Practical Application of Fiber Components manufactured by Bonacom in Fiber-Optic Gyroscope

 

Gyro is an inertial sensor for the rotation rate measurement. At present, fiber optic gyro, micro-optic gyro, laser gyro has great development potential because of

its own advantages.The two main different typologies of optical gyroscopes consist in active and passive architectures (see Figure 17). In the active configuration the closed-loop optical path (i.e., the ring cavity) contains the optical source, forming a ring laser. The active configurations can be built in Bulk Optics or in integrated Optics technology, although only the Bulk Optics solutions have achieved commercial maturity. Differently, in passive architectures, the optical source is external to the closed optical loop (i.e., a fiber coil) as in the Interferometric Fiber Optic Gyroscope. Ring Laser Gyroscopes and Interferometric Fiber Optic Gyroscopes, whose features differ in terms of size, weight, power requirements, performance, and cost, are the more diffused optical gyroscope technology.

    

The Interferometric Fiber Optic Gyroscopes (IFOGs) are based on an open optical path (i.e., a turns fiber optics coil) where two independent counter-propagati-

ng odes, externally introduced through a laser sources, suffers of phase shift induced by the Sagnac effect, that is transduced in an interference pattern variati-

on simple IFOG configuration is shown in Figure 18 where the light, which comes from SLED, is coupled by a Bonacom’s fiber coupler(BNFUC-1-55-S) at the coil ends of a single mode fiber.

  

Resonant fiber optic gyro (RFOG) based on the Sagnac effect has the advantages of high sensitivity and large dynamic range. When compared with the traditional interferometric fiber optic gyro (IFOG), RFOG can achieve the same detection precision as IFOG with a much shorter fiber length, which gives evident superiority in the further integration, as well as improves its application value in the fields of navigation, aerospace, defense industries, and guidance systems.

 

RFOG system structure is depicted in Figure 19. The laser light emitted by a narrow-line-width semiconductor laser is divided into two equal power beams by a

50:50 coupler( C1,BNFUC-1-55-50,Bonacom Technology,Shenzhen,China) after passing through an isolator(BNIS-55-S,Bonacom Technology). The two light beams passed through the LiNbO3 phase modulator (PM)1 and PM2, respectively, which are modulated by the modulated signals of different frequencies. Afterwards,the two beams are incident to the FRR through the circulators (CIR,BNCIR-55-3),Bonacom Technology), namely, CIR1 and CIR2, in the CCW and CW directions, respectively. C2 is the coupler connected to the FRR. Finally, the two light beams are output to photodiode (PD) 2 and PD1 via CIR2 and CIR1, respectively.

  

The usage of RFOGs (Resonant Fiber Optic Gyroscopes) instead of IFOGs, allows to reduce fiber length, thus leading to lower dimensions. In the era of miniat-urization, the possibility of integrating optical waveguides leads to even smaller solutions.

 

Key Gyro Performance Factors 

Five critical parameters for consumer grade gyros are:

(1) Angle Random Walk (ARW)

(2) Bias Offset Error

(3) Bias Instability

(4) Temperature Sensitivity

(5) Shock and Vibration Sensitivity

 

In particular, commercially available gyroscope technologies, such as Mechanical Gyroscopes, silicon MEMS Gyroscopes, Ring Laser Gyroscopes (RLGs) and Fiber-Optic Gyroscopes (FOGs) are discussed,focusing attention on the main features, performances, technologies, applications and market players.

 

Bonacom manufactures various polarization maintaining(PM) fiber components for Fiber-Optic Gyroscopes application, e.g.: in-line polarizer(ILP), in-line-deplorizer(ILDP),polarization beam splitter(PBS), optical isolator(PM/non-PM), isolator polarization beam splitter hybrid(IPBS), optical circulator(PM/non-PM), fiber coupler(filter/fused based-PM/non-PM), PM FWDM, polarization maintaining variable optical attenuator(PM VOA) with broadband working wavelength at 1310nm,1550nm.

 

We also offer custom optical modules and subsystems by integrating multiple broadband components such as isolator coupler FWDM PBS hybrid. These components are ideal choices for developing expanding global Fiber-Optic Gyroscopes systems. Contact Bonacom Technology to discuss your requirements.