(Underlined patents contributed significantly to advances in optical communication.)

(1)"Laser oscillator"
Pat. 1300605
M. Nakazawa, M. Tokuda, and N. Uchida

 (2) "Optical transmission system"
Pat. 1383691
M. Nakazawa and M. Tokuda
 (Optical transmission system with Raman amplification)

(3) "Measurement method and apparatus for polarization-maintaining fibers"
Pat. 1392357
M. Nakazawa, M. Tokuda, and Y. Negishi
 

(4) "Splicing method of polarization-maintaining fibers"
Pat. 1485495
M. Nakazawa, N. Shibata, T. Horiguchi, and M. Tokuda

(5) "Soliton laser"
Pats. 1518983, 1927948
M. Nakazawa, T. Nakashima, and M. Tokuda

(6)"Optical time domain reflectometer"
Pats. 1540417, 1936868
M. Nakazawa, M. Tokuda, and N. Uchida
 (OTDR system for single-mode fibers with optical masking using TeO2 crystal)

(7) "Optical fiber transmission system"
Pat. 1618457
M. Nakazawa, T. Nakashima, and S. Seikai

(8)"Optical fiber gyroscope"
Pat. 1702843
M. Nakazawa, T. Nakashima, and M. Tokuda

(9)"Optical amplification using fiber nonlinearity"
Pat. 1832637
M. Tokuda and M. Nakazawa

(10) "Optical pulse compressor"
Pats. 1961622, 2002147, 2015178, 2664187
M. Nakazawa, Y. Kimura, T. Nakashima, S. Seikai, and H. Kubota

(11) "Wavelength tunable fiber laser"
Pat. 1974539
Y. Kimura, M. Nakazawa, and S. Seikai

(12) "Soliton generation method and its repeater system with amplification"
Pats. 2037594, 2108068, 2659234
M. Nakazawa, K. Suzuki, Y. Kimura, and Y. Kubota

(13) "Fiber Raman soliton laser"
Pat. 2056854
S. Seikai and M. Nakazawa

(14) "Optical fiber amplifier"
Pat. 2128337
Y. Kimura and M. Nakazawa
 (Optical amplification using 1.48 μm InGaAsP laser diode)

(15) "Distributed optical fiber amplifier"
Pat. 2507590
Y. Kimura, M. Nakazawa and K. Suzuki

(16) "Fiber laser"
Pat. 2563697
Y. Yoshida and M. Nakazawa
 (Regenerative mode-locking of fiber laser)

(17) " Generation method of optical soliton and its transmission"
Pat. 2612080
M. Nakazawa, K. Suzuki, and Y. Kimura
 (Soliton transmission using EDFAs)

(18) "Optical soliton transmission method"
Pat. 2628927
E. Yamada, M. Nakazawa, and K. Suzuki

(19) "Optical pulse generation apparatus and transmission method"
Pats. 2015302, 2656837
M. Nakazawa, K. Suzuki, and Y. Kimura

(20) "Glass waveguide laser array"
Pats. 2656971, 2656972
M. Nakazawa, Y. Kimura, and K. Imoto

(21) "Fiber laser"
Pat. 2678176
E. Yoshida and M. Nakazawa

(22) "Optical soliton TDM transmission system"
Pat. 2693423
S. Seikai and M. Nakazawa

(23) "Optical soliton transmission method"
Pats. 2716049, 2755329, 2788951, 2825109,
H. Kubota, M. Nakazawa, and K. Suzuki
 (Soliton transmission control)

(24) "Optical soliton transmission method"
Pats. 2825989
M. Nakazawa, H. Kubota, E. Yamada, and K. Suzuki

and other 60 patents.  He has approximately 120 patents pending.

(1) "Atomic frequency standard laser pulse oscillator"
Pat. 6,333,942
M. Nakazawa and E. Yoshida
December 25, 2001
　

(2) "Optical pulse generator"
Pat. 6,108,465 　
R. Iida, A. Ichikawa, Y. Kumagai, Y. Asahina, M. Nakazawa, and E. Yoshida
August 22, 2000

(3) "Optical pulse generator"
Pat. 6,101,021
Y. Kumagai, A. Ichikawa, R. Iida, M. Nakazawa, and E. Yoshida
August 8, 2000

(4) "Laser pulse oscillator"
Pat. 5,926,492
E. Yoshida and M. Nakazawa
July 20, 1999

(5) "Lead-containing fluoride glass, optical fiber and process for producing it"
Pat. 5,695,880
T. Kogo, H. Kanamori, M. Onishi, Y. Miyajima, and M. Nakazawa
December 9, 1997

(6) "Optical pulse compression device"
Pat. 5,583,959
M. Nakazawa and E. Yoshida
December 10, 1996

(7) "Lead-containing fluoride glass, optical fiber and process for producing it"
Pat. 5,432,131
T. Kogo, H. Kanamori, M. Onishi, Y. Miyajima, and M. Nakazawa
July 11, 1995

(8) "Rare earth element-doped optical waveguide and process for producing the same"
Pat. 5,206,925
M. Nakazawa, Y. Kimura, K. Imoto, S. Kashimura, T. Kamoshida, and F. Kikuchi
April 27, 1993

(9) "Optical waveguide type star coupler"
Pat. 5,134,672
K. Imoto, M. Nakazawa, and Y. Kimura
July 28, 1992