Precision Electro-Optic and Laser Technologies

D2-135 Offset Phase Lock Servo



  • Offset Phase Locks up to ≥9.5 GHz
  • Feed forward for fast frequency jumping
  • Offset Frequency stability determined by external reference stability
  • User-adjustable servo loop parameters
  • Internal ramp generator
  • Options for optical or electronic beat-note input

Precisely control slave laser frequency offset

The D2-135 Offset Phase Lock Servo (OPLS) is designed to precisely control and quickly adjust the frequency detuning between two lasers.  The D2-135 provides for an extremely tight phase lock between the master and the slave. The D2-250 Heterodyne Module conveniently enables the overlap and fiber coupling of two laser beams. This mates with a FC fiber connector on the D2-135 providing an easy optical input for the beat note. Alternatively, the fiber connector can be exchanged with an SMA to input an electronic beat-note.  Detect the optical beat note with the D2-160 or a third-party high-speed detector.  The D2-135 OPLS provides full servo-loop customization for optimization to most lasers.

Phase Lock with OPLS

Typical Phase Lock using the D2-135 and two D2-100-DBR lasers.  Note x-axis is divided by 2 so that the actual offset is 400 MHz.

The  D2-135 can incorporate a fast photo detector to accept an optical beat note with 760 nm ≤ λ ≤ 860 nm. The optical beat note is coupled to the detector in a multimode fiber with SC fiber connection. Alternatively, the D2-135 can be configured to accept an electrical beat note obtained from a stand-alone fast detector such as the D2-160 or third-party detectors.

The D2-135 integrates into our Rackless Rack.  As such, it may be powered with our D2-005  or from an adjacent D2 electronics module.  If used as a stand-alone product it may be powered with either a D2-005 or from a user supplied power supply via a breakout board.  View a typical configuration for using the D2-135.

General Parameters
Min Max
Achievable Offsets 250 MHz >9.5 GHz
Beat Note Divisors 8, 16, 32, 64
External Reference Frequency Range 30 to 240 MHz Compared with divided down beat note
Loop Filter Transfer Function PID Adjustable poles & gain
Gain Range 0 to -76 dB
Loop Filter Bandwidth 10 MHz
Output Voltage -10 V +10 V
Feed Forward Range ±5 V
D2-135-SMA electrical beat note input
Electrical Input Connector SMA
Electrical Beat Note Input Range -10 dBm +10 dBm
Electrical Beat Note Input Impedance 50 Ω
Achievable Offset in MHz
Internal VCO Reference (High Mode)
Offset Min Offset Max
N=8 770 1700
N=16 1540 3400
N=32 3080 6800
N=64 6160 10000
Internal VCO Reference (Low Mode)
Offset Min Offset Max
N=8 385 850
N=16 770 1700
N=32 1540 3400
N=64 3080 6800
External Reference: 30 – 240 MHz
Offset Min Offset Max
N=8 240 1920
N=16 480 3840
N=32 960 7680
N=64 1920 10000