 .0000 µA 2 .5 % + 9 m V 0 .1 1% + 400 µ V 135 µs 2 .000000 mA 6 .0 % + 90 mV 0 .3 0% + 4 m V 21 µs 20 .00000 mA 2 .5 % + 9 m V 0 .1 1% + 400 µ V 21 µs Model 2502 specifications Model 2502 specifications